Maternal Depression and Child IQ are Mutually Influential

Patricia East, PhD

Highly depressed mothers provide less emotional and material support to their child, a recent study found, which in turn influenced the child’s cognitive development up to age 16.

Additionally, researchers found some evidence of the reverse influence. A child’s lower cognitive abilities were found to inhibit their mother’s emotional and material investment, which in turn lead to higher levels of maternal depression.

“We found that mothers who were highly depressed didn’t invest emotionally or in providing learning materials to support their child, such as toys and books, as much as mothers who were not depressed. This, in turn, impacted the child’s IQ at ages 1, 5, 10 and 16,” said Patricia East, PhD, research scientist with the Department of Pediatrics at UC San Diego School of Medicine, and one of the study investigators. “The consistency and longevity of these results speak to the enduring effect that depression has on a mother’s parenting and her child’s development.”

The study included 875 middle- or lower-middle-class Chilean women and their children (52% males). Researchers surveyed families in Santiago, Chile at four intervals when children were 1, 5, 10, and 16 years old. They gauged how emotionally attentive each mother was to her child and how much age-appropriate educational material she provided.

Additionally, trained psychologists administered the Center for Epidemiologic Studies-Depression Scale (CES-D) to mothers at each interval. The 20-item scale asked about how often mothers experienced depressive symptoms resulting in scores of 0-60 points. Scores of ≥16 are considered to exhibit possible depressive symptomatology and at any given interval about half of participating mothers scored >16. Children completed age-appropriate cognitive assessments at each interval.

The average verbal IQ score for all children at age 5 was 7.64 on a scale of 1-9. Children with severely depressed mothers had an average verbal IQ score of 7.30 compared to children without depressed mothers who had average scores of 7.78.

“Although seemingly small, differences in IQ from 7.78 to 7.30 are highly meaningful in terms of children’s verbal skills and vocabulary,” said East.

Another study of maternal depression found that children of mothers with persistent postnatal depression were at increased risk for behavioral problems as toddlers, lower math grades at 16 years, and self-reported depression at 18 years.

“Many mothers suffer from depression in the first 6 months after childbirth, but for some, depression lingers,” said East. “Our study results show the long-term consequences that a child can experience due to chronic maternal depression.”

Authors of the Chilean study stressed the importance of diagnosing and treating maternal depression, particularly given its wide prevalence and its long-term effects on children’s IQ. They added that further analysis is needed to see how maternal depression affects children in other ways including their own depressive symptoms, academic achievement, and health.

“For health care providers, the results show that early identification, intervention, and treatment of maternal depression are key,” said East. “Providing resources to depressed moms will help them manage their symptoms in a productive way and ensure their children reach their full potential.”