Accepted Manuscript Title: The effect of estrogen synthesis inhibition on hippocampal memory Author: Janine Bayer Gabriele Rune Heidrun Schultz Michael J. Tobia Imke Mebes Olaf Katzler Tobias Sommer PII: DOI: Reference:

S0306-4530(15)00098-0 http://dx.doi.org/doi:10.1016/j.psyneuen.2015.03.011 PNEC 2950

To appear in: Received date: Revised date: Accepted date:

9-12-2014 5-3-2015 5-3-2015

Please cite this article as: Bayer, J., Rune, G., Schultz, H., Tobia, M.J., Mebes, I., Katzler, O., Sommer, T.,The effect of estrogen synthesis inhibition on hippocampal memory, Psychoneuroendocrinology (2015), http://dx.doi.org/10.1016/j.psyneuen.2015.03.011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Estrogen synthesis inhibition and memory. Bayer et al.

1/1

The effect of estrogen synthesis inhibition on hippocampal memory

ip t

Janine Bayera, Gabriele Runeb, Heidrun Schultza, Michael J. Tobiaac, Imke Mebesd, Olaf

cr

Katzlere , Tobias Sommera

a

us

Running title: Estrogen synthesis inhibition and memory.

Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf,

b

an

Hamburg, Germany

Department of Neuroanatomy, University Medical Center Hamburg-Eppendorf, Hamburg,

c

M

Germany

Department of Radiology, Pennsylvania State University College of Medicine, Hershey,

d

ed

Pennsylvania, United States of America

Department of Gynecology, University Medical Center Hamburg-Eppendorf, Hamburg,

Mammazentrum am Jerusalem Krankenhaus, Hamburg, Germany

Ac ce

e

pt

Germany

Corresponding author: Janine Bayer, Department of Systems Neuroscience, University Medical

Center

Hamburg-Eppendorf,

Martinistr.

52,

20246

Hamburg,

Germany,

[email protected], Tel.: +49-40-7410-55781, Fax.: +49-40-7410-59955

Email addresses:

Gabriele Rune, [email protected]; Heidrun Schultz, [email protected];

Michael Tobia, [email protected]; Imke Mebes, [email protected]; Olaf Katzler, [email protected]; Tobias Sommer, [email protected]

Page 1 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

2/2

Abstract 17-beta-estradiol (E2) facilitates long term-potentiation (LTP) and increases spine synapse

ip t

density in hippocampal neurons of ovariectomized rodents. Consistent with these beneficial effects on the cellular level, E2 improves hippocampus-dependent memory. A prominent

cr

approach to study E2 effects in rodents is the inhibition of its synthesis by letrozole, which reduces LTPs and spine synapse density. In the current longitudinal functional magnetic

us

resonance imaging (fMRI) study, we translated this approach to humans and compared the

an

impact of E2 synthesis inhibition on memory performance and hippocampal activity in postmenopausal women taking letrozole (n = 21) to controls (n = 24). In particular, we employed

M

various behavioral memory paradigms that allow the disentanglement of hippocampusdependent and -independent memory. Consistent with the literature on rodents, E2 synthesis

ed

inhibition specifically impaired hippocampus-dependent memory, however, this did not apply to the same degree to all of the employed paradigms. On the neuronal level, E2 depletion tended to decrease hippocampal activity during encoding, whereas it increased activity in the

pt

anterior cingulate and the dorsolateral prefrontal cortex. We thus infer that the inhibition of

Ac ce

E2 synthesis specifically impairs hippocampal functioning in humans, whereas the increased prefrontal activity presumably reflects a compensatory mechanism, which is already known from studies on cognitive aging and Alzheimer's disease.

Keywords: memory; hippocampus; estrogen; aromatase inhibitors; dual process model

Page 2 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

3/3

1. Introduction Since the observation that hippocampal synapse density covaries with oestrus-cycle-

ip t

dependent changes in 17-beta-estradiol (E2) concentrations, it has been known that E2 also influences non-reproductive brain circuits (Woolley et al., 1990). For example, the

cr

experimental administration of E2 and its precursors increases spine synapse density,

us

promotes spine maturation and enhances the magnitude of long-term potentiation (LTP; Li et al., 2004; Smith et al., 2009). Interestingly, these effects on hippocampal plasticity are not

an

mainly mediated by E2 derived from the gonads (Fester et al., 2006; Rune et al., 2006; Kretz et al., 2004). Instead, the de novo synthesis of E2 by hippocampal neurons is essential to

M

the maintenance of hippocampal synapses (Kretz et al., 2004). Hippocampal E2 levels can actually exceed serum E2 levels (Hojo et al., 2004; Kato and Kawato, 2013). Systemic

ed

application of the aromatase inhibitor letrozole, i.e. the decrease of endogenous E2 levels, reduces spine synapse density and impairs LTP, even in the hippocampus of ovariectomized

al., 2010).

pt

female mice, i.e. in the absence of E2 synthesized in the ovaries (Vierk et al., 2012; Zhou et

Ac ce

Consistent with the cellular actions of E2, a positive association between E2 and hippocampus-dependent spatial memory has been described in rodents (Gibbs et al., 2004; Harburger et al., 2007). In humans, the effects of E2 on memory have mostly been explored in the context of hormone therapies (HT), where E2 is primarily exogenously applied to treat osteoporosis and other menopause-related health problems. Based on the different HT regimens with respect to the hormonal compounds, doses and time of onset after menopause, the observed effects of HT on memory are highly inconsistent (Hogervorst and Bandelow, 2010). Contrary to the effects of exogenous E2 treatment employed in the HT-studies, we explored

Page 3 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

4/4

the understudied influence of endogenously synthesized E2 in postmenopausal women. In particular, we characterized the effect of letrozole - which is used for neoadjuvant treatment of estrogen receptor positive breast cancer - on memory and hippocampal activity. We

ip t

focused on postmenopausal women as they have low peripheral E2 baseline levels, similar to the ovariectomized rodents that showed reduced hippocampal plasticity in response to

cr

letrozole treatment (Fester et al., 2012; Zhou et al., 2010). A longitudinal design was employed in which a cohort of postmenopausal women with an indication for letrozole

us

treatment was tested prior to, and 3 to 6 months after onset of aromatase inhibition, and this cohort was then compared to an age-matched control group.

an

To characterize the impact of E2 depletion on neural plasticity in the hippocampus (Zhou et al., 2010), we studied brain activity during episodic memory formation using fMRI. In

M

particular, we employed an established paradigm (Staresina and Davachi, 2006), in which hippocampal activity during encoding correlates with subsequent memory performance. We

the control group.

ed

hypothesized a relative decline in memory-related hippocampal activity in the AI compared to

pt

Episodic memory can be based on hippocampus-dependent, but also on hippocampus-

Ac ce

independent processes. Whereas the hippocampus is critically involved in retrieving an item together with associated contextual information (associative memory or recollection), recognizing an item without any associated information (item memory or familiarity) can be based purely on the parahippocampal cortices (Davachi, 2006). Behaviorally, we therefore employed three process-specific memory tests to disentangle the effect of E2 depletion on hippocampus-dependent and -independent forms of episodic memory. Such process-specific memory tests are highly sensitive to subtle changes in memory performance and allow a more specific inference to the underlying neural substrates, i.e. the hippocampus vs. parahippocampal cortices (Yonelinas, 2002). We hypothesized that there is a specific decline

Page 4 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

5/5

in hippocampus-dependent but not in parahippocampus-dependent memory processes, i.e. in recollection but not familiarity. Additionally, standard neuropsychological tests and questionnaires were applied to identify potential confounding variables between participants

ip t

of the AI and control group.

cr

2. Material and methods 2.1 Participants and general procedure

us

Participants of the 'Aromatase Inhibition group' (AI group) were recruited during the breast

an

cancer consulting hour at the University Medical-Center of Hamburg Eppendorf and at the Mammazentrum of the Jerusalem Hospital in Hamburg. Participants for the control group (C

