A Happy Marriage Affects Genetic Mental Health Risk

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3194556 / Pixabay

Source: 3194556 / Pixabay

Intimate romantic relationships are intimately linked to mental health. Close relationships correlate significantly with overall psychopathology as well as specific mental disorders.

Research has linked marital quality specifically and consistently to disorders of mood and anxiety, as well as substance use and personality disorders. High-quality marriages, in particular, appear to buffer people against psychological distress.

The effect may operate via many different routes, both direct and indirect. A quality marriage may provide social, emotional, and financial support. It may provide a sense of accomplishment and meaning.

Spouses may keep each other accountable for healthy behavior, such as keeping doctor appointments and other important commitments. Marriage also provides both partners with regular access to sexual pleasure and satisfaction, which in turn helps improve life satisfaction.

Another less intuitive way marriage may contribute to health is its effects on an individual’s genes. Genes have been found to contribute to most psychological disorders, and these genetic influences tend to consist of small effects of multiple genes, as opposed to one large effect of a single gene.

Research has also shown that the activation and deactivation of certain genes depends in part on environmental factors. In other words, a given disorder’s heritability (a measure of how much differences in people’s genes account for differences in their traits) is not set in stone but rather dependent on the environment. This notion is quite intuitive.

A seed has all the genetic potential to grow into a healthy tree. However, it will not fulfill this genetic potential absent a supportive environment such as sufficient light, water, and rich soil nutrients.

The idea that genetic influences on a disorder are contingent on an environmental stressor or trigger is not new. It is the fundamental assumption of the diathesis-stress model, a well-researched framework for understanding how disorders develop. In this model, an existing genetic vulnerability may remain dormant unless some environmental stress activates it.

For example, the heritability of externalizing behavior (rule-breaking, impulsivity, inattention aggression) is higher for individuals experiencing negative peer and neighborhood environments.

One way a good marriage may affect health is through its moderating effects on risky genes. In other words, certain genes that predispose individuals to mental health problems may be deactivated when the individual is in a high-quality marriage. Indeed, research has suggested that marriage quality may affect the heritability of certain tendencies.

For example, the heritability of internalizing psychopathology (such as depression and anxiety) is greater for people in low-quality marriages. At the same time, environmental influences were highest for people in satisfying relationships.

A recent (2021) study by Purdue University psychologist Susan South and colleagues sought to extend these findings by looking at how marital quality may affect genetic influences on psychopathology for different mental health problems as indexed by a polygenic risk score (PRS), a measure of one’s disease risk due to multiple genes.

The authors sought to find whether “marital quality may serve as an important context for the expression of genetic influences on psychopathology.” Specifically, they examined whether marital satisfaction may affect the link between the PRSs and a range of mental health syndromes that have been linked to marital quality, including major depressive disorder, generalized anxiety, the personality trait of neuroticism, and alcohol use.

To that end, the researchers analyzed data from the Midlife in the United States Project (MIDUS), collected on individuals ages 25 – 74 thrice between 1995 and 2013. A subsample of that project (N = 2,118) also completed a biomarker project in which PRSs were derived from genetic analyses conducted on blood samples.

South and her colleagues limited their sample to individuals who reported being married or living with a romantic partner (N = 898). The data on mental health phenotypes (outcomes), PRSs for those phenotypes, and relationship satisfaction were analyzed.

The authors first found a strong effect of marital satisfaction on mental health. “The most consistent finding was the effect of marital satisfaction on psychopathology. Marital satisfaction was robustly related to total depressive symptoms, maximum number of drinks, and neuroticism.” Marital quality, in other words, is linked to a host of mental health outcomes. These findings, however, do not resolve the causality question since causality may run both ways. To wit: depression may cause the deterioration of a marriage. A deteriorating marriage may facilitate the onset of depression.

But what about the main hypothesis that marital quality will affect genetic risk? Among the outcomes studied, the authors found this effect only for Generalized Anxiety Disorder (GAD). The PRS for anxiety was more strongly associated with GAD at low levels of marital satisfaction. Relationship satisfaction, on the other hand, was found to buffer against the effects of the PRS score on anxiety. The authors write:

Genetic predisposition for anxiety is most likely to be triggered or expressed among individuals with unsatisfying or conflict-laden intimate romantic relationships but buffered among individuals with very satisfying relationships.

The authors conclude:

Our findings suggest that for generalized anxiety, a genetic susceptibility to environmental influences on anxiety may be highly influenced by relationship quality.

This study adds to the body of research suggesting that one-way marriage exerts its salutatory effects on certain aspects of psychological well-being through its effect on the activation of risk-related genes.

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