Recent newspaper reports again have raised the suggestion that Alzheimer's Disease is caused by a virus-like substance. Misunderstandings about these reports can lead to anxiety about the transmissibility of the disease.
Although scientists have searched diligently for such a connection, there is no evidence whatever that Alzheimer's Disease can be transmitted from one person to another.
Scientists at the University of California recently have reported that the amyloid in the brains of Alzheimer's patients resemble protein substances found in the brains of animals infected with a rare viral disease. The similarity is based on the finding that both amyloid, found in brains of Alzheimer's victims and in prions, small viral-like particles found in animals infected with a transmissible neurodegenerative illness, respond to staining by Congo red dye in the same way. However, different proteins may stain in similar ways and other researchers point out important differences in these poorly understood proteins. Perhaps, most important, amyloid is a nonspecific substance found in many human diseases. It is most likely a general response to disease.
Concerns about transmissibility have arisen among staff about CreutzfeldtJakob disease. This is an extremely rare dementing illness known to be transmissible. Victims of Creutzfeldt- Jakob disease deteriorate rapidly and die in less than two years after the onset of their symptoms. Although this disease has been transmitted by corneal transplantation and by brain biopsy instrument, no nurse caring for a patient with the illness and no researchers studying brain tissue have contracted the disease. Because the disease is clearly different from Alzheimer's and is so rare, there is little cause for concern among professionals caring for confused persons.
The possibility of genetic transmission of Alzheimer's is more interesting. Studies have shown that first-degree relatives of an Alzheimer's victim have four times as great a risk of developing the disease - from 2-3% risk in the general population to 8% risk for families. Evidence of greater genetic risk has not yet been confirmed. There are rare families in which the disease shows a pattern typical of autosomal dominant genetic transmission: a 50% risk for first-degree relatives. In many other families, the disease appears with no prior family history.
It is important to reassure families that the risk of developing the disease is low. In fact, most people are much more likely to die of something else before any dementing symptoms appear. Those few families with a clear pattern may need to make appropriate financial and caregiving plans for their futures. At the same time, these families must be reassured we do not understand how Alzheimer's is acquired. We all, after all, carry some genetic proclivity toward one or another fatal disorder, for example, heart disease or cancer. Anxiety about either viral or genetic transmission of Alzheimer's is completely unwarranted at present.