Daytime cortisol and stress reactivity in the offspring of parents with bipolar disorder.

The hypothalamic-pituitary-adrenal (HPA) axis is compromised in major depression and bipolar disorder (BD). It is not known however whether HPA abnormalities predate the onset of these disorders. Preliminary data indicated that the adolescent offspring of parents with BD (high-risk), as compared to adolescents of parents with no mental disorder (low-risk), had higher levels of daytime salivary cortisol. The present study re-examined the cortisol increase after awakening and basal cortisol levels in a larger sample, and tested the hypothesis that high-risk offspring are more reactive to psychosocial stress than low-risk offspring. Saliva samples were collected from 58 adolescents, 29 high-risk (14 male/15 female, 16.8 years) and 29 (14 male/15 female, 16.6 years) low-risk, in their natural environment during at least two days. Twenty-five high-risk (13 male/12 female) and 25 low-risk (13 male/12 female) youth completed a child adaptation (15 years) or the standard version of the "Trier Social Stress Test". Consistent with our previous finding, high-risk offspring had higher daytime levels of cortisol in their natural environment than low-risk offspring, and the difference was unrelated to clinical symptoms or other known confounds. Irrespective of risk status, female participants had higher daytime levels of cortisol than male participants. In contrast, there were no group differences in the cortisol response to the laboratory psychosocial stressor. The offspring of parents with BD show evidence of increased daytime basal HPA functioning with normal reactivity to psychosocial stress.