Gender Difference in the Effect of Examination Stress on Brain Oscillations during Memory Tasks

Abstract

Background: Researches revealed that increased levels of stress hormones lead to enhancement of memory consolidation in rodents. Recently, it became apparent that the brain oscillations reflect cognitive aspects and information processing in the brain. Quantitative electroencephalogram (qEEG) provides an objective assessment of the electrical activity of the brain via many techniques such as power spectral analysis and coherence. Aim: To assess the effect of gender on the qEEG oscillations during the delayed memory retrieval after exposure to acute stress. Subjects and Methods: This prospective (longitudinal) study was applied on 34 healthy undergraduate medical students from both genders (17 males and 17 females) in the Faculty of Medicine, Suez Canal University. The qEEG analysis was done in neurology department, Suez Canal University Hospital using the relative power (RP) during memory tasks. Serum cortisol was analyzed by enzyme linked immunosorbent assay (ELISA) as a measure for stress. Results: The results revealed insignificant effect of gender on the quantitative analysis of EEG oscillations regarding the mean relative power in all frequency bands (delta "δ": 2.36±0.72; 2.04±0.46, theta "Ɵ": 13.72±3.13; 12.72±3.58, alpha "α": 12.72±3.58; 18.50±3.81 and beta "β": 33.26±3.23; 32.72±4.47 for males and females respectively during the examination period). Whereas, there was a positive correlation between the serum cortisol level and the mean relative power of delta (r: 0.53, p=0.03), and theta (r: 0.55, p=0.02) and a negative correlation with beta (r:-0.51, p= 0.04) bands in males only. Conclusion: There are positive correlations for delta and theta bands and negative correlation for beta band between the quantitative electroencephalographic analysis (RP) with the hormonal measure of the stress in spite of the insignificant changes in the EEG oscillations in the non-stress and stress periods.