Statins may protect against Alzheimer’s, study suggests

Statins could help to prevent Alzheimer’s disease, according to research at the University of Southern California, Los Angeles.

The study, published in the journal JAMA Neurology, is based on health data from 400,000 Americans over the age of 65. The researchers found that Alzheimer’s risk fell by 15 per cent in women who took the heart disease drugs and by 12 per cent in men. They also found that taking the drugs consistently made the risk fall further still.

The drugs work by reducing cholesterol in the blood. This increases blood flow to the brain, which helps to prevent the death of brain cells. The researchers suspect that cholesterol plays a role in the formation of amyloid plaque, a protein deposit in the brain that can affect memory and cognitive function.

Dr Julie Zissimopoulos, the study’s lead author, said: ‘We may not need to wait for a cure to make a difference for patients currently at risk of the disease. Existing drugs, alone or in combination, may affect Alzheimer’s risk.

‘We looked to statins as a candidate because they are widely used and have resulted in the reduction of cholesterol.’

Different forms of the drug seemed to have varying levels of effectiveness for different races. Simvastatin, for instance, appeared to lower Alzheimer’s risk for white, Hispanic and black women, as well as white and Hispanic men.

Dr Doug Brown, director of research at the Alzheimer’s Society, said clinical trials would be needed to prove a causal link between statin usage and Alzheimer’s.

Instant analysis
This paper looked at the rates of Alzheimer’s disease according to type of statin consumed. Different forms of statins can be consumed that are either ‘water loving’ (hydrophilic) or ‘fat loving’ (lipophilic). This affects their absorption and how they cross the blood-brain barrier.

A sample of nearly 400,000 statin users (of varying degrees of consumption and compliance) was followed up for an average of 7.2 years.

The data seems to show that non-treated patients tend toward a higher incidence of Alzheimer’s than those with a statin treatment, both overall and also when separated out according to statin type.

However, due to the greater spread of the data in some of the subgroupings (by race and socioeconomic status), conclusions cannot easily be drawn.

There is also an alternative reading of the results. If a patient were at a higher mortality risk they would be given a high dose of statin, but then if they suffered a cardiac event, they might exit the study earlier, reducing the Alzheimer’s rate. The authors did try to adjust for this but it could still potentially skew the data.

Ultimately, the study suggests that there is a possibility that statins help to reduce the incidence of Alzheimer’s in patients to a degree. The inference is that statin selection could be important in particular groupings of patients, perhaps according to race.

The data for the rarer prescribed statins was too thin to draw proper conclusions. Also, the difference in the incidence of Alzheimer’s between the most prescribed statin and the non-treatment control group was only around 0.2 per cent, which makes me ponder, as ever, what alternative explanations there might be.
Research score: 2/5