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Midlife cholesterol levels not linked to Alzheimer’s disease

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Forget those headlines from the past few years linking hypercholesterolemia in midlife to risk of dementia in old age. Data presented in the November 23 issue of Neurology “suggest that midlife cholesterol level is not associated with an increased risk of Alzheimer’s disease.”

While animal studies have shown that high cholesterol leads to greater amyloid pathology, any link between cholesterol and dementia at the population level is less clear, Dr. Michelle M. Mielke, at Johns Hopkins University School of Medicine in Baltimore, Maryland, and colleagues observe.

They note that there’s evidence that the timing of high cholesterol may be important to the onset of dementia, so they examined the relationship between dementia and cholesterol levels measured from midlife to late-life in a population-based study.

The data came from a cohort of 1462 Swedish women aged 38-60 years in 1968-69 and followed until 2000-2001. Over the study period, 161 women developed dementia; about half were classified as having Alzheimer’s disease.

After adjustment for education, blood pressure, BMI and age, higher cholesterol levels in 1968 were not associated with an increased risk of Alzheimer’s disease. The hazard ratio (highest vs lowest cholesterol quartile) was 2.82, but it was not statistically significant, the investigators report.

“Perhaps more importantly, the present study found that decreasing cholesterol between visits was associated with an increased risk of dementia, but not Alzheimer’s disease,” they write. The quartile of greatest decrease in cholesterol was associated with a significant hazard ratio of 2.37 for dementia.

Dr. Mielke and colleagues believe that an unintentional decline in cholesterol that’s great than expected due to aging reflects underlying dementia processes.

They conclude that whether a person will develop dementia in late life cannot be determined based on midlife cholesterol levels. However, they recommend that midlife cholesterol levels be monitored and treated via diet, exercise, and medication in accordance with heart healthy guidelines.

Should these findings change clinical practice? asks Dr. Mary N. Haan of the University of California, San Francisco in an editorial.

“Because midlife vascular risk factors are already well-recognized targets for prevention of cardiovascular disease, adding risk reduction for dementia is something like gilding the lily,” she writes.

“However, based on the current evidence, we cannot tell middle-aged patients that lowering midlife cholesterol level or tell older patients that maintaining cholesterol level will necessarily reduce their risk of dementia or heart disease.”

Neurology 2010;75:1862-1863.