Expert article with contributions from PD Dr. Frederik Wessels. Learn how scientific studies debunk common myths about testosterone and what role the hormone really plays.
Testosterone is a hormone with far-reaching effects on both physical and mental health. Contrary to common myths, such as the supposedly normal age-related testosterone deficiency or the assumption that high testosterone levels promote aggressive behavior, science paints a more complex picture. In this article, we dispel such misconceptions and shed light on the diverse functions of testosterone and the effects of testosterone replacement therapy.
The public perception and stigmatization of testosterone
Testosterone is a hormone that is often misunderstood and surrounded by numerous myths. This is partly due to its close association with concepts of masculinity and physical strength, leading to a number of prejudices. The use of testosterone in doping and bodybuilding further contributes to the stigmatization of the hormone. Such misconceptions can shape public perception and frequently result in a polarized discussion about the role of testosterone. Furthermore, scientific findings are often distorted by popular media. By correcting misinformation, we aim to help reduce the stigma associated with this important hormone and promote a more informed discussion about its functions and effects.
Myth 1: “A testosterone deficiency in old age is normal”
It is a widespread belief that a decline in testosterone levels with age is a normal, inevitable consequence of the natural aging process. While a slightly lower production with age is indeed normal, many other factors can lead to a manifest, symptomatic testosterone deficiency. Lifestyle plays just as important a role as existing comorbidities (Kelly & Jones, 2015 ; Traish et al., 2011) .
Modern lifestyle and testosterone deficiency
Today's fast-paced and often unhealthy lifestyle can significantly impact testosterone production. Factors such as an unhealthy diet, physical inactivity, poor sleep habits, and chronic stress play a key role in reducing testosterone levels.
- Unhealthy diet: A diet low in essential nutrients but high in processed foods and sugar can disrupt hormonal balance. This can lead to insulin resistance, a condition negatively correlated with testosterone production (Allen & Key, 2000) .
- Physical inactivity: A lack of regular physical activity can prevent the body from producing sufficient testosterone. Exercise, especially strength training and high-intensity interval training, is known to increase testosterone levels (Riachy et al., 2020) .
- Lack of sleep: Less than 7-8 hours of sleep per night can significantly disrupt the hormonal balance. The body produces the most testosterone during sleep, especially during deep sleep phases (Agrawal et al., 2022) .
- Chronic stress: High, persistent stress leads to the release of the stress hormone cortisol. An excess of cortisol can significantly lower testosterone levels (Xiong et al., 2021) .
Comorbidities: Both cause and consequence of testosterone deficiency
Testosterone deficiency can not only cause various health problems, but also result from them. Comorbidities such as diabetes or cardiovascular disease can accelerate the onset of andropause and intensify symptoms (Putta et al., 2017) . Chronic diseases such as diabetes, kidney failure, and liver disease can directly affect testosterone levels. Hormonal imbalances that disrupt a specific signaling pathway in the body connecting the brain and reproductive organs can also lead to a deficiency (the so-called hypothalamic-pituitary-gonadal axis).
Research shows that approximately 30% of men between the ages of 40 and 79 suffer from testosterone deficiency. This problem is more common in older men and those with comorbidities. In particular, the so-called metabolic syndrome, which includes insulin resistance (type 2 diabetes), dyslipidemia, hypertension, and obesity, shows a strong correlation with testosterone deficiency due to its direct impairment of hormone production (Traish et al., 2011) .
For detailed information on the connection between the common disease type II diabetes and a testosterone deficiency, you can read our article: “ Why diabetics should definitely keep an eye on their testosterone levels ”.
The relationships between these diseases and testosterone levels are complex, but crucial for understanding the many causes of testosterone deficiency. For example, testosterone deficiency can not only lead to obesity, but can also be (partly) caused by obesity itself (Kelly and Jones, 2015) .
This bidirectional relationship is also the reason why it is assumed that the positive effects of testosterone replacement therapy (TRT) are not only due to direct metabolic effects on muscles and adipose tissue, but potentially also indirectly through an increase in motivation, energy and vitality, which helps, for example, overweight people to lead a more active life (Kelly and Jones (2015) ) .
Why is this important?
