High cortisol levels in the offspring of parents with bipolar disorder during two weeks of daily sampling.

OBJECTIVES: The hypothalamic-pituitary-adrenal (HPA) axis is compromised in major depression, bipolar disorder (BD), and in the offspring of parents with major depression. Less is known about the offspring of parents with BD (FH+). The present project provides follow-up to a previous study showing that the adolescent (mean age 16.7 years) FH+ offspring had higher salivary cortisol levels than the offspring of parents with no mental disorder (FH-) throughout the day in their natural environment, and that girls had higher cortisol levels than boys (Ellenbogen MA, Hodgins S, Walker C-D, Adam S, Couture S. Daytime cortisol and stress reactivity in the offspring of parents with bipolar disorder. Psychoneuroendocrinology 2006; 31: 1164-1180). The goal of the present study was to determine whether FH+ offspring, approximately two years later, continued to exhibit elevated cortisol levels relative to FH- offspring during two weeks of daily sampling. METHODS: The present study examined salivary cortisol levels in 24 (18.3 +/- 2.6 years) FH+ and 22 (18.0 +/- 2.3 years) FH- offspring who are part of the same longitudinal cohort as the previous study. Saliva was collected at 1300 h and 1500 h in the natural environment of the offspring during 14 consecutive days. RESULTS: Multilevel modelling analyses indicated that FH+ offspring had higher afternoon levels of cortisol in their natural environment than FH- offspring, but group differences in slope and gender differences were not found. CONCLUSIONS: The FH+ offspring exhibited increased daytime secretion of cortisol that, at the level of the group, persisted into late adolescence and young adulthood. Perhaps this change in HPA functioning is associated with an increased vulnerability for the development of an affective disorder.