Role of age at onset in the clinical presentation of bipolar disorder in Indian population

OBJECTIVE: The objective of this study was to determine any association of age at onset (AAO) with clinical presentation of bipolar disorder (BD) and family history of illness. MATERIALS AND METHODS: A hospital-based cross-sectional observational study was conducted including 162 patients having a diagnosis of BD current episode manic. Individuals were divided into three subgroups according to AAO, i.e., early-onset BD (EOBD) (AAO ≤21 years), intermediate-onset BD (AAO – 22–34 years), and late-onset BD (AAO ≥35 years). The subgroups were compared on clinical variables; items of the Young Mania Rating Scale (YMRS), Hamilton Depression Rating Scale (HAM-D), and Scale for the Assessment of Positive Symptoms (SAPS); and family history of illness. RESULTS: The early-onset group had significantly more episodes per year than the other groups (P < 0.001). The prevalence of family history of mood disorder was also significantly higher in the early-onset group than the other subgroups. AAO was found to be significantly associated with different items of YMRS, HAM-D, and SAPS. The early-onset group had higher rating on irritability, motor activity–energy, sexual interest, depressed mood, delusions, and thought disorders, whereas the late-onset group had higher rating on elevated mood. CONCLUSION: EOBD can be considered as a specific phenotype of BD, which is more homogenous, severe, and inheritable form of illness.