Journal ofAffecfiue Disorders, 23 (1991) 9-23 0 1991 Elsevier Science Publishers B.V. All rights reserved ADONIS 016503279100116L

0165-0327/91/$03.50

JAD 00829

The relationship between perimenstrual depressive mood and depressive illness Pamela

Warner

‘, John Bancroft

‘, Amanda

Dixson ’ and Michele

Hampson



’ MRC Reproductirae Biology Unit, Edinburgh and 2 Mapperley Hospital, Nottingham, U.K. (Received 16 July 1990) (Revision received 22 May 1991) (Accepted 30 May 1991)

Summary In a study of 144 women, mainly self-designated PMS sufferers, the premenstrual depression experienced was, apart from its shorter duration, quantitatively and qualitatively similar to major depressive disorder for a substantial proportion of subjects. The associations with previous history of depression were complex: the severity of premenstrual depression was related to previous history of postnatal depression, whereas its duration (i.e., whether it persisted through the menstrual phase or longer) was related to a history of treatment with antidepressants. Two independent dimensions are proposed. (i) A menstrual cycle-related factor which in vulnerable women can result in severe and disabling premenstrual dysphoria, and which may be aetiologically related to a subgroup of postnatal depression. (ii) In a minority of women a more general propensity for depressive illness evidenced as a tendency for any premenstrual depression to be prolonged.

Key words:

Perimenstrual

depression;

Severity;

Duration

Introduction Women, likely than

at all ages beyond men to experience

puberty, are more depressive illness,

Address for correspondence: Pamela Warner, MRC Reproductive Biology Unit, The Kennedy Tower, Royal Edinburgh Hospital, Morningside Park, Edinburgh EHlO 5HF, U.K.

but it is in the reproductive years that this difference is most noticeable, with the rate being almost double in the age range 25-44 years (Reiger et al., 1988). It is also during these years that depressive symptoms related to the menstrual cycle are experienced recurrently by many women, and it is in the mid-thirties that complaints of premenstrual syndrome (PMS) are most prevalent (Moos, 1968; Hallman, 1986; Warner and Bancroft, 1990). The possibility remains that these recurrent menstrual-related depressive mood

changes are in some way contributing to this apparent sex difference in depression, either by increasing the likelihood of major depressive illness or by confounding the epidemiological evidence of past depressive history. While there is substantial evidence linking PMS with psychiatric morbidity (e.g., Clare, 1983; MacKenzie et al., 1986; Blazer et al., 19881, in particular depressive illness, there are difficulties in interpretation of these findings arising from the methods utilized to ‘measure’ both PMS and depressive disorder. The differing criteria of the various classification systems for psychiatric disorder, and the ad hoc adjustments made to these in some studies (Kashiwagi et al., 1976; Halbreich and Endicott, 1985), make comparison difficult. On the one hand it has been reported that women with a lifetime history of major depressive disorder (MDD) are more likely to report premenstrual mood change than either women who have never been mentally ill or those who have experienced other types of mental illness (Endicott et al., 1981; Halbreich and Endicott, 1985), and that women reporting premenstrual mood change have greater lifetime prevalence of MDD than women without such a history (Endicott et al., 1981; De Jong et al., 1985). On the other hand Stout et al. (1986) found that women attending a PMS clinic were much more likely to report previous histories of dysthymia, phobias and obsessive compulsive disorders than women from a community sample, but were significantly less likely to receive a lifetime diagnosis of MDD. The DSM-III criteria for MDD utilized by Stout et al. required 2 or more continuous weeks of depression, whereas the three studies reported above utilized RDC criteria, modified to require only 1 week of depression, and Stout et al. concluded that this provides some explanation for the conflicting findings. Furthermore, the validity of ‘lifetime prevalence’ established by means of such psychiatric classification systems has been questioned (e.g., Parker, 19871, and indeed it is also debatable whether, using such systems, a period of recurrent menstrual-related depression many years before could be satisfactorily distinguished from dysthymia or MDD. Classification of subjects as current sufferers of PMS is also problematic. Definitions of PMS

vary but most have in common improvement of symptoms either at the onset of menstruation or shortly after (e.g., Sampson, 1987; Steiner and Haskett, 1987). In our prospective studies of the menstrual cycle approximately half of the women have reported that their premenstrual depressed mood persisted and in some cases reached its peak during menstruation (Bancroft et al., 1988; Walker and Bancroft, 1990). It is not always clear how some of the reported criteria for PMS would be affected by this negative mood persisting into menses. Nor is it always clear how many or which of the psychological symptoms, if any, have been utilised in the decision process (Stout et al., 1986; Kashiwagi et al., 1976). In a large questionnaire survey of readers of a women’s magazine, 5457 respondents rated retrospectively the severity of various symptoms for three time periods during their most recent menstrual cycle, the premenstrual week, during menstruation and the postmenstrual week (Warner and Bancroft, 1990). ‘Negative mood’ (i.e., average of seven mood variables exceeding ‘moderate’) was reported only during the premenstrual week by 36%, and during the premenstrual and menstrual weeks by 42.5% of these respondents. The more prolonged ‘premenstrual and menstrual’ pattern was more prevalent among parous women. Furthermore women whose ‘negative mood’ persisted past the premenstrual week were more likely to have reported depression as one of their premenstrual symptoms. This raised the possibility that these two groups might be aetiologically distinct and that it would be the more prolonged group who would show a propensity for depressive illness. This paper reports a study which aims (1) to assess the association between current perimenstrual depressed mood and a previous history of depressive illness, using criteria of previous depressive illness based on treatment received, (2) to test the hypothesis that this association is stronger with premenstrual depression which persists during menstruation, and (3) to assess whether the depressed mood experienced perimenstrually is qualitatively as well as quantitatively comparable to that experienced during major depressive illness apart from its obviously shorter duration.

