Symptoms of aging tied to brain chemistry
By Penny Stern, MD
NEW YORK, Jan 07, 2000 (Reuters Health) -- Some of the changes
associated with aging appear to be due to the loss of a particular type
of chemical receptor in the brain, scientists report in this month's
issue of The American Journal of Psychiatry.
Dr. Nora D. Volkow, based at the Brookhaven National Laboratory in
Upton, New York, headed the team of researchers. ''This study
investigated the effects of aging on dopamine, which is a chemical in
the brain that modulates the communications between areas in the brain
that are involved with movement, cognition, motivation, and reward,''
she told Reuters Health. Cognition can be defined as memory and learning
ability.
Volkow and her team recruited 37 healthy individuals of varying ages to
participate in the study. Using an imaging technique called positron
emission tomography (PET) scanning to visualize the brain, the
investigators ``measured both the levels of (dopamine D2) receptors as
well as regional brain glucose metabolism, which serves as an index of
brain function,'' she explained.
After analysis of the data, the researchers found that aging correlated
with a loss of dopamine receptors ``and that these losses were
associated with a decline in activity in the frontal regions of the
brain,'' Volkow said. The researchers ``interpret these results as an
indication that the age-related losses in brain dopamine activity result
in dysfunction of brain regions that are known to be involved with
cognition, attention, and mood,'' she added.
The significance of these findings is clear to Volkow. ''They suggest
that the decline in cognitive abilities and the higher propensity for
depression in the elderly may in part be due to the losses of brain
dopamine receptors,'' she said, adding that treatment aimed at
preventing the loss of dopamine receptors may help prevent some of the
memory and mood changes that occur with aging.
Based on these findings, two possible avenues of intervention could
potentially limit dopamine receptor losses: drugs and life style
changes, according to Volkow. Certain medications ``could help
prevent... degeneration (of the dopamine systems),'' she noted. And,
life style changes ``that include physical exercise, exposure to novel
stimuli, exposure to experiences that motivate the individual, learning
new skills, appropriate diet, (and) social interactions'' may keep the
dopamine systems intact, she continued.
Commenting that a lack of stimulation may impair how well brain cells
communicate with each other, Volkow explained that ''passive life styles
with very fixed routines... that are not motivating may facilitate
degenerative changes in the brain that occur with aging.''
In fact, Volkow told Reuters Health, her team's next research step will
be ``to understand how variables related to life style -- such as
exercise, diet, and sleep -- affect the loss of dopamine receptors as
they occur with age.''
SOURCE: The American Journal of Psychiatry January 2000.
Copyright © 1996-2000 Reuters Limited.
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Judith Richards, London, Ontario, Canada
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