CO-MORBID DEPRESSION AND DRINKING OUTCOME IN THOSE WITH ALCOHOL DEPENDENCE

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1 Alcohol & Alcoholism Vol. 33, No. 5, pp. 482^87, 1998 CO-MORBID DEPRESSION AND DRINKING OUTCOME IN THOSE WITH ALCOHOL DEPENDENCE KATE M. DAVIDSON* and IVY M. BLACKBURN 1 Alcohol Problems Clinic, Royal Edinburgh Hospital, Edinburgh EH 10 5HF and 'Collingwood Clinic, Cognitive and Behavioural Therapies Centre, St Nicholas Hospital, Gosforth, Newcastle upon Tyne NE3 3XT, UK (Received 15 October 1997; in revised form 17 February 1998; accepted 3 March 1998) Abstract Depressed and non-depressed (pre-admission and post-detoxification) alcohol-dependent patients were followed-up on two occasions over a period of 5 months following detoxification from alcohol. Detailed measures of alcohol consumption, alcohol-related problems and abstinence status were taken throughout the follow-up period. No significant differences were found between those with a diagnosis of depression and those with alcohol dependence alone, regardless of whether diagnosis of depression was made post-detoxification or pre-admission, on any drinking outcome measure including abstinence status, alcohol consumption, pattern of drinking, or alcohol-related problems. Neither a diagnosis of depression in the post-detoxification period nor in the pre-admission episode was related to drinking outcome at follow-up, which suggests that co-morbid depression does not confer a worse outcome in those with alcohol dependence. INTRODUCTION Co-morbid psychiatric disorders, especially a diagnosis of affective disorder, are common in individuals with alcohol dependence (Halikas et al., 1981; Powell et al., 1982; O'Sullivan et al., 1983; Schuckit, 1985; Hesselbrock et al., 1985; Herz et al., 1990), but the relevance of depression in determining drinking outcome for individuals remains unclear. O'Sullivan et al. (1988) reported that patients with a lifetime diagnosis of unipolar affective disorder and alcoholism had received significantly more treatment for drinking bouts than patients with alcoholism alone or those with alcoholism and bipolar affective disorder over a 2-year period, suggesting that those with a lifetime diagnosis of depression in addition to alcoholism had a poorer outcome than those with alcoholism alone. However, there were no significant differences in the rate of abstinence, or in the number of days drinking between the groups at follow-up, despite exposure to extra treatment in the affectively disordered group. 'Author to whom correspondence should be addressed at Department of Psychological Medicine, University of Glasgow, Gartnavel Royal Hospital, 1055 Great Western Road, Glasgow G12 0XH, UK. In a 1-year follow-up study of alcoholics, Rounsaville et al. (1987) found that outcome differed for men and women and depended on lifetime diagnosis of additional disorders. Men with depression, drug users, and those with 'other diagnoses' had a worse prognosis in terms of receiving more treatment for alcohol problems, drinking more frequently and more heavily, and scoring more highly on a personality inventory at follow-up than the group with no additional disorders. Women, in contrast to men, showed a worse drinking outcome if they had no additional lifetime disorders, indicating better outcome for women with a lifetime, including current diagnosis, of major depression. In a further follow-up of the same patients over an additional 2 years, comorbid depression was associated with reduced intensity of drinking, but no gender differences were found in outcome measures (Kranzler et al., 1996). Few studies have examined the effect of current mood state on drinking outcome. In a postal follow-up investigation of the relationship between the severity of depressive symptomatology and excessive drinking and drug use, Hatsukami and Pickens (1982) found that relapse rate and self-rated depressive symptomatology increased over time and that those who had Medical Council on Alcoholism

