Vaccine developed to fight Alzheimer's disease considered "promising"

June 13, 2006

A team headed by Yoh Matsumoto at the Tokyo Metropolitan Institute for Neuroscience in Japan has developed a DNA vaccine, with no side effects, to fight Alzheimer's disease and call the drug "promising." The vaccine, thus far, has only been tested on mice and is only in the experimental stages.

Tests are going to soon be done on monkeys and if that turns out successful then tests on humans could be done in perhaps three years, said lead researcher Yoh Matsumoto of the Tokyo Metropolitan Institute for Neuroscience in Japan.

"This work represents a promising new line of vaccine development but more research would be needed to see if this could be replicated safely in humans," said Doctor Clive Holmes of the Alzheimer's Research Trust.

The vaccine is given by an injection and works by reducing the amount of certain amyloid proteins, which scientists believe are the cause of the illness. The study says that the amount of amyloid proteins in different areas of the brain was reduced, in some cases, up to 50%. In the lowest amounts, the protein was reduced 15.5%. In direct areas of the brain, such as the hippocampus and cerebral cortex, the reduction of the protein was 40-50%. Amyloid proteins, when over produced, are believed to cause the symptoms of the illness by forming masses in the brain, which spread. The vaccine involves injecting the mice with the protein and then the DNA vaccine. The vaccine codes itself to the protein, stopping the spread of the masses by not allowing the protein to reproduce.

"DNA vaccines are given by intramuscular injection, which stimulates the production of anti-amyloid-beta antibodies. In the early stage, we highly expect that DNA vaccination will prevent disease progression and, hopefully, normalize brain function," said Matsumoto.

However, Matsumoto also said that patients who are experiencing "advanced cases" of the illness will have "irreversible damage" even if they received the vaccine.

"In advanced cases, however, neuronal loss and brain atrophy are very severe and irreversible. So it may be difficult to obtain clinical improvement with DNA vaccination," said Matsumoto.

In 2003 18 of the 298 people testing the vaccine had symptoms of brain swelling and the trials were stopped. At least 6% of those testing the vaccine had an over-reaction, which caused swelling of the brain and some even suffered brain damage.

Researchers say the new development is "safe" but that it will be "years" before any real and extensive clinical tests of the vaccine begin.

"Any of these vaccines could prove safe and effective. But we are years away from seeing them widely used in clinical practice -- but perhaps as few as three years away," said chairman of the Alzheimer's Association's Medical and Scientific Advisory Council, Dr. Sam Gandy.

"The findings support the idea that a vaccine is our best hope for fighting this devastating disease for which there is currently no cure," said Doctor Susanne Sorensen, of the Alzheimer's Society.