Threat-related Mental Imagery Impairs Endogenous Pain Modulation in Healthy Individuals

Mental imagery-based simulations of threat can evoke “as-if-real” emotional and motivational responses, which may alter top-down pain processing. This study investigated the impact of mental imagery simulations of threat on endogenous pain modulation in n = 71 healthy participants using a cuff-pressure algometry protocol. In block one, participants were assessed on their baseline pain detection threshold (PDT), pressure pain tolerance (PTT), and their conditioned pain modulation (CPM) responses. In the second block, participants underwent the same procedures again but were randomly allocated to imagine the dominant leg cuff as being made of bubble wrap (benign imagery condition; n = 36) or metal wire (threat imagery condition; n = 35). In between blocks, participants went to a separate room to interact with a piece of real bubble wrap or metal wire around their legs, facilitating mental imagery generation in Block 2. Partially consistent with our hypothesis, mental imagery impacted CPM effects for pain detection threshold (PDT), which was significantly reduced in the Wire relative to the Bubble-wrap condition. Mental imagery did not influence pressure pain tolerance (PPT). These results indicate that mental simulation of threat impaired threshold-based CPM responses. Our data suggest that mental simulation of threat may contribute to dysfunctional central pain processing which may be relevant to the maintenance of clinical pain conditions.