M

group) were recruited during the breast consulting hour and through advertisements. Twenty-three postmenopausal participants aged between 56 and 75 years (M = 67.39, SD =

ed

4.70) with receptor-sensitive breast cancer stage I to stage III and an indication for neoadjuvant aromatase inhibitor therapy (AI group) completed the current study. Information on the individual disease burden of the AI participants was not acquired. A sample of twenty-

pt

six postmenopausal women aged between 52 and 79 years (M = 67.29, SD = 7.19), without

Ac ce

an indication for aromatase inhibitor therapy, constituted the control group. The C group consisted of 24 women without a current cancer diagnosis, one woman with a ductal carcinoma in situ and one woman who had undergone a mastectomy after breast-cancer diagnosis. One woman from the control group had received chemotherapy 11 months prior to testing. None of the other women from either the AI group or the C group had a history of chemotherapy. None of the participants received a cranial radiotherapy; the number of participants receiving a local radiotherapy of the breast is listed in Table 1. One control and two AI participants were excluded from all analyses, based on scores below the cut off value of 12 in the DemTect dementia screening test (for remaining sample sizes, see

Page 5 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

6/6

Supplementary Table 1). For the reasons specified in Supplementary Table 1, the sample size for particular tests was slightly reduced. All participants were right-handed. All procedures were carried out with the adequate understanding and written consent of the

ip t

participants. The study was approved by the ethics committee of the medical association of Hamburg, and the participants were paid financial compensation for their participation.

cr

Participants were studied longitudinally at two measurement points (T1 & T2), which each comprised testing on two days. T1 served as a baseline and was scheduled more than 4

us

months after breast cancer surgery (M = 224.67 days, SD = 52.77) and before onset of AI therapy in the AI group. T2 was scheduled so that subjects from the AI group had received at

an

least three months of AI therapy (M = 127.10 days, SD = 28.06). At each measurement point, episodic memory performance was explicitly characterized using four different memory

M

paradigms, i.e. a visual, a verbal source and an associative memory recognition task plus a neuropsychological free recall test, as well as a self-reported subjective memory

ed

questionnaire (see Supplementary Table 1). The associative memory task was performed in the scanner. In addition, neuropsychological tests (Table 3) and psychosocial questionnaires

pt

(see Table 2) were administered to identify potential confounding group differences with

Ac ce

respect to intelligence, executive functions, verbal fluency, working memory, anxiety, depression, quality of life, menopausal symptoms and experienced memory and attention failures. Because E2 synthesis is reduced by >98% in postmenopausal women, no E2 levels were assessed (Geisler and Lønning, 2005).

- Please insert Table 1 around here.Table 1. Means (M), standard deviations (SD) and case numbers (n) for sample characteristics. The last column shows p-values (p) of independent-sample t-tests.

Page 6 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

7/7

2.2 Memory paradigms Behavioral memory performance was assessed by means of two recognition tasks, i.e. a

ip t

verbal source memory task and a visual memory task, as well as by a neuropsychological memory test (see supplementary methods for detailed description of the tasks). The verbal

cr

source memory task was adapted from Prull and colleagues (2006). In this paradigm, subjects first encode two word lists. During retrieval, subjects see the words from the two

us

lists, intermixed with new words, and have to identify words from a specific list (e.g. the first list). This paradigm allows the estimation of the contribution of recollection (hippocampus-

an

dependent) and familiarity (hippocampus-independent) to recognition performance based on the process dissociation framework (Jacoby, 1991). The visual memory task was adapted

M

from Howard and colleagues (Howard et al., 2006). In this task, subjects first encode photos from various travel destinations. During retrieval, old pictures are presented intermixed with

ed

new pictures. Participants have to judge on a 6-point Likert scale, ranging from ‘very sure old’ to ‘very sure new’, whether they recognize the picture and how confident they are about

pt

their decision. This paradigm allows the estimation of the contribution of recollection and

Ac ce

familiarity to recognition performance, based on fitting the dual-process model to the individual

receiver-operating

characteristic

curves

(Yonelinas,

2002).

As

a

neuropsychologically validated free recall test, the 'Verbaler Lern- und Merkfähigkeitstest' (VLMT; Helmstaedter et al., 2001), the German equivalent of the Rey auditory verbal learning test (RAVLT), was administered. In this test, a list of 15 words is read to the subject five times. After each round, subjects are asked to recall as many words as possible; performance in the fifth round is considered 'immediate verbal memory'. Next, a new, interfering list of 15 words is read to the subject only once. Subjects then recall as many words as they can from that list, directly followed by another recall of list 1. After a 30 minute

Page 7 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

8/8

delay, subjects again recall the words from list 2 ('delayed verbal memory'). To study changes in the neural activity during episodic memory encoding, a modified version of an established word-color association task was employed (Supplementary Figure 2;

ip t

Staresina and Davachi, 2006). In this task, subjects encode words presented on a colored square while lying in the scanner. During retrieval, also performed inside the scanner but

cr

without acquiring fMRI-volumes, subjects first have to freely recall the encoded words. Subsequently, the target words are presented intermixed with new words. For every word

us

participants have to indicate whether they recognize the word, and with which color it was paired during encoding. See supplementary material for detailed descriptions of all memory

an

tasks.

To assess subjective memory failures, the 'Fragenbogen zur Erfassung alltäglicher

M

Gedächtnisleistungen' (FEAG), the German version of the 'Inventory of Memory

ed

Experiences' (IME), was used.

2.3 Acquisition, preprocessing and analysis of functional imaging data

pt

High-resolution T1-weighted structural MR images were acquired in a 3 T system (Siemens

Ac ce

Trio) by using a standard 3D-MPRAGE sequence (TR 2300 ms, TE 2.89 ms, flip angle 9°, 1 mm slices, field of view 256 x 192; 240 slices). Event-related functional MRI scans were acquired with an echo planar imaging T2*-sensitive sequence in 40 contiguous axial slices (2 mm thickness with 1 mm gap; TR, 2380 ms; TE, 25 ms; flip angle, 80°; field of view, 204 x 204; matrix 102 x 102).

Functional MRI data were preprocessed and analyzed using standard workflows of Statistical Parametric Mapping (SPM8; Wellcome Department of Imaging Neuroscience, London, UK; see supplementary material for details). In the functional analysis, activity during encoding of items was modeled dependent on the subsequent memory performance,

Page 8 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

9/9

i.e. whether an item was later free recalled, whether it was recognized and the associated color was also correctly recognized, or whether it was recognized but the associated color was incorrectly recognized. Areas where activity associated to successful encoding was

ip t

affected by E2 depletion were identified by a time by condition interaction on the group level. Results of all analyses were considered significant at p < .05; the family-wise error was

cr

corrected for multiple comparisons of the entire scan volume and within predefined anatomical regions of interest (ROIs), namely the hippocampus, the anterior cingulate cortex

us

(ACC) and the dorsolateral prefrontal cortex (DLPFC; Amunts et al., 2005; Tzourio-Mazoyer

an

et al., 2002).

M

3. Results 3.1 Behavioral Results

ed

3.1.1 Sample Table 1 summarizes characteristics of the participants included in statistical analyses.

pt

Experimental groups did not significantly differ with respect to age, delay between

Ac ce

measurement points, the number of years since menopause, the use of HT, the number of nulliparous women or years of education (Table 1).

