Eur Arch Psychiatry Clin Neurosci (2015) 265:647–653 DOI 10.1007/s00406-015-0617-x
ORIGINAL PAPER
Postmortem volumetric analysis of the nucleus accumbens in male heroin addicts: implications for deep brain stimulation Ulf J. Müller1,2 · Kurt Truebner3 · Kolja Schiltz1,2 · Jens Kuhn4 · Christian Mawrin2,5 · Henrik Dobrowolny1,2 · Hans‑Gert Bernstein1,2 · Bernhard Bogerts1,2 · Johann Steiner1,2
Received: 29 March 2015 / Accepted: 7 July 2015 / Published online: 19 July 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Deep brain stimulation (DBS) of the nucleus accumbens (NAc) is increasingly investigated in neuropsychiatric disorders. DBS requires computer-assisted 3D planning to implant the stimulation electrode precisely. Recently, there has been a debate about the true dimensions of NAc in healthy as well as in mentally ill individuals. Knowing its true dimensions in different neuropsychiatric disorders may improve even more precise targeting of NAc for therapeutic DBS. Volumes of NAc of heroin addicts (n = 14) and healthy controls (n = 12) were calculated by using morphometry of serial whole-brain sections. Total brain volume was larger in the heroin group (mean 1478.85 ± 62.34 vs. mean 1352.38 ± 103.24 cm3), as the heroin group was more than 10 years younger (p = 0.001). However, the mean volume of the NAc in heroin addicts was smaller than in controls (0.528 ± 0.166 vs. 0.623 ± 0.196 cm3; p = 0.019). This group effect did not significantly differ between the hemispheres. When assessed separately, left-hemispheric NAc volume was
Ulf J. Müller and Kurt Truebner have contributed equally to this work. * Ulf J. Müller [email protected]; [email protected] 1
Department of Psychiatry, University of Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
2
Center for Behavioral Brain Sciences, Magdeburg, Germany
3
Institute of Legal Medicine, University of Duisburg-Essen, Essen, Germany
4
Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
5
Department of Neuropathology, University of Magdeburg, Magdeburg, Germany
15 % lower (p = 0.020), while right-hemispheric NAc volume was 16 % lower (p = 0.047) in the heroin-addicted group compared to controls. Based on these diagnosisrelated differences, we believe it is important to further analyze NAc volumes in different psychiatric disorders to further improve precise targeting and electrode placement. Keywords Heroin · Addiction · Nucleus accumbens · Deep brain stimulation · Postmortem
Introduction It has been estimated that over 15 million people are addicted to heroin worldwide and that it accounts for up to ten million disability-adjusted life years (DALY) [1]. Despite a substantial increase in data on the neurobiology of heroin addiction, treatment of heroin addiction still mainly relies on maintenance treatment with a controllable and thus less dangerous medical substitute opiate replacing heroin. However, although maintenance treatment obviously has positive effects on survival of patients, overall physical health and social functioning [2], it is noteworthy that patients are neither detoxified nor abstinent from the addictive substance, which therefore continues to affect the brain’s reward system adversely. The effect of heroin on the nucleus accumbens (NAc), one of the key areas of the reward system, bears similarities with the effects of other psychotropic drugs such as alcohol or cocaine. Based on the knowledge of the importance of the NAc in addiction, the idea of deep brain stimulation (DBS) of the NAc to treat alcohol addiction has been introduced in 2007 [3]. Accordingly, our group obtained further promising results of DBS in a case series of severely alcohol-addicted individuals [4–7]. The concept of treating addiction via
13
648
DBS of NAc has recently been broadened to heroin addiction [8–10] and is supported by further evidence in animal models of DBS in addiction [11, 12]. In addition, DBS of the NAc is not only investigated in addiction, but its crucial role is also under investigation in depression [13, 14], obesity [15], obsessive compulsive disorder [16] and Tourette syndrome [17]. For OCD, DBS of the ventral striatum including the NAc has recently even been approved by the FDA (under human device exemption) and the European authorities. However, despite these promising preliminary clinical and experimental data, DBS for addiction remains an experimental intervention with many aspects still unknown. Worldwide, stereotactic surgeons commonly use the “Atlas for Stereotaxy of the Human Brain” by Schaltenbrand [18] for targeting the brain area where the electrodes are to be implanted. Following a publication by Halpern et al. [19], Mavridis et al. recently showed in a letter to the editor that the dimensions of the NAc were much larger in their own study of postmortem human brains from non-addicted individuals than the published 8 × 6 × 6 mm according to the Schaltenbrand Atlas. These recent results earnestly challenge the accuracy of the important location data that have previously been relied on for precise DBS planning [20]. Halpern et al. concluded in a further comment that “histological and immunochemical techniques are needed to elucidate more clearly the true dimensions of the NAc” [20]. Thus, our postmortem study aimed at assessing possible differences in NAc volume between heroin-addicted patients and healthy non-addicted control subjects.
