Risk of stroke, brain atrophy linked to modifiable lifestyle choices with MRI

Researchers have found young adults' lifestyle choices can increase their risk of stroke and dementia later in life, even with good cardiovascular health and without evidence of cerebrovascular disease, according to an Aug. 21 study in the Journal of the American Medical Association.  

Using MRI, Paul Leeson, PhD, a professor of cardiovascular medicine at the University of Oxford, and colleagues found higher cerebral vessel density, higher cerebral blood flow and fewer white matter hyperintensities on brain scans. The findings were associated with cardiovascular risk factors such as high blood pressure, smoking, alcohol consumption and a higher body mass index (BMI), according to the researchers. 

The study included 125 participants (49 percent women) between 18 and 40 years old who had no clinical evidence of cerebrovascular disease. Among the participants, 29 had a history of high blood pressure and 21 were taking antihypertension medicine.  

A cardiovascular risk assessment was conducted for each participant as well as a brain MRI during a fasting state and before exercise, according to the researchers.  

Each participant was awarded one point toward a score (ranging from one to eight) based on the following factors: BMI less than 25, highest level of physical activity, less than eight alcoholic drinks consumed in one week, nonsmoker for more than six months, blood pressure lower than 130/80 mm Hg, nonhypertensive diastolic response to exercise, total cholesterol level less than 200 mg/dL and fasting glucose level less than 100 mg/dL.  

White matter hyperintensity lesions and associated volumes were segmented using the brain intensity abnormality classification algorithm (BIANCA), according to the researchers. Additionally, brain blood arrival time and cerebral blood flow was assessed by MRI in a subgroup of 52 participants.  

Overall, the researchers found participants had a mean score of six for modifiable cardiovascular risk factors at recommended levels and were correlated with cerebrovascular morphology and white matter hyperintensity count in multivariable models.  

“For each additional modifiable risk factor categorized as healthy, vessel density was greater by 0.3 vessels/cm3, vessel caliber was greater by 8 μm and white matter hyperintensity lesions were fewer by 1.6 lesions,” Lesson et al. wrote. “Among the 52 participants with available data, cerebral blood flow varied with vessel density and was 2.5 mL/100 g/min higher for each healthier category of a modifiable risk factor.”  

Smoking, alcohol consumption, and diastolic blood pressure during exercise also attributed to the number of white-matter hyperintensity lesions in the study population. The subset of 52 participants in the lowest tertile for the modifiable cardiovascular score displayed lower vessel density and an average value for cerebral blood flow of 55 mL/100 g/min, which is in the bottom of the current study cohort, according to the researchers.  

“The distribution of MRI findings observed in the current study raises the potential that some individuals may be starting to diverge to different risk trajectories for brain vascular health in early adulthood,” the researchers wrote. “The observed association between brain vascular measures and modifiable risk factors raises the potential for targeted intervention to prevent progression to disease.”  

Overall, the authors noted that additional research is needed to accurately verify their study, however their findings demonstrate how medical imaging could improve the understanding of cardiovascular risk factors in correlation with early brain changes.