Spouses tend to share psychiatric disorders

While a traditional adage says that opposites attract, the opposite is true when it comes to couples and psychiatric disorders.A large study comparing spouses across three different countries found that individuals with a psychiatric disorder tended to be paired with a partner with the same disorder, and the trend appears to be independent of culture or nation. Researchers, writing in Nature Human Behaviour, stated that the pattern was consistent across countries, cultures and generations.While past studies have shown there is a tendency of spouses to share the same diagnosis, there are still questions around the impact of socio-cultural influences, generational effects as well as heritability. Studying this area can lead to a better understanding of the genetic architecture of psychiatric disorders and could impact counselling, the researchers said. The paper points out there are various reasons why partners often share a diagnosis. This can range from people picking a mate that is similar to them (and relatable), a shared environment making people more alike and social constraints which may influence who one can marry or partner with.“While some of these driving forces are more sensitive to cultural changes, their cumulative effect over generations can lead to an evident impact on trait variation and disease prevalence,” the study said.The study included data on a combined total of more than 14 million people from Taiwan, Sweden and Denmark. It included data for over 5 million couples, and revealed 1.4 million people who had been diagnosed with major depressive disorder (MDD) to more than 31,000 with anorexia nervosa (AN). There were also 6 million matched controls.The Danish national registry included data for 571,534 couples, while the Swedish national registry included 707,263 pairs.The Taiwan part of the study used data from Taiwan’s National Health Insurance Research Database (NHIRD). The researchers evaluated the degree of spousal correlations across nine psychiatric disorders over a 90 year period, and compared these to estimates derived from the two Nordic registries.Generational changes in Taiwan for people born after the 1930s were investigated as well, with the researchers looking at data in chunks of 10-year intervals. All all registry entries from 1997 to 2018 in the Taiwan National Insurance database were used to identify potential participants, as well as familial relationships. Same-sex marriage couples were excluded, as were people who had multiple spouses registered. The final number of eligible pairs used in the analyses was 4,954,870.Of this, the Taiwanese data included 79,551 probands who had been diagnosed with schizophrenia (SCZ); 218,867 with bipolar disorder (BPD); 1,005,055 with MDD; 1,091 with autism spectrum disorder (ASD); 10,436 with attention deficit hyperactivity disorder (ADHD); 592,245 with substance use disorder (SUD); 32,914 with OCD; 654,661with anxiety and 1,615 with AN.Analyses revealed that individuals with a psychiatric disorder had a significantly higher probability of marrying someone who also had the same psychiatric disorder than someone without. But there were some differences in the patterns over subsequent decades. For example, SUD between spouses became more common in more recent decades, which may reflect changes in trends of substance use in general.“In contrast, the spousal correlation of OCD/OCD trended downward for both female and male probands,” in the Taiwan cohort. The paper did not speculate on why.But in general Dr. Chun Chieh Fan, coauthor of the study, told the Canadian Healthcare Network that he was impressed with the fact that “Spousal correlations of psychiatric disorders are very consistent across almost half a century despite drastic changes in the societal environment of Taiwan.” Dr. Fan is an associate professor of population and genetics, at the University of Tulsa. Overall, the patterns were similar to those found in the Swedish and Danish data. “This evidence supports a widespread existence of spousal correlations across psychiatric disorders, regardless of country and cultural context,” the study said.Dr. Fan stated that he and his colleagues were surprised to see such degree of similarities between such different countries. “Despite differences in cultural contexts, patterns of spousal correlation across psychiatric disorders have limited variation between Taiwan and Nordic countries,” the study said.The researchers also looked at couples who shared a psychiatric disorder and who had offspring. Here is was found that the parents were more than twice as likely to have offspring with the same disorder than children who had only one parent with the disorder. The increased risk stood out most for schizophrenia, MDD, BPD and SUDs. Dr. Fan noted that schizophrenia and BPD are highly heritable while MDD and SUD are only modestly heritable.“Our interpretation is that the shared environment or nurturing effects of parents got passed down to offspring, in addition to the inherited genetic risks. It suggests one particular mechanism as the driver for spousal correlations, (such as) assortative mating,” he said. ‘Assortative mating’ is the attraction to, or choosing of, a mate who has similar characteristics.While the work can’t yet be directly translatable to clinical practice “we think it is good for doctors to consider family as a unit when they help their patients to overcome mental health challenges,” he said.

Spouses tend to share psychiatric disorders

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