2 CO-MORBID DEPRESSION AND DRINKING OUTCOME 483 remained abstinent from drug and/or alcohol use had significantly lower rates of depressive symptomatology than those who had relapsed. The above authors also found that the severity of depressive symptoms did not increase over time. Hasin et al. (1989, 1996) followed-up depressed male and female patients who had a current diagnosis of alcoholism over a 2- and a 5-year period to investigate remission from alcoholism. Longer follow-up, over 5 years, indicated a better outcome for depression associated with remission of alcoholism (Hasin et al., 1996). This study did not compare those with alcoholism and depression to those with alcoholism alone, so the effect of depression on outcome cannot be fully evaluated. Additionally, no information was given on alcohol consumption or degree of depression during outcome and this, in combination with a categorical definition of remission and relapse, limited the analysis of change in drinking and in depression over time. Although there are indications that those with alcoholism and an additional lifetime diagnosis of affective disorder may receive additional alcoholrelated treatment, compared to those with alcoholism alone, the pattern of alcohol consumption at follow-up appears to vary depending on the study and it remains unclear in what way drinking outcome is influenced by co-morbid pre-admission and post-detoxification diagnoses. The present study evaluated the prognostic significance of a current, as well as pre-admission, diagnosis of depression using multiple measures of drinking outcome for those with alcohol dependence. SUBJECTS AND METHODS Subjects This paper describes the drinking outcome of subjects who have been described in an earlier paper (Davidson, 1995). The sample consisted of 82 subjects, 55 men (67%) and 27 women (33%), with a mean age (±SD) of 41.1 ± All subjects had completed a 3-week admission to a city-centre clinic for alcohol problems. Of the original 82 patients, a total of 74 individuals (90%) attended at least one of the two follow-up assessments. Sixty-four patients (78%) attended for first follow-up 6 weeks after discharge and 68 (83%) attended the second follow-up 22 weeks following discharge. No significant differences were found between those who attended and those who did not attend follow-up in terms of gender [48 men and 26 women who attended vs 7 men and 1 woman who did not attend (x 2 = 0.81, d.f. 1, )], or in terms of post-detoxification diagnosis [no depression vs minor and major depression (combined) (j; 2 = 0.00, d.f. 1, )], or preadmission diagnosis [minor and no depression (combined) vs major depression (/ 2 = 0.00, d.f. 1, )]. Diagnosis The present study separated out the effect of having a diagnosis of depression in the postdetoxification period from pre-admission diagnosis of depression, as it was hypothesized that current psychopathology is more likely to be reliably assessed (Andreasen et al., 1981) and is more likely to influence short-term behaviour than an episode of illness which may have arisen in the more distant past. The Schedule for Affective Disorders and Schizophrenia (SADS regular version; Endicott and Spitzer, 1978) was administered and Research Diagnostic Criteria (RDC; Spitzer et al., 1978) were applied to obtain a diagnosis of depression. All patients were abstinent from alcohol for at least 7 days (range 7-10 days) prior to the SADS interview. For each patient, diagnoses were obtained for both the current episode 'at its worst' (before admission) and for the time interval between onset of abstinence and the SADS interview (post-detoxification diagnosis). Information on alcohol consumption Information on alcohol consumption at followup was obtained using the retrospective diary method: for each follow-up period, patients were asked to recall the type and quantity of alcohol consumed in the past week and whether or not this pattern was typical in the reference follow-up period. Any variations were noted. A calendar was provided to help the patients in remembering dates and events on which they could base their recall of drinking. The principal investigator completed the retrospective assessment of the patient's drinking and then showed the assessment to the patient in order to check the information. From this information, the number of units of alcohol consumed (1 U = 8 g) was estimated. Abstinence

3 484 K. M. DAVIDSON and I. M. BLACKBURN Table 1. Relationship between abstinence from alcohol at follow-up and pre-admission and post-detoxification diagnosis of depression Pre-admission diagnosis Minor and no depression Major depression First follow-up (n = 64) Second follow-up (n = 68) Post-detoxification diagnosis No depression Major and minor depression First follow-up (n 64) Second follow-up (n = 68) OO OO was defined as continuous self-report of no alcohol consumption within each follow-up period being assessed. Alcohol-related problems Patients who had been consuming alcohol during the follow-up period were asked whether or not their drinking had resulted in any problems for them in the intervening period. Details of type and number of alcohol-related problems were noted in terms of categories specified in the SADS. Social problems (n = 7) included items such as difficulties with family or friends because of drinking, physical violence associated with drinking, and being picked up by the police because of drinking. Problems associated with physical dependency (n = 10) included items such as memory loss for events that occurred while conscious during a drinking episode, tremors due to drinking and having a seizure after stopping drinking. RESULTS Abstinence and diagnosis of depression The RDC for definite and probable major depressive disorder were combined for the purposes of analysing data. Table 1 shows that there was no relationship between post-detoxification diagnosis of depression (major and minor depression combined) and abstinence status at first follow-up (y 2 = 0.00, d.f. 1, ) or at second follow-up (y 2 = 0.00, d.f. 1, ), and that there was alsq no significant relationship between preadmission diagnosis (minor and no depression combined) and abstinence at first follow-up (/ 2 = 0.06, d.f. 1, ) or at second follow-up (X 2 = 0.21, d.f. 1, ). The remaining analyses concern those who reported consumption of alcohol during follow-up. Relationship between pre-admission and postdetoxification diagnostic groups and alcoholrelated variables at outcome One-way analysis of variance was used to analyse all variables in Tables 2 and 3. Pre-admission diagnostic groups. For the 55 patients known to have relapsed, there were no significant differences between the pre-admission diagnostic groups on any of the drinking measures (number of days to the first drink, number of days drinking in the first or second follow-up period, total quantity of units of alcohol consumed during the first or second follow-up, number of units of alcohol consumed on the heaviest drinking day or on the lightest drinking day at first or second follow-up). Post-detoxification diagnostic groups. Results for the post-detoxification diagnostic groups show the same pattern as above, namely no significant difference was found between the three postdetoxification diagnostic groups on any of the drinking outcome measures (number of days to the first drink, number of days drinking in the first or second follow-up period, total quantity of units of

4 CO-MORBID DEPRESSION AND DRINKING OUTCOME 485 Table 2. outcome at first and second follow-up for the pre-admission and post-detoxification diagnostic groups No depression Minor depression Major depression F d.f. P First follow-up: Pre-admission (n) Post-detoxification (n) No. of days from discharge to first drink No. of days drinking Total no. of units of alcohol drunk No. of units drunk on heaviest day No. of units drunk on lightest day Second follow-up: Pre-admission (n) Post-detoxification (n) No. of days drinking at second follow-up Total no. of units of alcohol drunk No. of units drunk on heaviest day No. of units drunk on lightest day n = 10/9/ (34.0) 23.1 (29.0) 7.0 (8.3) 9.4 (8.6) 64.3 (47.9) (179.1) 22.0 (15.2) 27.0 (14.9) 6.5 (7.6) 8.0 (8.3) (40.8) 51.0 (48.1) (971.9) (687.6) 26.5 (13.6) 25.1 (14.8) 12.7 (14.5) 9.1 (12.5) (5.7) 34.1 (54.0) 6.0 (4.1) 7.3 (6.8) 50.0 (31.5) 66.4(42.1) 16.5 (9.1) 20.1 (17.4) 6.8 (7.8) 4.0 (3.4) (573) 58.5(41.3) (637.1) 01.8 (1527.2) 25.7 (13.6) 28.2 (17.3) 4.9 (3.4) 8.9 (4.7) (14.7) 18.4 (37.5) 13.4 (22.0) 27.4 (47.3) (170.5) 160.2(5.9) 26.7 (15.5) 21.8 (.2) 7.2 (73) 8.0 (6.2) (43.0) 50.0 (43.0) (9773) (763.8) 26.6 (17.6) 30.3 (20.9) 93 (10.7) 9.9 (9.5) ^2 2,52 2^2 2,52 2^2 2,52 2^1 2,51 n_s. The figures in bold denote pre-admission values. alcohol consumed during the first or second follow-up, number of units of alcohol consumed on the heaviest drinking day or on the lightest drinking day at first or second follow-up). In addition, factorial analyses of variance revealed no significant interactions between gender and either pre-admission or post-detoxification diagnosis on any of the drinking outcome measures at followup. Alcohol-related problems Table 3 shows the number of alcohol-related problems for the three post-detoxification and preadmission diagnostic groups across the total length of outcome. The groups were not significantly differentiated from each other in the number of alcohol-related problems (post-detoxification diagnosis: F = 0., d.f. 2,71, ; pre-admission diagnosis: f = 0.19, d.f. 2,71, ). Similarly, the groups at outcome were not differentiated by the number of physical dependency problems (postdetoxification diagnosis: F = 0.03, d.f. 2,71, ; pre-admission diagnosis: F=0.03, d.f. 2,71, ) or in the number of alcohol-related social problems (post-detoxification diagnosis: F= 1.08, d.f. 2,71, ; pre-admission diagnosis: F = 0., d.f. 