3.1.2 Questionnaires

Means, standard deviations and p-values of statistical analyses for the questionnaires are summarized in Table 2 and Table 3. Questionnaires were used to assess potential confounds such as potential group differences in mood, anxiety, perceived stress and subjective quality of life that could be caused by disease burden and AI therapy in the AI

Page 9 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

10/10

group. To present the full picture, we will also highlight trend-level significant results, because in such a relatively heterogeneous sample a high inter-individual variability is expected within the groups, which increases the risk of type II errors.

ip t

Regarding menopausal symptoms, subjects reported more urogenital menopausal symptoms at T2 compared to T1, irrespective of group (F(1, 43) = 4.07, p = .050). In line with

cr

existing literature on common side effects of AI therapy, somatic menopausal symptoms showed a significant time by group interaction (F(1, 43) = 1.93, p = .006; see Table 2;

us

Gallicchio et al., 2012) driven by an increase in somatic menopausal symptoms in the AI but not the control group.

an

Concerning psychological questionnaires, subjects reported higher psychological tension (F(1, 43) = 3.14, p = .083) and more attentional failures at T2 compared to T1, irrespective of

M

group (trend-level significance; F(1, 43) = 3.24, p = .079). Controls showed significantly higher trait anxiety (t(42) = 2.14, p = .038) and reported more perceived demands, i.e.

ed

perceived external stressors (trend-level significance; F(1, 43) = 3.90, p = .055). Additionally, participants of the control group reported more attentional failures than the AI group (F(1, 43)

pt

= 6.52, p = .014). Perceived demands (F(1, 43) = 5.68, p = .022) and state anxiety showed a

Ac ce

time by group interaction (trend-level significance; F(1, 42) = 3.53, p = .067), driven by an increase over time in the control but not in the AI group. Generalized anxiety also showed a time by group interaction (trend-level significance; F(1, 43) = 3.42, p = .071), again driven by an increase in the control group only. The observation that the controls reported more anxiety at the second measurement point is consistent with the findings of Knowles et al (1996). The authors claim that anxiety changes in non-treatment groups can be related to a more accurate reporting of anxiety symptoms at the second measurement point (Knowles et al., 1996). As participants become more familiar with the questionnaire, they become better in understanding the questions and respond more adequately. The AI group, on the other

Page 10 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

11/11

hand, had generally lower trait anxiety levels, but they filled out the questionnaires for the first time briefly after receiving their breast cancer diagnoses, an event that is most likely associated with a relative peak in currently experienced anxiety. Therefore, it is certainly

ip t

plausible that this group did not show a similar increase in anxiety symptoms, as did the control group, when they filled out the questionnaire again. There were no significant main

cr

effects or interactions with respect to depression or perceived global health.

In summary, participants of the AI group did not show significant increases in anxiety, stress

us

or depression, so that potential (negative) effects of E2 deprivation on memory performance in the AI group are not confounded by changes in psychological well-being. On the contrary,

an

the AI group performed slightly better in tests of fluid intelligence, executive control and

the two groups.

ed

3.1.3 Neuropsychological testing

M

working memory, which is most likely related to differences in the recruitment strategies for

Means, standard deviations and p-values of statistical analyses for the neuropsychological

pt

tests are summarized in Table 2 and Table 3. Neuropsychological tests (except of the VLMT)

Ac ce

were used to investigate potential further cognitive side effects of AI therapy, aside from changes in hippocampus-dependent memory. Short-term memory in the forward block span improved from T1 to T2, irrespective of group (see Table 3). Improvements were detected in the lexical switch, a test of verbal fluency, as well as in figural memory (both tests trend-level significance; F(1, 43) = 2.94, p = .094; F(1, 39) = 3.13, p = .085). It is of note that these performance gains associated with familiarization to the testing procedure occurred, although parallel versions of the respective tasks were used on each occasion. The effects of repeated testing are a common issue in longitudinal studies, and can even mask the effects of cognitive aging (Salthouse, 2010).

Page 11 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

12/12

The participants of the AI group were faster with respect to general processing speed (F(1, 43) = 5.02, p = .028) and had a better working memory for the block span backward (F(1, 42) = 4.95, p = .032), Moreover, participants of the AI group performed better in the block

ip t

design test, a test of abstract intelligence, and the attentional switch, a test of executive function, than the controls (both tests trend-level significance; t(43) = -1.82, p = .075; F(1,

cr

43) = 4.01, p = .052).

Altogether, general neuropsychological performance did not yield a significant influence of

us

E2 deprivation. As such, potential decrements in hippocampus-dependent memory performance cannot be attributed to changes in other cognitive domains (i.e. executive

an

functions) assessed in the present study.

M

- Please insert Table 2 around here.-

ed

Table 2. Means (M), standard deviations (SD) and case numbers (n) for psychosocial questionnaires. The last three columns present p-values (p) of the statistical analyses (* = p < .05.** = p < .05 † = p

pt

< .1). Significant or trend-level significant means and p-values are highlighted in bold font.

#

As these

tests were conducted only once, statistical analyses were performed by means of two-sample t-tests. Significant change (p < .05) from T1 to T2 within the respective group (paired-sample t-test).

b

Ac ce

a

Statistical trend towards a significant change (p < .1) from T1 to T2 within the respective group (pairedsample t-test).

1

German equivalent to the Inventory of Memory Experiences (IME; Hermann &

Neisser, 1978).

- Please insert Table 3 around here.-

Table 3. Results of neuropsychological tasks. The last three columns present p-values (p) of the statistical analyses (* = p < .05,** = p < .05, † = p < .1). Significant or trend-level significant means and p-values are highlighted in bold font.

#

As these tests were conducted only once, statistical

analyses were performed by means of two-sample t-tests.

b

Statistical trend towards a significant

Page 12 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

13/13

ip t

change (p < .1) from T1 to T2 within the respective group (paired-sample t-test).

3.1.4 Assessment of memory performance

cr

Subjective memory failures

us

The questionnaire assessing subjective memory failures was used to explore whether AI therapy has a subjective impact on everyday memory. In addition, potential subjective

an

changes in memory performance could be contrasted with the objective memory outcomes. Irrespective of group, subjects reported an increase in memory failures at T2 compared to T1

M

(F(1, 43) = 4.21, p = .046; Table 2). Irrespective of time point, controls reported significantly more memory failures than the AI participants (F(1, 43) = 4.30, p = .044). Subjective memory

ed

failure did not show a significant time by group interaction. In summary, current data give no

pt

evidence that AI therapy affects subjective everyday memory performance.

VLMT (German equivalent of the Rey auditory verbal learning test)

Ac ce

The VLMT was used to test the primary hypothesis that AI therapy specifically impairs hippocampus-dependent memory, as it has been shown that predominantly delayed memory in this task is affected by hippocampal lesions. The immediate condition of the VLMT showed neither significant effects of time (F(1,40) = 0.79, p = .379) nor group (F(1,40) = 2.11, p = .154), nor a significant time by group interaction F(1,40) = 0.79, p = .379). The delayed condition of the VLMT did not show significant effects of time (F(1,36) = 0.06, p = .804) or group (F(1,36) = 2.49, p = .124), but yielded a significant group by time interaction (F(1,36) = 4.60, p = .039) that was driven by an increase in the control, but not the AI group. Altogether, only the hippocampus-dependent condition of the verbal memory test showed a

Page 13 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

14/14

significant impact of AI therapy. In particular, whereas the control group benefited from the familiarization with the testing procedure and performed better at the second visit, this was

ip t

not the case for AI participants.

Verbal Source Memory Task

cr

The verbal source memory task was employed to test the primary hypothesis that AI therapy specifically impairs source memory that relies on the hippocampus-dependent process

us

recollection. The design of the verbal source memory task does not allow the calculation of corrected hit rates. Recollection as estimated by the process dissociation procedure did not

an

vary significantly between time points (F(1,43) = 0.93, p = .762) or groups, (F(1,43) = 0.004, p = .953), but showed a significant time by group interaction (F(1,43) = 12.410, p = .001;

M

Figure 1, A) that was driven by a decrease in the AI and an increase in the control group. Familiarity, also estimated by the process dissociation procedure, were higher at T2

ed

compared with T1 (F(1,43) = 4.42, p = .041), but differed neither significantly between groups (F(1,43) = 1.75, p = .193), nor did they show a time by group interaction (F(1,42) = 0.74, p =

pt

.395). In sum, only the hippocampus-dependent memory process recollection was

Ac ce

significantly affected by AI therapy. Again, the observed group difference was mainly driven by the increase in performance in the control group that benefited from familiarization with the testing procedure.

