Posted by Sue Landsman on Dec.10, 2009

©iStockphoto.com - lovleah

The “nature vs. nurture” debate is old and well known. Are a person’s problems due to how they’re made, or how they’re raised?

A recent German study suggests that nurture can make nature. Everyone knows that children raised in difficult environments often have problems later in life. People have long been studying abused and neglected children to see how they fare in adulthood, and it’s not hard to see how this kind of a start could lead to depression and other psychiatric difficulty later in life. So far, though, there hasn’t been a direct link or any kind of understanding of how this works on a molecular basis.

Now there’s evidence of a possible direct cause and effect. Trauma and stress early in life, the study suggests, change genetic makeup and cause behavioral problems such as depression later in life.

Scientists at the Max Planck Institute of Psychiatry worked with baby mice who were stressed by early separation from their mothers. The mice were removed from their mothers for three hours a day for the first ten days of their lives. Other mice were allowed to stay with their mothers. The second group of mice, called a “control,” were raised exactly the same as the other mice so that the researchers could see how the stressed mice would differ from “normal” ones.

The researchers then tested the blood of all of the mice at regular intervals (6 weeks, 3 months, 1 year) for corticosterone, a stress-related hormone. Because animals, including humans, produce varying amounts of corticosterone throughout the day and under differing amounts of stress, it is a good indicator for the presence and level of stress. The mice who had been separated from their mothers had predictably higher corticosteroid levels.

This was no surprise. It also was no surprise that the stressed mice had significant behavior problems. Their memory was worse than that of the control mice, and they also did not perform as well in swim tests. The unstressed mice were more able to cope with the stress of the test. Again, not surprising: give me a swim test on a bad day and I’ll probably forget my bathing suit as well as throw a nutty at the side of the pool.

What was surprising was that the stressed mice all had DNA altered in a specific way. DNA is the molecular building block of life, and it encodes the directions for making us who and what we are. The stressed mice all showed chemical changes in a gene that tells the mice’s cells how to make a hormone named arginine vasopressin. As a result, the stressed mice produced more vasopressin than the unstressed ones. Arginine vasopressin is a hormone that is released in the blood and in the brain. It raises blood pressure, affects mood and other neurological traits, as well as influencing the production of the stress hormone corticosterone.

But was the vasopressin really responsible for the mice’s behavior, or was it just another symptom of stress? The researchers wanted to prove that the genetic change was directly responsible for the errant behavior they were seeing. The way to do that was to make some of the stressed mice “immune” to vasopressin and see if their behavior changed. In fact, the stressed mice that were given a drug that rendered the hormone impotent no longer had memory or coping problems.

The significance of this is that it helps us understand that there is a molecular and genetic basis to some psychiatric problems, specifically those related to stress. In addition to underscoring the importance of proper care of children, it also can give people with stress-related disorders hope for medical relief of their conditions.

Share

Posted under GDM Kids, Tweens, Teens, Health & Fitness, Health Alerts.