Bipolar versus unipolar psychotic outpatient depression

Journal of Affective Disorders 55 (1999) 63–66 www.elsevier.com / locate / jad

Brief report

Bipolar versus unipolar psychotic outpatient depression Franco Benazzi* Department of Psychiatry, Public Hospital ‘ Morgagni’, 47100 Forlı`, Italy Received 29 May 1998; received in revised form 25 October 1998; accepted 28 November 1998

Abstract Background: The relationship between bipolar and unipolar psychotic depression has not been well studied. Therefore, the aim of the present study was to compare bipolar with unipolar psychotic outpatient depression. Methods: Seventy consecutive unipolar (n 5 40) and bipolar (n 5 30) psychotic depressed outpatients were interviewed with the Structured Clinical Interview for DSM-IV, the Montgomery Asberg Depression Rating Scale, the Global Assessment of Functioning Scale, and the Brief Psychiatric Rating Scale. Results: Of the variables studied (age, duration of illness, severity, recurrences, atypical features, chronicity, gender, comorbidity, hallucinations, delusions), none was significantly different between unipolar and bipolar psychotic patients. Conclusions: Bipolar psychotic depression was similar to unipolar psychotic depression on variables reported in the literature to distinguish bipolar from unipolar disorder. Clinical implications: The findings might suggest, but do not necessarily imply, that psychotic depression might be a distinct clinical entity. Limitations: Single interviewer, nonblind cross-sectional assessment, outpatient sample, sample size.  1999 Elsevier Science B.V. All rights reserved. Keywords: Psychotic depression; Bipolar; Unipolar; Outpatients

1. Introduction There are many differences (clinical features, age, gender, prevalence, course, and familial pattern) between major depressive and bipolar disorders (American Psychiatric Association, 1993; Depression Guideline Panel, 1993; American Psychiatric Association, 1994a,b). It is not clear if there are similar differences between bipolar and unipolar psychotic *Present address: Via Pozzetto 17, 48015 Castiglione di Cervia RA, Italy. Tel.: 1 39-335-6191852; fax: 1 39-543-30069. E-mail address: [email protected] (F. Benazzi)

depression. A MEDLINE search found only one study (Breslau and Meltzer, 1988) comparing unipolar with bipolar psychotic depression, reporting no difference in gender and age at onset. Studies comparing bipolar and unipolar nonpsychotic depression (Goodwin and Jamison, 1990; Cassano et al., 1992; Mitchell et al., 1992; Akiskal, 1996; Mitchell and Sengoz, 1996; Benazzi, 1997) have reported lower age at onset, more episodes, more, less, or similar psychomotor retardation, more, less, or similar psychomotor agitation, higher or lower suicidal behaviour, more comorbidity, more atypical features, similar, higher, or lower chronic course, and shorter

0165-0327 / 99 / $ – see front matter  1999 Elsevier Science B.V. All rights reserved. PII: S0165-0327( 98 )00217-1

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episodes in bipolar depression. The aim of the present study was to compare unipolar with bipolar psychotic outpatient depression, looking for clinical similarities and differences.

cal software, College Station, Texas, 1997). P values were two-tailed, and probability level was 0.05.

