**4. Mental health comorbidities**

Review of the recent literature suggests that 0.17% to 1.3% of adolescents and young adults identify as transgender [26]. Transgender individuals experience disproportionately high rates of negative mental health outcomes, as compared with their cisgender heterosexual peers, as well as their gender-normative lesbian, gay and bisexual peers [27]. Recent studies have offered a deeper understanding of the prevalence of depression among trans- and gender-variant youth, providing evidence that rates of depression are 2.4 to 3.5 times higher than in their cisgender peers, 50.6% vs. 20.6% in a retrospective matched cohort (n = 360) of 12–29 years old patients at community health centre in Boston [28] and 41.3% vs. 11.8% in a high school-based sample (n = 8,166) from New Zealand [29]. A study by Veale et al. measured stigma-related experiences, social supports, and mental health (self-injury, suicide, depression, and anxiety) among a sample of 923 Canadian transgender adolescents and young adults aged 14 to 25; they reported that over two-thirds (68.3%) of the sample experienced a major depressive episode in the past year [30].

The large scale 2015 U.S. Transgender Survey (USTS) with 27,715 respondents with a median age of 26 years, found that 40.4% of respondents reported attempted suicide in their lifetime, 81.7% of respondents had seriously thought about killing themselves in their lifetimes, and 48.3% had done so in the past year while 7.3% had attempted suicide in the past year; respondents who reported having a disability had higher prevalence on all suicide-related measures than those without disabilities [31].

Another large survey that was primarily capturing an eating-related pathology revealed that transgender students had increased rates of eating disorder diagnosis compared to cisgender heterosexual women (15.8% vs. 1.85%), this set of data was collected from 289,024 students via the American College Surveys from 233 U.S. universities [32].
