Relationship between blood pressure and cognitive decline in normal cognitive population: A four‐year follow‐up study in rural Xi'an

Abstract

AbstractBackgroundHypertension is a modifiable risk factor for cognitive impairment, although the relationship between hypertension and cognitive impairment is not fully understood. The objective of to clarify the relationship between blood pressure and cognitive decline in cognitive normal population through a longitudinal follow‐up study.MethodCognitively normal population was selected from people who lived in the suburbs of Xi’an, China.The mini‐mental state examination (MMSE) and neuropsychological battery were used to assess cognition. Four years later, MMSE was tested again and cognitive decline was defined as a decrease in MMSE scores ≥2 points.The relationship between blood pressure parameters [systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MABP),] and cognitive impairment was analyzed by logistic regression models using interaction and stratified analysis. Blood pressure and age were regarded as both continuous and categorical data。ResultA total of 1024 participants completed the study, among whom 168 subjects (16.41%) presented cognitive decline.Interaction analysis for the total population showed that SBP (when regarded as continuous data) was positively correlated with cognitive impairment (OR = 1.173 [95% CI,1.030‐1.335] per 10mmHg, P = 0.016); however, the age by SBP interaction term was inclined to be negatively correlated with cognitive impairment (OR = 0.850 [95% CI, 0.711–1.016] per10mmHg×year, P = 0.074), indicating that the relationship between SBP and cognitive impairment was age‐dependent. When the blood pressure and age were considered as binary data, the results were similar to those obtained when they were considered as continuous variables.Stratified multivariate analysis revealed that the relationship between SBP (when regarded as continuous data) and cognitive impairment was positive for patients aged 50‐59 years (OR = 1.209 [95% CI:1.025–1.427] per 10mmHg, P = 0.024).However, positive results were not obtained for DBP and MABP.ConclusionElevated blood pressure is positively correlated with cognitive impairment in the middle age(50‐59), but this positive association declines with increasing age.