The National Research Council and Institute of Medicine estimates that depression affects 7.5 million parents in the United States each year. And although the U.S. Preventive Services Task Force recently recommended that all adults be screened for depression, doctors still don’t have a surefire way to diagnose the disease. This is a huge problem, particularly because having a depressed parent takes a huge toll on kids and teens. Not only are kids with a depressed parent more likely to develop depression themselves, but a new study published in JAMA Psychiatry suggests there’s a direct link between having a depressed parent and getting poor marks in school.
The study, which was led by Dr. Brian Lee of Drexel University, was conducted in Sweden, where things like mental health and academic performance records are relatively easy to come by. Researchers collected data on 1,124,162 children born in Sweden between 1984 and 1994, which amounts to about 93 percent of all people born in those ten years (talk about a representative sample!). Compulsory schooling in Sweden lasts until 16, at which point students are given a grade between 0 (failing) and 20 (A) in 16 subjects, leading to a total score between 0 and, for a young genius, 320. To make the data easier to digest, researchers divided grades into chunks of 10 — 1 to 10 was the lowest, 11 to 20 was the second lowest, and so on.
Depression diagnoses of parents were collected from Sweden’s national patient register, a giant useful depository of medical information we last saw last week; researchers defined a patient as suffering from depression if they had “any registered diagnosis of a depressive episode or mood disorder” in their file. (The register is fairly accurate but not perfect — a different study compared register diagnoses with clinical diagnoses and found an 88 percent agreement.) Researchers looked at whether any diagnoses of depression in a parent under these criteria was associated with school performance, but they also looked at how a diagnosis during specific periods of a child’s life was related to school performance — those periods were before birth, after birth (0 to 11 months), and during ages 1 to 5, 6 to 10, and 11 to 16.
In total, 33,906 mothers (about 3 percent) and 23,724 fathers (2.1 percent) qualified as depressed under these criteria before the final year of their child’s compulsory education, although, as the study’s authors note, those numbers are probably much higher given that depression is severely underdiagnosed.
The researchers found that parental depression in all periods of a child’s life was independently associated with worse school performance, meaning that, all else being equal, a kid with a parent who was depressed at any point would likely exhibit a hit to their school performance. Kids were negatively affected no matter which parent was depressed, but evidence suggests both male and female children experienced greater adverse effects when their mothers — as opposed to their fathers — were depressed. Girls ages 6 to 10 and 11 to 16, in particular, suffered academically when their mothers were depressed, which researchers suggest is because the burden of taking care of a mentally ill parent (especially a mentally ill mother) usually falls upon girls.
So, how much of a negative effect did having a depressed parent have on a given student’s academic performance? Overall, a rather huge one. Taking the rather well-documented relationship between household income and academic achievement as a comparison point, Lee and his team found that, all else being equal, the difference in academic performance between a kid with a depressed parent and without one was about equivalent to the difference between a kid in the top quintile (20 percent) of Sweden’s family income distribution and a kid in the bottom quintile.
All of these factors — mental health, income, social position, child development — are intertwined, Lee says. But because it’s easier to treat someone for depression than, say, improve their socioeconomic status, the authors argue that this is an area that deserves more attention. In other words: Treating parents’ mental illness may improve not only their lives but the lives of the next generation.