A landmark multinational study reveals that spousal similarities in psychiatric disorders persist across cultures and generations, spanning nearly 90 years. Researchers analyzed data from more than 14 million individuals to investigate how psychiatric traits align between partners.
Previous research suggested that spouses may share certain psychiatric disorders, but these studies were limited in scope. The new study, published in Nature Human Behaviour, provides the first large-scale, cross-cultural analysis of spousal correlations across nine psychiatric disorders, offering insights into the stability of these patterns over time.
The research examined approximately five million spousal pairs in Taiwan, 571,534 pairs in Denmark, and data from 707,263 pairs in Sweden. Combined, the study analyzed 14.8 million individuals, including up to six million matched controls. Case numbers ranged from 31,195 for anorexia nervosa to 1.4 million for major depressive disorder.
In Taiwan, positive spousal resemblance was observed across all nine psychiatric disorders. These findings largely mirrored patterns in Nordic countries, except for anorexia nervosa, bipolar disorder, and obsessive-compulsive disorder, which showed regional differences.
The study also explored generational trends in Taiwan. Rates of multiple substance use disorders increased in successive birth cohorts, while obsessive-compulsive disorder resemblance between spouses declined. Sex-specific differences were minimal, and attention-deficit/hyperactivity disorder showed no consistent trend.
Parent–offspring resemblance followed similar patterns, with increased risk for major depressive disorder and substance use disorder when present in both parents, and decreased resemblance for obsessive-compulsive disorder. Family risk was particularly elevated when both parents shared a diagnosis of schizophrenia, bipolar disorder, major depressive disorder, or substance use disorder.
Genetic analyses supported these observations. Spousal resemblance correlated with heritability and genetic correlations identified in Genome-Wide Association Studies (GWAS), highlighting a potential genetic component to assortative mating in psychiatric disorders.
The findings suggest that psychiatric disorders are influenced not only by genetics and environment but also by non-random mating patterns. Researchers argue that future genetic studies must account for spousal resemblance to better understand the heritability and familial transmission of psychiatric disorders.
This groundbreaking study emphasizes that shared psychiatric traits between partners are widespread, culturally consistent, and persistent across generations—adding a crucial dimension to the understanding of mental health risks.
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