by Cy Willson
The Latest Studies Simplified
How transdermal T can affect your woman, your willingness to fight, and more. Here’s the latest testosterone science.
1. Transdermal T and Your Lady’s Lady Parts
Transdermal testosterone replacement therapy (TRT) uses gels, patches, or creams applied to the skin. Many guys who go the transdermal route apply it to areas of their bodies with thin skin instead of doing what the instructions say: apply it to areas covered by a T-shirt. This seems to elevate blood levels more quickly and lead to better results.
Do I have to say it? Okay. They’re rubbing it into their scrotums and perhaps a certain related area.
The drawback? Well, according to a recent case report, this method might cause your romantic partner to experience problems if you’re not washing well after applications. The female in this case went to her doctor after experiencing facial hair growth, a deepening voice, and no menstruation over two years.
Her bloodwork revealed a total testosterone level of 1,776 ng/dl, a level beyond the physiological range even for men, along with a free testosterone level you’d expect to see in a man, not a woman.
While her male partner reported cleaning up before intimacy, he apparently didn’t do all that great of a job “down there” because this poor woman experienced substantial intravaginal absorption of the testosterone formulation. Wash up, guys!
2. Testosterone and Threat Perception
A group of researchers published an interesting study evaluating the ability of a group of young men to detect various emotional expressions after exogenous testosterone administration.
In this case, they gave the men either a placebo gel or 150 mg of transdermal testosterone gel and performed their evaluations at the 3-hour mark. That’s the time previous data showed peak plasma testosterone concentrations from this dose, which is right around the high-normal to slightly supraphysiological range.
There was no change in perception of fear or neutral facial expressions, but those receiving testosterone showed a lower sensitivity to angry facial expressions.
So when we see an angry face, we might think, “Hey, that dude is a threat, and maybe I should walk the other way.” According to the authors, the dosed-up guys were more likely to resist avoiding conflict and underestimating another male’s dominance and aggressiveness while increasing their aggression.
The authors use these data to further support the “Challenge Hypothesis,” which argues that when men are challenged – through competition or physical confrontation – testosterone rises to elicit behavioral changes that contribute to fitness (from an evolutionary standpoint).
In other words, your ancestor may have faced competition from other males for food or other resources, and these behavioral changes in response to these challenges allowed him to secure resources rather than cede them to others, allowing him to ultimately pass on his genes. The Challenge Hypothesis is an interesting one and likely has some merit. However, several other factors contribute to behavioral responses in those circumstances.
These data seemingly fit with previous studies showing that even large doses of exogenous testosterone alone don’t cause aggressive behavior. And baseline testosterone and changes in testosterone are only weakly associated with aggression. It may simply be that it only does so depending on certain genetic factors, social context, and personality traits.
3. Do Men’s Testosterone Levels Fluctuate by the Season?
It seems reasonable that men’s testosterone levels may increase in the spring or summer when they’re more likely to be outside and exploring the world as opposed to the fall and winter when they’re more likely to be hunkered down and keeping warm.
From an evolutionary standpoint, this makes sense. A previous study provides support for this notion. However, that study didn’t look to see if testosterone levels changed depending on the time of year in the same individual.
In a new study, researchers evaluated testosterone levels in a large group of men living in a location that has seasons (Pittsburgh, Pennsylvania) and one without (Miami, Florida). They also obtained at least two testosterone measurements for these individuals. The result? A statistical analysis revealed no significant difference between testosterone levels measured in the fall, spring, or summer.
While this doesn’t necessarily mean the matter is completely settled, it does provide some evidence that seasonal variations in testosterone, at least in male humans, are probably small at the population level.
References
References
- Juan Gabriel Melendez-Rivera, Scott James Steven, FRI403 The Unintended Consequences Of Applying Topical Testosterone Directly To The Scrotum, Journal of the Endocrine Society, Volume 7, Issue Supplement_1, October-November 2023, bvad114.1596,
- Miller D, Gurayah A, Weber A, Schuppe K, Zarli M, Dullea A, Hwang K, Ramasamy R. Seasonal Variation in Serum Testosterone Levels: Evidence from 2 Large Institutional Databases. Urol Res Pract. 2023 Sep;49(5):307-311. doi: 10.5152/tud.2023.23077. PMID: 37877878.
- Nan Y, Mehta P, Liao J, Zheng Y, Han C, Wu Y. Testosterone administration decreases sensitivity to angry facial expressions in healthy males: A computational modeling approach. Psychoneuroendocrinology. 2023 Dec 28;161:106948. doi: 10.1016/j.psyneuen.2023.106948. Epub ahead of print. PMID: 38211451.
- Geniole SN, Bird BM, McVittie JS, Purcell RB, Archer J, Carré JM. Is testosterone linked to human aggression? A meta-analytic examination of the relationship between baseline, dynamic, and manipulated testosterone on human aggression. Horm Behav. 2020 Jul;123:104644. doi: 10.1016/j.yhbeh.2019.104644. Epub 2019 Dec 28. PMID: 31785281.