VCU researchers offer new three-part test to study anxiety and depression in young girls

By Lorraine Cichowski and Judy Silberg

RICHMOND, Va. – Researchers at Virginia Commonwealth University have developed an innovative method that looks at genes and environment in a new way to identify young girls who are at high risk for depression once they enter puberty. 

The model, which is published in an October special issue of the Journal of Child Psychology and Psychiatry, for the first time simultaneously considers three ways that genes linked to anxiety in young girls influence later depression:  1) genes influencing anxiety at a young age increase the liability of a child for developing later depression; 2) girls at genetically high risk for anxiety are exposed disproportionately to adverse life events, such as her parents’ divorce or bad grades on a report card, and 3) girls with a higher genetic liability and exposure to adverse life events are more sensitive than other girls to the damaging effects of their environment. 

“Genes do play a role in determining why one person gets depression and one person doesn’t, but the direct effect of the genes isn’t that large,” says Judy L. Silberg, Ph.D., associate professor of human genetics and a researcher at VCU’s Virginia Institute for Psychiatric and Behavioral Genetics. “Finding the genes is important, but it is not the only positive contribution that genetically informative studies can make in understanding the mechanisms underlying behavioral development. Genes explain about 30 percent of the difference in people. There are more complicated mechanisms at work.

“Our analysis of anxiety and depression shows that genetic factors have different effects at different stages of development. A common set of genes can first manifest as anxiety in little girls.  When those girls enter puberty, that anxiety can turn into depression. Moreover, the same genes that affect early anxiety increase the girl’s risk to exposure to depressing environments, and, moreover, how sensitive they will be to those environments. Girls with a genetic liability to anxiety in middle childhood are, therefore, subject to a ‘triple hit,’ greatly increasing their risk to depression in adolescence.”

Silberg and her colleagues studied data assessing pre-pubertal and post-pubertal anxiety and depression as well as various life events affecting 687 pairs of female twins included in the Virginia Twin Study for Adolescent Behavioral Development (VTSABD). The VTSABD is an ongoing 15-year study based at VCU and designed to understand the role of genetic and social factors in the development of psychiatric problems in children and adolescents. The life events considered to be important included parent becoming less interested or less loving with her, illness or injury to herself, breaking up with someone she had been dating regularly, separation or divorce of her parents, failing grades on a report card, death of a close friend and brother or sister leaving home.

The researchers found that including the impact of life events with consideration of the main impact of genes and environment gave a more accurate assessment of how a girl’s environment and unique family situation would influence her tendency to get depression after puberty. Their statistical analysis showed that failure to include the life events in the genetic analysis of depression trivialized the role that the girl played in her own development and led to overestimation of the contribution of unique family events.

Silberg says the model could help clinicians and parents better assess which young girls might be in the most danger of developing depression.

“This is a way of looking out for young girls and getting a handle on early intervention,” Silberg says. “When you have a little girl – between the ages of 8 and 12 – who is anxious and shy and who doesn’t cause any trouble and may have a parent who is depressed, you may want to get her help before she becomes depressed when she enters the age of puberty.”

The study advances earlier work done by the Virginia Institute of Behavioral Genetics on the impact of genes on adolescent depression. It was funded by grants from the National Institute of Mental Health and the Carman Trust. The institute is directed by Lindon J. Eaves, Ph.D., D.Sc., Distinguished Professor of human genetics, professor of psychiatry and co-author of the study.