Just recently in the newspaper and article ran telling of a test that could now be given that may help determine if a person is at risk of developing Alzheimer's Disease.(AD) Are you aware of this test --what is it called--and is there any substantial evidence that this is true? Thanks for any info you have on this subject.
Answered by Richard E. Gans, M. D.
A recent study appeared in the journal, Science (Scinto, Leonard F.M., et.al. "A Potential Noninvasive Neurobiological Test of Alzheimer's Disease" Vol 266, November 11, 1994, pp. 1051-1054) reporting the potential for a noninvasive test for Alzheimer's Disease. The test involved the use of very dilute eye drops of the same type that are used to dilate the pupils during an eye examination. The drops used were diluted to such an extent that they would not dilate the pupils of normal individuals, but were reported to dilate the pupils of those suspected of having Alzheimer's Disease.
Alzheimer's Disease is a severe, unrelenting illness that causes progressive dementia and disability. It strikes as many as 10% of people over the age of 65. The only formal way in which to diagnose Alzheimer's is to examine the brain of the individual at autopsy, after the person dies. Nevertheless, there are patterns of behavior that allow a clinical diagnosis of the condition in relatively early stages. Previous research has shown that in as many as 25-40% of circumstances, these clinical suspicions may be incorrect. The hope of this study is to find a simple test that can predict Alzheimer's Disease before the dementia develops.
Tropicamide 1% is one of the medications used to dilate pupils for eye examinations. In this study, tropicamide was diluted to 0.01%. In this concentration, the medication was too weak to dilate the pupils of most people. The researchers found, however, that in 18 of 19 (95%) of individuals who had been clinically diagnosed to have Alzheimer's or were suspected of having the disease, that the dilute tropicamide was able to dilate their pupils significantly. People with dementia from other causes did not exhibit the pupillary dilatation. Their thought was that individuals with Alzheimer's Disease have an unusual, exaggerated sensitivity to this medication, compared to people who don't have the condition.
Although the results of this study are interesting, they have not been substantiated by repeated testing, nor have they been conducted on large numbers of individuals. Further studies will be necessary before any significant conclusions can be reached.
PLEASE NOTE: The information contained on this system is not intended to supplant individual professional consultation, but is offered as a community education service. Advice on individual problems should be obtained directly from a professional.
Copyright, 1994. Richard E. Gans, M.D.
Last Modified: August 23, 1996