A better understanding of these relationships allows for targeted prevention and treatment of testosterone deficiency in older adults. Therefore, if a symptomatic deficiency is diagnosed in older adults, it should not simply be considered "normal" and accepted. Rather, treatment should involve lifestyle interventions as well as, where medically indicated, testosterone replacement therapy (TRT) according to current medical guidelines. This treatment can significantly improve quality of life and alleviate the symptoms associated with testosterone deficiency (Hijazi & Cunningham, 2005 ; Stanworth & Jones, 2008 ; Tishova et al., 2024) .
Myth 2: “Testosterone makes you aggressive”
The key hormone testosterone influences far more than just physical characteristics. In addition to its impact on metabolism and tissue structure, it affects mood, energy, cognitive functions, and sexual health (Hintikka et al., 2009) .
A common misconception is the assumption that high testosterone levels inevitably lead to aggressive behavior. This idea persists in society, but science offers a more nuanced picture of the psychological effects of testosterone: it influences psychological and social behaviors and plays a crucial role in self-confidence, motivation, and interactions in social environments (Zitzmann, 2020) .
Testosterone and mental well-being
A normal testosterone level is crucial for mental balance and emotional well-being. It also influences risk-taking behavior and stress management (Xiong et al., 2021) . Testosterone also affects cognitive functions, including memory and concentration (Sternbach, 1998 ; Smith et al., 2018) .
Low testosterone levels can negatively affect mood and energy levels, which in turn leads to reduced self-confidence and impaired self-esteem. Those affected often feel tired, demotivated, and less productive, which presents challenges in both their personal and professional lives (Zitzmann, 2020) .
The role of testosterone in a social context
Furthermore, balanced testosterone levels support the development of positive social interactions. They contribute to improved risk-taking behavior, enabling men to better weigh options and make more rational decisions in challenging situations. This leads to a healthier lifestyle and strengthens social networks (Booth et al., 2006) . Testosterone also has a positive influence on emotional intelligence. Appropriate testosterone levels improve the ability to recognize emotions in oneself and others and to respond appropriately. This fosters emotional connectedness and relationship skills (Tyborowska et al., 2023) .
A balanced testosterone level can significantly influence a man's self-confidence and self-esteem (Dalton & Ghosal, 2018) . It promotes assertiveness and strengthens leadership qualities, which can be particularly important in professional settings. Men with balanced testosterone levels tend to appear more self-assured and decisive in social situations (Jockenhövel et al., 2009) .
Debunking the myth: Testosterone leads to aggression
Research has shown that there is no direct link between high testosterone levels and increased aggression. According to a study by the University of Zurich and Royal Holloway London, testosterone can lead to fairer behavior in competitive situations and increase social sensitivity without promoting aggression (Eisenegger et al., 2009) . Rather, testosterone appears to influence social interaction in a way that fosters understanding and cooperation within a group.
Dominance behavior instead of aggression
In fact, the role of testosterone is more complex than often assumed and is associated more with dominance behavior than with aggression (Zitzmann, 2020) . Dominance, defined as the drive to achieve or maintain high social status, often manifests itself in non-aggressive ways, as can be observed in primates. For example, in rhesus monkeys, which have high testosterone levels, behaviors such as staring and threatening gestures, rather than direct aggression, are more likely to lead to high social status (Higley et al., 1996) .
It influences psychological and neurochemical processes that are important for maintaining high social status, thereby promoting high motivation, low fearfulness, and stress resilience. In animals, testosterone enhances reward-based behavior (Nyby, 2008) . Low testosterone levels lead to apathy in humans, while in healthy individuals, testosterone promotes motivation to act (Zitzmann, 2020) .
Practical implications for the potential effects of testosterone replacement therapy
Regulating testosterone levels is therefore essential for mental well-being and constructive social interaction. It plays a central role in supporting self-confidence and social adaptability. A sound understanding of its functions makes it possible to classify the multifaceted potential psychological effects of testosterone replacement therapy.
Detailed information on the psychological functions of testosterone can be found in our blog post “ Testosterone and Self-Confidence: How Hormones Influence Our Social Behavior ”.
Myth 3: “Testosterone causes prostate cancer”
The assumption that testosterone replacement therapy (TRT) could increase the risk of developing prostate cancer has long been a cause of concern among physicians and patients. An international study even identified this as the biggest concern physicians have regarding TRT (Gooren & Behre, 2012) .
