Elevated daytime cortisol levels: A biomarker of subsequent major affective disorder?

Background: Several studies have reported that the offspring of parents with affective disorders secrete high levels of daytime cortisol. A few studies have shown that high cortisol levels preceded the onset of affective symptoms. Only one study to date has found that an elevation in cortisol preceded the onset of an affective disorder, but this was observed only in those youth carrying the short allele of the serotonin transporter gene promoter polymorphism (Goodyer etal., 2009). Methods: We followed 28 offspring of parents with bipolar disorder and 31 offspring of parents with no affective disorder from an average age of 17.5 years to an average age of 20.0 years to determine if cortisol levels at baseline predicted the subsequent development of an affective disorder. At baseline and at follow-up participants completed a diagnostic assessment, and at baseline they provided saliva samples. Daytime cortisol levels were computed as the mean of eight to 24 samples measured across two to six days. Results: Among the 59 participants, cortisol levels at the mean age of 17.5 years predicted the development of an affective disorder during the subsequent 2.5 year (odds ratio: 2.1, 95% confidence interval = 1.0-4.1, p < 0.05) after controlling for offspring mental disorders at the first assessment and having a parent with bipolar disorder. Limitations: The findings should be interpreted with caution, as the sample size was small. Conclusion: Elevated daytime cortisol levels in late adolescence may be a biomarker of vulnerability for affective disorders. (C) 2011 Elsevier B.V. All rights reserved.