Alzheimer’s disease vaccines: promises and pitfalls

Feasibility of immunotherapy for Alzheimer’s disease has been postulated, and numerous strategies of active and passive immunization have been applied in animals and humans. This article summarizes accumulated knowledge in clinical trials and animal experiments, and foresees the future perspective. Clinical trials have clearly shown that clearance of senile plaque amyloid is insufficient for improving clinical symptoms and signs, suggesting a possibility that in addition to plaque amyloid, amyloid b oligomers and intracellular amyloid b should be targeted. Furthermore, avoidance of autoimmune encephalitis and adverse inflammation must be considered. Since the exact targeting molecule is unknown at present, polyclonal immunization strategies with activation of T helper type 2 T cells seem to be promising. Also prevention rather than treatment will be successful until we establish measures to cope with the progression mechanism of Alzheimer’s disease.