Higher cognitive reserve does not reduce effects of covert vascular brain injury

Vascular brain injury and cognitive reserve markers were independently associated with cognition, such that higher cognitive reserve did not reduce the adverse effects of covert vascular brain injury.

“Most of the research on cognitive reserve has focused on markers that influence the expression of Alzheimer’s disease pathology in older individuals, with comparatively few studies of cognitive reserve in midlife or of cognitive dysfunction from cerebrovascular pathology,” Romella Durrani, BHSc, of the department of clinical neurosciences and Hotchkiss Brain Institute at the University of Calgary in Canada, and colleagues wrote in Neurology. “A few studies suggest that the association of white matter hyperintensities (WMH) with lower cognition is attenuated in persons with higher education. However, whether other potential factors modify the degree of cognitive dysfunction in persons with WMH is not known.”

Researchers analyzed cross-sectional data of 10,450 individuals aged 35 to 81 years (mean age, 58.8 years; 55.8% women) from the harmonized Canadian Alliance for Healthy Hearts and Healthy Minds and the Prospective Urban and Rural Epidemiology studies to determine whether cognitive reserve reduced the effects of vascular brain injury on cognition. Researchers combined education, involvement in social activities, marital status, height and leisure physical activity into a composite score and used these as markers of cognitive reserve. They defined vascular brain injury as non-lacunar brain infarcts or high WMH burden on MRI. They used the Montreal Cognitive Assessment Tool (MoCA) and the Digit Symbol Substitution Test (DSST) to evaluate cognition.

Results showed independent associations between higher cognition and education, moderate leisure physical activity, being in a marital partnership, being taller and participating in social groups. The composite cognitive reserve score was also independently associated with higher cognition.

Durrani and colleagues noted an association between vascular brain injury and lower cognition (beta for MoCA = -0.35; 95% CI, –0.53 to –0.17; beta for DSST = -2.19; 95% CI, –3.22 to –1.15). The composite cognitive reserve variable did not modify this association.

“Our data suggests that enhancing cognitive reserve through better early life education, physical activity and social engagement may potentially help improve cognition but is not likely to mitigate the deleterious effects of covert cerebrovascular disease,” the researchers wrote. “Therefore, an effective dementia prevention strategy will need to promote both cognitive-enhancing social and behavioral activities while also reducing the risk of incident [covert brain infarcts] and WMH progression. This should include individual and health policy interventions to improve early life education and promote active social participation, encourage strong family relationships and increased physical activity, as well as new strategies to reduce progression of covert cerebrovascular disease.”