But I'm not more aggressive—a behavior change often tied to testosterone. That's not surprising to Robert Sapolsky, ., a neuroendocrinologist at Stanford University and a leading researcher on stress and behavior. "It's really not the case that testosterone 'causes' aggressive behavior," he says. "Instead, it makes the brain more sensitive to social cues that trigger aggression. And in support of that, a guy's testosterone level isn't a very good predictor of how likely he is to be aggressive."
The actual cause of depression is not yet clear. However, doctors and scientists believe that it is a result of an imbalance in the chemicals signaling the brain. Studies are ongoing to identify the imbalance and the signaling chemicals. Various illnesses and some adverse life situations may spark depression. However, a majority of men with lower testosterone levels also exhibits depression signs. Most of them are obese or overweight. It points out the relation between depression and body fat. Average testosterone levels may reverse the situation for men.