11

Methods Measures used in this study The Menstrual Health Questionnaire (MHQ) This included detailed questions about menstrual, obstetric, and psychiatric history, and was piloted extensively with women attending a PMS clinic and modified to eliminate unclear or difficult items. It included the following. (aj Perimenstrual symptom ratings. Each of 20 symptoms was rated on a O-5 severity scale for three phases around the most recent menstrual period: the premenstrual week, during menstruation and the postmenstrual week (as in the original magazine questionnaire). Only the symptom ‘feeling depressed’, which was used in categorising the subjects, is reported in this paper. (b) PreLlious depressive illness. Eight questions about previous depression were asked including ‘Have you ever been treated with antidepressants, e.g. amitriptyline, tryptizol, tofranil, prothiaden, bolvidon, etc.?‘. Subjects were asked the number of separate courses of treatment they had had, ‘the total number of weeks that the longest course lasted’ and whether the antidepressants had been prescribed for ‘depression, anxiety or other problems’. Similar questions were asked about the use of tranquillisers. The definition of a precious episode of treated depression was clear evidence from the questionnaire that antidepressants had been prescribed for depression for a minimum of 3 weeks. In addition (c) Prerious postnatal depression. to questions about ‘baby blues’ during the first postnatal week, the subject was asked to indicate whether in the 6 months following each of her pregnancies she: (1) experienced no depression lasting more than a week, (2) experienced depression for more than a week but not severely, (3) was very depressed but did not seek medical help, or (4) was very depressed and saw a doctor about it. Indication of either (3) or (4) for at least one pregnancy was taken as ecidence of previous postnatal depression. The Beck Depression Inventory (BDI) This widely used self-rating questionnaire

(Beck et al., 1988) was modified to apply to ‘the past week’ only. The relevant score ranges for clinical classification are ‘not depressed’ (O-91, ‘mild to moderate depression’ (10-181, ‘moderate to severe (19-29), ‘severe depression’ (30-57). Both the raw BDI scores and the severity classification were utilised, with the latter being collapsed to a binary scale in some analyses in order to maintain reasonable cell sizes, i.e., the lower two and higher two classifications combined as ‘low’ and ‘high’ BDI scores respectively.

The Current State of Wellbeing Questionnaire (CS W) This self-administered questionnaire was devised for the study to establish whether the subject met the RDC criteria for major depressive disorder and its ‘endogenous’ subtype (Spitzer et was to establish al., 1975). As our objective whether the brief episode of perimenstrual depression was qualitatively similar to major depressive disorder apart from its duration, questioning was restricted to the 7 days of the phase in question, and the RDC criterion for duration was reduced from 2 weeks to 1 week. The questionnaire has 55 items covering all the 23 RDC criteria for the diagnosis of major depressive disorder, and the subtype of endogenous depression. Forty-nine questions required a yes/no response. Seven pairs of questions covered the same topic and were highly consistent. The remaining questions (e.g., degree of early waking, duration of depressed mood) involved more detailed responses. The original version of this questionnaire was piloted with women attending a PMS clinic, and a simplified version was given to patients at various stages of recovery from a psychiatric illness. Neither group reported any difficulty in understanding the questions or completing the questionnaire. The reliability and validity was tested in 12 of the second group against a semistandardised interview. There was agreement with regard to diagnosis (or not) of MDD in 10 cases, with one false-positive and one false-negative. Responses were categorised as (1) major depressive disorder (meeting RDC criteria modified to a l-week duration) and (2) endogenous subtype (RDC).

12

Daily ratings In a follow-up study daily ratings were made over two cycles for depression and 11 other mood and physical symptoms (using a O-5 intensity scale). The extent of and factors associated with prospective confirmation of retrospective perimenstrual ratings will be reported fully in a separate paper, but some of the findings will be mentioned briefly here.

Procedure Each woman was sent: (1) the MHQ (one copy); (2) the BDI (two copies); and (3) the CSW (two copies). One copy each of the BDI and CSW was to be completed at the end of a premenstrual week, the other on the 14th day after the start of a period (i.e., approximately the end of the postmenstrual week), at which time the MHQ was also to be completed. Thus the MHQ retrospective perimenstrual ratings were for very recent experience, i.e., the past week and the 2 weeks preceding it.

Subjects In a women’s magazine survey, mentioned above (Warner and Bancroft, 1990), more than 90% of respondents offered to participate in further research on the menstrual cycle. Using their responses in the original survey at August 1985 (2 years prior to the current study), we defined our ‘population under study’ as follows: aged 25-45 years, past users of oral contraceptives, living with husband or partner, and with one to four children, the youngest aged over 6 months (n = 2074). Based on their ratings of the specific mood item ‘feeling depressed’ for three phases around their last menstrual cycle, 2 years previously, three panels of women were identified for subsequent sampling: panel 1 had reported no depression in any of the three phases (‘no depression’, n = 323) and the remaining two panels had reported moderate to severe depression, confined to the premenstrual week in the case of panel 2 (‘premenstrual only’, n = 8571, and to both the premenstrual and menstrual phases in panel 3 (‘premenstrual and menstrual’, n = 475). The precise criteria, which included requirements for im-

provement, are as detailed under ‘Current categorisation’. Samples of 101 women were selected from each panel, matched jointly for age, number of children and age of youngest child. AI1 women in the original survey had indicated whether they believed they suffered from PMS. In this respect our samples were representative of the panels from which they were drawn, with the proportions identifying themselves as PMS sufferers being 58%, 65% and 74% respectively, and those saying they were not, 13%, 2% and 1%; the remainder were uncertain. Thus the absence of depression in panel 1 does not necessarily mean freedom from other premenstrual symptoms. Letters were sent inviting the sampled subjects to participate in this further study. There was no response, or a negative response, from 21% of those mailed, with little difference in response rate across the three sample groups. Ten percent of women who replied were not eligible because of menopause, hysterectomy, oral contraceptive use, pregnancy or hormone treatment, with again no overall differences between the three samples. Thus the number of women willing and eligible to take part in the study, and sent questionnaires, was 206; 67 in sample 1, 69 in sample 2 and 70 in sample 3. Seventy-five percent completed and returned the questionnaires (n = 154), with completion least likely in sample 2 (71%) and most likely in sample 1 (78%). Ciuren t ca tegorisa tion As the initial sampling was based on ratings of the most recent cycle 2 years previously whereas the hypotheses under study related to current perimenstrual mood patterns, the subjects were recategorised according to their most recent (MHQ) perimenstrual depression ratings. In order to avoid confusion we have referred to ‘samples’ when describing the original sampling categorisation, and to ‘groups’ following recategorisation. The criteria for both categorisations were as follows: for group I (no depression) the depression rating had to be less than 3 (moderate) in all three phases of the cycle; for group 2 (premenstrual only) the depression rating had to be 3 or more (4 severe, 5 very severe> in the premenstrual week only, with at least a 2-point improve-

