Association between vascular risk factors and incident significant cognitive impairment in Chinese older people in Hong Kong in a six-year study

Abstract

Objective: This study aimed to examine the association between vascular risk factors, namely hypertension, diabetes mellitus and hypercholesterolemia, and incident significant cognitive impairment in community-dwelling Chinese older people in Hong Kong. Methods: Community-dwelling Chinese older people aged 65 years and above who attended Nam Shan Elderly Health Centre in 2005 with no history of dementia or stroke constituted the baseline sample. Retrospective data retrieval for the presence of vascular risk factors at baseline was conducted. Annual clinical assessment on cognition was offered in the 6-year study period. Significant cognitive impairment was defined by presence of dementia in accordance with DSM-IV-TR, scoring below the cut-off point on the Cantonese version of the Mini-Mental State Examination, and / or a global Clinical Dementia Rating score of 1-3. Results: A total of 1925 subjects were recruited into our study; 161 (8.4%) subjects developed significant cognitive impairment in the 6-year study period. Subjects with incident significant cognitive impairment was older (75 vs. 73 years; Mann-Whitney U test, p < 0.001) with lower education attainment (30.4% vs. 23.9% of illiteracy; χ2 test, p = 0.06). However, there was no statistically significant difference in the point prevalence of pre-existing hypertension (χ2 test, p = 0.68), diabetes mellitus (χ2 test, p = 0.21), and hypercholesterolemia (χ2 test, p = 0.31) between subjects who developed significant cognitive impairment and those who remained cognitively stable. Interestingly, baseline pulse pressure, but not systolic or diastolic blood pressure, was found to be higher among subjects with incident significant cognitive impairment (70 mm Hg vs. 66 mm Hg; Mann-Whitney U test, p = 0.03). Conclusions: This study did not have evidence to show that hypertension, diabetes mellitus, and hypercholesterolemia were associated with incident significant cognitive impairment in the Chinese older people in Hong Kong. Further studies are needed to examine the role of pulse pressure in contributing to cognitive decline in late life.