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Tyrosine reverses a cold-induced working memory deficit in humans
D Shurtleff1, J R Thomas, J Schrot
1Thermal Stress Adaptation Program, Naval Medical Research Institute, Bethesda, MD 20889-5607.
Pharmacology, Biochemistry, and Behavior
|April 1, 1994
Summary
Cold stress impairs working memory by affecting brain catecholamines. Supplementing with the precursor tyrosine prevented this memory deficit in a cold environment, suggesting a way to mitigate cold-induced cognitive impairment.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Environmental Medicine
Background:
- Acute cold exposure can negatively impact short-term memory.
- This impairment may stem from disruptions in brain catecholamine release.
- Tyrosine, a catecholamine precursor, is investigated as a potential countermeasure.
Purpose of the Study:
- To determine if L-tyrosine supplementation can prevent working memory deficits induced by cold stress.
- To assess the effect of tyrosine on cognitive performance in a cold environment.
Main Methods:
- A computer-based delayed matching-to-sample (DMTS) task was used to measure working memory.
- Eight male volunteers were exposed to either 4°C (cold) or 22°C (control) ambient temperatures.
- Participants ingested either L-tyrosine (150 mg/kg) or a placebo before the task.
Main Results:
- Working memory performance, measured by matching accuracy, decreased with increasing delay intervals.
- Cold exposure significantly reduced matching accuracy compared to thermoneutral conditions when given a placebo.
- L-tyrosine administration improved matching accuracy in the cold, particularly at longer delay intervals, restoring performance to levels seen in the control condition.
Conclusions:
- L-tyrosine supplementation can effectively prevent cold-induced working memory impairment.
- Tyrosine's benefits appear specific to cold stress conditions, showing no effect at thermoneutral temperatures.
- This suggests targeting catecholamine pathways with tyrosine may be a viable strategy to maintain cognitive function during cold exposure.