Visual memory task

The visual memory task was used to test the primary hypothesis that AI therapy specifically impairs the hippocampus-dependent memory process, i.e. recollection, but not familiarity. Corrected hit rates revealed a main effect of time (trend-level significance; F(1,41) = 3.05, p = .088), with better performances at T 2 (M = 0.43 ± 0.16) compared to T1 (M = 0.41 ± 0.14).

Page 14 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

15/15

Additionally, corrected hit rates yielded a significant main effect of group (F(1,41) = 6.74, p = .031), in that the AI group (M = 0.48 ± 0.14) performed better than the controls (M = 0.37 ± 0.14). Corrected hit rates did not show a significant group by time interaction (F(1,41) = 1.32,

ip t

p = .256). Recollection, as estimated by fitting the data to the dual process model, did not yield a

cr

significant main effect of time (F(1,41) = 2.01, p = .164), but the main effect of group suggested higher recollection in the AI compared with the control group (trend-level

us

significance; F(1,41) = 3.12, p = .085). Recollection showed a time by group interaction (trend-level significance; F(1,41) = 3.41, p = .072; Figure 1, B) driven by a significant

an

increase in the control (t(21) = -3.24, p = .004) but not in the AI group (t(20) = 0.25, p = .809). Familiarity, also estimated by fitting the data to the dual process model, did not change

M

significantly across time points (F(1,41) = 0.06, p = .803), but showed a significant main effect of group (F(1,41) = 6.40, p = .015; Figure 2, B) indicating higher familiarity in the AI

ed

group. The group by time interaction suggested an increase in familiarity in the AI relative to the control group (trend-level significance; F(1,41) = 3.89, p = .055). In summary, the current

pt

data provide only weak evidence that AI therapy impairs hippocampus-dependent memory in

Ac ce

the visual domain (Figure 1, B).

Word-color association task (fMRI paradigm) The word-color association task was used to evoke robust hippocampal activity during memory encoding in the MR-scanner. Corrected hit rates (item memory) increased from T1 to T2, irrespective of group (F(1,39) = 20.723, p < .001), but did not show a significant main effect of group or a group by time interaction (F(1,39) = 0.35, p = .559). Similarly, the proportion of free recall (F(1,39) = 16.96, p < .001) and correctly associated colors (F(1,39) = 28.62, p < .001) improved from T1 to T2, but did not show a significant main effect of group or

Page 15 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

16/16

a group by time interaction (free recall: F(1,39) = 0.08, p = .782; associative memory: F(1,39) = 2.59, p = .116). Overall, there was no evidence for a group difference in memory

ip t

performance in the distracting environment of the MR-scanner.

cr

- Please insert Figure 1 around here.-

3.2 Results of functional imaging (word-color association task)

us

Functional imaging data were assessed in order to examine whether AI therapy affects memory-related hippocampal and/or prefrontal activity during successful memory encoding.

an

Analysis of functional MRI data revealed a significant cluster within the right hippocampus, associated to the linear contrast testing for encoding success (x = 24, y = -30, z = -6; Z =

M

3.57, pSVC = .027; Figure 2, A). A cluster within the left hippocampus did not survive small volume correction (SVC; x = -22, y = -22, z = -12; Z = 2.74, pSVC = .249). A cluster within the

ed

right hippocampus showed lower BOLD responses for participants after AI therapy relative to controls (trend-level significance; x = 26, y = -16, z = -12; Z = 3.14, pSVC = .097; Figure 2, B).

pt

A cluster within the prefrontal cortex covering the ACC (x = 16, y = 30, z = 32; Z = 3.87, pSVC

Ac ce

= .012) and the DLPFC (x = 14, y = 28, z = 32; Z = 3.77, pSVC = .019), showed higher BOLDresponses for encoding success in participants after AI-therapy relative to controls (Figure 2, C). No other brain regions showed significant main effects or interactions surviving a threshold of p < .05, corrected for the whole brain or the reduced search volumes. In addition, testing for pairwise difference between the levels of encoding success also did not identify significant voxels. In sum, present data provide only weak evidence for decreased memory-related hippocampal activity after AI therapy. In contrast, AI therapy significantly enhanced memoryrelated prefrontal activity in the ACC and the DLPFC.

Page 16 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

17/17

ip t

- Please insert Figure 2 around here.-

4. Discussion

cr

E2 depletion specifically decreased hippocampus-dependent recollection in the two verbal memory paradigms, i.e. the verbal source-memory task and the German equivalent of the

us

Rey auditory verbal learning test. Performance in the visual memory task showed a similar pattern, but group differences reached only trend-level statistical significance. This is, to our

an

knowledge, the first evidence that E2 depletion in postmenopausal women specifically impairs hippocampus-dependent memory and modulates the memory-related BOLD effect.

M

With respect to neural correlates, activity in the right hippocampus during successful encoding showed a statistical trend to decrease as a consequence of E2 depletion. The right

ed

ACC and DLPFC showed the opposite pattern of activity, i.e. an increase during successful episodic encoding with lower E2 levels.

pt

The specificity of the subtle impairment of recollection-based recognition memory is

Both

Ac ce

corroborated by the consistency of the finding across the two employed recognition tasks. paradigms

assess

recollection

and

familiarity

by

different

experimental

operationalizations and estimate their contributions to recognition by distinct procedures. According to a widely accepted model of recognition memory, recollection is the memory for an item together with associated contextual information (Yonelinas, 2002). Familiarity is considered to be a signal-detection process which does not lead to the retrieval of contextual details (Yonelinas, 2002). Rodent and human studies have shown that recollection is a hippocampus-dependent process, whereas familiarity is mediated by the surrounding cortices (Diana et al., 2007; Fortin et al., 2004). The verbal source memory task measured

Page 17 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

18/18

the contribution of recollection objectively, i.e. through assessing memory for list membership of each target. Previous studies employing this paradigm showed that recollection correlates positively with neuropsychological functions mediated by temporal but

ip t

not frontal regions (Prull et al., 2006). The visual memory task assessed the contribution of recollection through subjective meta-memory judgments, i.e. through assessing the

cr

confidence for each memory decision. Again, previous usage of this paradigm showed that hippocampal lesions cause impaired recollection while sparing familiarity (Aggleton et al.,

us

2005; Jäger et al., 2009; Vann et al., 2009). E2 depletion also affected delayed verbal memory in the VLMT. Although this task does not permit the estimation of process

an

parameters, it is of note that deficits in the delayed condition of VLMT are only shown by participants with temporal-lobe, but not extra-temporal lobe, epilepsy (Helmstaedter et al.,

M

2009). As particularly the delayed recall of words correlates with hippocampal volume (Golomb et al., 1994), the current result could be interpreted in terms of decreased

ed

hippocampal efficacy as a result of AI therapy. As opposed to this, a decline in prefrontal functions also results in delayed recall deficits, but affects initial learning to a similar degree

pt

(Alexander et al., 2003). As such, current data indicate a specific deficit in hippocampus-

Ac ce

dependent verbal memory after AI therapy. Only the word-color association task that was performed in the MR-scanner did not show an effect of E2 depletion on the behavioral level, which might be caused by reduced sensitivity in this highly unusual context. However, the fMRI data suggest a decrease in memory-related hippocampal activity (although only a statistical trend) and an increased activation within the ACC and the DLPFC after E2 depletion. These findings are in line with the negative effect of aromatase inhibition on spine synapse density and LTP (Vierk et al., 2012; Zhou et al., 2010). Moreover, they connect to the observation that systemic letrozole treatment specifically affects spine density in the hippocampus but not prefrontal areas.

