Gender Differences in the 5 Years Course of Bipolar Disorder after a First Manic Episode: A Retrospective Review.

Sir,

Previous studies in bipolar disorder (BD) have reported near equal gender prevalence and age at onset of BD. In terms of the clinical presentation and course of BD, females have been reported to have more depressive symptoms, more mixed episodes, greater presence of psychotic symptoms, and more rapid cycling than males.[12] Manic episodes are reportedly more common in males,[3] who are also documented to likely have mania as their first episode of BD.[4]

Literature on the course of BD in the Indian population is sparse and there are no studies evaluating gender differences in the clinical presentation of first episode mania (FEM) from India. The available course and outcome studies have documented a preponderance of manic episodes and onset of BD with mania.[567] Median time to recurrence is reportedly shorter in females. Both studies have highlighted that the course of BD in India may be different from what has been reported from the west.

The objective of this study was to investigate gender differences in the clinical presentation of FEM and the 5-year course of BD following a FEM.

Data were collected from the patient records at the National Institute of Mental Health and Neurosciences, Bengaluru, during 2013–2014. All patients who received a diagnosis of mania with/without psychotic symptoms and a diagnosis of BD - mania with/without psychotic symptoms (with a history of only depressive episodes) (ICD-10; WHO, 1992) in the calendar year 2008 were included in the review (n = 108). Details extracted were sociodemographic, clinical, and treatment details of FEM and the course of BD as documented during follow-up visits over a 5-year period from 2008 to 2013 as part of a larger study evaluating the course of BD over the aforementioned period. We examined gender differences in these variables. The study was approved by the Institute Ethics Committee.

Data were analyzed using the IBM Statistical Package for Social Sciences (SPSS) software, version 16.0. Descriptive statistics were used. Chi-square test was used to analyze categorical variables and independent samples t-test for continuous variables.

Of the108 patients, 39 were females and 69 were males. No gender differences emerged with respect to age (mean age: females = 33 ± 8.1 vs. males = 33 ± 9.6), marital, educational, and occupational status (all P > 0. 07). Mean age at onset of illness, mean age at first presentation to the hospital, and the mean duration of the first manic episode were also comparable in the two groups (all P > 0.7). 16/39 (41%) females and 23/69 (33.33%) males had experienced at least one prior depressive episode, which was comparable (χ2 = 0.639; P = 0.424).

In the FEM, increased activity levels were found to be significantly more in females (females = 38 [97.4%] vs. males = 59 [85.5%], χ2 = 3.88; P = 0.05). Other manic symptoms were not significantly different in the two groups (all P > 0.1).

There were no significant gender differences in terms of the treatment prescribed for the FEM (all P > 0.39). Time to syndromal recovery (as per ICD-10) was similar in both groups (P = 0.77). No significant differences were observed between the genders with respect to the drug class of the medication prescribed (mood stabilizer vs. antipsychotic), adverse effects, compliance, and number of follow-up visits (all P > 0.4). During the 5-year follow-up period, the total number of mood episodes, hypomanic, depressive, and manic episodes in the two groups was comparable (all P > 0.2).

We did not find any gender difference in the 5-year course of BD, following a first manic episode, in our sample.

Gender differences in first episode psychotic mania were reported in an earlier study, wherein substance dependence was greater in males and childhood abuse in females.[8] Another study did not report any gender difference in symptom severity or response to treatment in mania occurring during the course of BD. However, in the 12-week and 12-month follow-up period following the manic episode, more females had had a depressive recurrence. In our study, significantly more females were noted to have increased activity levels during the FEM and had better response to treatment than men.

Previous studies found a correlation between the mood episodes of BD and gender, with more depressive episodes in females and more manic episodes in males.[910] Females reportedly spent a greater proportion of their illness in depression.[1] Similar to the Baldassano et al. study, we did not find any gender difference in the lifetime depressive episodes in our sample.[11] The average duration of illness in the Altshuler (2010) study was 22 years compared to 5 years in our sample. It is likely that gender differences may become more apparent with longer duration of illness and may not be prominent early in the course of BD.

Being a retrospective review remains the main limitation of this study. Mood rating scales were not done as this was a naturalistic study but is a limitation. Prospective studies would help us understand better the gender differences in the course of early BD, particularly in the absence of such literature from the Indian subcontinent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.