Aging and cerebral amyloid: early detection of amyloid in the human brain using biochemical extraction and immunostain.

To search for relationships between aging and cerebral amyloid, the brains of 66 clinically nondemented individuals were investigated, using the following three approaches for verification of the amyloid: Congo red staining as a histochemical method; immunostaining using anti-beta protein antiserum as an immunohistochemical identification; and biochemical extraction of amyloid from nonfixed brain tissues. That the incidence of cerebral amyloid increased with aging was determined using all three approaches. Immunostaining using anti-beta protein antiserum was more sensitive than Congo red staining. The biochemical extraction was most sensitive for detection of amyloid, and revealed that amyloid was extracted initially from more than half (67%) of the brains of 9 persons in their 50s and from almost all (97%) brains of 35 persons over 60 years of age. Amyloid was extracted even from brains in which amyloid deposits were not detected by histochemical or immunohistochemical methods. This result shows early appearance of the age-related cerebral amyloid.