The role of blood pressure in cognitive impairment in an elderly population

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Abstract
Objective The aim of this study was to investigate the cross-sectional relationship between arterial blood pressure and cognitive impairment in a group of elderly subjects, controlling for such confounding variables as age, education, depression, drug use and antihypertensive treatment. Design and setting A cross-sectional survey in Campania, a region in southern Italy. Subjects and methods A random sample of 1339 elderly subjects aged 65–95 years (mean 73.9 ± 6.2 years) selected from the electoral rolls was interviewed by trained physicians. Sociodemographic characteristics, results of Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS), blood pressure and whether antihypertensive treatment was being administered were recorded. When subjects with neurological diseases and those under psychotropic therapy were excluded from the analyses, the population numbered 1106. Results The MMSE score was less than 24 for 27.9% of the subjects and the mean GDS score was 10.8 ± 6.3. The mean systolic blood pressure (SBP) was 145.3 ± 19.0 mmHg and the mean diastolic blood pressure (DBP) was 82.0 ± 9.2 mmHg. Logistic regression analysis showed that female sex, age, GDS score and DBP but not SBP were predictive of cognitive impairment. Educational level and antihypertensive treatment, on the contrary, play a protective role. DBP was associated with cognitive impairment in subjects aged 75 years (odds ratio 1.62, 95% confidence interval 1.16–2.25) and over (odds ratio 5.16, 95% confidence interval 1.50–17.71) but not in those aged 65–74 years. Conclusion DBP but not SBP is predictive of cognitive impairment in subjects aged 75 years and over without neurological disorders independently from sex, age, education, GDS and antihypertensive treatment.