cientists have developed a technique
that allows them to watch the destruction by Alzheimer's
disease travel through the brains of living patients ``like a
flow of lava,'' as one researcher put it.
The technique, described today in The Journal of
Neuroscience, may help pharmaceutical companies evaluate the
effectiveness of Alzheimer's drugs and aid in the early
identification of people who are at highest risk for
developing the disease. In the technique, a computer analyses
single brain scans taken over time and generates
``People have used imaging before, but the studies have
really been like taking Polaroid pictures at the ballet,''
said Dr. Paul Thompson, an assistant professor of neurology at
the University of California at Los Angeles and the lead
author of the report. ``This is really the first study to
chart the dynamic spread of Alzheimer's in the brain.'
Dr. Thompson's research team collaborated with
investigators from the University of Queensland in Australia,
Addenbrooke's Hospital in Cambridge, England, and
GlaxoSmithKline Pharmaceuticals in conducting the study.
The videos were based on the analysis of subtle changes in
the MRI scans of 12 patients with Alzheimer's, compared with
those of of 14 elderly people without the disease. The videos
depict the average loss of brain cells in different brain
areas for the Alzheimer's patients.
Researchers have long known through autopsy studies that
Alzheimer's patients show the progressive death of nerve cells
in many areas of the brain. But in the videos, the damage can
be seen moving from structures involved with memory to brain
areas involved in emotion and in the control of behavior.
Other regions of the brain - sensory centers responsible
for vision and touch, for example - remained untouched, Dr.
The researchers found that the loss of brain tissue
progressed at a rate of 4 percent to 5 percent each year in
the Alzheimer's patients, while in healthy brains, only about
0.5 percent is lost each year in aging.
Dr. Thomas Chase, chief of experimental therapeutics at the
National Institute of Neurological Disorders and Stroke and an
expert on Alzheimer's treatment, said that the new technique
``adds to our understanding of the time course that unfolds in
an Alzheimer's brain and therefore is of general interest.''
The ability to see the disease progressing over time in the
whole brain might in the future help scientists separate out
different subtypes of Alzheimer's, Dr. Chase said.
Dr. Antonio Convit, a research scientist at the Nathan S.
Kline Institute for Psychiatric Research, called the video
technique ``a very promising technology that elegantly
confirms previous imaging reports.''