3. Results

2. Material and methods The study was made in his outpatient private practice by a psychiatrist with a 15-year experience in mood disorders (more than 4000 personal visits per year in private practice, more than 1000 in the public service; more than 400 new patients per year in private practice, more than 100 in the public service). Outpatients seen in the public service are usually more severe. In the study area, people prefer private psychiatrists (visits are not expensive, and most people can afford them), unless they are very severe or have economic problems. Therefore, this private practice sample is representative of mood disorder outpatients. Seventy consecutive patients presenting for treatment of a DSM-IV major depressive episode with psychotic features (with minimal or no concurrent pharmacotherapy at intake), occurring in major depressive / bipolar I / bipolar II disorders (unipolar / bipolar psychotic depression), were included. Substance abuse and severe personality disorder patients were not included, as they are rarely seen in private practice. They were interviewed at intake with the Structured Clinical Interview for DSM-IV Axis I Disorders-Clinician Version (First et al., 1997), the Montgomery Asberg Depression Rating Scale (MADRS) (Montgomery and Asberg, 1979), the Global Assessment of Functioning (GAF) Scale (American Psychiatric Association, 1994a), and the Brief Psychiatric Rating Scale (BPRS) (Overall, 1988). Often, family members supplemented the clinical information during the interview. Patients and family members were carefully interviewed about the temporal relationship between psychotic features and major depressive episode, and their durations, which are fundamental for the diagnosis of psychotic depression versus schizo-affective disorder and schizophrenia. Axis I comorbidity was recorded if spontaneously reported. Means were compared with t-test, proportions with two-sample test of proportions ( STATA 5 statisti-

A total of 42.8% had bipolar depression, 57.1% had unipolar depression, while 36.7% of bipolar patients were bipolar I, 63.3% were bipolar II. Comparisons between bipolar and unipolar psychotic depression are presented in Table 1. No significant difference was found.

4. Discussion The results disagree with reported differences between major depressive and bipolar disorders. They are similar, relative to gender and age at onset, to the results of a previous similar study (Breslau and Meltzer, 1988). Age at onset is lower in bipolar than in major depressive disorder (American Psychiatric Association, 1993; Depression Guideline Panel, 1993; American Psychiatric Association, 1994a,b). It resulted not significantly different, suggesting that bipolar and unipolar psychotic depression might not be distinct disorders (McMahon et al., 1994). Apparent unipolar depression has bipolar switch in 5–8% of patients, and psychosis predicts the shift (Akiskal et al., 1995; Coryell et al., 1995). It seems unlikely that this 5–8% of patients (two to three patients in this sample) may have lowered the age at onset of unipolar patients, making it similar to that of bipolar patients. The proportion of females is greater than that of males in major depressive and bipolar II disorders, and equal to that of males in bipolar I disorder (American Psychiatric Association, 1993; Depression Guideline Panel, 1993; American Psychiatric Association, 1994a,b). It was not significantly different in the present study. There are more recurrences in bipolar than in major depressive disorder (American Psychiatric Association, 1994a). However, bipolar II depression without comorbid substance abuse and severe personality disorder (as in the present study) does not have more recurrences than unipolar depression (Cooke et al., 1995; Benazzi, 1997). Although not statistically significant, the 15% difference in recurrences found in the present

F. Benazzi / Journal of Affective Disorders 55 (1999) 63 – 66

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Table 1 Comparisons between bipolar psychotic (BP) and unipolar psychotic (UP) depression Characteristics

BP (N 5 30)

UP (N 5 40)

Age at intake [years, mean (S.D.)] Age at onset first major depressive episode [years, mean (S.D.)] Duration of illness [years, mean (S.D.)] Baseline MADRS [mean (S.D.)] Baseline GAF [mean (S.D.)] Baseline BPRS [mean (S.D.)] More than three major depressive episodes (%) DSM-IV atypical features (%) Chronic and without full interepisode recovery major depressive episode ( . 2 years) (%) Females (%) Axis I comorbidity (%) Hallucinations (%) Delusions (%)

48.0 (13.4) 33.5 (13.3)

48.6 (14.9) 35.8 (15.0)

t 5 0.17, df 5 68, P 5 0.8624, 95% C.I. 2 6.2–7.4 t 5 0.66, df 5 68, P 5 0.5077, 95% C.I. 2 4.5–9.1

