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Cuddled Babies Protected From Stress

From: C-afp@clari.net (AFP)
Organization: Copyright 1997 by Agence France-Presse
Date: Fri, 12 Sep 1997 8:40:53 PDT

The study by a medical research team at the University of Montreal bases this conclusion on observation of baby rats which were frequently licked and groomed by their mothers and subsequently developed a better response to tension and stress.

The study found that the rats which were cuddled during the first 10 days of their lives developed a more efficient chemical control mechanism for the hormone that creates stress than rats which were neglected.

"We believe that the effects of early environment on the development of HPA responses to stress reflect a naturally occurring plasticity whereby factors such as maternal care are able to program rudimentary, biological responses to threatening stimuli," the study says.

In an accompanying editorial, Dr Robert Sapolsky of Stanford University in California points out that while 40 years of scientific research have established the importance of environment in neonatal development, "few (studies) have shown differences this subtle to be associated with so global a change."

"Although the specifics of licking and grooming do not extend to humans, the broader point emphasizing the importance of early experience certainly does," the editorial says.

From: C-reuters@clari.net (Reuter / Maggie Fox, Health and Science Correspondent)
Subject: Study shows how loving moms make calmer adults
Organization: Copyright 1997 by Reuters
Date: Thu, 11 Sep 1997 19:00:40 PDT

Michael Meaney and colleagues at McGill University in Montreal, Canada, said tests on rats showed babies who got more attention from their mothers grew up with better responses to stress, and had measurable differences in brain hormones.

Reporting in the journal Science, they said the findings could translate to humans and urged studies to see if this was true.

``Maternal behavior regulates the activity of certain genes in certain areas of the brain, which in turn influences an animal's response to stress, which in turn regulates their vulnerability to stress-related disease,'' Meaney said in a telephone interview.

``Does this pathway exist in our own species? If you look at the relationship between stress and disease, we know that producing very high levels of stress hormones promotes the development of heart disease, diabetes, alcoholism, depression and so on,'' Meaney added.

``The higher the level of stress hormones that you produce, the greater the vulnerability to stress-related illness.''

Meaney and colleagues measured the brain chemicals in baby rats that had highly attentive mothers, who groomed and actively cuddled them while feeding. They compared these to brain chemicals in baby rats whose mothers were not so active.

They looked specifically at pituitary adenocorticotrophic hormone (ACTH), which is involved in the release of hormones by the brain's adrenal cortex -- including stress hormones like corticosterone.

Other hormones produced along with ACTH are enkephalins and endorphins, which affect mood and responses to pain.

As adults, the rats whose mothers had licked and groomed them more had significantly reduced levels of hormones like ACTH in response to stress. There were no differences in normal hormone levels.

Meaney's team could directly correlate the amount of licking they got as babies to the amount of hormone produced in response to stress as adults. ``That, I will tell you right now, surprised me,'' Meaney said.

Rats have different relationships with their babies than humans, but Meaney said the human equivalent of licking would be obvious. ``I think basically cuddling, nurturing, and instilling a sense of confidence -- (saying) 'I love you, I'm glad you're my baby' and so on.''

Meaney said animals like rats and humans both lived in a variety of environments and this response could be a way of programming babies for the particular niche they would grow up in. Babies destined to live stressful lives would thus be ready to respond more effectively and escape stress-related illness.

Robert Sapolsky, a biologist at California's Stanford University, said the rat study should spur research on what happens in humans.

``We are in an era filled with parental quandaries such as the type of daycare to provide, the inner-city specter of the dissolution of the family, teen pregnancy, and low government spending on child-related social services during critical periods of brain development,'' he wrote in a commentary.

Research published earlier this week found that teenagers who had close relationships with their parents were less likely to have behavioral problems.