13 TABLE

1

CHARACTERISTICS (N = 144)

OF

PARTICIPATING

SUBJECTS

% of N Recategorised group I: No depression 2: Premenstrual depression 3: Premenstrual and menstrual 4: All three phases depression 5: Menstrual only

depression

17 30 40 9 4

Age (vearsi 25-29 30-34 35-39 40-44 > 45

5 31 42 21 1

Number of children 1 2 3 >4

15 61 22 2

Age of youngestchild (years) 15

3 34 23 20 20

(n (n (n (n (n

= = = = =

24) 44) 57) 13) 6)

ment between the premenstrual week and either of the remaining two phases; and for group 3 (premenstrual and menstrual) the depression rating had to be 3 or more in both the premenstrual and menstrual phases, with a 2-point improvement from either of these two phases to the postmenstrual week, which must be less than 3. For the recategorisation two additional groups were required: group 4 for whom moderate to severe depression was reported in all three phases (n = 101, or where it was reported premenstrually and menstrually but there was insufficient improvement during the postmenstrual week to qualify for group 3 (n = 3; the pattern of ratings being 3, 3, 2 for the three phases); and group 5, where moderate to severe depression was reported but only during the menstrual phase. We called these the ‘all three phases’ and the ‘menstrual only’ groups respectively. The result of the recategorisation is shown in Table 1. Eight women (4%) were excluded at this stage because they were currently taking antide-

pressant medication which was likely to affect their current mood pattern (two, two and four subjects from samples 1, 2 and 3 respectively), and a further two women had to be excluded because they could not be recategorised, one (from sample 2) because she had not rated the depression symptom, the other (sample 1) because her ratings of 0, 0, 3 were unclassifiable. Overall 51% of the subjects remained in the same category as they had been 2 years previously (43%, 52% and 59% in the three samples respectively). Analysis

Chi-square was the main method of analysis. For the relationship between raw BDI scores and retrospective depression ratings Spearman’s rank order correlation was used, and ‘within-cycle’ changes in raw BDI scores were analysed separately within groups by the paired t-test. After testing the main hypotheses further exploratory analyses were conducted, some to examine these hypotheses more subtly, others to explore the interrelationships between the various measures. For these the nominal (unadjusted) significance levels have been quoted. For completeness some tables will include percentages based on numbers of less than 15; these will be bracketed to indicate their very low precision. Examination

of possible participation

bias

In accordance with Altman (1984) the interpretation of analyses to check the matching of the sampled and categorised groups, and the associations between subject characteristics and participation at different stages of the study, will err on the side of caution, i.e., findings in such analyses may be considered ‘significant’ at probability levels of 0.10 or occasionally higher, depending on the potential impact on the main analyses. The demographic characteristics of the participants are given in Table 1. For the three ‘participating’ samples (n = 49, 46 and 49) matching was satisfactory, even though four subjects had given birth in the intervening 2 years (but at least 6 months prior to this study). However, after recategorisation (based on current depression ratings), comparison of the three largest groups, 1, 2 and 3, showed matching to be lost for number of

14

children (i.e., group 1 (no depression) were much less likely to have one child and more likely to have two children: 0% and 92% respectively - cf. Table 1; x2 = 12.5, df 4, P = 0.014). Our extensive data for the original survey respondents whom we sampled also allow us to compare participants and non-participants in relation to several variables of potential importance, in particular postnatal depression (PND). In the original survey women indicated whether they had experienced depression after their last childbirth, and if so whether it was ‘moderate’ or ‘severe’. The proportions in the three samples reporting ‘severe’ PND were 6%, 23% and 21%, reflecting very closely the proportions in the panels from which the samples had been drawn. These prevalences are comparable to previous reports, e.g., Cox et al. (1982) reported 13% with disabling depressive illness, and a further 16% with depressive episodes not sufficiently severe to constitute ‘illness’. Table 2 shows the proportions of sampled subjects ‘actually participating’, for each sample as a whole and subclassified according to whether they reported PND after their most recent birth (‘severe’/ ‘moderate’). Although the overall participation rate was very similar in the three samples (47-49%), the last two columns of Table 2

TABLE

show that those reporting PND were most likely to participate if in sample 3, whereas for those not reporting PND participation was highest in sample 1. This bias must be taken into account when interpreting our results. Results Although the rationale of our criteria, with respect to groups 2, 3 and 4, who all reported experiencing depression premenstrually, was to distinguish subjects on the basis of the duration of this depression, it was found that there was also a difference in severity premenstrually across the three groups. There was a trend for group 3 to have the most severe and group 4 the least severe premenstrual ratings, with the proportions rating their depression ‘very severe’ in groups 2,3 and 4 being 27%, 42% and 15% respectively. Thus duration is somewhat confounded with severity, and accordingly our tests of hypotheses involving duration (i.e., the comparison between groups 2, 3 and 4) will also have to take account of secerity . BDI scores The difference between premenstrual postmenstrual BDI scores was calculated

and within

2

PARTICIPATION RATE FOR SUBJECTS POSTNATAL DEPRESSION IN EARLIER All subjects (nl

IN ORIGINAL SURVEY a

SAMPLES

SUBDIVIDED

Numbers reporting moderate/severe PND after most recent birth Subjects reporting PND

Subjects without PND

(n,)

(n*)

ACCORDING

Participation

TO SELF-REPORT

OF

rate

Overall (% of n)

Subjects reporting PND (% of n,)

Subjects without PND (% of n,)

Original sample 1: No depression 2: Premenstrual depression 3: Premenstrual and menstrual depression

101 b 1Olb 101

30 47 49

69 52 52

49 47 49

40 43 51

54 4H 46

All samples combined

303 b

126

173

48

45

50

’ ‘Postnatal depression’ is data obtained in an earlier survey, and relates to most recent birth only. b For each of samples 1 and 2 two subjects have missing data for the PND variable so are excluded from the PND subdivision not from the first and fourth columns (‘overall’).

