Autoantibodies to amyloid-beta and Alzheimer's disease.

Immunization against amyloid-beta has been suggested as a possible preventive or therapeutic treatment for Alzheimer's disease. We hypothesized that some individuals may have autoantibodies to amyloid-beta and that this may be protective. We analyzed the plasma of 365 individuals, drawn from a larger longitudinal epidemiological study, for the presence of antibodies to amyloid-beta. There were detectable but very low levels of anti-amyloid-beta antibodies in just over 50% of all samples and modest levels in under 5% of all samples. However, neither the presence nor the level of anti-amyloid-beta antibodies correlated with the likelihood of developing dementia or with plasma levels of amyloid-beta peptide. These data suggest that low levels of anti-amyloid-beta autoantibodies are frequent in the elderly population but do not confer protection against developing dementia.