The potential downside of this positive feedback loop, Coates argues, is that testosterone levels can eventually surge past optimal levels and have the opposite effect – leading to overconfidence and poor decision-making. When this happens to animals, Coates, observed, they “go out in the open, pick too many fights [and] patrol areas that are too large…Risk taking becomes risky behaviour.”
Testosterone levels generally peak during adolescence and early adulthood. As you get older, your testosterone level gradually declines — typically about 1 percent a year after age 30 or 40. It is important to determine in older men if a low testosterone level is simply due to the decline of normal aging or if it is due to a disease (hypogonadism).