Page 18 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

19/19

Current data suggest that successful encoding depends less on the hippocampus and more on prefrontal areas after inhibition of E2 synthesis. Consistent with this interpretation, compensatory activity in prefrontal areas is a common finding in research on cognitive

ip t

decline in aging and Alzheimer’s disease (Bäckman et al., 1999; Cabeza et al., 2002; Gould et al., 2006; Grady et al., 2002; Gutchess et al., 2005). Specifically, elderly subjects with

cr

intact memory performance show decreased activity in the medial temporal lobe, but enhanced prefrontal activity compared with young subjects (Gutchess et al., 2005).

us

Additionally, Gutchess and colleagues report that activity in the medial temporal lobe and prefrontal cortex was negatively correlated in the elderly subjects. More direct evidence has

an

been reported in rats, where optogenetic hippocampal inhibition was compensated by activity within the ACC (Goshen et al., 2011). The enhanced recruitment of the DLPFC in the

M

present study suggests that the participants of the AI group used organizational encoding strategies more intensely after AI therapy. Consistent with this interpretation, elderly subjects

ed

tend to use more semantic associations than young subjects during free recall, a potential behavioral compensatory mechanism for memory deficits (Golomb et al., 2008). It is thus

pt

conceivable, that enhanced activity in the ACC and DLPFC mirror compensatory

Ac ce

mechanisms in participants under E2 depletion. There are some limitations that should be addressed in future research. First of all, 21 AI participants, but only two controls, were receiving local radiotherapy of the breast during the study period. Although there is evidence that radiotherapy without chemotherapy impairs executive functions but not verbal memory (Jim et al., 2009; Phillips et al., 2012; Quesnel et al., 2009), we cannot rule out the possibility that radiotherapy influenced the present results. Similarly, we did not have individual information on disease stage. Cancer itself has been associated to decrements in executive functions (Ahles et al., 2007; Hedayati et al., 2011; Shilling et al., 2005) and impaired memory Wechsler logical memory test(Shilling et al.,

Page 19 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

20/20

2005), a test that depends on prefrontal as well as hippocampal functioning (Helmstaedter et al., 2009; Strenziok et al., 2013; Vargha-Khadem et al., 1997). Again, we can not exclude the possibility that disease stage influenced present results. In addition, the baseline

ip t

differences between groups might have influenced the observed interactions. These differences are likely based on the different recruiting strategies. However, as it was the AI

cr

group that outperformed the controls in some of the neuropsychological tests and showed less trait anxiety, one would expect that the observed group differences, if at all, would more

us

likely mask than increase potential effects of aromatase inhibition. Moreover, these group differences would seem to oppose the interpretation that rather unspecific side effects of AI

an

therapy (e.g. fatigue, depressive symptoms and anxiety) might have caused the subtle memory impairment. Finally, although it is plausible that the increase in memory-related

M

BOLD response in the ACC constitutes a compensatory mechanism for decreased hippocampal efficacy, current data do not provide sufficient evidence to proof this

literature (Poldrack, 2010).

ed

hypothesis. Moreover, the concept of neural efficiency is not yet proven by the existing

pt

The current study was designed to translate the findings on E2 depletion by letrozole

Ac ce

treatment in ovariectomized rodents to humans, with a focus on hippocampus-dependent memory. We show that E2 depletion leads to subtle impairments in hippocampus-dependent memory within the verbal and visual domain. This finding corresponds well with results of previous studies, in which AI therapy prevented re-testing related performance gains (Collins et al., 2009; Hedayati et al., 2012). In sum, we interpret the current data as evidence for the dependency of hippocampus-dependent memory on central E2 synthesis. The preservation of overall memory performance (ie. corrected hit rate) is most likely a result of compensatory mechanisms, such as the enhanced recruitment of prefrontal areas.

Page 20 of 40

21/21

us

cr

ip t

Estrogen synthesis inhibition and memory. Bayer et al.

an

5. References

Aaronson, N.K., Ahmedzai, S., Bergman, B., Bullinger, M., Cull, A., Duez, N.J., Filiberti, A.,

M

Flechtner, H., Fleishman, S.B., de Haes, J.C., 1993. The European Organization for Research and Treatment of Cancer QLQ-C30: a quality-of-life instrument for use in

ed

international clinical trials in oncology. J. Natl. Cancer Inst. 85, 365–376. Aggleton, J.P., Vann, S.D., Denby, C., Dix, S., Mayes, A.R., Roberts, N., Yonelinas, A.P., 2005. Sparing of the familiarity component of recognition memory in a patient with pathology.

pt

hippocampal

Neuropsychologia

43,

1810–1823.

Ac ce

doi:10.1016/j.neuropsychologia.2005.01.019 Ahles, T.A., Saykin, A.J., McDonald, B.C., Furstenberg, C.T., Cole, B.F., Hanscom, B.S., Mulrooney, T.J., Schwartz, G.N., Kaufman, P.A., 2007. Cognitive function in breast cancer patients prior to adjuvant treatment. Breast Cancer Res Treat 110, 143–152. doi:10.1007/s10549-007-9686-5

Alexander, M.P., Stuss, D.T., Fansabedian, N., 2003. California Verbal Learning Test: performance by patients with focal frontal and non
frontal lesions. Brain 126, 1493– 1503. doi:10.1093/brain/awg128 Amunts, K., Kedo, O., Kindler, M., Pieperhoff, P., Mohlberg, H., Shah, N., Habel, U.,

Page 21 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

22/22

Schneider, F., Zilles, K., 2005. Cytoarchitectonic mapping of the human amygdala, hippocampal region and

entorhinal cortex: intersubject variability and probability

maps. Anat. Embryol. 210, 343–352. doi:10.1007/s00429-005-0025-5

ip t

Bäckman, L., Andersson, J.L., Nyberg, L., Winblad, B., Nordberg, A., Almkvist, O., 1999. Brain regions associated with episodic retrieval in normal aging and Alzheimer’s

cr

disease. Neurology 52, 1861–1870.

Cabeza, R., Anderson, N.D., Locantore, J.K., McIntosh, A.R., 2002. Aging gracefully:

us

compensatory brain activity in high-performing older adults. Neuroimage 17, 1394– 1402.

an

Collins, B., Mackenzie, J., Stewart, A., Bielajew, C., Verma, S., 2009. Cognitive effects of hormonal therapy in early stage breast cancer patients: a prospective study. Psycho-

M

Oncology 18, 811–821. doi:10.1002/pon.1453

Davachi, L., 2006. Item, context and relational episodic encoding in humans. Current

ed

Opinion in Neurobiology, Motor systems / Neurobiology of behaviour 16, 693–700. doi:10.1016/j.conb.2006.10.012

pt

Diana, R.A., Yonelinas, A.P., Ranganath, C., 2007. Imaging recollection and familiarity in the

Ac ce

medial temporal lobe: a three-component model. Trends in cognitive sciences 11, 379–386.

Fester, L., Prange-Kiel, J., Zhou, L., Blittersdorf, B.V., Böhm, J., Jarry, H., Schumacher, M., Rune, G.M., 2012. Estrogen-regulated synaptogenesis in the hippocampus: sexual dimorphism in vivo but not in vitro. J. Steroid Biochem. Mol. Biol. 131, 24–29. doi:10.1016/j.jsbmb.2011.11.010 Fester, L., Ribeiro-Gouveia, V., Prange-Kiel, J., von Schassen, C., Bottner, M., Jarry, H., Rune, G.M., 2006. Proliferation and apoptosis of hippocampal granule cells require local oestrogen synthesis. J Neurochem 97, 1136–1144. doi:10.1111/j.1471-

Page 22 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

23/23

4159.2006.03809.x Fliege, H., 2005. The Perceived Stress Questionnaire (PSQ) Reconsidered: Validation and Reference Values From Different Clinical and Healthy Adult Samples. Psychosomatic

ip t

Medicine 67, 78–88. doi:10.1097/01.psy.0000151491.80178.78 Fortin, N.J., Wright, S.P., Eichenbaum, H., 2004. Recollection-like memory retrieval in rats is

cr

dependent on the hippocampus. Nature 431, 188–191. doi:10.1038/nature02853

Gallicchio, L., MacDonald, R., Wood, B., Rushovich, E., Helzlsouer, K.J., 2012. Menopausal-

us

type symptoms among breast cancer patients on aromatase inhibitor therapy. Climacteric 15, 339–349. doi:10.3109/13697137.2011.620658

an

Geisler, J., Lønning, P.E., 2005. Aromatase Inhibition: Translation into a Successful Therapeutic Approach. Clin Cancer Res 11, 2809–2821. doi:10.1158/1078-

M

0432.CCR-04-2187

Gesellschaft für Neuropsychologie - Arbeitskreis “Aufmerksamkeit und Gedächtnis,” 1997.

ed

FEDA. Fragebogen erlebter Defizite der Aufmerksamkeit. Gibbs, R.B., Gabor, R., Cox, T., Johnson, D.A., 2004. Effects of raloxifene and estradiol on acetylcholine

release

pt

hippocampal

and

spatial

learning

in

the

rat.

