Statins May Help Alzheimer's Patients
Tuesday, September 11, 2007
Statins, drugs commonly prescribed to treat cardiovascular disease, may also protect people from developing the tangles of nerve fibers found in the brains of Alzheimer's disease patients, according to a study that examined the brains of 110 deceased Group Health Cooperative members.
Authors of the study, released Aug. 27, said the findings are preliminary but intriguing because they could signal that statins prevent the brain changes that signal the progression of Alzheimer's disease.
Those patients who had taken statins before they died showed significantly lower levels of tangles in their brains, said researchers from Group Health, the University of Washington and the Veterans Affairs Puget Sound Health Care System.
Eric Larson, a co-author who is executive director of the Group Health Center for Health Studies, said this is the first time researchers have been able to correlate years of exposure to statins with microscopic changes in brain tissue by performing autopsies.
"This has great therapeutic importance if it's confirmed," Larson said.
For now, though, Larson and co-author Thomas Montine, a UW neuropathologist, said that while the study was "hopeful news," they are not recommending everyone start taking statins.
"Our data says these drugs appear to be doing something in the human brain," Montine said. "Whether this will translate into behavioral changes, we can't say."
The study, published in the Aug. 28 edition of the journal Neurology, was not a randomized study, nor did it look at behavioral changes.
And it clearly won't be the last word on the subject. Earlier studies, including a large one at the University of Washington published in 2005 by some of the same researchers, have found that statins had no effect on participants' abilities to think and remember. Before that, some studies suggested statins did reduce the risk of Alzheimer's.
In both the earlier UW study and the current study, subjects had taken statins for only five years or less. It may be that longer use of statins would offer more protection, Larson said.
In addition, in these and other previous studies, participants had taken various types of statins, which include such drugs as atorvastatin (Lipitor) and simvastatin (Zocor). Larson said that could account for some of the conflicting results.
Both Larson and Montine said more research is needed to sort out what's going on. "There's got to be a resolution at some point to these conflicting studies," Montine said.
Generally speaking, statins lower cholesterol by inhibiting an enzyme that is needed for cholesterol to form. Just how that may or may not be related to the plaques and tangles found in the brains of Alzheimer's patients is not clear, Montine said.
"There are a lot of possibilities," he said. "We don't know the answer yet."
The latest study did not find significant correlation between statin use and formation of plaques, which are larger protein deposits that form outside nerve cells. Researchers generally believe that the processes of plaque formation are related to the beginning of Alzheimer's, while tangle formation signals disease progression, he said.
"It's unclear how the two are linked," Montine said. "That's the million-dollar question in Alzheimer's research."
The research participants were between 65 and 79 when they died and had been enrolled in the "Adult Changes in Thought" study, a joint project of Group Health and the University of Washington that began in 1994. It now includes almost 4,000 people, all originally Group Health members. A smaller subset, around 1,000, have agreed to let researchers autopsy their bodies after they die.
"Their courage has allowed us to gain a new perspective, no question about that," Montine said.
Larson, like many researchers, says it's hard to overestimate the importance of finding ways to delay or completely ward off the onset of Alzheimer's disease, which is the most common cause of dementia in later life. It affects 4 million people in the United States.
"Anything you can do to prevent or delay that disease will have a huge effect on our older population, our kids and our community, because we're all in this together," he said.