Can statins protect against Alzheimer's?

13th December 2016 – Taking cholesterol-lowering statins may help cut the risk of developing Alzheimer's disease, according to a study in the US.

Researchers at the University of Southern California say the results are mixed, depending on which statin was used and the ethnic background of those taking them.

Experts in the UK caution that, although the study involved a large sample of people, it is not robust enough to prove cause and effect. They say other studies have so far failed to show that statins can prevent brain deterioration.

Healthcare records

The findings are based on the health records of 399,979 statin users aged 65 or more in the US who come from a range of ethnic backgrounds, including black, white and Hispanic. The researchers recorded how many prescriptions each individual had, as well as the strength of the dose, for 4 of the most popular statins: simvastatin, atorvastatin, pravastatin and rosuvastatin.

Over a 4-year period, from 2009 to 2013, 1.72% of women and 1.32% of men were diagnosed with Alzheimer's annually. The highest incidence of Alzheimer's was seen in Hispanic and black women and the lowest among white men.

Individuals who regularly took the most statins over at least 2 years saw a reduction in risk of Alzheimer's by between 12% and 15%. However, the reduction in risk varied according to ethnic background and sex.

The study, published online by JAMA Neurology, also found that different statins worked better for some groups than others.

Lower cholesterol

The researchers speculate that the protective effect of statins may result from their ability to lower cholesterol levels which reduces the formation of beta-amyloid, which in turn plays a role in the development of dementia.

The 'observational' nature of the study, involving an analysis of third party data, means that it is not possible to say conclusively that statins can reduce the risk of Alzheimer's. The researchers say clinical trials are needed to establish cause and effect.

However, they conclude: "Statins may potentially affect Alzheimer disease risk, so physicians should consider which statin is prescribed to their patients."

'No definitive answer'

Several UK experts have commented on the findings in statements. John Hardy, professor of neuroscience at University College London, says: "The possible role of statins in [Alzheimer's] prevention has been debated for nearly 20 years.

"This paper contributes to that discussion but does not really lead to a definitive answer: rather it suggests, based on health records analysis, that in some groups there is a protection, but in others there are not."

Jane Armitage, professor of clinical trials and epidemiology at the University of Oxford, comments: "In order to find out if statins protect against Alzheimer's disease, randomised studies are needed in which the people who are given a statin are as similar as possible to those who are not. Unfortunately, such long-term trials are hard to do. The randomised trials of statins lasting 5-6 years do not suggest that statins protect against cognitive decline."