MedWire News: Children born to parents with bipiolar disorder appear to have increased cortisol levels that persist over time, say researchers.

“The present findings are consistent with the speculation that subtle abnormalities of the hypothalamic-pituitary-adrenal [HPA] system may predate the development of an effective disorder,” say Mark Ellenbogen (Concordia University, Montreal, Quebec, Canada) and colleagues.

“Similar conclusions have been put forth in studies of high-risk adolescents and the offspring of patients with major depression, suggesting that these changes in cortisol levels are not specific to families with bipolar disorder.”

For the study, the researchers examined daily salivary cortisol levels over a 2-week period in 24 individuals born to parents with bipolar disorder and 22 individuals born to mentally healthy parents. The average age of the participants was 18 years.

Differences in salivary cortisol levels between these individuals had already been demonstrated in a study conducted 2 years previously, when levels were measured over the course of a normal day. The children of parents with bipolar disorder had higher levels on average than those of mentally healthy parents.

The current findings concur with this previous research and demonstrate a persistence of the elevated cortisol levels in individuals born to parents with bipolar disorder from late adolescence to young adulthood.

Indeed, the offspring of parents with bipolar disorder had higher afternoon levels of cortisol than the offspring of mentally healthy parents, at an average over the 14 days of 0.179 versus 0.151 μg/dl at 1300h and 0.155 versus 0.130 at 1500h.

“The findings could not be attributed to group differences in affective diagnoses, subclinical symptoms, internalizing or externalizing behaviors, daily hassles, general functioning, age, the use of a medication, food consumption, exercise, and/or smoking,” say Ellenbogen and team in the journal Bipolar Disorders.

They conclude: “Although the causes of these peripheral changes are not known, elevated levels of cortisol may represent an early and subtle phenotypic marker associated with an increased vulnerability for the development of an affective disorder.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

Free abstract