Age of sexual initiation and depression in adolescents: Data from the 1993 Pelotas (Brazil) Birth Cohort.

BACKGROUND: Studies have shown that sexual initiation at earlier ages increases the risk of depressive symptoms in adolescents. However, little is known about its association with major depressive episode (MDE).

METHODS: The association between age of sexual initiation and MDE at 18 years was assessed in the 1993 Pelotas Birth Cohort using multiple logistic regression. Sexual initiation characteristics (age and type of partner) were assessed at the 15- and 18-years follow-up. The age of sexual initiation was evaluated in categories (11-14, 15-16, 17+ years). The type of partner was categorized into: boyfriend/ girlfriend, casual partner and other. MDE was assessed using the Mini International Neuropsychiatric Interview (MINI).

RESULTS: From the 4027 adolescents assessed, the prevalence of MDE was higher in females (10.1%) than in males (3.4%), and 66.7% of the males and 58.6% of the females reported sexual initiation up to 16 years (p < 0.001). Female adolescents who had sexual initiation <17 years had higher odds of MDE (15-16 years: OR 2.29; 11-14 years: OR 2.23), however no association was found for males. The type of partner in the first sexual intercourse was not associated to depression.

LIMITATIONS: Possibility of recall bias on the age of sexual initiation, and low statistical power for some analyses.

CONCLUSIONS: A positive association between age of sexual initiation and MDE was observed only in females. More investigation is needed to understand the mechanisms through which age of sexual initiation can affect the risk of depression and whether the association persists in adulthood.