Association of Intensive vs Standard Blood Pressure Control With Magnetic Resonance Imaging Biomarkers of Alzheimer Disease

Abstract

Magnetic resonance imaging (MRI) data from the Systolic Blood Pressure Intervention Trial (SPRINT), the Action to Control Cardiovascular Risk in Diabetes (ACCORD) blood pressure trial, and the Intensive vs Standard Ambulatory Blood Pressure Lowering to Prevent Functional Decline in the Elderly (INFINITY) trial have all indicated less progression of white matter lesions (WML or leukoaraiosis), a biomarker for cerebrovascular injury, with more intensive blood pressure control.^1-3 However, the effect of intensive treatment on other mechanistic markers of cognitive impairment and dementia has yet to be explored. The most common cause of dementia in older adults is Alzheimer disease (AD).⁴ Vascular disease is a very common comorbidity and may play a factor in initiating or accelerating AD neuropathology.^5,6 Some studies have found that treating hypertension may reduce the incidence of AD⁷; however, it is unclear whether this could be a direct effect on AD-related neurodegeneration or comorbid vascular pathology. The neurodegeneration of AD results in brain atrophy, favoring but not limited to particular brain regions, and biomarkers measuring these changes may be more sensitive to early AD-related change than downstream cognitive or clinical variables, such as incident dementia.⁸ Both ACCORD and SPRINT showed small but statistically significant decreases in total brain volume (TBV) with intensive treatment compared with standard treatment,^1,9 although it is unclear to what extent these differences reflect atrophy vs factors such as hydration status.¹⁰