2,71, ). Factorial analyses of variance revealed no significant interactions between gender and either pre-admission or postdetoxification diagnoses on any of the above measures of alcohol-related problems. DISCUSSION No differences were found between either postdetoxification or pre-admission diagnostic groups in terms of abstinence rates and, for those who had relapsed, no differences were found in the time to the first drink, quantity and pattern, or consequences, of alcohol consumption. Those with alcohol dependence alone did not differ on drinking outcome measures from those with minor or major depression, regardless of whether this was depression diagnosed in the post-detoxification period or as a pre-admission diagnosis. Those who were depressed after detoxification

5 486 K. M. DAVIDSON and I. M. BLACKBURN Table 3. Alcohol-related problems across total follow-up for pre-admission and post-detoxification diagnostic groups No depression Minor depression Major depression Pre-admission diagnosis (n) Post-detoxification diagnosis (n) Total no. of problems No. of social problems No. of physical dependency problems (3.8) 5.2 (4.0) 2.1 (1.5) 2.1 (1.5) 3.4 (2.5) 3.3 (2.8) (4.4) 5.8 (3.9) 1.9 (1.7) 2.7(1.8) 3.1 (2.7) 3.2 (2.3) (3.9) 5.4 (3.9) 23 (1.6) 1.9(1.6) 3 J (2.7) 3.5 (2.5) ns ns The figures in bold denote pre-admission values. were more likely to have received treatment for depression (Davidson, 1995) during admission and during follow-up than those without depression. Despite this additional treatment, no differences were found in drinking outcome between the groups. The findings of the present study are broadly consistent with several other studies, which have found no differences in drinking outcomes between depressed and non-depressed alcoholics (Schuckit, 1985; O'Sullivan et al, 1988) but differ from the findings of Kranzler et al. (1996) whose longer term follow-up of 3 years indicated lower drinking intensity in those with a lifetime diagnosis of co-morbid depression. Generally these follow-up studies spanned between 1 and 3 years, whereas the present study concentrated on a shorter follow-up period of just over 5 months, but included more fine details of alcohol consumption at follow-up. This shorter duration of follow-up allowed a closer examination of alcohol consumption. These findings suggest that neither pre-admission nor post-detoxification diagnosis of depression influence abstinence status or drinking behaviour in those for whom a diagnosis of alcohol dependence is established. If a diagnosis of depression is to have an influence on drinking outcome, it could be argued that this relationship would be evident within a relatively short time frame. The findings might thus suggest that depression and alcohol dependence are separate and noninteracting diagnoses. This is, however, unlikely, as there was a strong relationship between the two diagnoses in terms of co-occurrence and the prevalence of depression in this sample was greater for the episode of drinking which led to admission than it was after detoxification (Davidson, 1995). It is possible that an interaction between diagnoses could have been obscured in the present study as diagnoses were made for the episode which led to admission and post-detoxification only. It may be that any relationship between alcohol consumption and affective symptomatology only becomes evident at some more advanced time point and that diagnoses made at one, or even two points in time, as in this study, do not take into account the possibility of episodes of depression which may arise after discharge during follow-up. In addition, the small numbers of patients who met diagnostic criteria for major depression post-detoxification and who had no depression before admission may also have led to a lack of power to detect differences in the outcome measures between the groups. Although in the present study alcohol-related outcomes were not affected by pre-admission or post-detoxification diagnoses of depression, it does not necessarily follow that other clinically relevant outcomes are associated with co-morbid depression. For example, discharge diagnoses of depression or personality disorder in alcoholics carry a worse prognosis in terms of suicide than non-depressive and other diagnostic groups over longer follow-up (Duffy and Kreitman, 1993). Future follow-up studies which include an assessment of diagnostic status might demonstrate more clearly differential outcomes. REFERENCES Andreasen, N., Grove, W., Shapiro, R., Keller, M., Hirschfeld, R. and McDonald-Scott, P. (1981)

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