NEW YORK (Reuters Health) - In the largest cohort study to date, treatment with a cholesterol-lowering statin drug was found to reduce new cases of Alzheimer's disease, regardless of the specific type of statin used or a person's genetic risk for the disease.

Numerous studies have looked at the relationship between statin use and the development of Alzheimer's disease, with conflicting results. One explanation for the inconsistencies is that only the fat soluble or "lipophilic" statins, which could get into the brain more easily than water soluble or "hydrophilic" statins, were included in the studies.

To explore these issues, Dr. M. M. B. Breteler and colleagues at the Erasmus Medical Centre in Rotterdam, the Netherlands, analyzed data from the prospective, population-based Rotterdam Study. The analysis included 6992 subjects, 55 years old or older, who were free of dementia when examined between 1990 and 1993.

During follow-up until 2005 (an average of 9.2 years), 582 subjects were diagnosed with Alzheimer's. After controlling for social, demographic and clinical factors that might raise a person's risk of getting the disease, statin users had a significant 43 percent reduced risk of Alzheimer's disease compared with those who never used statins.

The protective effect was similar for fat soluble and water soluble statins. Examples of fat soluble statins are atorvastatin (Lipitor), simvastatin (Zocor), lovastatin (Mevacor), or fluvastatin (Lescol). An example of a water soluble statin is pravastatin (Pravachol).

The protective effect of statin use against Alzheimer's disease was also similar for persons with and without the major gene mutation associated with an increased risk of Alzheimer's disease (i.e., the apolipoprotein E-epsilon-4 allele).

On the other hand, the use of other cholesterol-lowering drugs such as fibrates or nicotinic acid failed to exhibit similar benefit, Breteler's team reports.

The findings appear in this month's issue of the Journal of Neurology, Neurosurgery and Psychiatry.

In a commentary published with the study, Dr. Larry Sparks at the Sun Health Research Institute in Sun City, Arizona, states: "All in all, it is clear that somewhere between normal cognitive performance and profound dementia of Alzheimer's disease, statin therapy exerts a beneficial effect."

He points out that nearly 20 previous studies have assessed the effect of statin use on later risk of Alzheimer's disease in older people, and the majority found substantial benefit.

Sparks concludes that "it is our task to identify at what point in time statin therapy might be of the greatest benefit in order to effectively target which patients to treat with cholesterol-lowering statins."

SOURCE: Journal of Neurology, Neurosurgery and Psychiatry, January 2009.

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