Do male hormones affect how quickly men age?
Declining testosterone measurably accelerates ageing of muscles, bones and sexual function, but the links to mood and skin are far less certain. Testosterone supplementation can relieve some symptoms, but always discuss the risk profile with your doctor before starting.
Testosterone in men declines gradually from around the age of 35. By the age of 75, the average man retains only about 65% of the testosterone level he had as a young adult. More than a quarter of men over 75 even fall below the normal lower limit. This is well documented in both population studies and long-running research.
That decline has measurable effects on the body. Loss of muscle mass and muscle strength ('sarcopenia') and reduced bone density are the most solidly supported effects. Notably, bone breakdown is driven not only by testosterone but also by oestrogen, which the male body produces in small amounts. Lower testosterone therefore also means lower oestrogen, and that accelerates bone loss. Reduced libido and erectile problems are likewise well documented in testosterone deficiency, although the link with measured blood levels is not always one-to-one.
Less clear is the influence on mood and memory. There are indications that testosterone deficiency is associated with low mood and difficulty concentrating, but a direct causal relationship is hard to prove. Testosterone has not shown a consistent antidepressant effect in studies. The influence on skin and hair growth is entirely speculative based on the available data.
Not every decline has the same cause, and that matters for treatment. In younger older men, excess weight, the use of opiates or corticosteroids, or a chronic illness is often the culprit. That type of testosterone deficiency can sometimes be reversed by losing weight or treating the underlying condition. However, from around age 65-70, the testosterone-producing cells in the testes also become directly impaired. That type of failure is generally irreversible, regardless of lifestyle.
Testosterone supplementation is an option that relieves symptoms for some men, but its long-term safety has not been well mapped. In cases of existing prostate cancer it is inadvisable in any event. The effect on cardiovascular disease is uncertain, and large long-term studies in older men are still lacking. The decision about supplementation belongs with a doctor who has also established the cause of the deficiency.
The claims are based on multiple population studies and clinical review articles. The decline of testosterone itself and its effects on muscle and bone are well supported. The effects on mood and skin are associative only and less well documented. Safety data for long-term testosterone supplementation in older men are limited.