Materials and methods Subjects All brains were obtained from the Magdeburg Brain Bank. Sampling and preservation of the human brain material were done in accordance with the Declaration of Helsinki, German law and the local institutional review board at the University of Magdeburg. Analysis included 14 chronic male heroin addicts who died from drug overdose (aged 30.9 ± 7.6 years; postmortem interval 50.9 ± 43.7 h) and 12 male controls (aged 44.4 ± 10.5 years; postmortem interval 36.0 ± 24.0 h, see Table 1). All patients were matched for age and postmortem delay (“duration of autolysis”) as closely as possible. Information on clinical characteristics was extracted from the clinical records and by structured interviews with people closely related to the subjects by using a psychological autopsy [21]. An experienced neuropathologist (CM) ruled out qualitative neuropathological changes due to neurodegenerative disorders (such as Alzheimer’s disease, Parkinson’s
13
Eur Arch Psychiatry Clin Neurosci (2015) 265:647–653
disease, Pick’s disease), tumors, inflammatory, vascular or traumatic processes. None of the heroin addicts was HIV-positive. The diagnosis of suicide was established by a forensic pathologist (KT). A toxicology screen on blood and urine for ethanol and other substances of abuse was performed at each medico-legal autopsy. Tissue processing Tissue preparation was performed as previously described [22]. Brains were removed and fixed in toto in 8 % phosphate-buffered formaldehyde for at least 2 months. Frontal and occipital poles were separated by coronal cuts anterior to the genu and posterior to the splenium of the corpus callosum. After embedding all parts of the brains in paraffin wax, serial, whole-brain coronal sections of the middle block were cut on a large-scale microtome (Balzers, Liechtenstein) at 20 μm and mounted. Volume shrinkage was determined for each brain before and after dehydration and embedding of tissue. Volume shrinkage factors were calculated using the formula: VF = (A1/A2)3/2 (VF = volume shrinkage factor; A1 = cross-sectional area before processing of tissue; A2 = cross-sectional area after processing of tissue). Mean shrinkage factor was 2.15. Morphometric analysis Histological and planimetric procedures were performed as previously described by us in detail [23, 24]: For anatomical orientation and morphometric investigations, every 25th serial coronal whole-brain section (thickness 20 µm) was stained with a combined cell and fiber staining according to Nissl (cresyl violet) and Heidenhain-Woelcke and sampled [25, 26], resulting in an intersectional distance of 0.5 mm. Measurements of cross-sectional areas of the structures were performed by planimetry from fourfold magnifications of the sections. Delineation of the NAc in coronal serial sections has been performed as previously described (see Fig. 1a–c) [23, 24]. NAc volumes were calculated by multiplying cross-sectional areas by the distance between the sections and adding up volumes obtained by this procedure along the entire rostrocaudal axis of the NAc. Statistical analysis Statistical analyses were performed with the SPSS 15.0 program (Statistical Package for the Social Sciences, Chicago, IL, USA). Demographic data were compared using t tests. The volumetric data were normally distributed as indicated by Kolmogorov–Smirnov tests. Analysis of covariance (ANCOVA) revealed no significant influence of
Eur Arch Psychiatry Clin Neurosci (2015) 265:647–653
649
Table 1 Demographic data of the analyzed patients with heroin addiction (n = 14) and healthy control subjects (n = 12). All tested subjects in this study were male Case number Age (year) Duration of autolysis Volume of whole (h) brain (cm3)
Volume of nucleus accumbens left (cm3)
Volume of nucleus accumbens right (cm3)
Cause of death
Heroin addicts (n = 14) 1 25 2 25 3 33 4 24 5 31 6 40 7 21 8 32 9 47 10 11 12 13 14 Mean SD
40 30 32 31 21 30.9 7.6
Controls (n = 12) 1 47 2 47
11 30 85 49 10 16 164 16 96
1407.91 1446.48 1427.19 1475.41 1475.41 1562.20 1398.26 1542.91 1446.48
0.451 0.687 0.692 0.335 0.286 0.617 0.612 0.522 0.576
0.263 0.532 0.553 0.317 0.163 0.641 0.645 0.470 0.474
Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose
81 63 16 43 33 50.9 43.7
1542.91 1456.12 1407.91 1581.49 1533.27 1478.85 62.34
0.725 0.476 0.422 0.539 0.651 0.542 0.135
0.743 0.409 0.920 0.621 0.453 0.515 0.197
Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose –
24 24
1398.26 1157.18
1.145 0.321
1.141 0.457
Myocardial infarction Acute respiratory failure (aspiration) Cardiac insufficiency Myocardial infarction Myocardial infarction Ruptured aortic aneurysm Pneumonia Pulmonary embolism Cardiovascular failure Autoerotic accident (strangulation) Bleeding to death Myocardial infarction –
3 4 5 6
56 38 40 64
30 19 96 35
1398.26 1494.70 1494.70 1263.26
0.671 0.736 0.715 0.667
0.690 0.769 0.665 0.463
7 8 9 10
39 54 46 45
4 24 24 44
1353.91 1378.98 1248.79 1301.83
0.648 0.499 0.549 0.600
0.469 0.459 0.490 0.445
11 12 Mean
28 29 44.4
48 60 36.0
1446.48 1292.19 1352.38
0.531 0.548 0.636
0.699 0.574 0.610
SD
10.5
24.0
103.24
0.196
0.203
SD standard deviation
the potential confounding factors “age” [F(1,23) = 0.136, p = 0.715] and “duration of autolysis” [F(1,23) = 1.03, p = 0.321] on volumes of the NAc. “Whole-brain volume” on the contrary significantly influenced NAc volumes [F(1,23) = 4.534, p = 0.044]. This effect did not differ between hemispheres [F(1,23) = 0.013, p = 0.912]. Thus, diagnosis-related effects in the NAc have been calculated by ANCOVA with the covariate “whole-brain volume.” All statistical tests were two-tailed, and significance was defined as p
ORIGINAL PAPER
Postmortem volumetric analysis of the nucleus accumbens in male heroin addicts: implications for deep brain stimulation Ulf J. Müller1,2 · Kurt Truebner3 · Kolja Schiltz1,2 · Jens Kuhn4 · Christian Mawrin2,5 · Henrik Dobrowolny1,2 · Hans‑Gert Bernstein1,2 · Bernhard Bogerts1,2 · Johann Steiner1,2
Received: 29 March 2015 / Accepted: 7 July 2015 / Published online: 19 July 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Deep brain stimulation (DBS) of the nucleus accumbens (NAc) is increasingly investigated in neuropsychiatric disorders. DBS requires computer-assisted 3D planning to implant the stimulation electrode precisely. Recently, there has been a debate about the true dimensions of NAc in healthy as well as in mentally ill individuals. Knowing its true dimensions in different neuropsychiatric disorders may improve even more precise targeting of NAc for therapeutic DBS. Volumes of NAc of heroin addicts (n = 14) and healthy controls (n = 12) were calculated by using morphometry of serial whole-brain sections. Total brain volume was larger in the heroin group (mean 1478.85 ± 62.34 vs. mean 1352.38 ± 103.24 cm3), as the heroin group was more than 10 years younger (p = 0.001). However, the mean volume of the NAc in heroin addicts was smaller than in controls (0.528 ± 0.166 vs. 0.623 ± 0.196 cm3; p = 0.019). This group effect did not significantly differ between the hemispheres. When assessed separately, left-hemispheric NAc volume was
Ulf J. Müller and Kurt Truebner have contributed equally to this work. * Ulf J. Müller [email protected]; [email protected] 1
Department of Psychiatry, University of Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
2
Center for Behavioral Brain Sciences, Magdeburg, Germany
3
Institute of Legal Medicine, University of Duisburg-Essen, Essen, Germany
4
Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
5
Department of Neuropathology, University of Magdeburg, Magdeburg, Germany
15 % lower (p = 0.020), while right-hemispheric NAc volume was 16 % lower (p = 0.047) in the heroin-addicted group compared to controls. Based on these diagnosisrelated differences, we believe it is important to further analyze NAc volumes in different psychiatric disorders to further improve precise targeting and electrode placement. Keywords Heroin · Addiction · Nucleus accumbens · Deep brain stimulation · Postmortem
