Depletion Of Body Chemical Can Cause Memory, Mood ChangesNovember 19, 2002 (Center
for the Advancement of Health) -- The chemical in turkey that may cause people to nod off
after Thanksgiving dinner also plays a role in maintaining good mood and memory,
especially among people with a family history of depression, says new research published
in the journal Brain, Behavior, and Immunity. Lead
author Wim J. Riedel, Ph.D., and colleagues at the Brain and Behavior Institute at the
University of Maastricht in the Netherlands examined the effects of the body's depletion
of an amino acid called tryptophan on mood and cognitive function. They also
measured how long the effects of the depletion lasted. Tryptophan,
known for its presence in turkey and commonly blamed in the media for creating the
sluggish after-meal sensations experienced by many Thanksgiving diners, is a metabolic
precursor to the chemical messenger known as serotonin. In addition to turkey, the
chemical is found in foods like milk, bread, cheese and bananas. Tryptophan depletion
decreases serotonin levels in the brain, which in turn can lead to depression and other
problems. While the study is not definitive and does not offer a solid conclusion that
eating more tryptophan will enhance memory or mood, it does indicate a possible
connection. "Experimental
lowering of tryptophan, and hence serotonin, appears to impair learning and memory
and can cause depressed mood, especially in people who have a family history of depression",
Riedel says. The
experiments involved 27 volunteers, 16 of whom had an immediate relative with major
depression. Researchers lowered the level of tryptophan in the volunteers' bodies,
and memory tests showed impairment in their ability to recall and recognize words they
learned during, but not before, the tryptophan depletion time period. However, the
volunteers did better on focused attention tasks, concentrated listening tasks and tasks
measuring the speed of memory retrieval. The
results also showed that tryptophan depletion induced mood depression in half of
the subjects who had a family history of depression but in only 9 percent of those with no
family history of depression. The latter finding suggests that people with depression
in their families are more vulnerable to changes in serotonin levels. The mood
depression effects ended within 24 hours in all of the volunteers, however. "These
findings may have implications for people who have a history of major depression in their
families and people whose tryptophan becomes depleted because of dieting," the
authors note. "They also may have implications for people whose tryptophan becomes
depleted because they are undergoing immunotherapy for cancer."
Source: www.intellihealth.com
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