Cortisol levels show links between parent and child mental illness

The impact of mental health conditions passed on from parents to their children varies depending on the child’s sex, according to a new study from the University of Waterloo.

The study analyzed data from 100 children diagnosed with a mental disorder, such as depression and anxiety. It found that parental symptoms of depression and anxiety were associated with increased hair cortisol concentration in all children, but boys and girls reacted differently, depending on their diagnosis.

“We wanted to understand what the driving link is between parent and child mental health,” said Mark Ferro, a professor of public health at Waterloo. “In boys, higher cortisol levels were linked with diagnoses of major depression or generalized anxiety, but lower cortisol was found in those with ADHD or oppositional defiant disorder. For girls, lower cortisol levels were associated with ADHD or depression.”

children playing

Cortisol is the body’s main stress hormone. Unlike most previous studies, the researchers used hair cortisol to measure chronic stress. “It is a better gauge than saliva and urine samples, which tend to fluctuate much more over time,” said Ferro, who is the Canada Research Chair in Youth Mental Health.

The researchers note in their paper that more than 20 per cent of parents live with a mental illness, resulting in 33 per cent of their children aged 4 to 17 years also having a diagnosis, compared to 20 per cent children in the general population.

“From a research standpoint, we need to think more about sex differences,” said Ferro. “We are not sure why these differences exist, although we suspect, given the age range of our sample, that hormonal changes and perhaps the use of oral contraception, play a role. Larger longitudinal studies would be a good next step.

“From a clinical perspective, the important thing is for health professionals to continue to adopt a family-centred approach to child mental health, knowing that parents’ mental health affects their children.”

The study, Hair cortisol concentration mediates the association between parent and child psychopathology, authored by Mark Ferro (Waterloo) and Andrea Gonzalez (McMaster), was published in Psychoneuroendocrinology.

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