Reverse Dipping of Systolic Blood Pressure Is Associated With Increased Dementia Risk in Older Men

Abstract

A lower day-to-night systolic blood pressure (BP) dip has previously been associated with poor brain health and cognitive functions. Here, we sought to examine whether reduced (nighttime/daytime ratio of systolic BP >0.9 and ≤1) and reverse (nighttime/daytime ratio of systolic BP >1) dipping of systolic BP is associated with the prospective risk of being diagnosed with any dementia in Swedish older men. Twenty-four-hour ambulatory BP monitoring was used to estimate the nocturnal systolic BP dipping status of men at mean age 71 (n=997; 35% on antihypertensive medication) and 77.6 (n=611; 41% on antihypertensive medication). Dementia incidence during the observational period up to 24 years (n=286 cases) was determined by reviewing participants’ medical history and independently confirmed by at least 2 experienced geriatricians. Using time-updated Cox regression (ie, time-updated information on covariates and exposure), we found that reverse systolic BP dipping was associated with a higher risk of being diagnosed with any dementia (adjusted HR, 1.64 [95% CI, 1.14–2.34], P =0.007) and Alzheimer’s disease (1.67 [1.01–2.76], P =0.047) but not vascular dementia (1.29 [0.55–3.06], P =0.559). In contrast, reduced dipping of nocturnal systolic BP was not associated with a higher risk of being diagnosed with dementia. Our findings suggest that reverse systolic BP dipping may represent an independent risk factor for dementia and Alzheimer’s disease in older men. Future studies should decipher whether therapies lowering nocturnal systolic BP below daytime levels, such as bedtime dosing of antihypertensive medication, can meaningfully curb the development of dementia.