but

15

categories. The mean differences (*SEM) in groups l-4 were 5.5 (+ 1.41, 11.25 (+ 1.61, 14.6 (&- 1.8) and 3.4 (k 1.7) respectively. Using the paired t-test, significant differences were found in groups 1, 2 and 3 (P = 0.001, 0.000, 0.000 respectively) and a trend in group 4 (P = 0.07). The association between the raw BDI scores and the retrospective depression ratings, utilised to categorise subjects, was assessed for the whole sample (i.e., ignoring categories). In the premenstrual phase there was a strong correlation between the concurrent BDI score (completed at the end of the premenstrual week) and the retrospective rating for the premenstrual week (Spearman r = 0.70, P = O.OOO>, even though for half of the subjects the BDI score covered the premenstrual phase for the menstrual period following that covered by the retrospective ratings (due to balancing of order of administration of premenstrual and postmenstrual measures). For the postmenstrual data the BDI and depression ratings were completed at the same time, for the preceding week, by all subjects; the correlation was somewhat weaker (r = 0.43, P = 0.0001, partly because most of the scores were confined to a lower (and hence narrower) part of the range. The distributions of premenstrual and postmenstrual BDI scores, classified according to the severity ranges given above, are shown in Fig. 1. In both phases there was heterogeneity of distribution across groups (x2 = 54.6, d’ 12, P = 0.0000, and x2 = 19.1, df 8, P= 0.014 respec-

1001 8060% 40. 20-

Groups:

1

2

3

4

All

Premenstrual Phase

1

2

3

Post-menstrual

4

All Phase

Fig. 1. Beck classification of depression by phase and group (0 mild to moderate, 0 moderate to severe; and n severe). Note: The classification ‘no depression’ is not shown, but in each histogram it comprises the remainder of subjects, i.e., its prevalence will make the total up to 100%). In both phases the n’s for the five histograms are in order 24, 44, 57, 13 and 144.

tively, with the moderate/severe and severe classifications combined in the latter analysis). Postmenstrually, group 4 had most subjects classified with some depression, as might be expected, though surprisingly they did not have more ‘high’ scores. Indeed the few women with ‘high’ BDI scores postmenstrually were to be found in groups 2 and 3. Premenstrually, group 3 had the most severe scores, significantly more so than group 2 (x2 = 9.9, df 3, P = 0.019). However, as explained above the potential confounding effect of severity (of premenstrual depression ratings) has to be taken into account in such group comparisons (which seek to assess the effect of duration). When this was done it was found that the prevalence of ‘high’ premenstrual BDI scores was most strongly associated with a grouping based on severity of premenstrual depression ratings (as might be expected from the correlations quoted above), and that duration (in terms of menstrual rating) was relevant if, and only if, the premenstrual ratings were severe. This would explain the excess of ‘high’ BDI scores in group 3 (most of whom have severe ratings, as well as duration) and the relative dearth of ‘high’ scores in group 4 (who have in the main only moderate ratings premenstrually, so that their ‘duration’ is irrelevant). The above findings were essentially unchanged if group 4 was excluded, so it would seem that they are not dependent on ‘cyclicity’ (in the sense of postmenstrual remission). Qualitative criteria for major depressive disorder The percentages of women meeting the ‘short-duration’ RDC criteria for major depressive disorder and for the endogenous subtype are shown in Table 3a, for the group as a whole, and for each of the revised categories (excluding group 5 for whom II is only 6). In the premenstrual week the distributions across groups for both diagnostic categories were heterogeneous (x2 = 25.3, df 4, P = 0.0000 and x2 = 13.5, df 4, P = 0.0089 respectively), but groups 2 and 3 were not significantly different for either variable. In the postmenstrual week, the distribution was not found to be heterogeneous. On investigating the relative contributions of severity and duration, it was found that the likelihood of meeting the diagnostic criteria was re-

16 TABLE

3

PERCENTAGE OF SUBJECTS IN RETROSPECTIVELY RECATEGORISED CRITERIA FOR CURRENT MDD ON THE CSW, (b) REPORTING PREVIOUS DEPRESSION AND COMBINATIONS OF THESE HISTORIES Group 1 No depression (n = 24) % (a) Current RLK diagnosis MDD-positive Premenstrual Postmenstrual Endogenous Premenstrual subtype Postmenstrual

phase phase phase phase

(h) Pust history PND - any _ seeing doctor Treated depression PND only Treated depression only Both PND and treated depression a One subject

had missing

Group 2 Premenstrual depression (n = 44) ‘z/o

Group 3 Premenstrual menstrual depression (II = 57 ;‘I %

8 4 0 0

4x Y 25 2

25 17 4 21 0 4

34 IX 18 27 11 7

data for treated

depression

and postnatal

Group 4 All three phases depression (n = 13) 9%

Overall (incl. group 5) (n = 144) %a

Probability (x2, df 4)

61 10 26 5

(31) (15) (0) (0)

43 10 18 3

P < 0.001 NS P < 0.01 NS

56 30 30 32 7 23

(46) (31) (381 (23) (15) (23)

42 23 22 27 8 14

P = 0.035 NS P = 0.027

+

so for the last four lines of the table group

lated to the severity of the premenstrual depression rating (10% MDD if I mild, 30% if moderate, and 62% if severe; for endogenous subtype the corresponding figures are O%, 6% and 30%), but nor to duration (i.e., persistence of depression menstrually); hence the less marked difference between groups 2 and 3 in this respect. When group 4 (who do not have postmenstrual remission) were excluded these findings were virtually unchanged. There was also a strong association between diagnosis and the severity of the premenstrual BDI score (74% MDD in n = 57 with ‘high’ BDI versus 24% in remainder; 40% versus 3% for subtype). History of treated depression sion

GROUPS (a) MEETING QUALITATIVE TREATED DEPRESSION, POSTNATAL

depres-

Altogether, 31 women (22%) were categorised as having experienced a depressive episode for which they received antidepressant medication. (There were in addition eight women who were excluded from the study because of taking antidepressants at the time of the study.) Sixty women (42%) gave a history of postnatal depression, and

3 n = 56 and total

n = 143.

