Characteristics of depression among offspring at high and low familial risk of bipolar disorder.

OBJECTIVES: Having a parent with bipolar disorder (BP) is a very strong risk factor for developing BP. Similarly, depression among youth is a clinical risk factor for subsequent BP. We evaluated whether mood symptomatology in depressed youth is different between those at high and low familial risk to develop BP.

METHODS: The most severe major depressive episode in BP offspring (N=61) and community control offspring (N=20) was evaluated using expanded depression and mania rating scales derived from the Schedule for Affective Disorders and Schizophrenia for Children Present Version. The results were adjusted for any between-group significant demographic differences and for multiple comparisons.

RESULTS: The severity of depressive symptoms and the percentage of offspring with severe depressive symptoms, especially atypical depressive features, were significantly higher in the depressed offspring of BP parents compared to the depressed controls (Ps <.05). The depressive symptoms were helpful to identify a high-risk group (e.g., odds ratio [OR] for hypersomnia: 22.4, 95% confidence interval [CI]: 1.3-404, P=.04). In addition, there were significantly more depressed offspring of BP parents with subsyndromal manic symptoms than controls (52.5% vs 20%, OR: 4.2, 95% CI: 1.2-14.7, P<.01).

CONCLUSIONS: Depressed BP offspring had more severe depression including atypical depressive symptoms, and were more likely to have subsyndromal mixed manic symptoms than depressed control offspring. Prospective studies to evaluate whether these youth are at high risk to develop BP are warranted. If replicated, the results of this study have important clinical (e.g., treatment of depression in depressed offspring of BP parents) and research implications.