A history of high cholesterol is associated with an increased risk of developing dementia. Even mildly elevated cholesterol is associated with increased risk, so it is important to do everything you can to keep your cholesterol in the healthy range. All adults from middle age onwards should have their cholesterol regularly checked by their doctor.
What’s the evidence that cholesterol affects dementia risk?
Research consistently shows that people who have high total cholesterol levels during midlife are on average more likely to develop dementia compared to those with normal total cholesterol. Some studies have shown that people who have their high cholesterol treated with drugs called ‘statins’ have a lower risk of dementia. So treating high cholesterol is important for heart and brain health.
In a review of the studies on cholesterol, high total cholesterol measured at midlife was significantly associated with an increased risk of Alzheimer’s disease and dementia. Eight studies with a total of over 14,000 participants were included in the review (Anstey KJ, et al. Cholesterol as a risk factor for dementia and cognitive decline: A systematic review of prospective studies with meta-analysis. American Journal of Geriatric Psychiatry, 2008, 16:343–354).
Other studies have shown similar results. High cholesterol can be effectively treated. So to reduce your risk of dementia, stroke and heart disease ask your doctor to regularly check your cholesterol and make sure you follow their treatment advice if it is found to be high.
Evidence rating for cholesterol
The relationship between cholesterol levels and dementia risk is complicated as it changes with age.
Taking the evidence as a whole we can conclude that high total cholesterol, especially during midlife, does increase dementia risk. This evidence has been established in meta-analyses.
Other studies suggest that treating high cholesterol with statins reduces dementia risk.
In summary, the evidence suggests that:
- high total cholesterol during midlife increases the risk of later developing dementia
- total cholesterol decreases as dementia is developing
- late life cholesterol levels are not associated with dementia risk
- treating high cholesterol during midlife with statins may reduce the risk of dementia
How does cholesterol affect dementia risk?
Untreated high cholesterol over time can cause atherosclerosis (thickening of artery walls) and affect the blood supply to the brain. This increases the risk of heart disease, stroke and dementia. High cholesterol levels may also increase the production of plaques in the brain that are thought to cause Alzheimer’s disease.
How to maintain healthy cholesterol levels
Consumption of saturated fats contributes to increasing levels of ‘bad’ LDL cholesterol in your blood and to thickening of your artery walls. Foods high in saturated fat include full fat diary products, fatty meats, processed meats, pastry, coconut oil and milk, palm oil, fried take-away foods, packaged cakes and biscuits. These foods should be eaten only occasionally to minimise your saturated fat intake.
Consumption of monounsaturated and polyunsaturated fats contributes to reducing the 'bad' LDL cholesterol in your blood and increasing the 'good' HDL cholesterol. Monounsaturated fat is found in foods such as avocados, almonds, cashews, peanuts and cooking oils including sunflower, canola, soybean, olive, sesame and peanut oils. Polyunsaturated fat is found in foods such as fish, sesame seeds, margarine, linseed (flaxseed), sunflower and safflower oil, walnuts, pine nuts and brazil nuts. These foods can be enjoyed regularly to help keep your cholesterol levels healthy.
Being overweight can be associated with high cholesterol, so it is important to try and maintain a healthy body weight.
Regular physical activity can help maintain healthy cholesterol levels.
There are genetic factors that influence your cholesterol, so some people who do all the right things will still have high cholesterol and will need medication to maintain healthy levels.
The most important thing you can do to make sure your cholesterol levels are healthy is to have it checked regularly by your doctor. This requires a fasting blood test. If your cholesterol is high, follow your doctor’s treatment advice and take any medications as prescribed.
Further information about cholesterol is available from the Heart Foundation.