Background: Bipolar disorders have been extensively studied in the high-income countries but community-based studies from low-income countries are very rare. The main objectives of the current study are to estimate the lifetime prevalence of bipolar I disorder in the general population of the Butajira district in Ethiopia and to characterize the onset and course of the disorder in a predominantly treatment naïve population.
Method: Cases were identified by a door-to-door screening of the district's entire adult population aged 15 to 49 years (N=83,387), where 68,378 were successfully screened. CIDI and key informant method were used in the first stage of screening followed by confirmatory SCAN interviews.
Results: Three hundred fifteen cases were identified and complete information could be collected for 295 individuals. Of these, 55.3% were males, 83.1% were from a rural area, and 70.2% were illiterate. Lifetime prevalence of bipolar I disorder was estimated to be 0.6% for males and 0.3% for females. The mean age of cases was 29.5 years, with no significant sex difference. The mean age of first recognition of illness was 22.0 years; for men 22.3 years and for women 21.2 years. The mean age at onset of manic phase of the illness was found to be 22.0 years (22.5 for men and 21.4 for women). The mean age at onset of depressive phase was 23.4 years (24.1 for men and 22.5 for women). There was no significant sex difference in the age of onset of manic or depressive phases. In 22.7% of the cases bipolar I illness started with a depressive episode and in 77.3% of the cases it started with a manic episode. Two or more episodes of the illness were reported by 64.1%. Over half of the study subjects (55.9%) had never sought any help from modern healthcare sector, and only 13.2% had ever been admitted to psychiatric hospital. During the survey 7.1% of the cases were undergoing treatment. A previous suicide attempt was reported by 8.1% of the males and 5.4% of the females.
Conclusion: The overall lifetime prevalence and age of onset are within the range of findings from other studies in Western countries. In contrast to most previous studies, prevalence of the disorder among females was half of that among males. Our finding that prevalence of this disorder among males and females appeared to be different from many other studies warrants further research.