Physiologic correlates of culture-bound dissociation: A comparative study of Brazilian spiritist mediums and controls.

Mediumship and spirit possession are cultural phenomena found in many societies worldwide. In Brazil, Spiritism (a tradition in which mediumship is emphasized) is the third largest religious denomination. The present study aimed to investigate physiologic correlates of nonpathological dissociative experiences by comparing 20 female spiritist mediums with several years of socially sanctioned practice to 20 female nonmedium control subjects from the same religious context. We measured plasma levels of hormones and neuroactive substances, as well as vital signs and heart rate variability (HRV) parameters, before and immediately after spirit communication. Although no between-group differences were noted in basal physiological parameters, in response to the possession experiences the groups differed in heart rate and in plasma concentrations of noradrenaline, thyroid-stimulating hormone (TSH), prolactin, and creatine phosphokinase (CPK). The changes in parameters indicated an arousal response in mediums and a relaxation response in control participants, and the same pattern of changes was observed in HRV parameters from each group during the possession experiences. However, the changes in physiologic parameters for mediums were mild and of short duration: 1 hour after the possession experiences, no difference in cardiac autonomic regulation was noted. No significant group effect was noted for melatonin. Cognitive control processes may explain the arousal associated with the dissociative state. Findings from this study suggest that pathological and nonpathological dissociation may have different physiological correlates.