14.8 48.1 33.3 50.0 70.0 6.6 43.3

12.8 44.9 33.0 46.6 55.0 12.5 55.0

t 5 0.70, df 5 68, P 5 0.4861, 95% C.I. 2 7.6–3.6 t 5 1.79, df 5 68, P 5 0.0775, 95% C.I. 2 6.7–0.3 t 5 0.16, df 5 68, P 5 0.8701, 95% C.I. 2 3.9–3.3 t 5 1.81, df 5 65 a , P 5 0.0741, 95% C.I. 2 7.1–0.3 z 5 1.27, P 5 0.2020, 95% C.I. 2 7.5–37.5 z 5 0.81, P 5 0.4149, 95% C.I. 2 19.4–7.6 z 5 0.96, P 5 0.3326, 95% C.I. 2 35.1–11.7

a

(11.3) (7.1) (7.1) (7.4)

63.3 26.6 16.6 96.6

55.0 42.5 17.5 100

(12.2) (7.6) (7.9) (7.6)

z 5 0.69, z 5 1.37, z 5 0.09, z 5 1.17,

P 5 0.4854, P 5 0.1694, P 5 0.9212, P 5 0.2401,

95% 95% 95% 95%

C.I. C.I. C.I. C.I.

2 14.8–31.4 2 37.9–6.1 2 18.6–16.8 2 9.8–3.0

BPRS not available in three bipolar patients.

study may be clinically significant, and it might result also statistically significant in larger samples. It would support the separation of psychotic depression into a bipolar and a unipolar subtype (along with the presence of mania and hypomania, with their therapeutic implications). Chronicity is up to 30% in bipolar disorders, and up to 35% in major depressive disorder (American Psychiatric Association, 1993; Depression Guideline Panel, 1993; American Psychiatric Association, 1994a). It was not significantly different in the present study. Proportions of chronic patients were higher than previously reported, probably because not only chronic major depressive episode was included, but also the new DSM-IV chronicity specifier ‘without full interepisode recovery’. Atypical features are more common in bipolar depression than in major depressive disorder (apart from its seasonal pattern subtype) (American Psychiatric Association, 1994a; Akiskal, 1996; Benazzi, 1997). They were not significantly different in this study. Proportions of patients with atypical features were low (6–12%) compared with proportions reported in bipolar II depression (42%), and in unipolar depression (22%) (Benazzi, 1997). Atypical features might be less common in psychotic depression than in nonpsychotic depression because of its severity, as atypical depression has usually a moderate severity (Kendler et al., 1996). Axis I comorbidity is higher in bipolar II disorder than in

unipolar depression (Cassano et al., 1992). However, bipolar II depression without comorbid substance abuse and severe personality disorder (as in the present study) does not have more axis I comorbidity than unipolar depression (Benazzi, 1997; Cooke et al., 1995). Proportions of patients with comorbidity were not significantly different in this study. Although not statistically significant, the 16% proportion difference might be clinically significant, and it might also be statistically significant in larger samples. Proportions of patients with comorbidity were lower than proportions reported in bipolar II (61%) and unipolar (62%) depression (Benazzi, 1997), when comorbidity was spontaneously reported, as in the present study. One reason may be under-reporting of comorbid disorders, overshadowed by more severe depressive symptoms. Or comorbidity might really be lower in psychotic depression. That bipolar and unipolar psychotic depression did not show many of the differences reported in the literature between bipolar and major depressive disorders might suggest that psychosis modifies features distinguishing these disorders. Unipolar relatives of bipolar patients are more likely than unipolar relatives of controls to show psychotic features (Blacker et al., 1996), a finding partly supporting the results of the present study. As assessment was made at intake with minimal or no concurrent pharmacotherapy, it is unlikely that pharmacotherapy masked or altered

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symptoms, blunting differences. The present study was made in private practice, where depressed outpatients are generally less severe than public inoutpatients (American Psychiatric Association, 1993), limiting the validity of these findings to this sample. Exclusion of substance abuse and severe personality disorder patients may have selected a more homogeneous sample. Sample size may not have been able to detect differences perhaps evident in larger samples. In conclusion, bipolar psychotic depression was similar to unipolar psychotic depression on variables reported in the literature to distinguish bipolar from major depressive disorder. These findings might suggest, but do not necessarily imply, that psychotic depression (bipolar and unipolar) may be a distinct disorder.

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