The Risk of a High Cholesterol Level in Middle Age

Even a slightly raised cholesterol level in mid-life may increase the
likelihood that someone develops dementia in later life, according to
a study published in the journal Dementia & Geriatric Cognitive
Disorders.

Data for the study came from the Kaiser Permanente Northern California
Medical Group (a healthcare delivery organization). People aged 40 to
45 were recruited between 1964 and 1973; 9,844 of them were followed
for up to 40 years. During this time 598 of them developed Alzheimer's
disease or vascular dementia, determined from medical records between
1994 and 2007.

Total cholesterol levels of 220 mg/dL or above in samples taken at
enrollment raised the risk of subsequent Alzheimer's disease in a
"dose-dependent" fashion. (Data on low-density lipoprotein [LDL]
cholesterol levels were not available at the time of sampling.)

After adjustment for variations in age, gender, education,
race/ethnicity, midlife BMI, diabetes, high blood pressure, and
late-life stroke, the following hazard ratios or odds were obtained
for Alzheimer's, using the "below 198 mg/dL" risk as the 1.0, or the
reference level:

198–220 mg/dL 1.25

221–248 mg/dL 1.31

249–500 mg/dL 1.58

Vascular dementia risks didn't display this "dose-response" effect
with cholesterol levels, although the 221-248 mg/dL group had a high
hazard ratio – 1.50.

This study didn't explore whether controlling high cholesterol levels
with drugs or a healthy lifestyle could reduce the risk of developing
Alzheimer's. However, other studies have suggested that this is the
case. Most important is the recognition of the long time-lag between
the recorded raised cholesterol level and the onset of the disease. If
you have a high cholesterol in your forties, get busy; you can
probably reach normal values with a little effort, and spare yourself
an increased risk of Alzheimer's disease or vascular dementia.