Study Questions Statins' Value Against Alzheimer's

This conflicts with other research that found the drugs were effective

MONDAY, July 11, 2005 (HealthDayNews) -- Cholesterol-lowering drugs called statins have been linked to a decreased risk of Alzheimer's disease and other dementias, but a new study questions that association.

According to the results of this latest study, use of statins and other lipid-lowering drugs showed no association with reductions in the risk of Alzheimer's or other types of dementia in older adults.

Statins may reduce the risk of heart disease by blocking the production of cholesterol or by serving as an anti-inflammatory, experts say. Both these mechanisms may also play a part in the development of Alzheimer's disease and other dementias, according to the report in the July issue of the Archives of Neurology.

In their study, Dr. Thomas D. Rea, of the University of Washington, and colleagues collected data on nearly 2,800 people 65 or older enrolled in the Cardiovascular Health Study. At the start of the study, participants underwent MRIs and took a standardized test to determine that they did not have Alzheimer's or other dementias.

Researchers then followed these individuals every year to see if they had developed dementia, to asses their overall health, and to track what medications they were taking. During the follow-up period, 480 people developed dementia. Of these, 245 people developed Alzheimer's.

After accounting for other risk factors, Rea's team found that, compared with people who never took statins, those who did showed no reduction in their risk of developing Alzheimer's or any other dementia.

The reasons for the finding may include the length of time patients were taking statins, Rea's group noted.

"Several factors may explain why statin use was not associated with a lower risk of dementia," they wrote. "Participants were on average 75 years of age, and statin use was assessed for a median of five years. Statin exposure may need to occur earlier in adulthood or for longer periods to prevent dementia, although analyses that stratified the duration of statin use did not suggest a duration-dependent association."

One expert thinks this study offers patients a mixed message. While there was no overall reduction in Alzheimer's among people taking statins, "when you look at patients who had used a statin in the last year of the study, there appears to be a reduced risk of Alzheimer's," said Larry Sparks, director of the Roberts Laboratory for Neurodegenerative Disease Research at the Sun Health Research Institute, in Sun City, Ariz.

Sparks, whose own work has shown that statins reduce the risk of Alzheimer's, believes the study indicates the benefit of statins when taken over a long period of time. "Perhaps the longer an individual uses a statin, the greater the possibility there would be a reduced risk of Alzheimer's disease," he said.

In his own work, Sparks has shown that use of a statin drug does benefit people with Alzheimer's. "It slowed the progression of the disease and showed improvement on cognitive measures and depression," he said.

William Thies is vice president for medical and scientific affairs at the Alzheimer's Association. He thinks that only the results of ongoing clinical trials will settle the issue of statins' value against Alzheimer's. "At this point we have mixed results," he said. "Some studies suggest there is a value [to statins for preventing Alzheimer's] and some suggest that there's not."

One trial under way is being run by the National Institutes of Health, which is looking at the use of statins to treat dementia; another trial is sponsored by the drug company Pfizer, Thies said. "Ultimately, those trials are going to tell us, 'If you take somebody with the beginnings of dementia, if you treat them with a statin drug, will they get better?'" he said.

The results from one of the trials should be available in about one year, Thies said. There is no recommendation for using statins to prevent dementia, he noted.

But if you're taking a statin to lower your risk of heart disease, that's good, and "if that benefits your risk of dementia that's even better," Thies said.

More information

To learn more, visit the Alzheimer's Association.

SOURCES: Larry Sparks, Ph.D., director, Roberts Laboratory for Neurodegenerative Disease Research, Sun Health Research Institute, Sun City, Ariz.; William Thies, Ph.D., vice president for medical and scientific affairs, Alzheimer's Association, Chicago; July 2005, Archives of Neurology
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