Ac ce

Psychoneuroendocrinology 29, 741–748. doi:10.1016/S0306-4530(03)00118-5 Golomb, J.D., Peelle, J.E., Addis, K.M., Kahana, M.J., Wingfield, A., 2008. Effects of adult aging on utilization of temporal and semantic associations during free and serial recall. Memory & Cognition 36, 947–956. doi:10.3758/MC.36.5.947

Golomb, J., Kluger, A., de Leon, M.J., Ferris, S.H., Convit, A., Mittelman, M.S., Cohen, J., Rusinek, H., De Santi, S., George, A.E., 1994. Hippocampal formation size in normal human aging: a correlate of delayed secondary memory performance. Learn. Mem. 1, 45–54. Goshen, I., Brodsky, M., Prakash, R., Wallace, J., Gradinaru, V., Ramakrishnan, C.,

Page 23 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

24/24

Deisseroth, K., 2011. Dynamics of retrieval strategies for remote memories. Cell 147, 678–689. doi:10.1016/j.cell.2011.09.033 Gould, R.L., Arroyo, B., Brown, R.G., Owen, A.M., Bullmore, E.T., Howard, R.J., 2006. Brain

ip t

mechanisms of successful compensation during learning in Alzheimer disease. Neurology 67, 1011–1017. doi:10.1212/01.wnl.0000237534.31734.1b

cr

Grady, C.L., Bernstein, L.J., Beig, S., Siegenthaler, A.L., 2002. The effects of encoding task on age-related differences in the functional neuroanatomy of face memory.

us

Psychology and aging 17, 7.

Gutchess, A.H., Welsh, R.C., Hedden, T., Bangert, A., Minear, M., Liu, L.L., Park, D.C., 2005.

Compensate

for

an

Aging and the Neural Correlates of Successful Picture Encoding: Frontal Activations Decreased Medial-Temporal Activity.

Journal of

Cognitive

M

Neuroscience 17, 84–96. doi:10.1162/0898929052880048 Harburger, L., Bennett, J., Frick, K., 2007. Effects of estrogen and progesterone on spatial

ed

memory consolidation in aged females. Neurobiology of Aging 28, 602–610. doi:10.1016/j.neurobiolaging.2006.02.019

pt

Hautzinger, M., Bailer, M., 1993. Allgemeine Depressionsskala (ADS). Deutsche Form der

Ac ce

„Center for Epidemiologic Studies Depression Scale “(CES-D). Weinheim: Beltz Test. Hedayati, E., Alinaghizadeh, H., Schedin, A., Nyman, H., Albertsson, M., 2012. Effects of adjuvant treatment on cognitive function in women with early breast cancer. Eur. J. Oncol. Nurs. 16, 315–322. doi:10.1016/j.ejon.2011.07.006

Hedayati, E., Schedin, A., Nyman, H., Alinaghizadeh, H., Albertsson, M., 2011. The effects of breast cancer diagnosis and surgery on cognitive functions. Acta Oncol. 50, 1027– 1036. doi:10.3109/0284186X.2011.572911 Helmstaedter, C., Lendt, M., Lux, S., 2001. VLMT—Verbaler Lern- und Merkfähigkeitstest [Verbal Learning and Memory Test]. Hogrefe, Göttingen.

Page 24 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

25/25

Helmstaedter, C., Wietzke, J., Lutz, M.T., 2009. Unique and shared validity of the “Wechsler logical memory test”, the “California verbal learning test”, and the “verbal learning and memory test” in patients with epilepsy. Epilepsy Research 87, 203–212.

ip t

doi:10.1016/j.eplepsyres.2009.09.002 Hogervorst, E., Bandelow, S., 2010. Sex steroids to maintain cognitive function in women

cr

after the menopause: A meta-analyses of treatment trials. Maturitas 66, 56–71. doi:10.1016/j.maturitas.2010.02.005 1990. Lerntheoretisch orientiertes

Hirnleistungstraining. Grundlagen,

us

Holzapfel, H.,

Programmentwicklung und Manual. Verlag Modernes Lernen, Dortmund.

an

Hojo, Y., Hattori, T., Enami, T., Furukawa, A., Suzuki, K., Ishii, H., Mukai, H., Morrison, J.H., Janssen, W.G.M., Kominami, S., Harada, N., Kimoto, T., Kawato, S., 2004. Adult

M

male rat hippocampus synthesizes estradiol from pregnenolone by cytochromes P45017α and P450 aromatase localized in neurons. Proc Natl Acad Sci U S A 101,

ed

865–870. doi:10.1073/pnas.2630225100 Howard, M.W., Bessette-Symons, B., Zhang, Y., Hoyer, W.J., 2006. Aging Selectively Impairs

pt

Recollection in Recognition Memory for Pictures: Evidence From Modeling and

Ac ce

Receiver Operating Characteristic Curves. Psychology and Aging 21, 96–106. doi:10.1037/0882-7974.21.1.96

Jacoby, L.L., 1991. A process dissociation framework: Separating automatic from intentional uses of memory. Journal of Memory and Language 30, 513–541. doi:10.1016/0749596X(91)90025-F

Jäger, T., Szabo, K., Griebe, M., Bäzner, H., Möller, J., Hennerici, M.G., 2009. Selective disruption of hippocampus-mediated recognition memory processes after episodes of transient

global

amnesia.

Neuropsychologia

47,

70–76.

doi:10.1016/j.neuropsychologia.2008.08.019

Page 25 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

26/26

Jim, H.S.L., Donovan, K.A., Small, B.J., Andrykowski, M.A., Munster, P.N., Jacobsen, P.B., 2009. Cognitive functioning in breast cancer survivors: A controlled comparison. Cancer 115, 1776–1783. doi:10.1002/cncr.24192

ip t

Knowles, E.S., Coker, M.C., Scott, R.A., Cook, D.A., Neville, J.W., 1996. Measurementinduced improvement in anxiety: mean shifts with repeated assessment. Journal of

cr

personality and social psychology 71, 352.

Kato, A., Kawato, S., 2013. Female hippocampal estrogens have a significant correlation

us

with cyclic fluctuation of hippocampal spines. Front. Neural Circuits 7, 149. doi:10.3389/fncir.2013.00149

an

Kretz, O., Fester, L., Wehrenberg, U., Zhou, L., Brauckmann, S., Zhao, S., Prange-Kiel, J., Naumann, T., Jarry, H., Frotscher, M., Rune, G.M., 2004. Hippocampal Synapses

M

Depend on Hippocampal Estrogen Synthesis. J. Neurosci. 24, 5913–5921. doi:10.1523/JNEUROSCI.5186-03.2004

ed

Laux, L., Glanzmann, P., Schaffner, C.D., Spielberger, C.D., 1981. Das State-TraitAngstinventar (Testmappe mit Handanweisung, Fragebogen STAI-G Form X 1 und

pt

Fragebogen STAI-G Form X 2). Weinheim, Germany: Beltz.

Ac ce

Li, C., Brake, W.G., Romeo, R.D., Dunlop, J.C., Gordon, M., Buzescu, R., Magarinos, A.M., Allen, P.B., Greengard, P., Luine, V., McEwen, B.S., 2004. Estrogen alters hippocampal dendritic spine shape and enhances synaptic protein immunoreactivity and

spatial

memory

in

female

mice.

