More evidence accruing on the value of gender affirming hormones for transgender youth.
315 transgender teens were followed for two years after initiating gender affirming hormones.
The teens saw improved appearance congruence (alignment between one's perceived gender and physical appearance). In some transgender individuals appearance incongruence can cause or worsen gender dysphoria. They also saw lower depression and anxiety, and improved positive affect (more positive emotions) and improved life satisfaction.
315 is incredibly large for trans gender studies. Much of the prior research is working on samples of fewer than 100 in a lot of cases. And often for short periods of monitoring, much less among all these dimensions of wellbeing.
There wasn't any randomization. It was just following the treatment group. There wasn't a comparator group. But they analyzed how the psychosocial factors changed with the appearance congruence under the hypothesis that appearance incongruence was what was causing the distress and what the hormones would ameliorate.
That's been a significant barrier to better research. And there aren't many clinics or patients, especially for this age group. Ethically too IRBs are probably cautious on this research.
In any case read more of this study. It is more robust than you are giving it credit. They used latent growth curve modeling to examine the changes over time and compare the well-being baselines and rates of change to the appearance change between the individuals. It wasn't just plotting the average change over time.
Hence the bottom 3/4s of this table in the OP.