New Data Point to Nuanced Relationship Between Major Depression, Bipolar Disorder

A new study has found that the genetic links between major depression (MD) and bipolar disorder (BD) are not as clear cut as some hypothesize, but rather have both shared and relatively distinct genetic risks. The findings, which appear this week in JAMA Psychiatry, shed new light on the relationship between the two psychiatric conditions. Since BD and MD were first proposed as distinct disorders more than 60 years ago, questions have persisted over the shared genetic liabilities for each. To investigate, a team led by scientists from Lund University examined data on 2.7 million Swedish individuals born between 1960 and 1990, including family genetic risk scores for MD and BD and health data on nine other mood, anxiety, and psychotic disorders. They find that MD and MD shared a genetic vulnerability to mood disorders, but that people at high risk for MD and BD had substantial and relatively specific risks for anxiety disorders and psychosis, respectively. The results, the study's authors write, contradict hypotheses that BD and MD are genetically distinct or genetically closely interrelated, and instead support a more nuanced association. "Clarifying the genetic relationship between pairs of psychiatric disorders can be aided by moving beyond a consideration of risks solely for those two disorders to examine profiles of risk to a broader set of conditions," they conclude.