Background: Military flying sets high demands on the mental performance and stress tolerance of pilots. Neuroendocrine responses could be a method for evaluating stress tolerance.
Methods: Psychological workload and neuroendocrine responses associated with the psychomotor Wiener's test were studied in 80 male volunteers. These personnel had applied for the basic military flying program of the Finnish Air Force (FAF). After the first blood sample at 0930 h, the subjects were randomly assigned to test (n = 40) and control groups (n = 40). The test group performed the psychomotor test, which lasted 10 min. The second blood sample was collected 1 min after the test. The control group was clinically examined and the blood sample was taken in the same way.
Results: A high plasma ACTH level before the psychomotor test predicted (r = 0.36, p = 0.02) a poor overall result in the psychomotor test. After the psychomotor test, plasma adrenocorticotropin (ACTH) and beta-endorphin levels were significantly higher than before the test. They were also higher than in the control group. Plasma cortisol and prolactin levels increased after the psychomotor test, but the increase was not statistically significant. High ACTH, cortisol and prolactin increments were specific to a high amount of delayed (over 2 s) psychomotor responses, as a marker of information overload.
Conclusions: Elevated plasma ACTH, cortisol and prolactin levels, after the psychomotor test, were associated with a high amount of the delayed responses. This indicates that high neuroendocrine responses were connected with problems in stress tolerance during information processing. High neuroendocrine reactions under information load could, therefore, be used for identification of lowered stress tolerance.