Antibiotics Fight Alzheimer's: Study
By ANDRÉ PICARD
Globe and Mail
October 9, 2003
A regular dose of two common antibiotics shows promise in delaying the onset of Alzheimer's disease, according to a new Canadian study.
The research lends credence to the notion that common bacterial infections might play a role in determining who is stricken with the debilitating neurological disorder. It also offers hope of a cheap, simple treatment for Alzheimer's, a condition for which there is virtually no effective treatment.
"I can't get over the data: It's really the first time we've ever seen anything like this," said William Molloy, who holds the St. Peter's chair in aging at McMaster University in Hamilton, Ont., and is a co-author of the study.
He said the simple treatment "modified the course of Alzheimer's" and the effects seem to be long-lasting, something that has not been seen previously with Alzheimer's treatments.
However, Dr. Molloy stressed, the research needs to be replicated. He said patients should not be rushing out to take antibiotics on their own, but might want to discuss the approach with their physician.
Sandra Black, a neurologist at Sunnybrook and Women's Health Sciences Centre in Toronto who was not part of the research team, called the approach "pioneering" but said she would not begin prescribing antibiotics to her patients based on the findings.
"I think what the investigators in the study have done is brought to the attention of the world a potential treatment for Alzheimer's disease ... but I'm not sure we're at the point that we should be recommending this to families," she said.
The findings will be presented Saturday at the annual meeting of the Infectious Diseases Society of America Conference in San Diego. The prestige venue is vindication for the Canadians, who could not get a research grant to test their bold theory and had to fund it on their own.
The researchers caution that there is a significant downside to antibiotic therapy: The risk of fuelling antibiotic resistance. (When antibiotics are overused, bacteria mutate and become resistant to drugs. This creates so-called "super-bugs" that cannot be treated.)
This is of particular concern to seniors and, more specifically, to Alzheimer's sufferers, who are already more susceptible to infectious disease. Antibiotics can also interact with other medication and cause liver damage.
The study was conducted on 101 people with mild to moderate Alzheimer's who were being treated at five clinics throughout Canada.
Fifty-one of the participants were prescribed a daily regimen of 200 milligrams of doxycycline and 300 mg of rifampin. The balance received placebos. The study was triple-blinded, meaning the patients, physicians and investigators did not know who was receiving the antibiotics and who got the sugar pills.
All the patients were given a standard Alzheimer's disease test before the trial began, and another six months later. The test includes word recall, identifying common household items and carrying out simple tasks such as addressing a letter.
The researchers found that on a 70-point scale, the scores of those in the placebo group declined, on average, by 2.75 points more than those in the antibiotics group.
Although the reduction was modest, it means that the mental decline of patients taking antibiotics was slower. More important, while participants took the drugs for three months, the benefits seemed to last much longer.
While antibiotics are certainly not a cure for Alzheimer's, Mark Loeb, an assistant professor of clinical epidemiology and biostatistics at McMaster and lead author of the research, said the "antibiotic regimen might allow a person suffering from Alzheimer's disease to remain home and avoid going to a nursing home or another institution, at least for a period of time."
However, he stressed, the findings needed to be replicated, and more research needs to be done to determine the biological mechanisms at play.
The study was undertaken to test the theory that the common bacterium chlamydia pneumoniae might play a role in causing Alzheimer's. The antibiotics doxycycline and rifampin are very effective against the germ. However, the McMaster researchers found little evidence that levels of chlamydia pneumoniae fell significantly.
Dr. Loeb said another explanation might be that antibiotics work by interfering with the accumulation of protein plaque around the neurons of the brain. Plaque build-up is a tell-tell sign of Alzheimer's.
A third theory is that the anti-inflammatory qualities of antibiotics might be providing the benefit. When the body fights infection, be it a cold sore or pneumonia, inflammation, including swelling of the arteries, is triggered. There is growing evidence that these infections contribute to hardening of the arteries which, in turn, leads to a build-up of fatty deposits that can be at the root of heart disease and even Alzheimer's.
An estimated 364,000 Canadians suffer from Alzheimer's disease and related dementias, and that number is expected to more than double by 2031, because of the aging population. The condition is largely age-related: One in 13 people over the age of 65 and one in four people over the age of 85 suffer from Alzheimer's.
