Love Can Alleviate Pain
The early stages of a new, romantic relationship are associated with feelings of euphoria, which likely arise from brain mechanisms responsible for sensations of pleasure or reward. Imaging studies have shown that viewing pictures of a new, romantic partner elicits brain activity in multiple reward processing centers in the brain. Interestingly, these findings have now been replicated in a sample of Chinese participants, suggesting that patterns of brain activation elicited by viewing pictures of a romantic partner may be universal.
A research team headed by Sean Mackey, M.D., Ph.D., Chief of Stanford University School of Medicine’s Pain Management Division, wondered whether viewing pictures of a new, romantic partner could reduce experimentally induced pain. The research team examined whether or not viewing pictures of a new, romantic partner would be associated with specific patterns of brain activity that may mediate reward or relief of pain.
To investigate, Dr. Mackey’s team recruited 15 students to participate in the study during the first nine months of a new, romantic relationship. Each participant reported being intensely in love, which was confirmed numerically by use of the Passionate Love Scale. The participants included eight women and seven men, aged 19-21 years. Each participant underwent functional magnetic resonance imaging (fMRI) of the brain, which measures change in blood flow due to changes in brain activity. While in the brain scanner, each participant was asked to concentrate on each of the following: a picture of their romantic partner, a picture of an acquaintance of the same gender and similar attractiveness as the romantic partner, and a non-emotional word-association task.
Each condition was presented while the participants were made to experience no, moderate, or high levels of pain induced by exposure to varying levels of heat on the non-dominant hand for 15 seconds. Each pairing of condition and pain level was repeated six times in random order. Immediately after each pairing, participants used their dominant hand to rate the level of pain they experienced on a scale of 0 to 10 (0 = no pain at all and 10 = worst pain imaginable). After each pain rating, participants counted backwards for 13 seconds to minimize sensory and emotional carryover between trials.
In a study published in a recent issue of PLoS One, the research team reports that viewing pictures of a new, romantic partner significantly reduced pain, but viewing pictures of the acquaintance did not. fMRI results showed that several brain regions implicated in reward and emotion increased in activity during viewing of the romantic partners, including the frontal cortex, amygdala, and hypothalamus. In addition, fMRI data showed that brain regions implicated in the processing of pain, such as the insula, decreased in activity during viewing of the romantic partners. Interestingly, increased activation of brain regions such as the caudate and nucleus accumbens was associated with pain relief during viewing of the romantic partners but not during the word-association task. The caudate and nucleus accumbens have been consistently implicated in reward and include both classic brain reward pathways (namely, the “mesolimbic” and “nigrostriatal” pathways).
Not all of the patterns of brain activation induced by viewing pictures of romantic partners, however, were specific to reward. For example, some brain regions activated by the “love task” described here are also associated with activation of brain areas responsible for memory, attention, and sexual arousal. In addition, the researchers had no way to determine how much attention a given participant was paying to the pictures during the experiment. Surprisingly, there was no specific brain region that increased in activity during viewing pictures of a romantic partner to a degree similar to the extent of the pain relief experienced.
Overall, the results indicate that specific behavioral experiences can reduce pain without drugs. “When patients are doing markedly better and I find out they are in a new, passionate relationship, I may be less likely to think it’s the new medication I put them on, said Dr. Mackey. “I realize that maybe it has nothing to do with me,” he said.
The authors suggest that the pain relief associated with activation of brain reward systems described here may confer an evolutionary advantage in humans. Specifically, the alleviation of pain during the pursuit of a rewarding stimulus (in this case, the romantic partner) may facilitate attempts to attain specific goals even in spite of facing potentially harmful stimuli.
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