Do statins cause Alzheimer’s disease?

Yes and no. There is evidence that suggests statins cause cognitive impairment in some patients. However, statins have also been shown to decrease the risk of dementia and even improve cognitive impairment in other cases, though this positive effect hasn’t been as well supported by research.

Our brains need cholesterol to function. Cholesterol builds healthy myelin, a fatty covering which insulates nerve cells to make signals go faster. It’s vital for mitochondrial function and the production of steroid hormones involved in brain signaling. And the body uses cholesterol to transport antioxidants such as coenzyme Q10 that protect the brain.  (See our previous post about fat and the brain here.) Thus, anything that affects cholesterol levels in the central nervous system can cause problems with memory and cognition.

Studies have found that statins can negatively affect memory and cognition. High doses of statins have been shown to decrease brain cholesterol and are associated with cognitive decline. This effect is compounded by more lipophilic statins (meaning that they can bind to and be carried by fat) such as atorvastatin, simvastatin, and lovastatin, which are more able to cross the blood-brain-barrier and cause decreased brain cholesterol. Not surprisingly, these medications are more associated with cognitive decline.

The level of statins in the brain is also influenced by the individual’s ability to metabolize and clear the medication from the body. Some people have genetic differences that make less able to clear this class of medications effectively.

On the other hand, there is also evidence to suggest that statins may help to prevent cognitive impairment in some cases. Some forms of dementia, called vascular dementia, are caused by damage to the blood vessels which feed the brain tissue. It is possible that statins can prevent this kind of pathology, as research has shown statins to be beneficial for the prevention of strokes and microvascular damage that can cause vascular dementia.

Statins are also beneficial for decreasing inflammation. Inflammation is strongly implicated in the development of dementia, especially Alzheimer’s, because neuroinflammation is a trigger for the formation of the amyloid beta protein that disrupts brain function. This may be especially relevant for people with the APOE4 gene who are more likely to have  increased inflammation as a main contributor to cognitive impairment. Research shows that these patients might derive more benefit from the anti-inflammatory effects of statins.

So while the answer to the question isn’t cut and dried, one thing is clear: treatment and prevention of dementia needs to be based on the root cause in each individual, not a standardized approach. Health care providers need to be able to identify both types of patients: patients at risk for cognitive impairment from statins and those for whom statins could potentially decrease their risk. The best health care takes each patient’s genetic, lifestyle and environmental factors into account to make individualized plans for each patient’s care.