33 (23%) met the more stringent criterion, that it had resulted in a visit to the doctor. The prevalences of a history of treated depression, of the two levels of postnatal depression, and of combinations of these histories are shown in Table 3b for the four largest recategorised groups and for the study as a whole. For cases of treated depression the distribution shows a significant trend in the expected direction (x2 = 10.95, df 4, P = 0.027). However, the chi-square arises partly from the highest and lowest prevalences occurring in groups 4 and 5, the ‘all three phases’ and ‘menstrual only’ categories respectively, and the difference between groups 2 and 3 is not significant. For postnatal depression there is a similar pattern of prevalences (x2 = 10.3, df 4, P = 0.035) though in this case group 3 has a significantly higher proportion than group 2 (x2 = 4.85, df 1, P = 0.03). When the stricter criterion for postnatal depression, of seeing a doctor, is applied, the overall trend is weaker and not statistically significant. In contrast to treated depression, for both postnatal criteria there is quite a high prevalence

17

among group 1 subjects who currently report no, or only mild, depression premenstrually. There was an association between the two types of history (13% treated depression in those who did not report PND compared to 34% in those who did: x2 = 16.3, df 1, n = 142, P = 0.001). The interaction of the two types of depressive histories with group is shown at the bottom of Table 3b where it can be seen that the marked excess of postnatal depression in group 3 is largely attributable to those subjects with past histories of both postnatal depression and treated depression. Once again it is pertinent to consider whether the association with previous depressive history is dependent on the severity or the duration of the current perimenstrual mood change. Groups 2 and 3, which distinguish subjects on the basis of the duration of their premenstrual depression, can be further subdivided according to whether their premenstrual depression is moderate or severe. The prevalences of the depressive histories across these subgroupings is shown in Fig. 2. For ‘treated depression’ (Fig. 2a) the greatest difference was between groups 2 and 3, regardless of severity (i.e., between groupings based on duration only). For postnatal depression however, in addition to the differences in prevalence between groups 2 and 3 (possibly attributable to duration), there were differences of approximately the same

Fig. 2. Prevalence of depressive histories by group and severity of premenstrual depression (0 moderate, n = 13 and 14 in groups 2 and 3 respectively, and w severe/very severe, n = 31 and 42 respectively).

magnitude within each group, between the subgroupings based on severity (Fig. 2b). Taking these two associations together, it is not surprising that the prevalence of the combination of both histories (Fig. 2c) was markedly higher in those subjects experiencing both duration and severity, i.e., group 3 members with severe premenstrual ratings. On the other hand, if we consider those women with a history of postnatal depression only (i.e., who have been depressed postnatally but have never received antidepressants for depression), we find that they are most prevalent in the subgroupings with severe premenstrual ratings, with overall group (i.e., duration) being irrelevant (Fig. 2d). In all four analyses if group 4 members are included with group 3 the picture remains unchanged, so here also the findings do not appear to be dependent on postmenstrual remission. Thus in predicting prevalences of past history of ‘treated depression’ one would not expect either BDI score or the qualitative diagnostic criteria (each reflecting severity) to add anything further to the group categorisation (based on duration), and this is in fact the case. Prediction of history of any postnatal depression, on the other hand, is related to each of the three variables (for RDC, x2 = 7.4, df 1, P = 0.007; for subtype, x2 = 8.3, df 1, P = 0.004; and for premenstrual BDI, x2 = 23.4, df 1, P = 0.0007) and thus each can improve prediction when additional to the recategorised grouping. For example in group 3 all but one of the 15 subjects with a diagnosis of endogenous subtype reported a previous postnatal depression (93%), compared to 43% of the remainder. The premenstrual BDI, on its own, was the best predictor of previous history of postnatal depression, better than the group categorisation. Prevalences ranged from 23% in those with the lowest BDI classification, to 57% in those with ‘moderate to severe’ and 73% in those with ‘severe’ scores. Follow-up study: prospective assessment The objective of the follow-up was to ascertain whether prospective assessment and categorisation would yield substantially different findings to those obtained with retrospective data. In fact, confining our consideration to those 85 women

18

who completed both the main part of the study and the follow-up, there was striking similarity in findings for the main hypotheses regardless of whether retrospective or prospective classification was used, or whether analysis was confined to the subgroup of 57 (67%) women who prospectively ‘confirmed’ their retrospective categorisation. Discussion We have found associations between previous history of postnatal depression, treated depression and current perimenstrual depression which are of potential importance. Before discussing these associations in more detail, let us first consider the principal methodological issues in this study. The sample The phenomenon of cycle-related fluctuation in physical and emotional wellbeing (PMS) straddles the boundary between health and illness. As is common in such situations much of the research into PMS has involved clinic attenders: from PMS clinics (e.g., Stout et al., 1986; Dennerstein et al., 1988; Mira et al., 1985); psychiatric clinics (e.g., Halbreich and Endicott, 1985; RoyByrne et al., 1986); and other hospital clinics (e.g., Kashiwagi et al., 1976). Yet the selection factors determining which sufferers seek help, and at which clinics (cf. Sackett, 1977, ‘referral filter bias’) are seldom considered when interpreting the results of such studies. Where community samples have been utilised there has generally been some deficit: only a subset of the sample has been utilised (e.g., those with depressive symptoms by Blazer et al., 1988); PMS has not been properly assessed in the community sample (e.g., Blazer et al., 1988; Stout et al., 1986); or depressive illness has not been assessed (Hallman, 1986; Coppen and Kessel, 1963). Advertising for ‘volunteer’ subjects is common in PMS research, either by means of ‘posted notices’ in health clinics, colleges, etc. (e.g., Dennerstein et al., 1988; Halbreich and Endicott, 1985; van den Akker and Steptoe, 1985), or via advertisements in newspapers or magazines (e.g., Keye et al., 1986; Clare, 1983; Mackenzie et al.,

