Transmission studies from blood of Alzheimer disease patients and healthy relatives.

The etiology of Alzheimer disease (AD) is unknown. To investigate the transmissibility of AD, the buffy coat of the blood from 11 relatives of AD patients, including 2 with suspicious or early signs of AD, was inoculated intracerebrally into hamsters. In these pilot experiments, 5 individuals produced histologically documented spongiform encephalopathy on primary passage in recipient hamsters. Material from 3 of these positives was serially transmitted in a second passage. The histological alterations observed in the brains of positive hamsters were similar to those seen in experimental Creutzfeldt-Jakob disease (CJD). These transmission results raise the intriguing possibility that CJD-like agents may be involved in at least some forms of AD.