More than 3 percent of individuals globally have unruptured blood vessel abnormalities in the brain known as intracranial aneurysms, the vast majority of which will never rupture.

A subarachnoid haemorrhage (SAH), commonly known as a brain bleed, occurs in about 2.5 percent of intracranial aneurysms.

SAH is a form of stroke that develops when a blood vessel on the brain’s surface bursts and flows into the space between the brain and the skull.

“Ruptured aneurysms are highly fatal. It is, therefore, extremely important to identify modifiable risk factors that can help prevent aneurysms from rupturing,” says Susanna C. Larsson, the study author.

The study, published in the Journal of the American Heart Association, suggests that insomnia, along with the more well-known risk factors of smoking and high blood pressure, may be a potential risk factor for a brain bleed caused by a ruptured aneurysm.

The researchers wanted to know if certain parameters were linked to intracranial aneurysms and/or aneurysm rupture. They investigated the relationship between aneurysms and coffee consumption, sleep, physical activity, body mass index (BMI), blood glucose levels, type 2 diabetes, blood pressure, cholesterol, chronic inflammation, and kidney function, as well as established risk factors such as smoking and high blood pressure.

Data from various genome-wide association studies were analyzed to understand genetic links between lifestyle and cardiometabolic risk variables. The International Stroke Genetics Consortium used genetic data from a meta-analysis to identify over 6,300 cases of intracranial aneurysm and about 4,200 cases of aneurysmal subarachnoid haemorrhage. To establish genetic predisposition for aneurysms, cases of intracranial aneurysm and subarachnoid haemorrhage were compared to nearly 59,500 controls. According to the findings:

• A genetic predisposition for insomnia was associated with a 24% increased risk for intracranial aneurysm and aneurysmal subarachnoid hemorrhage.
• The risk for intracranial aneurysm was about three times higher for smokers vs. non-smokers.
• The risk for intracranial aneurysm was almost three times higher for each 10 mm Hg increase in diastolic blood pressure (the bottom number in a blood pressure reading).
• High triglyceride levels and high BMI did not demonstrate an increased risk for intracranial aneurysm and aneurysmal subarachnoid hemorrhage.

“The association between insomnia and intracranial aneurysm has not been reported previously, and these findings warrant confirmation in future studies,” says Larsson.

“Our research supports the thinking that risk factors that people can change or manage may impact brain aneurysms and hemorrhage risk. Once confirmed, future studies should examine ways to incorporate this knowledge into prevention programs and therapies.”

One of the study’s shortcomings was that there was insufficient information to effectively examine some of the risk factors. Furthermore, since the study only included adults of European origin, the findings may not be generalizable to individuals of different racial and ethnic backgrounds.

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