Studies show that the accumulation of beta amyloid protein in the brain is a key factor in the development of Alzheimer’s disease. Scientists have begun to devote their research efforts to finding a vaccine for Alzheimer’s that prevents or breaks down the buildup of beta amyloid in the brain.
The Search for an Alzheimer’s Vaccine
Initial research into Alzheimer’s prevention via immunization revealed that injections of beta amyloid caused laboratory mice to produce antibodies that protected them against the protein. The mice also demonstrated improved cognitive performance on memory tests.
The success of these trials quickly led to clinical trials in humans. In 2001, two pharmaceutical companies, Elan Corporation and Wyeth (now part of Pfizer Inc.), began immunizing over 300 individuals with Alzheimer’s symptoms. Scientists stopped the trials when the Alzheimer’s vaccine caused some of the subjects to develop severe brain inflammation. Scientists believe the inflammation was the result of an immune system defense response to the beta amyloid injections.
A follow-up study revealed that those who had received the vaccine for Alzheimer’s had fewer amyloid plaques and neurofibrillary tangles than those who had not received the Alzheimer’s vaccine. This finding confirmed that the vaccine was successful to some degree and alerted scientists to refocus their efforts on developing a vaccine for Alzheimer’s that would capture the benefits of early Alzheimer’s vaccines, while minimizing their negative side effects.
DNA Alzheimer’s Vaccine
Researchers have developed a new type of vaccine for Alzheimer’s, called a DNA vaccine. DNA vaccines don’t activate the immune system response as earlier Alzheimer’s vaccines did. Several DNA vaccines have proven very successful in animal studies. A group of scientists at the Tokyo Metropolitan Institute successfully tested one such vaccine on mice that had been bred to develop Alzheimer’s disease.
Researchers injected some mice with the DNA vaccine at approximately four months of age before they exhibited any amyloid plaques. They found the vaccinated mice had 38.5 percent fewer plaques at 18 months of age than the control group. The researchers also vaccinated a group of mice at one year, after they developed brain plaques. At 18 months of age, the vaccinated mice had developed 50 percent fewer amyloid plaques than the control group.
Alzheimer’s Prevention: From Mice to Men
The U.S. Food and Drug Administration (FDA) feels that this new generation of Alzheimer’s vaccines is now safe for human testing. The FDA has given several pharmaceutical companies the go-ahead to begin testing their DNA vaccines on human subjects.
American Health Assistance Foundation. (n.d.) Potential Alzheimer’s treatments. Retrieved June 15, 2010, from http://www.ahaf.org/alzheimers/treatment/potential/.
Fisher Center for Alzheimer’s Research Foundation. (2006). Alzheimer’s vaccine shows promise. Retrieved June 22, 2010 from http://www.alzinfo.org/newsarticle/templates/archivenewstemplate.asp?articleid=185