People suffering from insomnia are potentially at a higher risk of coronary artery disease, heart failure, and stroke, according to a study. In this first-of-its-kind study on insomnia, researchers examined data from 1.3m participants with or without cardiovascular disease (CVD) and stroke from 4 major public databases, including studies of atrial fibrillation and stroke. Previous observational studies have found an association of insomnia with an increased risk of developing these diseases but were unable to determine whether insomnia served as a catalyst or was solely relative.
Researchers distinctly utilised Mendelian randomisation (MR), a technique that uses genetic variants known to be connected with potential risk factor, to reduce bias in the results testing insomnia’s relation of genetic liability to numerous CVDs and forms of stroke: coronary artery disease (CAD; heart failure (HF); atrial fibrillation (AF); and ischemic stroke and its 3 major sub-types
The study selected single-nucleotide polymorphisms (SNPs) associated with insomnia complaints by participants to identify the genetic liability of insomnia at genome-wide significance; 243 SNPs were included in the analyses of CAD, 246 SNPs in the analyses of HF and AF, and 244 SNPs in the analyses of ischemic stroke. To account for multiple testing, researchers used 2-sided P values <0.007 (=0.05/7 outcomes) to determine statistical significance.
After correcting for multiple testing in the standard MR analysis (random-effects inverse-variance weighted method), researchers uncovered that genetic liability to insomnia was associated with significantly higher odds of CAD, HF and ischemic stroke as a whole, but not AF. Ischemic stroke subtypes were all associated with genetic liability to insomnia through statistically significant odds ratios (OR): ;arge artery stroke (OR = 1.13, 95% CI, 1.03-1.24; P = .01); small vessel stroke (OR = 1.08, 95% CI, 0.99-1.17; P = .08); and cardioembolic stroke (OR = 1.06, 95% CI, 0.99-1.14; P = .08)
Lead study author Dr Susanna Larsson, associate professor of cardiovascular and nutritional epidemiology at the Karolinska Institutet, emphasised that “sleep is a behaviour that can be changed by new habits and stress management." By changing habits to ameliorate insomnia severity, individuals can subsequently lower their risk for CVDs and subtypes of stroke.
While the data amplified associations of insomnia with heart disease and stroke, there were limitations in the study. The inability to delineate between HF and AF in the MR estimates may introduce bias towards these 2 categories. The focus of the MR study to evaluate whether liability to insomnia is associated with CVD rather than a cause of it further complicates the significance of the research.
“It’s important to identify the underlying reason for insomnia and treat it,” said Larsson. As insomnia affects 30% of the general population, further studies are needed to assess insomnia relation to CVDs and stroke.
Susanna C Larsson, Hugh S Markus
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[link url="https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.119.041830"]Circulation research letter[/link]