Why are some people better at handling stress than others? This is a question that the National Institutes of Health’s Institute of Mental Health (NIMH) funded research project wanted to find out.

The researchers already knew that a protein in the brain, called BDNF, was involved with mice that are vulnerable to stress and they also knew that the components that handle stress in the mouse brain are similar to the human brain. 

To measure vulnerability to stress researchers put small mice in a cage with larger mice and observed their social withdrawal. The mice that continued to avoid social interaction after a month were assumed to be overwhelmed by stress. It is in those mice that researchers found an abundance of the BDNF protein.

On closer examination researchers found that the stress vulnerable mice had excessive rates of activity in an area that makes the chemical messenger dopamine. Mice that were adaptive, and showed less signs of stress, had an increase level of potassium that actually dampened the activity in the area that makes dopamine.

The researchers compared the brain tissue of deceased people with a history of depression and that of brain tissue of mice that showed vulnerability to stress. What the researchers found is that in both groups of brain tissue samples contained a higher-than-average BDNF protein, which the researchers feel offers an explanation of the link between stress and depression.

Future studies will examine ways to block BDNF in hopes to develop compounds that improve resilience in people faced with situations that might otherwise result in post traumatic stress disorder (PTSD). Researchers caution that blocking BDNF at certain stages in the process could perturb other systems in a negative way, because the process does not happen in a vacuum.