Aging Independently of the Hormonal Status Changes Pain Responses in Young Postmenopausal Women

Both aging and hormonal status have an effect on pain perception. The goal of this study was to isolate as much as possible the effect of aging in postmenopausal women. Thirty-two women with regular menstrual cycles (RMW) and 18 postmenopausal women (PMW) underwent a 2-minute cold pressor test (CPT) to activate DNIC with a series of tonic heat pain stimulations with a contact thermode to assess ascending pain pathways. We found that this procedure induced much less pain during the first 15 seconds of stimulation the PMW group (P = 0.03), while the mean thermode pain ratings, pain tolerance, pain threshold, and DNIC analgesia were similar for both groups (P > 0.05). The absence of the peak pain in the PMW was probably due to reduced function of the myelinated Aδ fibers that naturally occurs with age.