In general, declining testosterone level is considered as a symptom of ageing in older men but according to a recent study made in the University of Adelaide, it is more commonly concerned with the health and behaviour of elderly.

For conducting this study, Professor Gary Wittert who is the head of medicine at University of Adelaide said that they tested and analyzed testosterone levels in 1500 men in tenure of five years. And as a result they got to know that it is just a myth to say that declining testosterone levels are a part of the ageing process. He added "Testosterone changes are largely explained by smoking behaviour and changes in health status, particularly obesity and depression".

The Commonwealth's National Health and Medical Research Council also supported this study of Professor Gary.

When testosterone levels were measured in men aged 35 to 54 years, researchers revealed that all those who are obese, or are found to be in a depressed state or are tobacco users; belong to the group of people with declining testosterone. So according to this study, there are many functions of a human body that are highly dependent on testosterone; these even include your fertility, sex drive and a healthy body composition.