1986; Haskett et al., 1980; Roy-Byrne et al., 1986; Mira et al., 1985). In such cases it is impossible to gauge the extent or nature of the target population and the factors influencing those who respond. In both clinic and non-clinic studies a further concern is the lack of reporting on the characteristics of those failing to complete, or excluded. In our survey (Warner and Bancroft, 1990) all readers were encouraged to participate, and as the questionnaire was published in the magazine, motivated readers could participate ‘at a safe distance’ merely by completing and mailing the questionnaire. In this present study we had the extensive data for this ‘population’, both to select samples matched for various demographic variables and, with scope unusual in other studies, to check for participation biases. The only bias that we identified as of concern was the difference in participation rates within our groups depending on whether or not postnatal depression had been reported for the last birth. This bias would strengthen the association between PND and group membership, slightly increasing the gradient from group 1 to group 3. Unfortunately we are not able to assess such bias in relation to a history of ‘treated depression’. Selection of PMS subjects There is little consensus on how many or which symptoms must be ‘cyclical’ for diagnosis of PMS. Sometimes the average of a number of symptoms is used (Roy-Byrne et al. (1986) and De Jong et al. (1985) took the mean for three moods including depression) but this has unpredictable outcome in the case of subjects experiencing both cyclic and non-cyclic symptoms. Furthermore there is every likelihood that there are differing aetiologies for the various symptoms experienced (Bancroft and Backstrom, 1985). Clare (1983), for example, found psychiatric status to be related to premenstrual mood but not physical symptoms. Selecting subjects on the basis of any one or more of a number of ‘PMS’ symptoms increases the likelihood of samples with heterogeneous aetiologies. Our categorisation of subjects on the basis of just one symptom, ‘feel depressed’, is an important distinction between this study and others. In fact,

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only 5% of our subjects believed that they were not PMS sufferers and the vast majority of the remainder gave retrospective reports of symptoms corroborative of PMS. Thus this is in effect a study of self-designated PMS sufferers, categorised according to the occurrence and duration of premenstrual depression. Our findings, of marked differences across these categories with respect to depressive history, emphasise the importance of categorisation based on specific symptoms. In addition our findings illustrate the importance of dividing the ‘non-cyclic’ subjects into those with ‘no symptom’ (i.e., group 1) and ‘prolonged symptom’ (i.e., group 4). In a number of previous reports these have been lumped together as ‘non-PMS’. On the other hand our findings do raise questions about the requirement for postmenstrual remission found in many definitions of ‘cyclicity’/PMS and in our criteria for categorisation as group 2 or 3. Although the size of group 4 was small it is noteworthy that the associations of BDI scores, qualitative characteristics of depression and history of postnatal depression with severity of premenstrual depression rating were unchanged whether or not the analysis included these group 4 subjects (who do not have such remission), and that the prevalence of a history of treated depression increased steadily with duration of perimenstrual depression, from group 2 to 3 to 4. This suggests that ‘cyclicity’, in terms of postmenstrual remission, may not be an important distinction with regard to the relevance of the premenstrual symptom of depression. Retrospective versus prospective assessment Although it is often stated that prospective ratings are necessary for the assessment of PMS, the scientific ‘cost’ of this requirement is seldom considered. Firstly there is commonly a high attrition rate when daily record keeping is requested, particularly in non-clinic samples (41% in our study). This potential for participation bias is often ignored when generalising from small samples of prospectively assessed subjects. We found that subjects who completed the prospective ‘follow-up’ ratings of this study were biased with respect to initial sample (more likely to be from sample 1); current RDC subtype (less likely to be

‘endogenous’, P = 0.019); and history of treated depression (less likely to have such a history, P = 0.08). Secondly, although it is held that prospective ratings should continue for two or more cycles, there is no consensus on how to deal with intercycle variability. In accordance with Hart et al. (1987) and Clare (1983) we found marked variability between cycles in our prospective assessment (only 23% of subjects were consistent enough to be prospectively categorised, and even if retrospective category was taken as a ‘casting vote’, where at least one of the prospective cycles matched it, there remained 24% who could not be categorised). Since the aetiologies of PMS are not yet identified, to demand consistency of pattern across cycles (or to average across cycles, which indirectly imposes the same condition) would be to pre-empt the findings of PMS research. Furthermore this inter-cycle variability may reflect an inherent and perhaps excessive ‘noisiness’ in prospective ratings. Indeed we found less consistency between categorisations based on prospective depression ratings of successive cycles (23%) than between categorisations based on retrospective perimenstrual ratings of cycles 2 years apart (51% of subjects were identically categorised for ‘sample’ and ‘group’). Support for our subjects’ retrospective depression ratings was also found in their significant correlations with ‘current BDI scores’ obtained for the premenstrual and postmenstrual weeks (over the whole study sample). Thus for retrospective depression ratings we concur with Hart et al. (1987) who concluded that a subject’s retrospective report of PMS symptomatology for a specific recent cycle is more accurate than has been thought. Some of the ill-repute of retrospective report, in particular the failure of prospective reports to ‘confirm’ retrospective ratings, may be accounted for by the methodological issues considered above: ratings not for a specific recent cycle; combining of symptoms; averaging across cycles; inter-cycle variability (or prospective ‘noise’); selection biases resulting from high attrition rates; mixing of subjects with ‘no symptoms’ and ‘prolonged symptoms’; and the arithmetic method of summarising prospective data, in particular where

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symptoms persist into menses. The disadvantages of using prospective ratings have to be carefully weighed against any real disadvantages of retrospective ratings. In our study there are clear-cut disadvantages of prospective assessment (i.e., halving of sample and further introduction of bias). On the other hand we found evidence in support of our subjects’ retrospective reports, and, most importantly, that there were strikingly similar findings for the main hypotheses in the followup sample regardless of whether prospective or retrospective categorisation was used. We have therefore concluded that findings should be reported for the whole study sample, retrospectively categorised. However, in future research there is clearly a need for retrospective methods of assessment to be further improved and validated. Assessment of depressive illness Whereas our results indicate reasonable validity for retrospective accounts of a very recent menstrual period, the use of retrospective accounts to establish a lifetime prevalence of depressive episodes, and to further distinguish between recurrent premenstrual depression, dysthymia or major depressive disorder occurring many years before, is another matter. In this study, by using our criterion of ‘treated depression’, i.e., the use of antidepressant medication for a minimum of 3 weeks, we have reduced the likelihood that our subjects confounded a past history of depressive illness with a past history of recurrent perimenstrual depression. Such an operational definition does depend firstly on the subject seeking (and accepting) treatment when necessary, and secondly on her general practitioner’s criterion for prescribing antidepressants. However, it is unlikely that antidepressants would be prescribed for women who are free from depression for a substantial part of the month. Our criteria for ‘postnatal depression’ are less rigorous than for ‘treated depression’. The form of questions makes it unlikely that postnatal depression was confused with ‘baby blues’, but it is certainly possible that perimenstrual depression, returning with menstrual cyclicity after childbirth, became confused with postnatal depression in some cases. However, the prevalences reported