PNAS

101,

2185–2190.

doi:10.1073/pnas.0307313101

Phillips, K.M., Jim, H.S., Small, B.J., Laronga, C., Andrykowski, M.A., Jacobsen, P.B., 2012. Cognitive functioning after cancer treatment: a 3-year longitudinal comparison of breast cancer survivors treated with chemotherapy or radiation and noncancer controls. Cancer 118, 1925–1932. doi:10.1002/cncr.26432

Page 26 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

27/27

Poldrack, R.A., 2010. Interpreting developmental changes in neuroimaging signals. Human Brain Mapping 31, 872–878. doi:10.1002/hbm.21039 Potthoff, P., Heinemann, L.A.J., Schneider, H.P.G., Rosemeier, H.P., Hauser, G.A., 2000.

ip t

Menopause-Rating Skala (MRS): Methodische Standardisierung in der deutschen Bevölkerung. Zentralbl Gynakol 122, 280–286.

Familiarity

in

Neuropsychological

Recognition Test

Memory:

Correlates.

Adult

Psychology

Age

and

doi:10.1037/0882-7974.21.1.107

Differences

Aging

us

and

cr

Prull, M.W., Dawes, L.L.C., Martin, A.M., III, Rosenberg, H.F., Light, L.L., 2006. Recollection

21,

and

107–118.

an

Quesnel, C., Savard, J., Ivers, H., 2009. Cognitive impairments associated with breast cancer treatments: results from a longitudinal study. Breast Cancer Res. Treat. 116,

M

113–123. doi:10.1007/s10549-008-0114-2

Rune, G.M., Lohse, C., Prange-Kiel, J., Fester, L., Frotscher, M., 2006. Synaptic Plasticity in

ed

the Hippocampus: Effects of Estrogen from the Gonads or Hippocampus? Neurochem Res 31, 145–155. doi:10.1007/s11064-005-9004-8

pt

Salthouse, T.A., 2010. Influence of age on practice effects in longitudinal neurocognitive

Ac ce

change. Neuropsychology 24, 563. Shilling, V., Jenkins, V., Morris, R., Deutsch, G., Bloomfield, D., 2005. The effects of adjuvant chemotherapy on cognition in women with breast cancer—preliminary results of an observational

longitudinal

study.

The

Breast

14,

142–150.

doi:10.1016/j.breast.2004.10.004

Smith, C.C., Vedder, L.C., McMahon, L.L., 2009. Estradiol and the relationship between dendritic spines, NR2B containing NMDA receptors, and the magnitude of long-term potentiation at hippocampal CA3–CA1 synapses. Psychoneuroendocrinology 34, S130–S142. doi:10.1016/j.psyneuen.2009.06.003

Page 27 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

28/28

Spitzer, R.L., Kroenke, K., Williams, J.B., Lowe, B., 2006. A brief measure for assessing generalized anxiety disorder: the GAD-7. Archives of internal medicine 166, 1092. Staresina, B.P., Davachi, L., 2006. Differential Encoding Mechanisms for Subsequent

ip t

Associative Recognition and Free Recall. Journal of Neuroscience 26, 9162–9172. doi:10.1523/JNEUROSCI.2877-06.2006

cr

Strenziok, M., Greenwood, P.M., Santa Cruz, S.A., Thompson, J.C., Parasuraman, R., 2013. Differential Contributions of Dorso-Ventral and Rostro-Caudal Prefrontal White Matter to

Cognitive

Control

in

Healthy

doi:10.1371/journal.pone.0081410

Older

Adults.

us

Tracts

PLoS

One

8.

an

Tzourio-Mazoyer, N., Landeau, B., Papathanassiou, D., Crivello, F., Etard, O., Delcroix, N., Mazoyer, B., Joliot, M., 2002. Automated anatomical labeling of activations in SPM

M

using a macroscopic anatomical parcellation of the MNI MRI single-subject brain. Neuroimage 15, 273–289. doi:10.1006/nimg.2001.0978

ed

Vann, S.D., Tsivilis, D., Denby, C.E., Quamme, J.R., Yonelinas, A.P., Aggleton, J.P., Montaldi, D., Mayes, A.R., 2009. Impaired recollection but spared familiarity in patients with

pt

extended hippocampal system damage revealed by 3 convergent methods. PNAS

Ac ce

106, 5442–5447. doi:10.1073/pnas.0812097106 Vargha-Khadem, F., Gadian, D.G., Watkins, K.E., Connelly, A., VanPaesschen, W., Mishkin, M., 1997. Differential effects of early hippocampal pathology on episodic and semantic memory. Science 277, 376–380. doi:10.1126/science.277.5324.376

Vierk, R., Glassmeier, G., Zhou, L., Brandt, N., Fester, L., Dudzinski, D., Wilkars, W., Bender, R.A., Lewerenz, M., Gloger, S., Graser, L., Schwarz, J., Rune, G.M., 2012. Aromatase Inhibition Abolishes LTP Generation in Female But Not in Male Mice. J. Neurosci. 32, 8116–8126. doi:10.1523/JNEUROSCI.5319-11.2012 Woolley, C.S., Gould, E., Frankfurt, M., McEwen, B., 1990. Naturally occurring fluctuation in

Page 28 of 40

Estrogen synthesis inhibition and memory. Bayer et al.

29/29

dendritic spine density on adult hippocampal pyramidal neurons. The Journal of Neuroscience 10, 4035 –4039. Yonelinas, A.P., 2002. The Nature of Recollection and Familiarity: A Review of 30 Years of Journal

of

Memory

and

Language

46,

441–517.

ip t

Research.

doi:10.1006/jmla.2002.2864

cr

Zhou, L., Fester, L., von Blittersdorff, B., Hassu, B., Nogens, H., Prange-Kiel, J., Jarry, H., Wegscheider, K., Rune, G.M., 2010. Aromatase Inhibitors Induce Spine Synapse

us

Loss in the Hippocampus of Ovariectomized Mice. Endocrinology 151, 1153–1160.

Ac ce

pt

ed

M

an

doi:10.1210/en.2009-0254

Page 29 of 40

Table(s)

20

0

Treatment Letrozole daily (2.5 mg) Switch from Letrozole to Anastrozole Anastrozole (1 mg) Local radiotherapy Hormone Replacement Therapy Current Past Never Nulliparity Years of Education 9 Years 10 Years 13 Years

an

0 10 11 3

0

M

8 10 3

1 10 13 5

0.615

0.567 0.612

6 13 5

Ac ce p

te

d

Table 1

0 2

us

1 2 21

p 0.791 0.518 0.518 p

ip t

C group M SD 68.29 7.03 167.75 43.88 17.9 9.72 n

cr

Age Delay (in Days) Years since Menopause

AI group M SD 66.9 4.63 159.33 42.46 17.1 7.45 n

Page 30 of 40

21

menopausal symptoms (psyche)

Menopause Rating Scale (MRS)

Table 2

Gesellschaft für Neuropsyc hologie Fragebogen zur Erfassung Arbeitskreis erlebter Defizite der Aufmerksamkeit und Aufmerksamkeit (FEDA) Gedächtnis (2005)

Holzapfel, 1990

21

Potthoff, Heinemann, menopausal Schneider, Rosemeier, symptoms & Hauser, 2000 (somatic) menopausal symptoms (urogenital)

Aaronson et al., 1993

Fragebogen zur Erfassung alltäglicher Gedächtnisleistungen (FEAG)1

21

Spitzer, Kroenke, Williams, & Lowe, 2006 anxiety

Generalized Anxiety Disorder Sc ale (GAD) Quality of Life-C30: Global Health Sc ore (QoL)

experienced attention failures

experienced memory failures

global health score

depression

21

21

20

21

21

21

demands

Hautzinger & Bailer, 1993

21 21

Allgemeine Depressionsskala (ADS)

