Recommended Levels of Cardiovascular Risk Factors Associated With Cerebral Vessel Density, Flow

Recommended levels of body mass index (BMI), physical activity, alcohol consumption, smoking, blood pressure, glucose, and cholesterol are associated with higher cerebral vessel density, greater cerebral blood flow, and fewer white matter hyperintensities in young adults without cerebrovascular disease, according to a cross-sectional study published in JAMA.

Adults between the ages of 18 and 40 years who had no clinical evidence of cerebrovascular disease were enrolled in the analysis. The investigators evaluated the association between modifiable cardiovascular disease risk factors at recommended levels with white matter hyperintensities and indices of cerebrovascular structure and function. Risk factors and their recommended levels included BMI <25, cardiovascular fitness and/or physical activity at the highest tertile, consumption of <8 drinks/week, being a nonsmoker for >6 months, blood pressure level of <130/80 mm Hg on waking, nonhypertensive diastolic response to exercise with a peak diastolic blood pressure of <90 mm Hg, total cholesterol level of <200 mg/dL, and fasting glucose level of <100 mg/dL.

Vessel density was significantly associated with systolic blood pressure (−0.02 vessels/cm³ per mm Hg; 95% CI, −0.04 to −0.0004 vessels/cm³ per mm Hg; P =.046), smoking (0.17 vessels/cm³ per pack-year; 95% CI, 0.06-0.28 vessels/cm³ per pack-year; P =.004), and BMI (−0.08 vessels/cm³ per 1 BMI unit; 95% CI, −0.15 to −0.01 vessels/cm³ per 1 BMI unit; P =.02) in multivariable models. In addition, vessel caliber was associated with both systolic blood pressure (−0.6 μm/mm Hg; 95% CI, −1.0 to −0.05 μm/mm Hg; P =.03) and smoking (4.0 μm/pack-year; 95% CI, 0.2-8.0 μm/pack-year; P =.04).

Vessel density was greater by 0.3 (95% CI, 0.1-0.5; P =.003) vessels/cm³ for each additional cardiovascular risk factor at recommended levels. In addition, for each risk factor categorized as healthy on a 0 to 8 scale, with the highest number score indicating healthy levels, vessel caliber was greater by 8 μm (95% CI, 3-13 μm; P =.01). There were also 1.6 (95% CI, −3.0 to −0.5; P =.006) fewer white matter hyperintensity lesions per additional risk factor at recommended levels. In a subgroup of 52 patients with magnetic resonance imaging data available for analysis, cerebral blood flow was 2.5 mL/100 g/minute higher for each healthier modifiable risk factor category (95% CI, 0.16-4.89 mL/100 g/minute; P =.03).

The relatively small number of participants, the recruitment of patients from a single center, and the cross-sectional nature of the analysis represent the primary limitations of the study.

Although the researchers suggest that the associations between cerebral perfusion, white matter lesion burden, and vessel morphology are uncertain, the patterns observed in their study possibly “suggest that resilience of the white matter, and potential to withstand risk exposures, may be influenced by the vascular morphology of an individual.”

Reference

Williamson W, Lewandowski AJ, Forkert ND, et al. Association of cardiovascular risk factors with MRI indices of cerebrovascular structure and function and white matter hyperintensities in young adults. JAMA. 2018;320(7):665-673.