Tyrosine supplementation mitigates working memory decrements during cold exposure

Area of Science:

• Environmental Psychology
• Neuroscience
• Human Physiology

Background:

• Acute environmental stress, such as cold exposure, can impair cognitive function.
• Dietary supplementation with tyrosine (TYR) has shown promise in preventing catecholamine depletion during stress in animal models.
• Understanding TYR's effects on human cognition under stress is crucial for performance optimization.

Purpose of the Study:

• To investigate the impact of severe cold exposure on human cognitive performance.
• To determine if dietary tyrosine supplementation can mitigate cold-induced cognitive deficits.
• To assess the effects of TYR on mood and physiological stress responses.

Main Methods:

• A double-blind, within-subjects design with 19 volunteers.
• Three experimental conditions: thermoneutral control (35°C) with placebo, cold exposure (approx. 10°C) with placebo, and cold exposure with TYR supplementation (300 mg/kg total).
• Cognitive tests (Match-to-Sample, choice reaction time), mood assessments, and salivary cortisol measurements were conducted during two 90-minute water immersions per session.

Main Results:

• Cold exposure significantly elevated cortisol levels and impaired cognitive performance, including reduced accuracy on memory tasks and increased reaction time and errors.
• TYR supplementation in the cold improved accuracy on the Match-to-Sample memory task and reduced study time, indicating enhanced information processing.
• TYR normalized reaction times on a memory task compared to cold/placebo conditions, suggesting a protective effect on working memory.

Conclusions:

• Severe cold exposure significantly degrades human cognitive function, affecting memory and information processing speed.
• Dietary tyrosine supplementation effectively alleviates cold-induced working memory decrements and improves cognitive performance under stress.
• TYR shows potential as a nutritional countermeasure to maintain cognitive function in cold environments.