Hormone profiles in humans experiencing military survival training

Background: Clinical models of the human response to intense, acute stress have been limited to laboratory settings or cross sectional characterizatio ns. As a result, data about the sensitivity of the human neuroendocrine act ivation to realistic stressors of varying magnitudes are limited. The U.S. Army survival course offers a unique opportunity to examine, in a controlle d manner, the human response to acute, realistic, military stress. Methods: Salivary data were collected in 109 subjects at baseline during fo ur stress exposure time points and at recovery. Serum data was collected at baseline and recovery in 72 subjects ana ar baseline ana during stress exp osure in a subgroup of subjects (n = 21). Results: Cortisol significantly increased during the captivity experience a nd was greatest after subjects' exposure to interrogations. Cortisol remain ed significantly elevated at recovery. Testosterone was significantly reduc ed within 12 hours of captivity. Reductions of both total and free T4 and o f total and free T3 were observed, as were increases in thyrotropin. Conclusions: The stress of military survival training produced dramatic alt erations in cortisol, percent free cortisol, testosterone, and thyroid indi ces. Different types of stressors had varying effects on the neuroendocrine indices. The degree of neuroendocrine changes observed may have significan t implications for subsequent responses to stress. (C) 2000 Society of Biol ogical Psychiatry.