Introduction It has been estimated that over 15 million people are addicted to heroin worldwide and that it accounts for up to ten million disability-adjusted life years (DALY) [1]. Despite a substantial increase in data on the neurobiology of heroin addiction, treatment of heroin addiction still mainly relies on maintenance treatment with a controllable and thus less dangerous medical substitute opiate replacing heroin. However, although maintenance treatment obviously has positive effects on survival of patients, overall physical health and social functioning [2], it is noteworthy that patients are neither detoxified nor abstinent from the addictive substance, which therefore continues to affect the brain’s reward system adversely. The effect of heroin on the nucleus accumbens (NAc), one of the key areas of the reward system, bears similarities with the effects of other psychotropic drugs such as alcohol or cocaine. Based on the knowledge of the importance of the NAc in addiction, the idea of deep brain stimulation (DBS) of the NAc to treat alcohol addiction has been introduced in 2007 [3]. Accordingly, our group obtained further promising results of DBS in a case series of severely alcohol-addicted individuals [4–7]. The concept of treating addiction via
13
648
DBS of NAc has recently been broadened to heroin addiction [8–10] and is supported by further evidence in animal models of DBS in addiction [11, 12]. In addition, DBS of the NAc is not only investigated in addiction, but its crucial role is also under investigation in depression [13, 14], obesity [15], obsessive compulsive disorder [16] and Tourette syndrome [17]. For OCD, DBS of the ventral striatum including the NAc has recently even been approved by the FDA (under human device exemption) and the European authorities. However, despite these promising preliminary clinical and experimental data, DBS for addiction remains an experimental intervention with many aspects still unknown. Worldwide, stereotactic surgeons commonly use the “Atlas for Stereotaxy of the Human Brain” by Schaltenbrand [18] for targeting the brain area where the electrodes are to be implanted. Following a publication by Halpern et al. [19], Mavridis et al. recently showed in a letter to the editor that the dimensions of the NAc were much larger in their own study of postmortem human brains from non-addicted individuals than the published 8 × 6 × 6 mm according to the Schaltenbrand Atlas. These recent results earnestly challenge the accuracy of the important location data that have previously been relied on for precise DBS planning [20]. Halpern et al. concluded in a further comment that “histological and immunochemical techniques are needed to elucidate more clearly the true dimensions of the NAc” [20]. Thus, our postmortem study aimed at assessing possible differences in NAc volume between heroin-addicted patients and healthy non-addicted control subjects.
Materials and methods Subjects All brains were obtained from the Magdeburg Brain Bank. Sampling and preservation of the human brain material were done in accordance with the Declaration of Helsinki, German law and the local institutional review board at the University of Magdeburg. Analysis included 14 chronic male heroin addicts who died from drug overdose (aged 30.9 ± 7.6 years; postmortem interval 50.9 ± 43.7 h) and 12 male controls (aged 44.4 ± 10.5 years; postmortem interval 36.0 ± 24.0 h, see Table 1). All patients were matched for age and postmortem delay (“duration of autolysis”) as closely as possible. Information on clinical characteristics was extracted from the clinical records and by structured interviews with people closely related to the subjects by using a psychological autopsy [21]. An experienced neuropathologist (CM) ruled out qualitative neuropathological changes due to neurodegenerative disorders (such as Alzheimer’s disease, Parkinson’s
13
Eur Arch Psychiatry Clin Neurosci (2015) 265:647–653
