Attentional and emotional tasks: gender differences in heart rate variability detected by short-term detrended fluctuation analysis

In this study we analyzed the heart rate variability of 21 subjects, 12 females and 9 males performing a two-step task. The subjects were requested to watch a relaxing movie for 30 minutes and, in a different day, to watch a stressful movie again for 30 minutes. The electrocardiographic signal was recorded for all the duration of the sessions. The series of the beat-to-beat time intervals were analyzed by detrended fluctuation analysis. The short-term variability index clearly indicated a significant gender difference independently of the specific movie, while the long-term variability index did not reveal any significant difference of gender and task. This finding contrasts with the results of physical stimulation, which abolishes the gender differences observed in resting conditions. The discrepancy may depend on lower autonomic engagement in cognitive/affective than in physical tasks as well as on a possible different balance of the sympathetic and parasympathetic activities.