21

Fliege, 2005 tension joy

21

state anxiety

Perceived Stress Questionnaire (PSQ) worries

21

trait anxiety

Laux, Glanzmann, Schaffner, & Spielberger, 1981

State-Trait Anxiety Inventory: Trait (STAI)

n

T1

94.64

53.14

2.29

1.79

2.88

5.00

3.29

8.30

8.90

3.21

2.43

2.12

91.76

55.02

1.90

2.24

4.00a

5.16

2.57

9.82

7.14

8.76 15.00

7.43

31.07

M

d

1.31

4.17

9.74

3.19

4.07 3.75

2.96

15.34

10.28

SD

AI group

te

9.51

7.81

8.62 15.33

7.73

32.48

30.57

M

Ac ce p v ariable

source

task/measure

2.96

9.03

2.20

3.24 4.25

2.58

11.72

SD

24

24

24

24 24

24

23

23

n

8.39

9.92

2.68

2.51

2.49

1.23

24

24

86.38

59.29

2.29

1.46

4.42

5.13

3.33

11.36

8.42

9.13 13.88

8.46

34.98

36.96

M

T1

11.24

84.73

62.33

2.54

1.94

4.02

5.09

4.25

12.53

13.97

.079†

.014*

.044*

.664

.586

.264

.876

.369

.709

.055†

.177 .125

.123

.158

.038*, #

.627

.631

.310

.954

.006**

.387

.071†

.320

.022*

.150 .883

.114

.067†

time * group

ANOVA group p

ip t

.046*

.832

.050*

.172

.520

.819

.525

.708

.465

.083†

.479

.475

time

cr

13.23

2.45

1.58

2.50

1.27

3.97

7.69

2.62

9.33†

3.04

8.77

2.54 3.42

†

SD

10.63 13.38

9.23

38.22

M

T2

us 13.11

2.31

1.69

2.65

1.02

2.75

7.60

2.39

3.21 3.80

3.02

10.98

9.52

SD

C group

an 24

24

24

24

M

T2

Table(s)

Page 31 of 40

Table 3.

figural memory

verbal memory

numerical memory

visuo-spatial memory

verbal fluency

verbal intelligence executive functions

abstract intelligence

task/measure

10.200

delay 8.944

49.722

7.150

digit span backward

immediate

8.600

digit span forward

6.700

block span backward

23.429

semantic switch 6.952

22.905

semantic fluency

block span forward

23.286

lexical switch

17.333

word-color interference 23.571

1.857

attentional switch

lexical fluency

0.005

phasic alertness

total score

3.201

5.064

9.086

SD

M

AI group

T2

SD

4.582

3.406

9.310

1.872

1.273

1.218

1.181

3.995

6.379

5.605

7.339

5.780

1.652

0.012

10.389

9.353

49.947

7.350

8.150

7.000

7.900

23.095

23.905

24.238

23.667

18.316

1.619

0.003

6.079

3.724

6.892

2.159

1.531

1.298

1.997

4.381

4.867

5.253

5.961

9.787

1.322

0.010

T1

321.417

30.208

13.958

28.750

M

7.870

7.250

44.458

7.250

7.833

5.917

6.667

22.292

25.500

21.667

22.542

21.750

2.458

SD

C group M

T2 SD

21.958

2.833

0.004

4.310

3.710

11.244

2.111

1.579

1.349

1.167

2.726

6.692

7.800

7.223 6.347

6.760

13.010

2.353

0.010

8.609

8.652

b

47.375

6.500

7.625

6.167

7.167

22.625

24.375

4.600

3.459

10.672

1.818

2.081

1.551

1.606

4.302

4.726

ANOVA

.085

†

.804

.379

.377

.102

.317

.124

ip t

.379

.130

.571

.039*

cr .154

.474

.542

.901

.032† .171

.337

.638

.319

.672

.857

.206

us .175

.003**

.390

.264

.463

.094† .953

.640

.603

.413

.052† .194

.424

.773

time * group

.755

.028*

.428#

.131#

.075†,#

group p

.775

.511

.855

.660

.901

time

1.000

an

23.250

22.958

M

9.561

2.226

0.009

66.447 318.417 80.467

7.896

6.517

10.719

d

0.003

te

280.667 49.595 281.857 36.748

31.619

16.619

matrix reasoning

total score general processing speed

34.190

M

T1

Ac ce p

block design

v ariable

Table(s)

Page 32 of 40

Ac ce pt e

d

M

an

us

cr

ip t

Figure(s)

Figure 1. Performance in memory tasks. Pale purple/green bars represent performance at baseline (T 1), colorful purple/green bars represent performance at the post measurement (T 2). For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article. Performance in the aromatase inhibitor group (AI group) is represented by purple color, performance in the control group (C group) is indexed by green color. A. Familiarity (left) and recollection (right) in the verbal source memory task. Familiarity showed a trend-level significant main effect of group, with higher values in the AI group compared with the C group. Recollection showed a significant group by time interaction (** = p < .01), with a trend-level significant decrease in recollection within the AI group and a significant increase in the C group. B. Familiarity (left) and recollection (right) in the visual memory task. AI therapy tended to have a positive effect on familiarity († = p < .1) while reducing practice effects in recollection. C. Memory for word-color associations and free recall in the word-color association task. Performance in this task was not significantly influenced by AI therapy. Error bars represent standard errors of the mean.

Page 33 of 40

ip t

Figure(s)

cr

Figure 2. For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article. A. Statistical map of the linear contrast of encoding success. Encoding

us

success was associated to a significant cluster within the right hippocampus; a cluster within the left hippocampus did not survive small volume correction. B. Statistical map of the reversed time by group interaction for encoding success, i.e. AI group (T 1 > T2) x C group (T1 < T2). A cluster in the right

an

hippocampus showed a trend-level significant group by time interaction. C. Statistical map of the time by group interaction, i.e. AI group (T1 < T2) x C group (T1 > T2). A cluster in the prefrontal cortex, covering the right anterior cingulate and the right dorsolateral prefrontal cortex, showed a significant

Ac ce pt e

d

M

group by time interaction. An uncorrected threshold of p < .005 was chosen for visualization purposes.

Page 34 of 40

Ac ce p

te

d

M

an

us

cr

ip t

Figure(s)

Page 35 of 40

Figure(s) 0.12

0.10

0.08

ip t

0.06

cr

0.04

us

0.02

0.55

Ac ce p

te

d

M

an

0.00

0.10

0.08

0.50

0.45

0.06

0.40 0.04

0.35 Page 36 of 40

0.00

0.00

*Conflict of Interest

Ac

ce pt

ed

M

an

us

cr

ip t

The authors declare no conflict of interest.

Page 37 of 40

*Contributors



Janine Bayer contributed to the conception and the design, conducted research, contributed in data analysis and interpretation and wrote the manuscript.



Gabriele Rune contributed to the conception and the design, participated in reviewing the



ip t

manuscript, approved the manuscript to be published. Heidrun Schultz contributed to data analysis, participated in reviewing the manuscript,

Michael J. Tobia contributed to data analysis, participated in reviewing the manuscript,

us



cr

approved the manuscript to be published.

approved the manuscript to be published.

Imke Mebes contributed to the acquisition of data, participated in reviewing the manuscript,



Olaf Katzler to the acquisition of data, participated in reviewing the manuscript, approved

ed

the manuscript to be published.

Tobias Sommer contributed to the conception and the design, contributed in data analysis

ce pt

and interpretation and wrote the manuscript.

Ac



M

approved the manuscript to be published.

an



Page 38 of 40

*Role of the Funding Source

Ac

ce pt

ed

M

an

us

cr

ip t

The study was funded by the German Research Foundation [DFG SO 952/2-1 and DFG SO 952/6-1].

Page 39 of 40

*Highlights (for review)

Estradiol depletion specifically impaired hippocampus-dependent memory.



Estradiol depletion tended to decrease memory-related hippocampal activity.



Estradiol depletion increased memory-related activity in prefrontal areas.



The increased prefrontal activity reflects most likely a compensatory mechanism.

Ac

ce pt

ed

M

an

us

cr

ip t



Page 40 of 40