The risk of stroke is affected by both genetics and lifestyle choices. However, according to new research published today in the Journal of the American Heart Association, living a healthy cardiovascular lifestyle may significantly lower the risk of stroke in a person’s lifetime, even for those who are at high risk for stroke.

According to senior study author Myriam Fornage, “we know that well-managed, modifiable risk factors, especially the treatment of hypertension, can noticeably lower an individual’s risk of stroke.”

“Our study confirmed,” adds the author, “that we may be able to mitigate the lifetime risk of stroke by modifying other risk factors, and that regardless of genetics — whether you have a high polygenic risk score or low polygenic risk score — maintaining good cardiovascular health decreases the lifetime risk of stroke. So, modifiable risk factors are crucial in preventing stroke.”

The data for the study came from the Atherosclerosis Risk in Communities (ARIC) Study, a community-based study of over 11,500 white and Black adults over the age of 45 who had no history of stroke at the time of enrolment. 45 percent of the participants in the study were men, while 55 percent were women.

Based on a stroke polygenic risk score, researchers calculated the lifetime probability of a first stroke according to hereditary risk factors. Over 3 million genetic variants, or single-nucleotide polymorphisms, were analyzed throughout the entire genome to create polygenic risk scores. Based on an examination of the number of single-nucleotide polymorphisms (SNPs) associated with stroke, participants were classified as having low, middle, or high genetic risk. The number of stroke-related SNPs was standardized at more than 2.7 million in white adults and more than 2.2 million in black individuals. The researchers looked into the potential influence of the American Heart Association’s Life’s Simple 7 guidelines and whether a higher Life’s Simple 7 cardiovascular score (equivalent to better cardiovascular health) mitigated the detrimental impact of a high hereditary risk on lifetime stroke risk.

The Life’s Simple 7 scores are a composite indicator of seven modifiable risk factors for cardiovascular disease: body mass index, total cholesterol, blood pressure, glucose levels, and smoking status. According to Life’s Simple 7, cardiovascular health is classified as being at its best, average, or inadequate based on each participant’s overall score for the optimum cardiovascular health components. To calculate lifetime stroke risk for this analysis, the polygenic risk score and Life’s Simple 7 scores were merged.

For the avoidance of doubt, this research relied on the 2010-established Life’s Simple 7 measures of the American Heart Association. Life’s Essential 8 guidelines were updated and reintroduced on June 29, 2022, to include sleep as an additional component of heart health, effective June 29, 2022.

The study revealed:

At age 45, people in the study with the lowest polygenic risk scores had a 9.6% chance of having a stroke over the rest of their lives. The risk of having a stroke over the course of a person’s life was 13.8% for people with an intermediate polygenic risk score and 23.2% for people with a high polygenic risk score.
People whose genes made them more likely to have a stroke and whose heart health was poor had a 24.8% chance of having a stroke in their lifetime.
The greatest reduction in lifetime risk of stroke was shown in those with optimum cardiovascular health across all polygenic risk score categories (low, middle, and high). Participants with a high polygenic risk and good cardiovascular health were found to have a lifetime stroke risk reduction of up to 43% compared to participants with poor cardiovascular health. This translated to an additional six years without having a stroke.

“This is the first step in using genetic information to identify people who may be at higher risk for stroke, and also in motivating people to make lifestyle changes for cardiovascular disease prevention,” Fornage explained. 

“This type of study shows us the possibilities for the future. Polygenic risk scores are not used clinically at this point; however, this may be the first step towards achieving personalized risk information to be used in lifestyle and health change. Having optimal cardiovascular health is crucial in stroke prevention.”  

The authors acknowledge that one of the study’s primary limitations is that a polygenic risk score is a tool that requires refinement before it can be used widely. The technique was created and validated only among white people, so it cannot be used to properly predict stroke risk in individuals from different racial or ethnic origins.

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