Ground breaking study finds the offspring of stressed mothers brains develop differently

While most mothers try to take it easy in those last weeks of pregnancy, new research has found that reducing stress may be vitally important for foetal brain development.

A ground breaking study has found that prenatal stress negatively affects the development of a lamb’s brain. In the first study of this type to take place not in the lab but in ‘real life’ conditions on a farm, researchers observed structural alterations in the neurons involved in emotional regulation and cognitive processing. The changes found in the lambs’ brains could theoretically apply to human babies as well.

The study, which is published in the journal Psychoneuroendocrinology and can be found online via ScienceDirect, was a collaboration between Scotland’s Rural College (SRUC), The French National Institute for Agricultural Research (INRA), the Norwegian School of Veterinary Science and Indiana University.

Prenatal stress in humans is associated with the development in both children and adults of such disorders as depression, post-traumatic stress disorder, and schizophrenia. A large body of laboratory experiments on mice and rats also demonstrates that stressful events experienced by a pregnant female produce a variety of negative effects.

“This project is truly unique for more than one reason,” Professor Adroaldo Zanella, Animal Welfare scientist at SRUC, says. “It is the first ever study that has proved these negative effects occur in real world conditions. Not only that, but the ewes in the higher stress group only ever experienced very mild stress, yet we saw these changes in the lambs’ brains.”

Norwegian-dala ewes in their last six weeks of pregnancy were separated into two groups for the experiment. One group received gentle treatment during the last weeks before giving birth. This consisted of human interaction occurring at predictable times, calm handling, soft voices and avoiding directly gazing into the ewes’ eyes (this has been shown to cause stress in sheep). The second group received aversive treatment, consisting of what are considered mild stressors—unpredictable handling times, erratic movements, loud voices and staring directly into the ewes’ eyes.

One month after the sheep gave birth; scientists studied the brains of the lambs. Lambs from ewes that received aversive handling showed changes in the structure of neurons in the brain regions involved in emotional regulation and cognitive processing. With their brains developing differently in these areas the lambs may respond to stressful situations differently, which could have further detrimental effects.

“We have seen this reflected in behaviour,” Professor Zanella says. “Our previous research found that lambs whose mothers received aversive handling while pregnant exhibit more fearfulness and their cognitive abilities are compromised. Right now we are working on a study that will assess how they are affected in the longer-term.”

Professor Cara Wellman of the Psychological and Brain Sciences Department of Indiana University said the research could also relate to the human brain.

She says: “We’ve translated it from the lab to the real world. You see it across multiple species. It is very likely that prenatal stresses can also produce these same brain changes in humans, which suggests that it’s going to influence cognitive and emotional processes in children.”

Yet this is not to say that all stress is simply negative. “There is some good evidence to suggest that you can’t generalise and say all stressors are bad.” Cara explains. “But there may be an optimal amount of stress. The appropriate amount of prenatal stress might prepare the offspring to respond to stress as an adult. Not enough might be just as harmful as too much.”

The study was sponsored by the Norwegian Research Council and the contribution of the first author, now working with INRA, Dr Marjorie Coulon, was funded through a fellowship from the Fyssen Foundation.

Scotland’s Rural College, INRA and Indiana University will continue to work together as it only through such collaborative work that will help them better understand the significance of these findings for animal welfare.

 

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