Noninvasive test detects Alzheimer's
By E. J. Mundell
MONTREAL, Oct 19, 1998 (Reuters) -- For the first time, scientists may
have found a noninvasive, accurate method of diagnosing Alzheimer's
disease in living patients. Definitive diagnosis of the disease
currently depends on the examination of samples of brain tissue, most
often at autopsy.
A scanning technology called near-infrared fluorescent spectroscopy
could ``form a basis for the noninvasive diagnosis of Alzheimer's
disease in living patients,'' report a team of researchers led by Dr.
Neil Kowall, director of the Geriatric Research Education Clinical
Center at Bedford Veteran's Administration Medical in Bedford,
Massachusetts.
Kowall presented the study findings this week at the annual meeting of
the American Neurological Association in Montreal.
Up till now, there has been no reliable, noninvasive means of detecting
Alzheimer's disease in the brains of living patients. Instead,
Alzheimer's disease is usually diagnosed from the patient's clinical
history. Symptoms of the disease include memory loss, confusion, and
personality changes.
Speaking with Reuters Health, Kowall explained that the near-infrared
end of the light spectrum passes easily and harmlessly through the bones
of the skull. Once these rays penetrate the brain itself, they reflect
back wavelength patterns corresponding to each type of tissue
encountered.
The researchers have tested the technology on post-mortem tissue samples
taken from the brains of both healthy and Alzheimer's patients. Kowall
reports that they discovered ``very clear differences'' between
fluoroscopy patterns produced by both types of tissues. In fact, in
blinded studies using the technology, experts had a near-100% accuracy
rate in diagnosing Alzheimer's-affected tissues.
The researchers plan to study the use of near-infrared fluorescent
spectroscopy in the diagnosis of living patients. Kowall speculates
that, if these techniques prove successful, the technology might be
available for clinical use within 3 to 5 years.
Although there are no effective treatments for cases of advanced
Alzheimer's, early detection may allow initiation of treatment
designed to slow the progression of Alzheimer's. ''There's some evidence
now that oxidative damage or inflammatory changes may be important, and
if you could detect someone very early and start treating them, you
would have a good chance of having
a good outcome,'' Kowall said.
Near-infrared fluorescent spectroscopy should fit easily into hospital
rooms -- and budgets. ``The instrument fits on a cart,'' Kowall said,
``you can roll it up to the bedside.'' And he said the price of the
technology has fallen. Equipment physicians can buy for $5,000 today
``would have been $150,000 and a hundred times less sensitive a few
years ago,'' Kowall explained.
--
Judith Richards, London, Ontario, Canada
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