June 27, 2019 – Holding hands with a romantic partner – a form of "supportive touch" – reduces pain-specific signal in the brain of women during a painful procedure, reports an experimental study in PAIN®, the official publication of the International Association for the Study of Pain (IASP). The journal is published in the Lippincott portfolio by Wolters Kluwer.
The study provides new evidence on the brain mechanisms involved in the pain-reducing (analgesic) effects of supportive or social touch, according to Marina López-Solà, PhD, Cincinnati Children's Hospital Medical Center and colleagues at the University of Colorado Boulder. The researchers write, "Social touch affects core brain processes that contribute to pain and pain-related affective distress in females, and should be considered alongside other treatments in medical and caregiving contexts."
Handholding Reduces Pain, With Effects on Pain-Specific Brain Signal and Interconnected Affective Brain Regions
The researchers evaluated the brain mechanisms behind the pain-reducing effects of supportive touch, defined as "interpersonal touch with an intention of providing emotional support." Studies have shown that holding hands with one's romantic partner provides significant pain relief – even during childbirth and other intensely painful "real-life" situations.
In the experiment, 30 healthy women underwent painful (but not harmful) heat stimulation. Behavioral and brain responses to pain were evaluated under two conditions: while the women held hands with a "committed, monogamous" romantic partner or while they held a rubber squeeze-ball. Changes in brain activity responsible for touch-induced analgesia were assessed by functional magnetic resonance imaging (fMRI).
As in previous studies, supportive touch reduced the intensity and unpleasantness of pain, compared to squeezing a rubber ball. Holding hands with a partner also increased emotional comfort – an effect that was greater for women reporting higher quality of their romantic relationship and greater closeness with their romantic partner.
The fMRI scans showed distinct effects of handholding on brain activity in response to pain, including a reduction in the brain's "neurologic pain signature" (NPS): a brain marker previously validated to specifically track experienced pain in healthy subjects. "Importantly, handholding significantly reduced NPS responses during both early and late pain," Dr. López-Solà and coauthors write. However, on their own, the changes in NPS couldn't fully explain the effects of handholding on pain.
Supportive touch also seemed to target pain-evoked changes in interconnected brain regions involved in stress, emotion, and attention. "The strongest mediators of analgesia were in a brain circuit traditionally associated with stress and defensive behavior in mammals," according to the authors. They believe that reducing stress-related brain responses during pain may be a key contributor to reducing the subjective experience of pain through social touch.
Handholding altered the state of brain connectivity throughout the painful experience, including connections between circuits involved in pain perception and those related to thinking about one's self and relationships with others.
The researchers note that their initial experiments focused on women because they are at greater risk of certain types of pain.
"Holding hands with a close romantic partner during pain exerts several protective brain and behavioral effects, " Dr. López-Solà and colleagues conclude. They believe that gaining insight into the brain mechanisms of pain reduction by social or supportive methods "is a first step toward understanding when and in whom each of these interventions may work best."
PAIN is IASP's official journal. Published monthly, PAIN presents original research on the nature, mechanisms, and treatment of pain. Available to IASP members as a membership benefit, this peer-reviewed journal provides a forum for the dissemination of multidisciplinary research in the basic and clinical sciences. It is cited in Current Contents and Index Medicus.
About the International Association for the Study of Pain
IASP is the leading professional organization for science, practice, and education in the field of pain. Membership is open to all professionals involved in research, diagnosis, or treatment of pain. IASP has more than 7,000 members in 133 countries, 90 national chapters, and 20 special interest groups (SIGs). IASP brings together scientists, clinicians, health-care providers, and policymakers to stimulate and support the study of pain and translate that knowledge into improved pain relief worldwide.
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