Stress, Neural Systems,and Genetic Code

An Interview with Neuroscientist Judy Cameron

Abstract: Research indicates some early life stresses can have a profound impact, resulting in changes in brain function and behavior, and even differences in the ways some genes express their particular genetic code signature. At various times during early development, different neural systems appear to have an increased sensitivity to stress and can influence long-term social behavior in a number of ways. A stable, nurturing environment is an important element in normalizing the development of a child experiencing stress.

Council Member Judy Cameron is Professor of Psychiatry at the University of Pittsburgh, Senior Scientist at the Oregon National Primate Research Center, and Professor of Behavioral Neuroscience, and Obstetrics & Gynecology at Oregon Health and Science University. She also directs training programs in reproductive biology and women’s health research at OHSU, and is director of the NIMH Conference Series on Comparative and Primate Research. She is a member of the Research Network on Early Experience and Brain Development. Her research focuses on the effects of everyday life stresses on long-term health. Three current areas of interest in her laboratory are the effects of genetic factors and early life experiences on anxious and depressive behaviors, identification of factors that lead to stress sensitivity versus stress resilience, and the interactions between metabolic and psychosocial stresses in the development of stress-sensitive disease processes.

Please give us a brief overview of your work.

Our laboratory studies the effects of early life experience on behavior, and the underlying neural systems within a developing brain that might guide that behavior. We also have separate research that identifies stress-sensitive and stress-resilient individuals and looks for differences in brain architecture between the two groups. The central question of this research is: Where does stress sensitivity come from? A third area of study that contributes indirectly to the Council agenda asks the question: What are the genes that are linked to many mental-health disorders in children? We have a large collaborative study under way to help us answer that question.

Science demonstrates the developing brain is most malleable in the first few years of life. What have you discovered about the way environments and experiences interact with genes?

There is an interaction—visualize a layering—between genetics and life experiences. You start by being born with genes that influence how you react to early life experiences, whether they are stressful life experiences or not. Each time you have a major life experience, that has a significant impact on the brain. It literally changes the way you behave, and that experience also changes genes’ expression. In other words, an experience won’t change what genes you inherited, but it will change which of those genes are being expressed. How genes regulate functions within your body will be changed as a result. A subsequent momentous experience—for example, you lose a parent—will again change your gene expression. Both genetics and life experiences determine outcome in a very interactive way. Science demonstrates clearly that children are shaped by both genes and experiences. So the old question about whether children are shaped by genes or experience should be retired. It’s both. And the truth is in the interaction.

What role does gene expression play in development? We know relationships with supportive caregivers offer great benefit to children of all ages, genetic makeup notwithstanding.

Each person is born with an individualized genetic code. For example, your height is going to be predominately determined by your relatives’ heights—your mother and father and grandparents. But even if your genes favor tallness, early life experience can cause stunted growth, probably by determining whether the tallness genes are expressed. Genetic code resides in the nucleus of a cell. To produce an outcome, it must be uncoded and transferred—scientists sometimes use the word “transcribed”—into proteins, and those proteins are sent out of the cell as intercellular messages. Think of it as sending a message, but in code. To get back to the height example, negative psychological stress can stunt a child’s growth—can cause “failure to thrive.” If, however, that child is taken out of the stressful condition, he or she can once again thrive. But even if the stressful situation is reversed, the child’s long-term growth is likely not to be as robust as it would be under normal conditions. Other functions of the brain, including those that influence social behavior and the development of psychological problems, like anxiety and depression, are even more susceptible to psychological stress.

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