The effect of testosterone on brain regions involved in emotion regulation changes over time, according to new research published in Developmental Science. Its role appears to shifts from facilitation during early adolescence to potentially impeding control in young adulthood. This highlights the complex and age-dependent influence of testosterone on the developing brain.
Testosterone is a sex hormone that plays several important roles in the body. It’s often thought of as a male hormone, because it’s produced in large amounts in men’s bodies, but it’s also present in smaller amounts in women. In women, testosterone is produced in the ovaries and adrenal glands.
In men, testosterone is mainly produced in the testes. It’s critical for male sexual development and function. During puberty, testosterone helps in developing secondary sexual characteristics such as facial hair, deeper voice, and muscle growth. It also maintains the health of the reproductive tissues, such as the testes and prostate, in adult men.
In addition to these sexual functions, testosterone also has several other important roles in the body. It helps to maintain bone density, fat distribution, muscle strength and mass, red blood cell production, and mood.
But testosterone seems to function differently at different stages of life. For instance, during puberty, higher levels of testosterone seem to improve emotional control, a skill that is important for handling social situations. However, in adults, higher levels of testosterone seem to decrease this type of emotional control.
This seems like a contradiction: why would the same hormone have opposite effects depending on age? The study aims to solve this puzzle by following the same individuals over time (a longitudinal study) to see how the role of testosterone changes as they mature.
“Adolescence is a critical period characterized by dynamic changes, particularly in social emotional development and neural maturation,” explained study author Anna Tyborowska, an assistant professor of clinical psychology at Radboud University.
“During this time, there is also an increase in pubertal hormones, such as testosterone. I was interested in this interaction between testosterone and the brain – especially with respect to social emotional control, during such an important developmental period.”
“And, even more so, I was intrigued by seemly opposing previous findings in adolescents vs. adults with respect to the association between testosterone and neural emotion control. So, I was interested in how the relationship between testosterone and neural emotion control changes across development within individuals.”
“Understanding these changes in typically developing individuals is the first step in investigating what may be different in cases of atypical development,” Tyborowska said. “This is particularly relevant given the peak in the onset of affective disorders (such as depression, anxiety, aggression-related disorders) during adolescence.”
The researchers analyzed data from a group of children who were part of a longitudinal study. The participants were from various socioeconomic backgrounds, which were representative of families with children in the Netherlands. These children were followed up at ages 14, 17, and 20 years. “The study was part of the Nijmegen Longitudinal Study at the Behavioural Science Institute (Radboud University), a unique study which has followed individuals for the past 25 years, since they were 1 year old,”
The researchers used functional magnetic resonance imaging (fMRI) to observe brain activity while the participants completed an approach-avoidance task. During the task, the participants responded to emotional faces (happy and angry) presented on a screen. The participants had to push or pull away from the faces using a joystick, depending on the emotion shown.
To ensure the quality of data, they excluded a few participants who had poor fMRI data quality or could not undergo MRI due to specific conditions. In the end, they had a total of 47 participants at age 14, 71 participants at age 17, and 68 participants at age 20.
The researchers also collected saliva samples to measure hormone levels (testosterone and cortisol) related to pubertal development. They used this information to study any potential associations between pubertal development and brain activity.
Tyborowska and her colleagues found that the effect of testosterone on the anterior prefrontal cortex (aPFC) changed as individuals transitioned from middle adolescence to young adulthood. At age 14, higher testosterone levels were associated with increased activity in the left aPFC during emotional action control, indicating that testosterone facilitated the neural control of emotions during early adolescence.
However, as participants reached age 17, the influence of testosterone on aPFC engagement decreased, suggesting that testosterone’s impact on emotional regulation diminished during late adolescence.
By the time participants reached young adulthood (age 20), the effect of testosterone on the aPFC shifted into an activational role, meaning that higher testosterone levels were now associated with reduced aPFC activity during emotional action control. This implies that testosterone was impeding the neural control of emotions in young adults.
Additionally, the study found that the changes in testosterone function were accompanied by increased testosterone-modulated amygdala reactivity. The amygdala is a brain region associated with processing emotions, and higher testosterone levels were related to greater amygdala responsiveness during emotional action control in young adulthood.
“Testosterone is often associated with aggression or dominant behavior,” Tyborowska told PsyPost. “However, this is a limited view on this complex hormone. In fact, it has a number of different roles across different developmental periods. During puberty, testosterone is actually beneficial for neural emotion control. Only later, during adulthood, a switch occurs – when higher levels of testosterone are no longer beneficial. The findings of the current study are important for understanding brain – hormone functioning in both adolescents and young adults.”
Regarding the next steps, Tyborowska said that “as with any first study, it’s important to replicate these results in other populations. Given the peak of onset of many affective disorders during adolescence, one of the next steps is to see whether alterations in the relationship between testosterone and the brain may be related to this.”
The study, “Developmental shift in testosterone influence on prefrontal emotion control“, was authored by Anna Tyborowska, Inge Volman, Hannah C. M. Niermann, Anna L. Dapprich, Sanny Smeekens, Antonius H. N. Cillessen, Ivan Toni, and Karin Roelofs.
