Hypertension increases the risk for nonamnestic mild cognitive impairment in the elderly, researchers at Columbia University, New York, have reported.
This finding suggests that preventing and treating hypertension “may have an important impact in lowering the risk of cognitive impairment,” the researchers said in the December 2007 issue of the Archives of Neurology. Previously, data linking hypertension to cognitive impairment and dementia had been inconclusive.
Dr. Christiane Reitz of the university's Gertrude H. Sergievsky Center and her associates assessed the development of mild cognitive impairment (MCI) in a longitudinal cohort study of 918 Medicare recipients 65 years or older living in northern Manhattan in New York.
The subjects underwent general medical examinations, neurologic assessments, and detailed neuropsychological evaluations at 18-month intervals, beginning in 1992-1994. The mean age was 76 years, and the cohort included large numbers of white, African American, and Hispanic subjects.
About 63% of the study subjects had hypertension at baseline. After a mean of 5 years of follow-up, 334 cases of incident MCI developed. A total of 160 were classified as amnestic and 174 as nonamnestic.
Hypertension was associated with an increased risk of all-cause MCI, which was found to be attributable almost entirely to nonamnestic MCI. No association was found between hypertension and amnestic MCI, nor between hypertension and a decline over time in memory or language abilities, the investigators said (Arch. Neurol. 2007;64:1734-40).
The link between hypertension and nonamnestic MCI remained robust after the data were adjusted to account for subject age, sex, years of education, ethnicity, and vascular risk factors such as diabetes, cholesterol level, smoking status, and the presence of heart disease.
The association also remained unchanged after the data were adjusted for use of antihypertensive medication and apolipoprotein-E genotype, Dr. Reitz and her associates said.
Their findings suggest that hypertension affects executive function rather than memory, though the mechanism of action remains unclear. Hypertension may cause cognitive impairment by inducing cerebrovascular disease, or it may contribute to a blood-brain barrier dysfunction.
Given these findings, “preventing and treating hypertension may have an important impact in lowering the risk of cognitive impairment,” they said.