disease, Pick’s disease), tumors, inflammatory, vascular or traumatic processes. None of the heroin addicts was HIV-positive. The diagnosis of suicide was established by a forensic pathologist (KT). A toxicology screen on blood and urine for ethanol and other substances of abuse was performed at each medico-legal autopsy. Tissue processing Tissue preparation was performed as previously described [22]. Brains were removed and fixed in toto in 8 % phosphate-buffered formaldehyde for at least 2 months. Frontal and occipital poles were separated by coronal cuts anterior to the genu and posterior to the splenium of the corpus callosum. After embedding all parts of the brains in paraffin wax, serial, whole-brain coronal sections of the middle block were cut on a large-scale microtome (Balzers, Liechtenstein) at 20 μm and mounted. Volume shrinkage was determined for each brain before and after dehydration and embedding of tissue. Volume shrinkage factors were calculated using the formula: VF = (A1/A2)3/2 (VF = volume shrinkage factor; A1 = cross-sectional area before processing of tissue; A2 = cross-sectional area after processing of tissue). Mean shrinkage factor was 2.15. Morphometric analysis Histological and planimetric procedures were performed as previously described by us in detail [23, 24]: For anatomical orientation and morphometric investigations, every 25th serial coronal whole-brain section (thickness 20 µm) was stained with a combined cell and fiber staining according to Nissl (cresyl violet) and Heidenhain-Woelcke and sampled [25, 26], resulting in an intersectional distance of 0.5 mm. Measurements of cross-sectional areas of the structures were performed by planimetry from fourfold magnifications of the sections. Delineation of the NAc in coronal serial sections has been performed as previously described (see Fig. 1a–c) [23, 24]. NAc volumes were calculated by multiplying cross-sectional areas by the distance between the sections and adding up volumes obtained by this procedure along the entire rostrocaudal axis of the NAc. Statistical analysis Statistical analyses were performed with the SPSS 15.0 program (Statistical Package for the Social Sciences, Chicago, IL, USA). Demographic data were compared using t tests. The volumetric data were normally distributed as indicated by Kolmogorov–Smirnov tests. Analysis of covariance (ANCOVA) revealed no significant influence of
Eur Arch Psychiatry Clin Neurosci (2015) 265:647–653
649
Table 1 Demographic data of the analyzed patients with heroin addiction (n = 14) and healthy control subjects (n = 12). All tested subjects in this study were male Case number Age (year) Duration of autolysis Volume of whole (h) brain (cm3)
Volume of nucleus accumbens left (cm3)
Volume of nucleus accumbens right (cm3)
Cause of death
Heroin addicts (n = 14) 1 25 2 25 3 33 4 24 5 31 6 40 7 21 8 32 9 47 10 11 12 13 14 Mean SD
40 30 32 31 21 30.9 7.6
Controls (n = 12) 1 47 2 47
11 30 85 49 10 16 164 16 96
1407.91 1446.48 1427.19 1475.41 1475.41 1562.20 1398.26 1542.91 1446.48
0.451 0.687 0.692 0.335 0.286 0.617 0.612 0.522 0.576
0.263 0.532 0.553 0.317 0.163 0.641 0.645 0.470 0.474
Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose
81 63 16 43 33 50.9 43.7
1542.91 1456.12 1407.91 1581.49 1533.27 1478.85 62.34
0.725 0.476 0.422 0.539 0.651 0.542 0.135
0.743 0.409 0.920 0.621 0.453 0.515 0.197
Heroin overdose Heroin overdose Heroin overdose Heroin overdose Heroin overdose –
24 24
1398.26 1157.18
1.145 0.321
1.141 0.457
Myocardial infarction Acute respiratory failure (aspiration) Cardiac insufficiency Myocardial infarction Myocardial infarction Ruptured aortic aneurysm Pneumonia Pulmonary embolism Cardiovascular failure Autoerotic accident (strangulation) Bleeding to death Myocardial infarction –
3 4 5 6
56 38 40 64
30 19 96 35
1398.26 1494.70 1494.70 1263.26
0.671 0.736 0.715 0.667
0.690 0.769 0.665 0.463
7 8 9 10
39 54 46 45
4 24 24 44
1353.91 1378.98 1248.79 1301.83
0.648 0.499 0.549 0.600
0.469 0.459 0.490 0.445
11 12 Mean
28 29 44.4
48 60 36.0
1446.48 1292.19 1352.38
0.531 0.548 0.636
0.699 0.574 0.610
SD
10.5
24.0
103.24
0.196
0.203
SD standard deviation
the potential confounding factors “age” [F(1,23) = 0.136, p = 0.715] and “duration of autolysis” [F(1,23) = 1.03, p = 0.321] on volumes of the NAc. “Whole-brain volume” on the contrary significantly influenced NAc volumes [F(1,23) = 4.534, p = 0.044]. This effect did not differ between hemispheres [F(1,23) = 0.013, p = 0.912]. Thus, diagnosis-related effects in the NAc have been calculated by ANCOVA with the covariate “whole-brain volume.” All statistical tests were two-tailed, and significance was defined as p
