Genetics Help Explain Link Between Chronic Pain and Depression

The connection between chronic pain and major depressive disorder (MDD) has been long studied in the medical world; and although the effort to identify precise drivers behind pain is still a work in progress, genetics and environmental factors have been in the forefront.

A team from the University of Edinburgh in the United Kingdom set out to uncover the impact of genetic and environmental factors on chronic pain, as well as how they influence the relationship with MDD.

To do this, the researchers gathered a cohort of 23,960 patients through general practitioners in the Generation Scotland: Scottish Family Health Study (GS:SFHS). They looked at genetics and shared family environment with spouses, siblings, and household relationships.

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“We then examined and partitioned the correlation between chronic pain and MDD and estimated the contribution of genetic factors and shared environment in GS:SFHS,” the authors explained. “Finally, we used data from two independent genome-wide association studies to test whether chronic pain has a polygenic architecture and examine whether genomic risk of psychiatric disorder predicted chronic pain and whether genomic risk of chronic pain predicted MDD.”

After being tested in the GS:SFHS cohort, it was repeated in 112,151 genotyping and phenotypic data from 500,000 people in the UK from the UK Biobank.

According to the results in PLOS Medicine, chronic pain has a 38.4% heritability and 18.7% correspondence with shared environment with spouses. One of the reasons for the spousal link could be due to assortative mating — which is choosing a spouse similar to oneself. In addition, the GS:SFHS and UK Biobank analyses both lined up with previous research showing a correlation between chronic pain and depression. The link tends to persist within families for genetic reasons, the team specified.

“Genetic factors, as well as chronic pain in a partner or spouse, contribute substantially to the risk of chronic pain for an individual,” the authors summed up. “Chronic pain is genetically correlated with MDD, has a polygenic architecture, and is associated with polygenic risk of MDD.”

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