A U-shaped Association Between Blood Pressure and Cognitive Impairment in Chinese Elderly

Abstract

Objectives Higher or lower blood pressure may relate to cognitive impairment, while the relationship between blood pressure and cognitive impairment among the elderly is not well-studied. The study objective was to determine whether blood pressure is associated with cognitive impairment in the elderly, and, if so, to accurately describe the association. Design Cross-sectional data from the sixth wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) conducted in 2011 Setting Community-based setting in longevity areas in China Participants 7,144 Chinese elderly aged 65 years and older were included in the sample Measures Systolic blood pressures (SBP) and diastolic blood pressures (DBP) were measured, pulse pressure (PP) was calculated as (SBP)-(DBP) and mean arterial pressures (MAP) was calculated as 1/3(SBP) + 2/3(DBP). Cognitive function was assessed via a validated Mini-Mental State Examination (MMSE). Results Based on the results of generalized additive models (GAMs), U-shaped associations were identified between cognitive impairment and SBP, DBP, PP and MAP. The cut-points at which risk for cognitive impairment (MMSE<24) was minimized were determined by quadratic models as 141 mmHg, 85 mmHg, 62 mmHg and 103 mmHg, respectively. In the logistic models, U-shaped associations remained for SBP, DBP, and MAP but not PP. Below the identified cut-points, each 1mmHg decrease in blood pressure corresponded to 0.7%, 1.1%, and 1.1% greater risk in the risk of cognitive impairment, respectively. Above the cut-points, each 1mmHg increase in blood pressure corresponded to 1.2%, 1.8%, and 2.1% greater risk of cognitive impairment for SBP, DBP and MAP, respectively. Conclusion A U-shaped association between blood pressure and cognitive function in an elderly Chinese population was found. Recognition of these instances is important identifying the high-risk population for cognitive impairment and to individualize blood pressure management for cognitive impairment prevention.

Systolic Blood Pressure and Cognitive Decline in Older Adults With Hypertension

“…H ypertension guidelines recommend lowering systolic blood pressure (SBP) in older patients, but cohort studies have raised concern that lowering SBP too much might harm these patients by, for example, accelerating cognitive decline. [1][2][3][4][5][6][7][8][9][10][11] A recent network metaanalysis of 17 hypertension trials proved the effectiveness and safety of lowering SBP to <130 mm Hg in patients with hypertension, 12 spurring the American College of Cardiology/American Heart Association to update their guidelines to recommend lowering SBP to <130 mm Hg for noninstitutionalized older patients. 13 Hypertension trials, however, often exclude older, frail patients and those with complex health problems, 14 and many have questioned the generalizability and applicability of the results of these studies.…”

High blood pressure in dementia: How low can we go?

“…Other longitudinal studies have shown an association between reduced cognitive function on processing speed and verbal memory and elevated BP in midlife, defined as a systolic BP (SBP) of 120‐139 mm Hg and diastolic blood pressure (DBP) of 80‐89 mm Hg . However, a few other studies reported either no association or a U‐shaped association, which is an elevated risk at lower and higher BP, between hypertension in midlife and cognition in late life …”

“…The evidence in several studies is mixed, including results that show a significant association between high BP and worsening cognitive function, no association, a U‐shaped association, or even the opposite association . One large study—the Framingham Heart Study—also reported no significant association between late‐life BP and cognitive function …”

Hypertension and Dementia: A comprehensive review from the HOPE Asia Network

“…Studies in Asia have shown that hypertension is associated with incidence of dementia in the elderly . Indeed, not only is hypertension directly related to cognitive function, but hypertension that occurs in midlife (around the age of 45‐55 years) also affects the incidence of cognitive impairments in later life .…”

“…Studies in Asia have shown that hypertension is associated with incidence of dementia in the elderly. [65][66][67][68][69] Indeed, not only is hypertension directly related to cognitive function, but hypertension that occurs in midlife (around the age of 45-55 years) also affects the incidence of cognitive impairments in later life. 46,70,71 An analysis conducted in conjunction with the Hisayama study, a prospective cohort study in Japan performed over 32 years (1973-2005), was designed to compare blood pressure in midlife and late life, and to compare these data with dementia output and its subtypes.…”