Building upon the stunning recent discovery that Alzheimer's disease
can be detected early by looking for telltale proteins in the eye,
researchers at this week’s
Frontiers in Optics meeting of the
Optical Society of America presented a pair of optical tests, both
in clinical trials, that can potentially diagnose the disease in its
beginning stages. Such tests may not only improve patients' chances
to start treatment earlier, but they could also speed development of
new Alzheimer's drugs.
Two years ago (Goldstein et al., Lancet, 12 April 2003), Lee
Goldstein of Harvard Medical School (email@example.com)
and his colleagues showed that the
exact same amyloid beta proteins which are a hallmark of Alzheimer's
disease are also found in the lens and its surrounding fluid. In
those portions of the eye, the proteins form amyloid deposits
similar to those in the brain. Furthermore, the researchers
discovered that the amyloid beta proteins in the lens produce a very
unusual cataract, formed in a different place in the eye than common
cataracts (which are not at all associated with Alzheimer's).
Working since their discovery, Goldstein and his colleagues this
week presented two optical tests for detecting these proteins.
Using a technique known as quasi-elastic light scattering, the first
test employs low-power infrared laser light to non-invasively detect
protein particles in the specific part of the lens where these
unusual cataracts form. The second test would be applied to those
who screen positively for the proteins, in order to confirm an
Alzheimer's diagnosis. This test uses a technique Goldstein and
colleagues call "fluorescence ligand scanning" (FLS). The
researchers apply special fluorescing eye drops with image-enhancing
molecules that bind to the amyloid beta molecules. If amyloid beta
molecules are present, the fluorescing molecules will light them up.
The first test is in human and animal trials and the
second test is in animal trials only.
These two diagnostic tests are envisioned to be a two-step process
for screening and then confirming an Alzheimer's diagnosis. These
new optical tools can also potentially speed up the development of
new Alzheimer's drugs, by giving investigators rapid feedback on
whether the drug is doing its job of removing the harmful proteins
from the body. Moreover, the researchers are using the same
technologies to develop new tests for rapidly detecting amyloid
plaques resulting from prion diseases, including mad cow, scrapie in
sheep, and Creutzfeldt-Jacob disease in humans.
The Frontiers in
Paper FTuBB4 at meeting,
October 18, 2005