Couples more likely to share same mental health conditions, study finds

A new international study reveals a surprising trend in romantic relationships: partners are more likely than expected to have the same mental health diagnoses.

The research, which analysed health records from over six million couples across Taiwan, Denmark, and Sweden, found that individuals with psychiatric conditions — such as depression, anxiety, bipolar disorder, ADHD, autism, substance-use disorders, obsessive-compulsive disorder, anorexia nervosa, and schizophrenia — often partner with someone experiencing a similar condition.

Experts suggest several psychological and social factors that could explain this phenomenon.

One factor is the tendency for individuals to seek partners who resemble themselves, not only in background or values but also in thinking patterns and daily habits. For instance, someone with anxiety or autism may be drawn to a partner who shares a preference for routine and structure, creating a sense of compatibility.

Shared environments may also play a role.

People with similar mental health challenges often frequent similar social settings, increasing the likelihood of meeting a partner with the same experiences. In the case of substance-use disorders, for example, social circles and venues where substances are common may bring people together.

Attachment styles, shaped by early life experiences, can influence partner choice as well. Individuals with anxious attachment — which is linked to conditions such as anxiety, depression, and bipolar disorder — may be drawn to partners who meet their emotional needs or mirror their patterns of seeking reassurance.

Finally, the sense of belonging within a shared social identity may make these relationships more appealing. Having a partner who understands and empathizes with one’s struggles can provide validation and emotional support that might be less accessible in other relationships.

The authors caution that the research is observational. It cannot determine whether shared diagnoses influenced partner choice or whether conditions developed after the relationship began. Diagnostic practices may also vary depending on healthcare providers, particularly if couples consult the same doctor, which could influence the findings.