The concerns regarding testosterone stem from its ability to stimulate the growth of prostate cells, including the proliferation of cancer cells. Therefore, in cases of existing prostate cancer, treatment is sometimes administered that withdraws the male sex hormone testosterone to inhibit tumor growth. This refers to hormone replacement therapy (HRT) for prostate cancer, in which androgens are reduced by inhibiting their production, release, or effects (Lehmann et al., 2021) . Since testosterone can indeed stimulate the growth of hormone-sensitive prostate cancer, HRT must not be performed in cases of existing prostate cancer; prostate cancer is thus an absolute contraindication. It is therefore essential that HRT be ruled out by a urologist before the start of therapy.
Fears have been disproven.
Current scientific studies and comprehensive meta-analyses have shown that there is no direct association between testosterone replacement therapy and an increased risk of developing prostate cancer (Zitzmann, 2020 ; Hormones, 2008) . A large-scale international study analyzing data from 3,886 men with prostate cancer and 6,438 age-matched controls showed no association between the risk of prostate cancer and serum concentrations of testosterone, calculated free testosterone, or dihydrotestosterone (Carpenter et al., 2008) .
A meta-analysis of 19 studies found that men with testosterone deficiency who received testosterone replacement therapy did not have a higher risk of prostate cancer than men who received a placebo (Calof et al., 2005) . The literature collected over the last 15 years strongly suggests that changes in serum testosterone levels have little or no effect on the incidence of prostate cancer (Bhasin et al., 2023 ; Lenfant et al., 2020 ; Morgentaler & Traish, 2009) .
Relevance for therapy
These findings enable men, together with their treating physicians, to make informed decisions about the use of testosterone replacement therapy without having to fear an increased risk of developing prostate cancer.
Myth 4: “Testosterone replacement therapy (TRT) increases cardiovascular risk”
A common misconception is that testosterone replacement therapy (TRT) significantly increases the risk of cardiovascular disease. This assumption has historically led many men, and even some doctors, to hesitate before considering TRT. However, current scientific research paints a more nuanced picture.
Debunking the myth: The latest findings
A comprehensive meta-analysis by Bu B. Yeap and colleagues, recently published in the Annals of Internal Medicine , investigated the associations of testosterone and related hormones with all-cause mortality, cardiovascular mortality, and the occurrence of cardiovascular disease in men. This study analyzed data from 24,109 men over a period of more than five years and found that men with low testosterone levels have a higher risk for all causes of death, and especially cardiovascular death (Yeap et al., 2024) .
What science says
The meta-analysis showed that men with testosterone concentrations below 7.4 nmol/L have increased all-cause mortality. Furthermore, low levels of sex hormone-binding globulin (SHBG) were positively associated with lower all-cause and cardiovascular mortality. SHBG binds testosterone in the blood, thereby reducing the proportion of free, biologically active testosterone. High SHBG levels therefore lead to lower concentrations of free testosterone, reducing the availability of this important hormone in the body.
Relevance for TRT
These findings suggest that well-monitored TRT does not increase cardiovascular risk, but may potentially help lower it by raising low testosterone levels to a healthy range. The myth that TRT increases cardiovascular risk is thus refuted by current scientific studies. It is important that each TRT regimen is individually tailored and monitored by a physician to achieve optimal health outcomes. This is another step towards correcting misconceptions and fostering an informed discussion about the role of testosterone in men's health.
Our conclusion, your knowledge
In conclusion, testosterone is far more than just a hormone; it plays a central role in physical, mental, and social health. This article has debunked the most common myths and shown that the actual effects of testosterone on the body are more nuanced than often assumed.
At the beginning of this article, we addressed the widespread myth that testosterone deficiency is a normal and inevitable development in old age. In fact, many factors can contribute to testosterone deficiency, and age is not the primary cause. We debunked the myth of induced aggression and highlighted the multifaceted importance of balanced testosterone levels for overall well-being and social interaction. We also refuted the misconception that testosterone replacement therapy increases the risk of developing prostate cancer. The myth that testosterone replacement therapy increases cardiovascular risk has also been refuted by recent scientific evidence.
It is essential that such information be made widely available, both to reduce existing stigmas and to promote public health through sound knowledge dissemination. By questioning myths and prioritizing scientific findings, we can foster a holistic and constructive discourse about the role of testosterone in modern medicine and society.
