X-Message-Number: 13074
Date: Sun, 09 Jan 2000 19:25:19 -0500
From: Jan Coetzee <>
Subject: Brain Drain

Brain Drain

         David Nicholson
         7 January 2000

         Chemical changes in the brain that may underlie
         the cognitive deterioration associated with ageing
         have been pinpointed by researchers in the US.

         The team, a collaboration between the US
         Department of Energy s Brookhaven Laboratory,
         the State University of New York and the
         University of Pennsylvania, found that age is
         associated with a significant decline in
         dopamaine D2 receptors. These receptors are
         molecules that transmit signals known to affect
         pleasure and reward.

         According to the lead author of the study, Dr
         Nora Volkow, such age-related loss of
         dopamaine  slows metabolism in regions of the
         brain that are related to cognition . She added
         that the study s findings may well be useful in
         developing interventions for age-related
         cognitive decline.

         Decrease in dopamaine with ageing has been
         corroborated by previous studies done by
         Volkow and others. They believe that there is a
         rate of six per cent of receptors lost with each
         decade of age, from 20 to 80 years. However,
         this new investigation led to the discovery that
         when dopamaine D2 receptors decreased, so did
         regional glucose metabolism in the areas of the
         brain known as the anterior cingulate gyrus.

         Functions such as problem solving, the ability to
         think abstractly, and the capacity to carry out
         multiple tasks are among those controlled by the
         anterior cingulate gyrus (the frontal region of the
         brain). It is also related to attention span, impulse
         control and mood. Decreased glucose
         metabolism therefore translates to decreased
         brain activity, or deterioration of brain function.

         However, the study also showed that while
         dopamaine declines with age in general, there is
         a correlation between dopamaine availability and
         brain metabolism even after removing age
         effects. This suggests that dopamine may
         influence brain metabolism regardless of age  
         it is not always the case that dopamine will
         decline with age, and some younger people may
         have less dopamine than some older individuals.

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