What does high cholesterol do to your brain as you age?
High cholesterol in middle age likely increases the risk of dementia, but at older ages the relationship is less clear and cholesterol-lowering drugs have not been proven effective for the brain. Stable cholesterol appears wiser than strongly fluctuating values; discuss your risk profile with your doctor if you are concerned.
High cholesterol in middle age is associated with a greater risk of dementia and cognitive decline in later life. This association has been found in multiple observational studies, but it is an association, not a proven cause-and-effect relationship. High cholesterol falls into the same risk category as high blood pressure and diabetes when it comes to vascular damage to the brain.
Interestingly, when measurements are taken only at an advanced age, that association disappears, or even reverses. In people aged 65 and older, higher cholesterol levels sometimes go hand in hand with better cognition. This may seem contradictory, but it is possibly related to selection: those who survive to old age with high cholesterol and no damage are a different group from those who do not.
What does present a clear risk in older adults is large fluctuations in cholesterol from year to year. Older adults with the greatest swings in total cholesterol had a 60% higher chance of developing dementia than those with stable values; for LDL (the 'bad' cholesterol) that figure was 48% higher. High variability was also associated with faster decline in memory and processing speed. No comparable association was found for fluctuations in HDL or triglycerides.
Then comes the logical question: do cholesterol-lowering drugs (statins) help the brain? In observational studies the picture looks promising, but in controlled experiments in which people were randomly assigned to statins or a placebo, no demonstrable benefit for cognition was found. Statins therefore do not demonstrably protect the brain in old age.
Cholesterol is, incidentally, not purely an enemy of the brain. It is a building block for the connections between brain cells, and levels that are too low can also be harmful. At the same time, cholesterol in cell membranes contributes to the production of amyloid-beta, the plaques associated with Alzheimer's disease. The balance is therefore complex, and there are as yet no firm recommendations for a specific cholesterol target purely for brain health.
All claims are based on observational studies and one review study (PMID 22269162, 39879572, 21778438, 39059424). The evidence for the relationship between cholesterol fluctuations and dementia is associational; for statins, RCTs are available that show no effect.
What does smoking do to your brain as you age?
Smoking accelerates brain ageing and increases the risk of dementia. Quitting smoking is one of the best-supported steps you can take to keep your brain healthy for as long as possible.
Do your brains really shrink as you get older?
Your brain does indeed shrink with age, particularly in areas involved in memory and planning. High blood pressure accelerates that process, while exercise and cognitive effort strengthen your brain's compensatory activity.
What does air pollution do to your brain in the long term?
Long-term exposure to air pollution, and fine particulate matter in particular, is associated with an increased risk of dementia and faster memory decline. The associations have been demonstrated in multiple human studies, but a direct cause-and-effect relationship has not yet been conclusively proven.
Can high blood pressure in your 40s cause dementia later in life?
High blood pressure in your forties demonstrably increases your risk of dementia later in life, and early treatment appears to reduce that risk. Get your blood pressure checked and discuss with your GP whether treatment is worthwhile.
What is a healthy cholesterol level and when should I be concerned?
A normal LDL value does not give a complete picture of your cardiovascular risk. Ask your doctor about your remnant cholesterol as well, especially if cardiovascular disease or Alzheimer's disease runs in your family.
Can your gut microbiome affect your cholesterol?
Your gut microbiome influences your cholesterol through bile acid conversion and the fermentation of fibres. Eating more fibre is the most concrete and safe step to take; supplements such as berberine are not yet sufficiently substantiated for daily use.