In the journey from childhood to adulthood, teenagers undergo significant social shifts, gravitating away from family towards peer groups. A recent study published in Developmental Cognitive Neuroscience provides fascinating insights into how testosterone may influence this shift, particularly in transgender boys, some of whom are undergoing hormone therapy as part of their gender-affirming care.
Testosterone plays a vital role in the development of secondary sexual characteristics and has profound effects beyond physical changes, including influencing social behavior and emotional processing. The new study was motivated by an observed shift during adolescence, where teenagers gradually spend less time with their caregivers and increasingly seek the company and approval of their peers. This transition is essential for forming stable social networks outside the family unit.
By focusing on transgender boys undergoing gender-affirming hormone treatment, the study aimed to provide a unique lens through which to understand how testosterone specifically affects neural responses to socio-affective stimuli from peers and caregivers.
“Understanding how testosterone affects the processing of emotional cues from caregivers vs. peers will help specify the mechanisms underlying social re-orientation in adolescence—and thus refine related theories of adolescent neurodevelopment for both cis- and transgender youth,” the researchers wrote.
For their study, the researchers recruited a sample of 44 transgender boys from a multidisciplinary gender development clinic located in the Midwest of the United States. The participants were divided into two groups based on their treatment status: 19 boys were receiving gender-affirming hormones (GAH+), specifically exogenous testosterone, while the remaining 25 were not receiving any exogenous hormones (GAH-). The inclusion criteria ensured that none of the participants had a history of puberty-blocking medication, which could influence the study’s outcomes.
To assess how testosterone impacts the processing of emotional cues, the study utilized functional magnetic resonance imaging (fMRI). During the fMRI sessions, participants were exposed to auditory stimuli consisting of recordings of emotional (happy and angry) voices from both their own caregiver and an unknown teenager.
The stimuli were designed to elicit neural responses in regions associated with emotional processing. Attention during this passive listening task was maintained by asking participants to press a button whenever they heard a specific non-emotional sound (a bicycle bell), ensuring engagement without significantly affecting their emotional processing.
The study found no overall effect of gender-affirming hormone (GAH) therapy on neural activation patterns across the board, suggesting that the presence of exogenous testosterone alone does not universally alter brain responses to social stimuli. However, the nuanced analysis revealed a significant three-way interaction involving GAH group, emotion type, and speaker type in the rostral anterior cingulate cortex (ACC), a brain region implicated in emotional processing and decision-making.
For the GAH+ group (transgender boys receiving testosterone therapy), there was a diminished response in the ACC to angry voices from their caregivers compared to angry voices from an unfamiliar teenager. This pattern suggests that testosterone may attenuate the emotional salience of negative cues from close familial figures while amplifying the response to similar cues from peers.
Conversely, the GAH- group (those not receiving testosterone) displayed an opposite pattern, with a greater neural response to the teenager’s happy voice over their caregiver’s happy voice, indicating a heightened sensitivity to positive social signals from peers in the absence of testosterone therapy.
These findings highlight the differential impact of testosterone on the brain’s processing of emotional cues, dependent on the source of these cues. For transgender boys receiving testosterone, the hormone appears to recalibrate the neural valuation of emotional signals, reducing the impact of negative familial cues while heightening sensitivity to peer emotions. This shift could be reflective of the broader social reorientation process occurring during adolescence, where peer relationships gain increasing importance over familial bonds.
Moreover, the study explored the association between neural response patterns and social behavior, as indexed by self-reported closeness with peers over caregivers. Across both groups, patterns of neural response correlated with participants’ social orientations; specifically, a reduced ACC response to caregivers’ angry voices was associated with greater closeness to peers relative to parents.
This finding suggests that the neural processing of emotional cues from different sources may be linked to the adolescent’s social network and emotional priorities, with testosterone playing a role in this reorientation process.
“Although preliminary, our results point to the possibility that changes in testosterone levels in adolescence result in modified processing of social cues in the ACC, a brain region associated with the evaluation of socio-affective information. Longitudinal work with larger samples will be necessary to elucidate how changes in testosterone contribute to youth’s social re-orientation towards peers and increasing independence from the family environment.”
The study, “Exogenous testosterone administration is associated with differential neural response to unfamiliar peer’s and own caregiver’s voice in transgender adolescents,” was authored by Michele Morningstar, Peyton Thomas, Avery M. Anderson, Whitney I. Mattson, Leena Nahata, Scott F. Leibowitz, Diane Chen, John F. Strang, and Eric E. Nelson.
