How early in life does exposure to stress raise a child’s likelihood to suffer anxiety, depression, or other stress-related disorders? If the child is a girl, the answer appears to be very early. This is one of the findings of a study performed by a team led by NARSAD Grant recipient Dr. Richard J. Davidson, Professor of Psychology and Psychiatry at the University of Wisconsin-Madison.
When a mother experiences high levels of stress during her female child’s infancy, chances are good that the child will show differences in important brain functions and will experience anxiety symptoms by the time she is a teenager, relative to girls whose mothers were not stressed. Boys showed none of the same specific propensities, regardless of the mother’s mental health status.
Merely being able to track such progressions is impressive. Extraordinary efforts to follow mothers and their children from the period of pregnancy through subsequent life have been made through the Wisconsin Study of Families and Work (WFSW), which was launched in 1991 with the registration of 570 children and their mothers. The study’s initial aim was to gauge the impact of maternity leave, day care and other factors on family life. It is now providing insights into the elusive relationships between stress, illness, and gender—a highly complex subject, involving not only many of the body’s biological systems, but also the problem of assessing individual differences, both in terms of biology and experience.
One of Dr. Davidson’s colleagues, Dr. Rasmus Birn, developed a method of using a new type of functional MRI scan (called fcMRI) to assess a critical function in the ‘resting’ brain pertinent to the study—one involving the integrity of a circuit linking the brain’s amygdala (its ‘fear center’) with a part of the prefrontal cortex that helps regulate the emotions. Using scans from 28 female and 29 male subjects now 21 or 22 years old, and followed from birth, the team found that girls with current weaker functional connections between the amygdala and prefrontal cortex had, as infants, lived in homes with stressed mothers. When tested as 4-year-olds, the same girls had above-average levels of the stress hormone cortisol. Dr. Davidson says the study, which appeared in December 2012 in Nature Neuroscience, “raises important questions to help guide clinicians in preventive strategies that could benefit all children by teaching them to propagate well-being and resilience.”
As for differences in gender response to maternal stress, the team proposes that “females may be more sensitive to the effects of early-life stress” on the function of the neuroendocrine system, as well as prone to alteration of the pattern by which chemical groups mark DNA in cells, called epigenetic marking—a potential cause of changes in gene expression.
Richard J. Davidson, Ph.D.
1995 and 2003 NARSAD Distinguished Investigator Grantee
Vilas Professor of Psychology and Psychiatry
Department of Psychology
Director, Lab for Affective Neuroscience
University of Wisconsin-Madison