Aggression and Testosterone
Aggression is the intent to harm oneself or another individual who would rather avoid such treatment. These acts may be impulsive (in the moment reactions of physical or verbal abuse) or instrumental (including passive aggression, with a longer-term goal in mind) and are generally linked with negative consequences. Unsurprisingly, then, although aggression is an evolutionary trait and perhaps one that we all experience on occasion, it is not a pattern of behaviour that most people want to be defined by!
And where there are conversations of aggression, there tend to be mentions of testosterone. Over the decades, testosterone has become a synonym for aggression: whether it is to explain why men are more aggressive than women, or why some men are more aggressive than others, ‘higher testosterone’ is probably the most common answer that people will throw your way. To help matters along, frequent reports of “roid rage” among body building and steroid-using communities has engrained the general idea that anything raising testosterone levels will make you more aggressive.
When people hear about testosterone replacement therapy (TRT) being used to overcome a testosterone deficiency, increased aggression could be a concern. In this article, however, we will clarify why this is not necessarily the case.
The Evidence on TRT and Aggression
Thanks to modern science, many studies have examined whether testosterone administration changes markers of aggression. These studies take a group of participants, typically with low testosterone levels at baseline (the beginning of the study), then measure and track changes in their aggression (via self-report or behavioural indices) in response to TRT.
The strongest study to date is a recent meta-analysis of 14 experimental trials, finding that TRT did not significantly change aggression overall.1 Because the included studies reported similar effect sizes (or lack of effect) despite using vastly different methodologies, it is also unlikely that a ‘true effect’ under a specific set of conditions was missed (such as when using a certain dose, frequency, and route of administration). In fact, the studies which prescribed supraphysiological doses of testosterone (200 mg - 600 mg weekly)—that is, above what the vast majority of people will ever be advised to take—still did not report significant changes to aggression or anger.2,3 In men with low testosterone at baseline, one of these studies even reported lower aggression from testosterone therapy.2
To support this position from a slightly different angle, recent brain imaging studies have found that testosterone therapy does not alter functional parts of the brain that control empathy (defined as the ability to understand and share the feelings of others).4 Not aggression, to be clear, but empathy is undoubtedly a social emotion that strongly influences a person’s risk of acting aggressively. So, with scarce evidence that testosterone therapy impacts a primary risk factor for aggression (empathy), and aggression itself, the bulk of research does not indicate much cause for concern in this regard.
That being said, as with many therapies, it is worth being mindful of individual response differences, even if there are no average changes among a group. For example, though one study found no average change in aggression among 121 healthy male adults, testosterone therapy did cause a minority of participants with traits of high dominance and low self-control to be more aggressive.5 Some research is currently trying to elucidate the potential personality profiles that could be susceptible to certain treatment responses such as raised aggression; still, even in this potential reality, TRT would be modulating existing high levels of aggressive behaviour among certain individuals, not causing aggression per se. 6
What about Steroids and “Roid Rage”?
It is true: there is good evidence that anabolic steroids increase self-reported aggression. Compared to TRT, “roid rage” is not so much of a fantasy.7 However, the effect size is small and dependent largely on dose. Only when anabolic steroids are taken in high amounts do some individuals, albeit a minority, put themselves at risk of substantial personality and mood changes. You may have heard a handful of shocking stories about anabolic steroid users acting outside of themselves to engage in violent and criminal behaviour, but these cases are extremely rare and should not be communicated as a general truth.
What often goes amiss among such conversations is that anabolic steroid use (or abuse) is not interchangeable with TRT under the supervision of a healthcare professional. Not only are many anabolic steroids very potent and sourced from ‘underground laboratories’ with questionable safety protocols (if any at all), but they are also typically taken in doses that are 10—100 times the natural production or conventional doses used in testosterone therapy.
Other considerations for “roid rage” are that 1) anabolic steroids may appeal to a male population with more aggressive personalities, and 2) most non-experimental studies on steroid use and aggression use participants who are more likely to engage in aggressive behaviour, such as drug users, offenders, prisoners, policemen, doormen, and nightclub bouncers. The steroid research to date is not too interested in whether the calm and collected folk will start a brawl at the local pub; more so, whether individuals with personality traits or jobs centred around aggression will start to act more aggressive. Therefore, it is hard to know how much of “roid rage” is from the anabolic steroids themselves, and how much is a by-product of the type of people that happen to take (or are studied taking) steroids.
Missing the Bigger Picture?
One of the more frustrating parts of the narrative that TRT increases aggression is that it distracts from its generally positive effects on mental health. In patients with low testosterone levels, a large pool of evidence has consistently indicated that testosterone therapy improves depressive symptoms, fatigue, and quality of life.8–10These are the types of messages that people should be hearing as much, if not more, than the fear of aggression that is not scientifically sound anyway. For many, the choice to start taking TRT is a positive and potentially life-changing one. If there remain concerns about aggressive behaviour from testosterone therapy, we recommend discussing them with your healthcare professional.
Take Home Points
- Evidence suggests that TRT does not increase aggression.
- Even in potentially susceptible individuals, TRT probably modulates existing high levels of aggressive behaviour rather than causes it per se.
- TRT is generally associated with positive mental health outcomes, particularly in men with low testosterone levels.
- Systematic anabolic steroid abuse (including that leading to "roid rage") is completely distinct from TRT which is supported by a healthcare professional
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1. Geniole SN, et al. Epub 2019;123:104644.
2. O’Connor DB, et al. Physiol Behav 2002;75(4):557–66.
3. Tricker R, et al. J Clin Endocrinol Metab 1996;81(10):3574–8.
4. Andrei AP, et al. Compr Psychoneuroendocrinol 2022;10:100134.
5. Carre JM, et at. Biol Psychiatry 2017;82(4):249–256.
6. Geniole SN, et al. Psychol Sci 30(4):481–494.
7. Chegeni R, et al. Psychopharmacology 2021;238(7):1911–1922.
8. Walther A, et al. JAMA 2019;76(1):31–40.
9. Ferreira MDA, Mendonca JA. Drugs Context 2022;11:8–12.
10. Rosen RC, et al. J Sex Med 14(9);1104–1115.