Study Shows Children of Depressed Mothers Have a Slower IQ Growth Compared to Children of Healthy Mothers

High intelligence is associated with increased self-control, social competency, academic achievement, mental health literacy, occupational success, and longevity. In contrast, cognitive deficits—as commonly represented by a low intellectual quotient (IQ)—are common in people with mental illness. 

The researchers conducted a longitudinal study to track IQs of 192 children of healthy mothers and mothers with a diagnosed mood disorder, including major depressive disorder and bipolar disorders. The researchers assessed the study participants’ IQs five times from toddlerhood through young adulthood, a period during which the risk is elevated for the first onset of psychiatric disorders, especially mood disorders.

“Our study’s findings replicate previous research that suggests that children born to and raised by mothers with a mood disorder may not be reaching their potential in the intellectual domain,” said Bonnie Klimes-Dougan, PhD, an associate professor of psychology and co-leader of the RAD (Research in Adolescent Depression) Lab. “However, impaired performance on IQ tests may not be uniform and may instead vary based on the child’s age, sex, and the type of parental mood disorder present. For instance, our findings indicate that risk accumulates across development for children of mothers with major depressive disorders. High IQ also appears to be a protective factor for early onset mood disorders, at least in males.”

According to Klimes-Dougan, this study’s findings highlight the need to better characterize how subgroups of parental mood disorders may differentially influence children’s risk across development.