Salivary cortisol secretion in remitted bipolar patients and offspring of bipolar parents

Abstract

It is generally believed that cortisol secretion normalizes during clinical remission in mood disorders. However, this assumption has been challenged by preliminary reports of enhanced cortisol secretion in remitted bipolar patients and in the offspring of bipolar parents. The purpose of this study is to replicate findings of increased cortisol secretion during clinical remission in bipolar patients and in the offspring of bipolar parents, rigorously controlling for known confounders. We conducted intensive cortisol sampling (six samples per day for three test days, on three consecutive weekends) on 15 bipolar type I and type II patients and 28 unrelated offspring of bipolar parents. Offspring had a history of unipolar depression. Participation was restricted to cases in complete sustained remission. Controls were matched as closely as possible for age, sex, and education. Mood and sleep measures were recorded on each sampling day. In total, 743 samples were collected from the patient group and 576 from controls. Correcting for repeat measures, there was no statistically significant difference in cortisol secretion at any sampling time between remitted bipolar patients, remitted offspring of bipolar parents, and normal controls. The cortisol waking response did not differ between patients and controls. Covariates, including sex, age, Beck depression score and hours of sleep, were not statistically significant. Our observations are consistent with the view that complete sustained clinical remission is associated with normal salivary cortisol levels throughout the day. A personal or family history of bipolar disorder per se does not appear to confer added risk for increased salivary cortisol secretion during sustained clinical remission.