above for the most recent birth (6-23%) are comparable to those reported by Cox et al. (1982) and others (O’Hara, 1987). The lifetime prevalences reported in Table 3 (for all births) are higher, as would be expected, but are conservative compared to ‘lifetime’ rates reported by Dennerstein et al. (1988; 63% in PMS subjects and 41% in controls). With these methodological considerations in mind, let us now discuss the main findings of the study. The degree and quality of perimenstrual depression We have assessed the severity of the perimenstrual depression by means of the BDI. This indicates that for many of these women the premenstrual mood change is severe. In group 3, 28% had scores in the severe range and 37% in the moderate to severe range of clinical depression, while in group 2 the percentages were 9% and 27% respectively. Such BDI scores were found to be related primarily to the severity of premenstrual depression ratings, and only if these were severe, also to duration (as reflected by menstrual ratings for depression). Our Current State of Wellbeing Questionnaire was initially tested in a small sample so we should be cautious in interpreting findings based on it until it has been tested further for validity and reliability. However the CSW did indicate that many of these women were experiencing mood change qualitatively similar to that of major depressive disorder. The presence of qualitative characteristics was related to the severity of the premenstrual depression, which is in keeping with Stout et al.‘s (1986) observation that it was duration rather than severity that distinguished premenstrual affective disorders from MDD. The association between perimenstrual depression and previous depressive illness We have shown that women reporting moderate to severe perimenstrual depression (i.e., categorised as either group 2 or 3) are more likely than those without such depression to have a previous history of ‘treated’ depression and postnatal depression. The novel hypothesis that we tested concerned the association between the duration of perimenstrual depression and a past

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history of depressive illness; in particular that the association would be greatest in those women whose perimenstrual depression persists through the menstrual phase (i.e., qualifying them for group 3). As far as a history of treated depression was concerned, the difference was not particularly between groups 2 and 3, but rather an ordinal increase from group 1 to group 4. When we investigated the relative contributions of severity and duration it was found that only duration was important. Thus a history of treated depression, as defined, is related to the current duration of premenstrual depression, and over and above this, is not related to its current quality or severity. However we need to qualify this support for our original hypothesis, in that such a history is more likely to be found among women who report premenstrual depression that persists during menstruation or even, in some cases, into the postmenstrual phase. When we consider our concept of postnatal depression a rather different picture emerges, with prevalence related to both duration and severity, to the extent that the prevalence in group 3 was significantly greater than in group 2. However if we consider just those women in groups 2, 3 and 4 with a history of postnatal but not treated depression (i.e., excluding those women for whom it is possible the PND was the result of a general propensity for depressive illness rather than a specific sequel to parturition), we find an association with severity but not with duration. This suggests a more specific link between postnatal depression and marked premenstrual depressive mood change. The possibility of a hormonal link between premenstrual syndrome and postnatal depression has been considered (Dalton, 1971; Steiner, 1979; O’Hara, 1987; Dennerstein et al., 1988). However, very few studies assessing concurrent postnatal depression have assessed pre-pregnancy PMS, and only Playfair and Gowers (1981) report an association between some (undefined) assessment of earlier PMS and current PND. Given that the modal age for onset of PMS is in the mid-thirties after the modal age for childbearing (i.e., the twenties), this is not surprising. By comparison, there is somewhat stronger evidence of a link between PND and pre-pregnancy dysmenor-

rhoea, classically a complaint of early adulthood (Playfair and Gowers, 1981; Pitt, 1968; Jacobson et al., 1965). Interestingly, when the link is explored in the reverse direction, there is evidence of PMS following postnatal depression (Dennerstein et al., 1988). Heggarty (1955) coined the name ‘postpuerperal recurrent depression’ for the premenstrual recurrences of depression, irritability and tension in women who had suffered PND. Dalton (1980) concludes that there is a 90% chance of developing PMS after PND. Most other studies relating current PMS status and past psychiatric health do not distinguish PND from other types of depressive illness. Our study is unique in relating PND specifically to perimenstrual depression. Our finding of an association between past PND and the quality and severity of current premenstrual depression increases the likelihood of an aetiological link, although the nature of that link, and the extent to which it is neuroendocrine or psychologically mediated, requires further elucidation. Conclusion The results reported above indicate two dimensions to perimenstrual depression: one the severity of the premenstrual depression, regardless of duration or indeed whether or not there is postmenstrual remission, the other the tendency for the mood change to be prolonged, regardless of its premenstrual severity. The fact that these dimensions were differently related to the qualitative and quantitative measures of current depressive experience, and to past histories of depression, suggests that they are independent. This leads us tentatively to the conclusion that in understanding perimenstrual depression we have at least two mechanisms to consider. One is the effect of the menstrual cycle, and in particular its premenstrual phase, on a woman’s wellbeing. During the premenstrual phase there is a susceptibility to dysphoria which in some women can be severe and disabling. In this present study our results suggest that amongst women experiencing premenstrual dysphoria those with the severest premenstrual reaction are most likely to have experienced depressive mood change after childbirth, possibly reflecting some common aeti-

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ological, neuroendocrine mechanism. Evidence for the other mechanism is the persistent depressed mood seen in some subjects perimenstrually, and the fact that it is these subjects, regardless of the severity of their premenstrual depression, who are particularly likely to have a history of treated depression. This propensity for depressive illness, found in a minority of women, may act together with the above menstrual cycle mechanism to render some women vulnerable to depressed mood that is severe premenstrually and prolonged into the menstrual phase or beyond. Future research will need to examine this distinction between different types of depressive illness and different patterns of perimenstrual mood change. Our proper understanding of this complex but important problem depends on appropriate longitudinal studies being carried out. References Altman, D.G. (1984) A fair trial? Br. Med. J. 289, 336-337. Bancroft, J. and Backstrom, T. (1985) The premenstrual syndrome. Clin. Endocrinol. 22, 313-336. Bancroft, J., Cook, A. and Williamson, L. (1988) Food craving, mood and the menstrual cycle. Psychol. Med. 18, 855-860. Beck, A.T., Steer, R.A. and Garbin, M.G. (1988) Psychometric properties of the Beck Depression Inventory: 25 years of evaluation. Clin. Psychol. Rev. 8, 77-100. Blazer, D., Swartz, M., Woodbury, M., Manton, K.G., Hughes, D. and George, L.K. (1988) Depressive symptoms and depressive diagnoses in a community population. Arch. Gen. Psychiatry 45, 1078-1084. Clare, A.W. (1983) Psychiatric and social aspects of premenstrual complaint. Psychol. Med. Monogr. Suppl. 4. Cambridge University Press, Cambridge. Coppen, A. and Kessel, N. (1963) Menstruation and personality. Br. J. Psychiatry 109, 711-721. Cox, J.L., Connor, Y.M and Kendell, R.E. (1982) Prospective study of the psychiatric disorders of childbirth. Br. J. Psychiatry 140, 111-117. Dalton, K. (1971) Prospective study into puerperal depression. Br. J. Psychiatry 118, 689-692. Dalton, K. (1980) Depression after Childbirth. Oxford University Press, Oxford. De Jong, R., Rubinow, D.R., Roy-Byrne, P., Hoban, C., Grover, G.N. and Post, R.M. (19851 Premenstrual mood disorder and psychiatric illness. Am. J. Psychiatry 142, 1359-1361. Dennerstein, L., Morse, CA. and Varnavides, K. (1988) Premenstrual tension and depression - is there a relationship? J. Psychosom. Obstet. Gynaecol. 8, 45-52.

