October 10, 2003
Researchers this week presented preliminary findings that two common antibiotics may afford some relief from the ravages of Alzheimer's disease. The antibiotics, doxycycline and rifampin, are both highly effective against a respiratory bug known as Chlamydia pneumonia, which some earlier research suggested may play a role in the development of Alzheimer's.
"Researchers have been looking into possible infectious causes of Alzheimer's for decades, but none have yet been found," comments Samuel E. Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board of the Fisher Center for Alzheimer's Research Foundation. "While the current results are provocative, independent confirmation is needed. Antibiotics and anti-viral drugs have not been proven effective against the disease, and patients should not be taking these medications to treat Alzheimer's."
These antibiotics may have benefits against Alzheimer's that are distinct from their infection-fighting properties, although further study is needed. Both of these antibiotics, and rifampin especially, for example, may prevent the buildup of beta amyloid, the toxic protein that builds up in the brain of those with Alzheimer's disease. They may also have inflammation-fighting properties that help protect the brain.
In the current study, investigators at McMaster University in Ontario enlisted 101 people with mild to moderate Alzheimer's at five medical centers across Canada. Half received daily doses of both doxycylince (200 mg) and rifampin (300 mg) for three months, while the others received look-alike dummy pills.
After six months, memory tests were administered. Results indicated that those who had been receiving the antibiotics had less mental decline than those who received a placebo. The antibiotic group showed slight improvement after 12 months as well, although those benefits were not considered statistically significant.
The researchers, however, did not find noticeable differences between the two groups in terms of levels of infection with the Clamydia pneumoniae bug, the common cause of pneumonia in seniors that some research has linked to Alzheimer's.
Another recent study pointed to common herpes viruses as a possible link to Alzheimer's (see the Fisher Center article "Cold Sore Virus Might Play A Role in Alzheimer’s" ), and other infectious organisms have been explored as possible causes of the disease. Still, any connection between Alzheimer's and infections remains highly speculative.
This interesting new avenue of Alzheimer's research requires further study in larger groups of patients.
By Toby Bilanow, Medical Writer for www.ALZinfo.org, The Alzheimer's Information Site. Reviewed by Samuel E. Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board, Fisher Center for Alzheimer's Research Foundation.