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.

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The effect of screening by atomic electrons on the form of allowed beta-ray spectra of the Fermi theory is calculated approximately, with the assumption of a screened potential based on the Thomas-Fermi model of the atom. The apparent deviation from theory caused by neglecting screening is given for the beta-emitters S 36 , Cu 64 , and RaE. Another smaller source of error in interpreting experimental results is the use of the non-relativistic approximation to the Coulomb correction factor. These effects cannot be neglected in an accurate analysis of data for Cu and heavier elements. * Note added in proof: Professor Lawrence M. Langer has kindly called our attention to an article by M. E. Rose [Phys. Rev. 49, 727 (1936)] in which the effect of screening was estimated. Rose's results do not agree well with ours, although they are of the same order of magnitude. 7 E. Fermi, Zeits. f. Physik 88, 161 (1934). 8 We use here the notation of Konopinski, Rev. Mod. Phys. 15, 210 (1943).