Analysis of almost 15 million people shows the trend increases with each decade, across cultures and generations

Spouses tend to share psychiatric disorders, massive study finds

Analysis of almost 15 million people shows the trend increases with each decade, across cultures and generations

Spouses are more likely to share psychiatric conditions than to have different ones.Credit: Dmitrii Marchenko/Getty

People with a psychiatric disorder are more likely to marry someone who has the same condition than to partner with someone who doesn’t, according to a massive study¹ suggesting that the pattern persists across cultures and generations.

Researchers had previously noted this trend in Nordic countries, but the phenomenon has seldom been investigated outside Europe until now.

The latest study, published in Nature Human Behaviour today, used data from more than 14.8 million people in Taiwan, Denmark and Sweden. It examined the proportion of people in those couples who had one of nine psychiatric disorders: schizophrenia, bipolar disorder, depression, anxiety, attention-deficit hyperactivity disorder, autism, obsessive–compulsive disorder (OCD), substance-use disorder and anorexia nervosa.

Scientists lack a definitive understanding of what causes people to develop psychiatric disorders — but genetics and environmental factors are both thought to play a part.

The team found that when one partner was diagnosed with one of the nine conditions, the other was significantly more likely to be diagnosed with the same or another psychiatric condition. Spouses were more likely to have the same conditions than to have different ones, says co-author Chun Chieh Fan, a population and genetics researcher at the Laureate Institute for Brain Research in Tulsa, Oklahoma.

“The main result is that the pattern holds across countries, across cultures, and, of course, generations,” Fan says. Even changes in psychiatric care over the past 50 years have not shifted the trend, he notes.

Only OCD, bipolar disorder and anorexia nervosa showed different patterns across countries. For instance, in Taiwan, married couples were more likely to share OCD than were couples in Nordic countries.

The study separated people into birth cohorts, from the 1930s to the 1990s spanning ten-year intervals. For most disorders, the chances of partners sharing a diagnosis increased slightly with each decade, particularly for those with disorders related to substance use.

What’s behind the trend?

Although the study did not investigate what causes the phenomenon, Fan says three theories could help to explain it. First, people might be attracted to those who resemble them. “Perhaps they better understand each other due to shared suffering, so they attract each other,” he says.

Second, a shared environment could make partners more alike — a process known as convergence. And third, the societal stigma of having a psychiatric disorder narrows a person’s choice of spouse.

Jan Fullerton, a psychiatric geneticist at the University of New South Wales in Sydney, Australia, says that social and environmental stressors could contribute to a new diagnosis in a previously unaffected partner, particularly if they had milder, undiagnosed symptoms.