Abstract 3165: Influence Of Hypertension On Cognition Is Mediated By Brain Injury

Abstract

Background Substantial evidence indicates that hypertension is a major risk factor for cognitive decline and incident dementia. Unfortunately, community based, longitudinal studies examining this association are limited. In addition, while it is assumed that vascular brain injury likely mediates this association, these studies are similarly limited. Methods The Sacramento Area Latino Study of Aging is a community based longitudinal study of life-style factors and cognitive performance among individuals 65 years and older. Comprehensive assessment including blood pressure measures and yearly cognitive testing was performed. In addition, a subgroup of 207 subjects received brain MRI with quantitative analysis of gray matter, hippocampus and white matter hyperintensity (WMH) volumes. We analyzed the relationship between baseline measures of blood pressure (systolic (SBP), diastolic (DBP) and pulse pressure (PP)), MRI measures and longitudinal cognitive performance over an average of six visits as measured by the 3MMSE using random mixed models regression analysis. Results On average, subject performance improved slightly during the first two visits after baseline measurement, but then began to deteriorate in a fashion best estimated by a quadratic term (trial*trial). 3MMSE performance was significantly and inversely associated with increased baseline SBP and PP, as well as linear (BP*trial) and quadratic (BP*trial*trial) declines over time (p<0.03 for all comparisons). Similarly, baseline 3MMSE performance was associated with gray matter and hippocampal volumes (p < 0.01 for all comparisons). Hippocampal and WMH volumes were also associated with change in 3MMSE performance over time (p <0.002 for all comparisons). In a multivariate model that included blood pressure and MRI measures, the MRI associations remained significant predictors of 3MMSE performance at baseline and over time, whereas blood pressure measures were no longer significant. Conclusion The impact of elevated blood pressure on cognition is mediated through measures of brain injury. This has implications for clinical trials of blood pressure modification designed to improve cognitive health in our aging society.