Triggering Descending Pain Inhibition by Observing Ourselves or a Loved-One in Pain.

Objectives: Recent studies demonstrate that empathy-evoked brain responses include the activation of brainstem structures responsible for triggering descending pain inhibition. Unfortunately, direct evidence linking empathy for pain and descending inhibitory controls (conditioned pain modulation) is lacking. This study, therefore, aimed to determine if the observation of ourselves or a loved-one in pain could activate descending pain inhibition without exposure to a noxious stimulation; which is otherwise required.

Methods: Descending pain inhibition was triggered by immersing the right arm of participants (15 heterosexual couples; mean age±SE: 28.89±2.14) in a bath of cold water. The effects of empathy on descending pain inhibition were observed by immersing the right arm of participants in a bath of lukewarm water while having them watch a video of either themselves or their spouse during a previous nociceptive immersion. Immersion of the arm in a bath of lukewarm water without empathic (video) observation was also included as a control condition.

Results: A strong inhibitory response activated by the mere observation of the video of themselves or their spouse in pain without a nociceptive conditioning stimulus. Associative statistics also showed that strong pain catastrophizing responses while watching the video resulted in stronger pain inhibition. Moreover, high levels of empathy were associated with stronger pain inhibition, but only for women.

Discussion: This study showed that observing someone in pain triggers descending pain inhibition. Results also demonstrate how empathy and gender are affecting pain modulation mechanisms.