Endicott, J., Halbreich, U., Schacht, S. and Nee, J. (1981) Premenstrual changes and affective disorders. Psychosom. Med. 43, 519-529. Halbreich, U. and Endicott, J. (1985) The relationship of dysphoric premenstrual changes to depressive disorder. Acta Psychiatr. Stand. 71, 331-338. Hallman, J. (1986) The premenstrual syndrome - an equivalent of depression? Acta Psychiatr. Stand. 73, 403-411. Hart, W.G., Coleman, G.J. and Russell, J.W. (1987) Assessment of premenstrual symptomatology: a re-evaluation of the predictive validity of self-report. J. Psychosom. Res. 31, 185-190. Haskett, R.F., Steiner, M., Osman, J.N. and Carroll, B.J. (1980) Severe premenstrual tension: delineation of a syndrome. Biol. Psychiatry 15, 121-139. Heggarty, A.B. (1955) Post-puerperal recurrent depression. Br. Med. J. 1, 637-640. Jacobson, L., Kaij, L. and Nilsson, A. (1965) Postpartum mental disorders in an unselected sample: frequency of symptoms and predisposing factors. Br. Med. J. 26, 16401643. Kashiwagi, T., McClure, J.N. and Wetzell, R.D. (1976) Premenstrual affective syndrome and psychiatric disorder. Dis. Nerv. Syst. 37, 116-119. Keye, W.R. Jr., Hammond, D.C. and Strang, T. (1986) Medical and psychological characteristics of women presenting with premenstrual symptoms. Obstet. Gynaecol. 68, 634637. Mackenzie, T.B., Wilcox, K. and Brown, H. (1986) Life time prevalence of psychiatric disorders in women with perimenstrual difficulties. J. Affect. Disord. 10, 15-19. Mira, M., Vizzard, J. and Abraham, S. (1985) Personality characteristics in the menstrual cycle. J. Psychosom. Obstet. Gynaecol. 4, 329-334. Moos, R. (1968) The development of a menstrual distress questionnaire. Psychosom. Med. 3, 853-867. O’Hara, M.W. (1987) Post-partum ‘blues’, depression and psychosis: a review. J. Psychosom. Obstet. Gynaecol. 7, 205-227. Parker, G. (1987) Are lifetime prevalence estimates in the ECA study accurate? Psychol. Med. 17, 275-282. Pitt, B. (1968) ‘Atypical’ depression following childbirth. Br. J. Psychiatry 144, 1325-1335. Playfair, H.R. and Gowers, J.I. (19811 Depression following childbirth - a search for predictive signs. J.R. Coil. Gen. Pratt. 31, 201-207. Reiger, D.A., Boyd, J.H., Burke, J.D., Rae, D.S., Kramer, M., Robins, L., George, L.K., Karno, M. and Lock, B.T. (1988) One month prevalence of mental disorder in the United States. Arch. Gen. Psychiatry 45, 977-986. Roy-Byrne, P.P., Rubinow, D.R., Hoban, M.C., Parry, B.L., Rosenthal, N.E., Nurnberger, J.I. and Byrnes, S. (1986) Premenstrual changes: a comparison of five populations. Psychiatry Res. 17, 77-85. Sackett, D.L. (1979) Bias in analytic research. J. Chronic Dis. 32, 51-63. Sampson, G.A. (1987) Premenstrual syndrome: characterisation, therapies and the law. In: B.E. Ginsburg and B.F.

23 Carter (Eds.), Premenstrual Syndrome; Ethical and Legal Implications in a Biomedical Perspective. Plenum, New York, NY, pp. 301-312. Spitzer, R.L., Endicott, J. and Robins, E. (1978) Research Diagnostic Criteria: rationale and reliability. Arch. Gen. Psychiatry 35, 773-782. Steiner, M. (1979) Psychobiology of mental disorders associated with childbearing. Acta Psychiatr. Stand. 60, 449-464. Steiner, M. and Haskett, R.F. (1987) The psychobiology of premenstrual syndrome: the Michigan Studies. In: B.E. Ginsburg and B.F. Carter (Eds.), Premenstrual Syndrome; Ethical and Legal Implications in a Biomedical Perspective. Plenum, New York, NY. pp. 369-385.

Stout, A.L., Steege, J.F., Blazer, D.G. and George, L.K. (1986) Comparison of lifetime psychiatric diagnoses in premenstrual syndrome clinic and community samples. J. Nerv. Ment. Dis. 174, 517-522. Van den Akker, 0. and Steptoe, A. (1985) The pattern and prevalence of symptoms during the menstrual cycle. Br. J. Psychiatry 147, 164-169. Walker, A. and Bancroft, J. (1990) The relationship between premenstrual symptoms and oral contraceptive use: a controlled study. Psychosom. Med. 52, 86-96. Warner, P. and Bancroft, J. (1990) Factors related to self-report of premenstrual syndrome. Br. J. Psychiatry 157, 249-260.

The relationship between perimenstrual depressive mood and depressive illness.

In a study of 144 women, mainly self-designated PMS sufferers, the premenstrual depression experienced was, apart from its shorter duration, quantitat...
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