24 October 2010

Love the pain away

by Kate Melville

Passionate, intense feelings of love can provide amazingly effective pain relief, claims a new Stanford University School of Medicine study which compares the physiological effects of love to painkillers or drugs such as cocaine.

"When people are in this passionate, all-consuming phase of love, there are significant alterations in their mood that are impacting their experience of pain," said Sean Mackey, an associate professor of anesthesia at Stanford and senior author of the study. "We're beginning to tease apart some of these reward systems in the brain and how they influence pain. These are very deep, old systems in our brain that involve dopamine - a primary neurotransmitter that influences mood, reward and motivation."

The concept for the study, published in PLoS ONE, was sparked several years ago at a neuroscience conference when study co-author Arthur Aron, an expert in the study of love, met up with Mackey and they began chatting.

"Art was talking about love," Mackey said. "I was talking about pain. He was talking about the brain systems involved with love. I was talking about the brain systems involved with pain. We realized there was this tremendous overlapping system. We started wondering, 'Is it possible that the two modulate each other?'"

After the conference, the researchers set up a study that would entail examining the brain images of undergraduates who claimed to be "in that first phase of intense love."

"We posted fliers around Stanford University and within hours we had undergrads banging on our door," Mackey said. The fliers asked for couples who were in the first nine months of a romantic relationship. "It was clearly the easiest study the pain center at Stanford has ever recruited for," Mackey said. "When you're in love you want to tell everybody about it."

The study intentionally focused on this early phase of passionate love rather than the longer-lasting, more mature phases of relationships. Specifically, subjects who were feeling euphoric, energetic, and obsessively thinking about their beloved and craving their presence.

In the study, each of the subjects was asked to bring in photos of their beloved and photos of an equally attractive acquaintance. The researchers then successively flashed the pictures before the subjects, while heating up a computer-controlled thermal stimulator placed in the palm of their hand to cause mild pain. At the same time, their brains were scanned in a fMRI machine.

The subjects were also tested for levels of pain relief while being distracted with word-association tasks as past studies have shown that distraction causes pain relief.

The results showed that both love and distraction did equally reduce pain, and at much higher levels than by concentrating on the photo of the attractive acquaintance, but interestingly the two methods of pain reduction used very different brain pathways.

"With the distraction test, the brain pathways leading to pain relief were mostly cognitive," Younger said. "The reduction of pain was associated with higher, cortical parts of the brain. [Whereas] love-induced analgesia is much more associated with the reward centers. It appears to involve more primitive aspects of the brain, activating deep structures that may block pain at a spinal level - similar to how opioid analgesics work."

"It turns out that the areas of the brain activated by intense love are the same areas that drugs use to reduce pain," said Aron. "When thinking about your beloved, there is intense activation in the reward area of the brain - the same area that lights up when you take cocaine."

One of the key sites for love-induced analgesia was the nucleus accumbens, a key reward addiction center for drugs of abuse. "This tells us that you don't have to just rely on drugs for pain relief," Aron said. "People are feeling intense rewards without the side effects of drugs."

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Source: Stanford University Medical Center