When we think about what leads to bipolar disorder, we often focus on genetics. But a new study of more than 115,000 people suggests the story is more complicated. Researchers looked at a genetic risk score for bipolar disorder alongside six measures of social hardship, including stress, discrimination in healthcare, and adverse childhood experiences. They found that each social factor was more strongly linked to having the condition than the genetic score was.
The data came from the diverse All of Us Research Program, which included 7,000 people with bipolar disorder. The genetic score, which estimates inherited risk, explained only a small fraction of who developed the condition—less than 2% of the variance in people of European ancestry, and even less in other groups. In contrast, the link to social factors was clearer. For example, people who reported four or more adverse childhood events were more than two and a half times as likely to have bipolar disorder.
Perhaps the most striking finding was about risk profiles. People in the lowest 10% for genetic risk, but who faced high social burdens, had rates of bipolar disorder that matched or even exceeded those in the top 10% for genetic risk who had low social burdens. This paints a picture where a difficult life can weigh as heavily as a genetic predisposition.
It's important to remember this is an observational study. It shows associations, not causes. It can't tell us if these stressful experiences directly trigger bipolar disorder, or if other factors are at play. The genetic scores used also work better for people of European ancestry, highlighting a need for more inclusive research. Still, the results strongly suggest that to understand mental health, we need to look at a person's whole life, not just their DNA.