Numbers of Hirano bodies in the hippocampus of normal and demented people with Alzheimer's disease.

Hirano bodies were counted in the pyramidal layer of the hippocampus in the brains of 34 demented patients with Alzheimer's disease or senile dementia of the Alzheimer type and 24 non-demented subjects of 60 years and over who had been psychometrically assessed. Hirano bodies were also counted in an additional 27 people between the ages of 18 and 59 who had not been assessed but were thought to be intellectually normal. Hirano bodies were found at all ages, but in normal subjects they were significantly more numerous from the age of 60 onwards. Demented subjects of 60 years and over with Alzheimer's disease had significantly more Hirano bodies than normal subjects in the same age range.