FWIW I could find this recent article using an Australian population that attempts to start to unpack it. It is of note that they had a greater number of their transgender teen population with ASD as well than most other studies. Not sure what to make of that in interpretation.
https://www.thelancet.com/journals/lanwpc/article/PIIS2666-6065(24)00078-6/fulltext
A few highlights:
First confirming the predominance of AFAB among transgender teens. 75% of those with ASD and 64% of those without. Those are very similar rates so my wondering if the increase was driven by AFAB autistic spectrum individuals glomming onto the identity does NOT get support.
Also “Overall, the autistic trait group displayed poorer mental health than the non-autistic trait group” which is “in keeping with the high rates of mental health difficulties commonly reported by those with ASD in non-trans specific populations in other clinical and community settings.15 However, in our study, rates of depressive and anxiety problems (in the clinical range) in the autistic trait group were as high as 73% and 65% respectively, which is even higher than the prevalence rates of depressive disorders (2.5%–47.1%) and anxiety disorders (1.5%–54%) reported in other studies involving non-trans autistic populations.”
Overall the autistic trait and not autistic trait groups of transgender teens were very similar: “Few differences in gender identity, gender expression and gender dysphoria were found in those with and without autistic traits; we also found that both groups experienced high levels of gender dysphoria. Taken together, these findings suggest that gender diversity appears similar in trans young people with and without autistic traits, but some subtle differences were observed including higher rates of social transition and body dissatisfaction in those with autistic traits.”
The implication as stated by the authors is that this study “reinforces the importance of trans young people with and without autistic traits being availed the same opportunities to access gender-affirming care”
I think follow up into adulthood for satisfaction with outcomes is a necessary next step.
Of course no support for large numbers becoming transgender to gain attention or enable bad behaviors.