Couples universally tend to share the same psychiatric disorders

Within couples, psychiatric illnesses and disorders are often found in both members, regardless of culture or generation, determines a study published in the journal Nature Human Behavior. “ We know that people often marry people with similar education, height, and weight.", explains the psychiatrist and first author of this work Chun Chief Fan to Science and Future. “ We expected to observe positive correlations between disease pairs, but were surprised to find how consistent and persistent they were. »

Couples have a strong tendency to share their psychiatric disorders

It must be said that the study is large. It examines 5 million Taiwanese couples, more than 570,000 Danish couples and 700,000 Swedish couples, data chosen for its quality and availability. The results show a strong correlation between the spouses' psychiatric illnesses and disorders regardless of their culture. The nine pathologies or disorders examined, chosen because they were the most studied in the dataset, are schizophrenia, bipolar disorder, anxiety, depression, autism, attention deficit hyperactivity disorder (ADHD), addiction and obsessive compulsive disorder (OCD).

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“ Spouse correlations in the same disorder pairs are always higher than in most other combinations, but other disorder pairs are also consistently and persistently observed", analyzes Chun Chief Fan. In short, couples are more likely to share the same pathology or disorder, or to a lesser extent another person with another pathology or disorder on the list. " All combinations have higher than expected frequencies, consistently and persistently across cultures and generations", adds the researcher. According to him, the strength of these results suggests that other psychiatric disorders or pathologies are affected by this correlation between spouses.

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Unknown causes

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While the study does not allow for an investigation into the causes of this preferential pairing based on mental health, the scientists put forward several hypotheses. First, it may be that couples share the same environment after marriage, making them more similar. Second, it may be that patients with psychiatric disorders have limited choices in spouses due to social constraints, increasing the likelihood that they will marry patients with psychiatric disorders. Third, it may also be that certain common characteristics attract two people to each other, such as a better understanding of each other's situation." lists Chun Chief Fan. The only clue to the underlying causes of this phenomenon is that they must be common across time and space, to explain this universal trend.

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Greater risk of transmission to children

Clinically, this work highlights the importance of exploring the mental health of the spouse of a patient already diagnosed, but also of the children. Since these pathologies all have associated genetic factors, and are therefore heritable, their presence in both parents significantly increases the risk that the children will also be affected. Offspring of two parents with the same disorder may more than double their risk of developing it compared to those with only one parent with the same disorder.", the researchers explain, particularly for schizophrenia, bipolar disorder, addiction and depression. This suggests that the observed correlations between psychiatric disorders in spouses are not a transient epiphenomenon, but a persistent force that determines the mode of hereditary transmission of disorders in human populations." they conclude.