Are depression and intelligence related? The answer may be in our genes
In the scientific realm of psychiatry, researchers often navigate more unknowns than knowns. Despite decades of scientific leaps and technological breakthroughs, the brain’s complexity remains elusive.
In a recent report, scientists announce a crucial piece of this puzzle lies deep in our genetic code. The team discovered a “surprising” shared genetic architecture between depression and another, seemingly counterintuitive factor: intelligence.
Cognitive ability is synonymous with intelligence in the study. The team detected overlapping gene variants associated with both cognitive ability and self-reported depression.
Each of the cohort studies included in this larger analysis measured intelligence differently through various mathematical, knowledge, and verbal cognitive tests. Researchers also tested individuals on their memory, executive function, processing speed, and IQ. Collectively, this trove of information is categorized as information about intelligence.
“The current findings suggest there is a genetic link between intelligence and mood disorders,” study co-author Ole Andreassen tells Inverse. Andreassen is a psychiatry genetics researcher at the University of Oslo.
“The nature of the genetic link is, however, not straightforward,” Andreassen explains.
This finding was published Monday in the journal Nature Human Behavior.
Is there a link between depression and intelligence?
The backstory — To date, the research exploring the connection between depression and intelligence has been mixed.
During a depressive episode, people often have reduced cognitive abilities, which is a key feature of the depressive phenomenon, as well as a diagnostic item, Andreassen explains. Depression can impair attention and memory, as well as decision-making skills.
However, people with depression may also have more “positive” cognitive associations including involvement in the arts and music, the researcher adds. Studies suggest creative people are more likely to experience mood disorders.
Based on the mixed data, researchers previously suspected there wasn’t a clear relationship between the two factors.
But in this study, scientists found a “dual relationship” that helps explain the seemingly conflicting positive and negative associations between depression and intelligence.
Digging into the details — Andreassen and his colleagues used a statistical approach to analyze recent large genome-wide association study datasets on major depression and intelligence. They collected data on major depression from the Psychiatric Genomics Consortium and 23andMe, which included cases where people reported any depression symptoms. The sample consisted of 135,458 cases of major depression and 344,901 controls.
Data on general cognitive ability were based on 269,867 individuals drawn from 14 different cohorts, with 72 percent from…