Changes in affect variability after starting gender-affirming hormone therapy

Negative affect variability is determined by how often and how strongly negative affect changes over time. Cisgender women report greater variability in affect than cisgender men. It has been suggested that sex hormone changes may influence affect variability. Transgender people frequently opt to use sex hormones in the form of gender-affirming hormone therapy (GAHT), but the extent to which GAHT can change negative affect variability is not yet clear. Therefore, this study aims to study changes in negative affect variability after starting GAHT. We have included data from 92 participants from the RESTED study: 47 persons starting masculinizing hormones (MH), i.e. testosterone, and 45 persons starting feminizing hormones (FH), i.e., estrogens and antiandrogens. Participants completed up to 7 consecutive daily diaries at each of three time points: before starting GAHT, and after 3 and 12 months of GAHT. The daily diaries collected participants' reports on symptoms related to negative affect: experienced low mood, less interest, tense feelings and restless feelings. We have used linear mixed models to compare negative affect variability during one week, corrected for mean negative affect, between groups (MH versus FH) and measurement time points. Results show that in the MH group, variability in tense feelings and restless feelings decreased after 3 and 12 months of GAHT, respectively. In the FH group, variability in low mood increased after 3 months and 12 months of GAHT, as did variability in restless feelings after 12 months of GAHT. Group comparisons indicate significant group differences in changes in variability in low mood and restless feelings, with stronger increases in variability of negative affect in the FH group compared to MH group after 3 and 12 months of GAHT. Our findings indicate that variability patterns in negative affect in transgender persons change after starting GAHT, with participants who start masculinizing hormones moving to a profile which more closely resembles that of cisgender men and participants who start feminizing hormones moving to a profile which more closely resembles that of cisgender women. Future studies should focus on measuring both negative and positive affect variability during GAHT, preferably through multiple measurements per day, taking into account diverse social and daily contextual factors during GAHT.