Physical presence may be required for women who are in relationships for the testosterone–partner interaction, where same-city partnered women have lower testosterone levels than long-distance partnered women. Testosterone levels do not rely on physical presence of a partner; testosterone levels of men engaging in same-city and long-distance relationships are similar. Collectively, these results suggest that the presence of competitive activities rather than bond-maintenance activities is more relevant to changes in testosterone levels. Married men who engage in bond-maintenance activities such as spending the day with their spouse or child have no different testosterone levels compared to times when they do not engage in such activities. Single men who have not had relationship experience have lower testosterone levels than single men with experience. Some men may also receive it for age-related decline in testosterone or for certain medical conditions when a doctor believes it can improve quality of life. In parallel, ongoing work is required to further elucidate the mechanisms by which T may influence CVD risk, including its effects on HDL and other plasma lipids. Thus, despite numerous research efforts to date, the role of hypogonadism in the pathogenesis of CVD remains unclear, as does the cardiovascular risk profile of TRT. Continued research is critical to better elucidate both the effects of T on HDL composition and function and the utility of various HDL metrics in CVD risk prediction. Focus has shifted from measuring HDL cholesterol content alone to assessing HDL particle function, which may prove a better predictor of CVD risk. Food and Drug Administration (FDA) in 2015 to require a warning label about possible heart risks for prescription testosterone products. A 2013 study of older men, many with existing health problems, reported a higher rate of heart attacks in those taking testosterone compared to those who were not. But a change in cholesterol does not always mean a person will develop heart disease. First, it is important to separate cholesterol changes from actual heart disease outcomes. For patients and doctors, knowing these differences is important for choosing the right therapy and planning regular cholesterol monitoring. Oral testosterone is less common in the United States because it can affect the liver. This steady pattern seems to have less impact on how the liver makes or clears cholesterol. Studies suggest that gels and creams may have a milder effect on cholesterol compared to injections. These swings may influence how the liver processes cholesterol. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game. Higher testosterone levels in men reduce the risk of becoming or staying unemployed. Serious side effects may include liver toxicity, heart disease (though a randomized trial found no evidence of major adverse cardiac events compared to placebo in men with low testosterone), and behavioral changes. Preliminary evidence suggests that low testosterone levels may be a risk factor for cognitive decline and possibly for dementia of the Alzheimer's type, a key argument in life extension medicine for the use of testosterone in anti-aging therapies.
