High cholesterol in middle age raises dementia risk later in life; Borderline high cholesterol raises vascular dementia risk

August 06, 2009

Mildly elevated total serum cholesterol in midlife modestly increases the risk of Alzheimer's disease and vascular dementia 30 years later according to the results of a large retrospective cohort study. “This is the first study, to our knowledge, to show that not only high cholesterol, but also borderline high cholesterol, is associated with dementia, and that it wasn't only associated with Alzheimer's disease but also with vascular dementia,” Dr. Rachel Whitmer, the study's senior author, noted in a telephone interview.

The study included 9,844 men and women whose cholesterol levels were determined between 1964 and 1973 when they were 40 to 45 years old. Between 1994 and 2007, a review of their medical records showed that 469 patients had Alzheimer's disease and 127 had vascular dementia.

In the fully adjusted model, with desirable cholesterol (< 200 mg/dL) as the reference, the hazard ratio for Alzheimer's disease three decades later was 1.57 for people with high midlife cholesterol (240 mg/dL or greater). Borderline high cholesterol (200 to 239 mg/dL) tended to increase the risk of Alzheimer's disease as well, but the results were not statistically significant.

However, midlife borderline high cholesterol was a significant risk factor for vascular dementia, with an adjusted hazard ratio of 1.50. “We need to start thinking about risk factors for dementia in middle age, and cholesterol is a risk factor for dementia that is somewhat modifiable,” said Dr. Whitmer, a research scientist and epidemiologist at the Kaiser Permanente Division of Research in Oakland, California. The study is published in the August 2009 issue of the journal Dementia and Geriatric Cognitive Disorders