Insomnia Linked to Higher Risk for
Aneurysm, SAH

Rosalind Stefanac

November 11, 2021

Researchers are reporting a novel association between insomnia and both intracranial aneurysm and aneurysmal subarachnoid hemorrhage (aSAH).

The investigators used a Mendelian randomization to investigate whether modifiable lifestyle and cardiometabolic risk factors affected the prevalence of ruptured or unruptured intracranial aneurysm (IA) and aSAH. In addition to common risk factors such as smoking and high blood pressure, they looked at sleep, coffee consumption, physical activity, body mass index, blood glucose levels, type 2 diabetes, cholesterol, chronic inflammation, and kidney function.

The data showed that a predisposition to insomnia, smoking and higher blood pressure were all associated with increased risk for both IA and aSAH. In fact, a genetic predisposition for insomnia increased the risk for both outcomes by 24%.

The risk for IA was almost threefold (odds ratio 2.92) for each 10 mm Hg increase in diastolic blood pressure and three times higher for smokers vs non-smokers. Other factors studied did not appear to be significantly associated with IA or aSAH risk.

"The association with insomnia was novel and somewhat surprising, even though insomnia has been shown to be associated with other vascular diseases in previous similar studies; there is also limited previous evidence suggesting a role of sleep apnea in increasing hemorrhagic stroke risk," says study author Susanna C. Larsson, PhD, associate professor in the unit of cardiovascular and nutritional epidemiology at the Karolinska Institute in Stockholm, Sweden.

"Coffee consumption and diabetes have not been clearly related to aSAH in previous studies, so the null findings were not very surprising," she added.

Given that sleep is difficult to modify and this is the first study to identify insomnia as a risk factor, she says these results should be interpreted with caution. "Hence, the primary take-home message from this study is to avoid smoking and to maintain a healthy blood pressure," she adds.

The findings were published online November 3 in the Journal of the American Heart Association.

Larry Goldstein, MD, professor and chair in the Department of Neurology at the University of Kentucky and co-director of the Kentucky Neuroscience Institute, says insomnia is a novel risk factor that needs to be validated in other data sets. "This Mendelian randomization is a relatively new [research] methodology and not widely understood yet, but I think we're going to see more studies using it," he says.

Even if further research reinforces an insomnia link to IA or aSAH risk, he added, "the next question is what do we do about it and will treating it modify the risk."

The researchers looked at data from several European-based genome-wide association studies to examine various genetic associations. Using genetic information from a meta-analysis conducted by the International Stroke Genetics Consortium, they identified some 6300 cases of IA and nearly 4200 cases of aSAH.

Cases of intracranial aneurysm and subarachnoid hemorrhage were compared to more than 59,500 controls to determine genetic predisposition for aneurysms. The authors note that there were limited data to adequately analyze all the risk factors.

With data reinforcing smoking and high blood pressure as causal risk factors for IA and aSAH, Larsson says patients should be advised to stop smoking and to change lifestyle habits (eg, be lean, be physically active, eat a healthy diet), or if lifestyle change is not enough, be treated for high blood pressure.

Goldstein noted that managing hypertension is always an imperative. "Even folks who have relatively minor degrees of hypertension may have some increased risk not only for subarachnoid hemorrhage but stroke in general," he says.

The authors were financially supported through the British Heart Foundation Centre of Research Excellence at Imperial College; the Academy of Finland Project 312123; European Union's Horizon 2020; the Swedish Research Council for Health, Working Life and Welfare; the Swedish Heart‐Lung Foundation; Swedish Research Council; and Netherlands Cardiovascular Research Initiative: An initiative with support of the Dutch Heart Foundation. Study author Dipender Gill, PhD, is employed part‐time by Novo Nordisk. The other authors have disclosed no relevant financial relationships.

Journal of the American Heart Association. Published online
November 3, 2021.  Full text

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