ABSTRACT
OBJECTIVES: The focus of this study is to establish Filipino data on the seasonality of bipolar mood disorder. METHODS: The seasonal pattern of 293 psychiatric hospital admissions and referrals for treatment of hypomanic, manic, depressed, and mixed bipolar episodes over a 3-year period were analyzed on a quarterly and bi-annual distribution of wet and dry season, using statistical analyses. RESULTS: No significant differences in frequency of admissions for hypomanic, manic, and depressed episodes were noted using quarterly and bi-annual distribution. Although there was no significant difference noted in the quarterly occurrence of mixed episode bipolar disorder for the years 2001 and 2002 respectively, when the over-all distribution of mixed episode bipolar disorder was compared, a significant difference was noted (Goodness of fit X2 =6.00; p 0.05 and Goodness of fit X2 = 2.00; p 0.05 respectively). A pattern was noted in that the peak occurrence was during the first quarter -January to March-and a nadir on the third quarter -July to September, which, was the same for the year 2000. CONCLUSION: The findings from this study of the Filipino sample is suggestive that proposed chief mechanism of seasonality of mood disorder which is the neurobiologic changes associated with the photoperiod may not adequately apply to occurrence of episodes of bipolar mood disorder in tropical geographic locations where there are no extreme variations in photoperiods, temperature, and climate.