By comparing brain tissue of people who had taken statins with those who had not, US scientists have established for the first time that taking statins may help to stave off the telltale signs of Alzheimer’s.
The study is reported in the August 28th issue of Neurology, a journal of the American Academy of Neurology and is the work of lead author Dr Gail (Ge) Li, an assistant professor of Psychiatry and Behavioral Sciences at the University of Washington School of Medicine, in Seattle, and colleagues.
The scientists already knew from previous research that there was a strong chance that people on statins might be less likely to develop Alzheimer’s disease, but as Li put it:
“Our study is the first to compare the brains of people who had received statins with those who had not.”
Li and colleagues examined the brain tissue of 110 people who had donated their brains to research upon their death. They were members of Group Health who were enrolled in the Adult Changes in Thought (ACT) programme and were aged between 65 and 79.
ACT is a joint project of Group Health, a consumer-governed, nonprofit health care system based in Seattle, Washington, and the University of Washington. It is a prospective cohort study that began in 1994 and the participants are a random sample of Group Health members aged 65 and above who were not experiencing thinking problems when they enrolled.
The researchers looked for the definitive hallmarks of Alzheimer’s: plaques and tangles in the brain. After controlling for a range of demographic and health variables such as age at death, gender, and strokes in the brain, Li and colleagues found there were significantly fewer plaques and tangles in the brains of people who had taken statins compared with those who had not.
Co-author, leader of the ACT study, and executive director of Group Health Center for Health Studies, Dr Eric Larson said:
“These results are exciting, novel, and have important implications for prevention strategies.”
But he was keen to point out that the results need to be confirmed because “ACT is not a randomized controlled trial.”
There are some randomized controlled trials testing the effect of certain statins on Alzheimer’s, especially those that cross the blood brain barrier.
Larson said that the ACT programme is more rigorous than the average observational epidemiological study because it is based in a community population, it uses reliable automated pharmacy records, and the autopsies were performed on people who had dementia and on people who did not.
Li said people with Alzheimer’s are a diverse group and that:
“Statins are probably more likely to help prevent the disease in certain kinds of people than others.”
The researchers hope that one day it may be possible to know precisely which patients will benefit from which type of statin for protecting against the onset of Alzheimer’s.
Statins are taken by millions of Americans every day to lower cholesterol and reduce risk and symptoms of heart disease. They are a class of drugs known as HMG coenzyme A reductase inhibitors that includes rosuvastatin (Crestor), atorvastatin (Lipitor), simvastatin (Zocor), and lovastatin (Mevacor).
Over 24 million people worldwide are living with Alzheimer’s, a progressive and ultimately fatal disorder where the brain degenerates as more and more misfolded amyloid protein plaques form around brain cells and tangles of tau protein form inside brain cells causing a person to gradually lose the ability to lead a normal life. It mostly affects people over the age of 65.
The most vulnerable regions of the brain include the amygdala, the hippocampus and surrounding regions, and neural pathways that transmit the catecholaminergic, seritonergic and cholinergic signals essential for memory, judgement, reasoning, and verbal fluency, among other cognitive skills.
“Statin therapy is associated with reduced neuropathologic changes of Alzheimer disease.”
G. Li, E. B. Larson, J. A. Sonnen, J. B. Shofer, E. C. Petrie, A. Schantz, E. R. Peskind, M. A. Raskind, J.C.S. Breitner, and T. J. Montine.
Neurology 2007 69: 878-885, published online 28 August.
Written by: Catharine Paddock