The only clinical trial for an experimental Alzheimer disease (AD) vaccine was halted last year when 15 of the trial participants developed severe brain inflammation. In the April issue of Nature Medicine, James Nicoll and colleagues present the first analysis of the vaccine's effects on the human brain.
In the US alone, AD affects nearly 4 million people, and the number is expected to triple in the next 30 years. The brain of an AD patient is characterized by tangled bundles of nerve fibers and amyloid 'plaques' -- clusters of a sticky protein called amyloid-beta. In mice, a vaccine directed against the amyloid-beta peptide clears the plaques and alleviates the memory loss associated with AD. Scientists had hoped it would do the same in people.
The autopsy of a patient from the halted trial reveals that in people, too, the vaccine clears the amyloid-beta peptide from most areas of the brain. The researchers also report evidence of meningoencephailitis, which is not characteristic of AD patients' brains, and suggest that it is a direct consequence of the vaccine. The results do not dismiss the potential usefulness of a vaccine for AD, they say, but should guide future experiments.
James A.R. Nicoll
Division of Clinical Neurosciences
Southampton General Hospital
Tel: +44 2380 796634
Author of accompanying News & Views piece:
Bradley T. Hyman
Department of Neurology
Massachusetts General Hospital
Boston, MA, USA
Tel: +1 617 726 2299
Also available online.
(C) Nature Medicine press release.
Message posted by: Trevor M. D'Souza