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Adrenergic responses to cognitive activity in a cold environment
J R Thomas1, S T Ahlers, J F House
1Environmental Medicine Department, Naval Medical Research Institute, Bethesda, Maryland 20814-5055.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|March 1, 1990
Summary
Cold and cognitive stress uniquely impact catecholamine levels. Epinephrine significantly increased under combined cold and cognitive tasks, unlike cold or cognitive tasks alone, affecting heart rate. Norepinephrine primarily responded to cold exposure.
Area of Science:
- Physiology
- Stress Response
- Neuroendocrinology
Background:
- Adrenergic responses to physical stressors like cold differ from cognitive stressors.
- Understanding combined stressor effects on catecholamines is crucial for human performance research.
Purpose of the Study:
- To investigate the separate and combined effects of cold exposure and cognitive activity on catecholamine levels (epinephrine and norepinephrine) and heart rate in male subjects.
Main Methods:
- Six male subjects were exposed to a 4°C cold environment, a cognitive performance assessment battery (PAB), and a combination of both conditions.
- Plasma levels of epinephrine and norepinephrine were measured.
- Heart rate was monitored throughout the experimental conditions.
Main Results:
- Plasma epinephrine increased substantially only under combined cold and PAB conditions, while cold exposure alone did not alter it.
- PAB performance at 23°C caused only a slight increase in epinephrine.
- Heart rate changes mirrored epinephrine alterations.
- Norepinephrine release was primarily elevated by cold exposure and unaffected by PAB performance.
Conclusions:
- Combined cold and cognitive stressors elicit a distinct and amplified epinephrine response compared to individual stressors.
- Norepinephrine response is mainly driven by cold exposure, suggesting differential regulation under combined stress.