Associations of Nocturnal Blood Pressure With Cognition by Self‐Identified Race in Middle‐Aged and Older Adults: The GENOA (Genetic Epidemiology Network of Arteriopathy) Study

Abstract

BackgroundWhether the association of blood pressure (BP) during sleep (nocturnal BP) with cognition differs by race is unknown.Methods and ResultsParticipants in the GENOA (Genetic Epidemiology Network of Arteriopathy) Study underwent ambulatory BP measurements, brain magnetic resonance imaging, and cognitive function testing (the Rey Auditory Verbal Learning Test, the Digit Symbol Substitution Task, and the Trail Making Test Part B) between 2000 and 2007. We examined multivariable linear regression models of the nocturnal BP‐cognition association. Among 755 participants (mean age, 63 years; 64% women; 42% self‐identified black race; 76% taking antihypertensive medication), mean nocturnal systolic BP (SBP)/diastolic BP was 126/69 mm Hg, daytime SBP/diastolic BP level was 139/82 mm Hg, and mean reduction in SBP from day to night (dipping) was 9%. Among the entire sample, a race interaction was observed in Digit Symbol Substitution Task and Trail Making Test Part B (both P<0.15). Race‐stratified analyses showed that a 1‐SD increase in nocturnal SBP levels was associated with poorer Digit Symbol Substitution Task and log‐transformed Trail Making Test Part B scores (unstandardized regression coefficient [95% confidence interval]: −1.98 [−3.28 to −0.69] and 0.06 [0.004–0.12]; both P<0.05) in black but not white individuals. Additional adjustments for white matter hyperintensity volumes or brain atrophy, measured via brain magnetic resonance imaging, did not change the results. Results were similar when nocturnal SBP dipping was assessed as the exposure, yet daytime SBP levels yielded no association with cognition.ConclusionsNocturnal SBP measurements may be useful in assessing the potential risk for lower cognitive function in middle‐aged and older adults, particularly in black individuals.

White matter hyperintensities mediate the association of nocturnal blood pressure with cognition

“…While cognitive impairment associated with vascular disease has historically been conceptualized to affect primarily executive functioning, there is also a well-established link with vascular brain health and memory functioning. 4,50 Given our previous work linking WMH to risk and progression of Alzheimer disease, a disease typically characterized clinically by an amnestic syndrome, memory function was our a priori hypothesis and primary interest in the current study.…”

“…The assessment of 24-hour ambulatory blood pressure allows more reliable measurement of blood pressure than what is typically measured clinically and the examination of blood pressure fluctuation over time. [1][2][3][4][5][6][7] One indicator of fluctuation, nocturnal blood pressure decline or dipping, is a physiologically relevant effect associated with healthy blood pressure regulation. 4,8 Nondipping, or a lack of nocturnal decline in blood pressure levels, is a frequent comorbidity with hypertension, with >40% of hypertensive older adults experiencing nondipping.…”

“…[1][2][3][4][5][6][7] One indicator of fluctuation, nocturnal blood pressure decline or dipping, is a physiologically relevant effect associated with healthy blood pressure regulation. 4,8 Nondipping, or a lack of nocturnal decline in blood pressure levels, is a frequent comorbidity with hypertension, with >40% of hypertensive older adults experiencing nondipping. 9,10 Nondipping is associated with an increased risk of type 2 diabetes mellitus, reduced renal function, and left ventricular hypertrophy, and with severe vascular events such as coronary heart disease, stroke, and mortality.…”

“…7,[11][12][13][14] A lack of nocturnal blood pressure dipping is a potential risk factor for small vessel cerebrovascular disease, although this relationship remains unclear. 2,4,[15][16][17] Small vessel cerebrovascular disease is associated with lower cognitive functioning and higher risk for stroke, dementia, altered motor function, and mortality among older adults. [18][19][20][21][22][23][24][25][26] White matter hyperintensities (WMH), which are regions of increased signal on T2-weighted brain MRI, are established markers of small vessel cerebrovascular disease.…”

Sleep duration and 24‐hour ambulatory blood pressure in adults not on antihypertensive medications

“…7,8 Many of the comorbidities associated with shorter sleep duration are end organ effects of hypertension, including progressive decline in renal function 6 and cardiovascular disease. 10,11 Additionally, both short sleep duration 29,30 and circadian abnormalities in BP [31][32][33] have been associated with neurocognitive decline and dementia. Taking this evidence into account, elevated ambulatory BP may be a mediator or early indicator of the association between shorter sleep duration and adverse outcomes.…”