Insomnia related to depression, cardiovascular disease | Science


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By Michael Price

Insomnia, often attributed to stress or poor sleep habits, may be closely linked to depression, heart disease and other physiological disorders, and now reveals two deep dives in the human genome.

"Both studies are very well done," says psychologist Philip Gehrman of the University of Pennsylvania's Perelman School of Medicine, who studies sleep behavior. Nevertheless, he points out, there is still a long way to go before genetic links with insomnia can be translated into new treatments for patients.

According to some estimates, insomnia costs the US workforce more than $ 63 billion per year in lost productivity. It's also incredibly common: one-third of the world's population suffers from insomnia-related symptoms at any time. Yet, the disorder remains poorly understood.

In a new article published today in Nature Genetics, researchers led by geneticist Danielle Posthuma of Vrije Universiteit in Amsterdam have conducted a genome-wide association study (GWAS), which looks for links between shared DNA sequences and particular clinical behaviors or symptoms. The group has analyzed the genomes of more than one million people, which, according to the authors, is the largest GWAS to date. The data comes from the UK Biobank, a large UK long-standing genetics study, and the 23andMe private genetics company. The prevalence of insomnia among people covered by both databases was about 30%, which is consistent with estimates for the general population.

Scientists eventually discovered 956 genes predicting some risk of insomnia. Many have already been associated with depression, neuroticism, diabetes, and cardiovascular disease, but they are only weakly related to other sleep characteristics, such as the quality of sleep and the fact of being morning or evening. The team also found a link between insomnia and MEIS1, a gene previously linked to restless legs syndrome.

In another study published today in Nature Genetics, a different team also led a GWAS on insomnia. The researchers, led by geneticist Richa Saxena of Massachusetts General Hospital in Boston, examined 453,379 genomes. They found 57 chromosomal locations containing about 236 genes associated with the symptoms of insomnia. MEIS1 It was also one of them and, again, there seemed to be a link between insomnia and the genes involved in depression, coronary heart disease and the lower quality of life reported. In addition, the team's analyzes suggest that insomnia may cause symptoms of depression and heart disease in some people.

"Insomnia is an important sleep disorder to take seriously, both for its impact on quality of life … and for depression and future heart disease," says Saxena.

The identification of these genetic targets could allow researchers to more effectively adapt medications and therapies, says Posthuma. For example, drug manufacturers could look for molecules that alter the activity of some of these genes. According to Posthuma, existing treatments for depression, such as antidepressants or cognitive-behavioral therapy, could also help ease the symptoms of insomnia.

Identifying the right targets among the hundreds of candidate genes suggested by these studies will be the next difficult step, says Gehrman. Scientists, he notes, need to "determine what associations are" real "or just random".


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