Effects of voluntary fluid intake deprivation on mental and psychomotor performance.

AIM: To assess if there is deterioration in mental and psychomotor performance during 24-hour voluntary fluid intake deprivation.

METHODS: A battery of computer generated psychological tests (Complex Reactionmeter Drenovac-series) was applied to 10 subjects to test light signal position discrimination, short-term memory, simple visual orientation, simple arithmetics, and complex motor coordination. We measured total test solving time, minimum (best) single task solving time, total ballast time, and total number of errors. Mood self-estimate scales of depression, working energy, anxiety, and self-confidence were used to determine the emotional status of subjects. During the first day of the experiment, subjects had free access to drinks. After a 48-hour interval, subjects voluntarily abstained from fluid intake for 24 hours. During that period, the testing was performed 7 times a day, at 3-hour intervals, except during the night. Z-transformation of the results enabled the comparison of 50 dependent measurements on the same subjects.

RESULTS: During dehydration, there was significant deterioration in total test solving time, minimum single task solving time, and total ballast time. No significant deterioration was found by mood self-estimate scales, except on the scale of energy at 23:00 hours.

CONCLUSION: Voluntary 24-hour fluid intake deprivation led to deterioration in objective parameters of psychological processing, but not in subjective parameters. The results suggest that the duration of fluid intake deprivation can be a useful indicator of mental and psychomotor deterioration level but not of mood self-estimates.