Evaluation of the Persistence Effect Acute Social Stress Test on the Alpha Band Power

Stress occurs frequently every day and has delayed effects. If the frequency of stress is too high and homoeostatic mechanisms cannot return the brain to the normal state, a person becomes prone to chronic stress. The aim of this study was to evaluate the survival of acute stress on electroencephalographic (EEG) changes along with hormonal changes and self-examination of stress in soldiers. A total of 24 healthy young men (soldiers) agreed to participate in the project. Before and 20 minutes after (recovery phase) performing the Trier social stress test (TSST); self-examination of stress, cortisol measurements in saliva and EEG recording were taken. Scores for emotional intelligence and IQ, and the depression, anxiety and stress score (DASS) were determined. There was a significant negative correlation between emotional intelligence and the DASS score in soldiers. Analysis of repeated measures showed that the level of salivary cortisol and the self-reported stress score were increased after the TSST (p<0.05). Whereas the cortisol level continued to increase, the self-report score was back to the pre-stress level after the recovery phase. The relative power of the alpha band in the closed eye was increased in most regions after stress, which was still high after recovery (P<0.001). Nonlinear indices of the fractal dimension of Ketz and spectral entropy in the prefrontal channels were reduced only after TSST and patients had returned to pre-stress levels after recovery (P<0.05). Increase of the alpha rhythm of almost all regions of brain and decrease of non-linear features, fractal Ketz and spectral entropy in the prefrontal region can be valid markers of stress in the brain.