Precautions in familial transmissible dementia: including familial Alzheimer's disease.

Recent studies suggest that some cases of familial Alzheimer's disease may be associated with a transmissible dementia. Animal experiments show that presymptomatic carriers of "slow virus" agents can transmit disease. Because of these findings, we have extended the precautions previously delineated to include those at risk of acquiring transmissible dementia, specifically, to the descendants of those affected with familial Alzheimer's disease or familial Creutzfeldt-Jakob's disease. Blood donation from such persons may pose a danger, because transmissible spongioform encephalopathy has been passed from animal to animal by blood serum and by the WBC layer of frozen whole blood.