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A hug, a handshake, a therapeutic massage. A newborn lying on a mother’s bare chest.

Physical touch can buoy well-being and lessen pain, depression and anxiety, according to a large new analysis of published research released on Monday in the journal Nature Human Behaviour.

Researchers from Germany and the Netherlands systematically reviewed years of research on touch, strokes, hugs and rubs. They also combined data from 137 studies, which included nearly 13,000 adults, children and infants. Each study compared individuals who had been physically touched in some way over the course of an experiment — or had touched an object like a fuzzy stuffed toy — to similar individuals who had not.

For example, one study showed that daily 20-minute gentle massages for six weeks in older people with dementia decreased aggressiveness and reduced the levels of a stress marker in the blood. Another found that massages boosted the mood of breast cancer patients. One study even showed that healthy young adults who caressed a robotic baby seal were happier, and felt less pain from a mild heat stimulus, than those who read an article about an astronomer.

Positive effects were particularly noticeable in premature babies, who “massively improve” with skin-to-skin contact, said Frédéric Michon, a researcher at the Netherlands Institute for Neuroscience and one of the study’s authors.

“There have been a lot of claims that touch is good, touch is healthy, touch is something that we all need,” said Rebecca Boehme, a neuroscientist at Linkoping University in Sweden, who reviewed the study for the journal. “But actually, nobody had looked at it from this broad, bird’s eye perspective.”

The analysis revealed some interesting and sometimes mysterious patterns. Among adults, sick people showed greater mental health benefits from touch than healthy people did. Who was doing the touching — a familiar person or a health care worker — didn’t matter. But the source of the touch did matter to newborns.

“One very intriguing finding that needs further support is that newborn babies benefit more from their parents’ touch than from a stranger’s touch,” said Ville Harjunen, a researcher at the University of Helsinki in Finland, who also reviewed the study for the journal. Babies’ preference for their parents could be related to smell, he speculated, or to the differences in the way parents hold them.

Women seem to benefit more from touch than men, which may be a cultural effect, Dr. Michon said. The frequency of the touch also mattered: A massage once every two years isn’t going to do much.

Several studies included in the review looked at what happened during the height of the Covid pandemic, when people were isolated and had less physical contact with others. “They found correlations during Covid times between touch deprivation and health aspects like depression and anxiety,” Dr. Michon said.

Touching the head appears to have more of a beneficial effect than touching the torso, some studies found. Dr. Michon couldn’t explain that finding, but thought it could have to do with the greater number of nerve endings on the face and scalp.

Another mystery: Studies of people in South America tended to show stronger health benefits of touch than did those studies that looked at people in North America or Europe. Dr. Michon said that culture may somehow play a role. But Dr. Boehme said the studies showing the differences between countries were too small to be definitive. “I think the mechanism behind this is biological,” she said. “I think that’s hard-wired and will be the same for all of us.”

In 2023, Jeeva Sankar, a pediatrics researcher at All India Institute of Medical Sciences, and a colleague published a rigorous review of skin-to-skin care for newborns. The analysis concluded that touch therapy for preterm or low-birth-weight infants should start as soon as possible and last eight hours or more, a recommendation that the World Health Organization adopted. Dr. Sankar said the new review was important because touch is often neglected in modern medical care, but it was too broad. He would have liked it to focus more on how various forms of touch could be integrated in medical care.

Dr. Michon stressed that the types of touch considered in these studies were positive experiences to which the volunteers agreed. “If someone doesn’t feel a touch as being pleasant, it’s likely going to stress them out,” he said.

Courtesy: The New York Times