Gender identity and mental health inequalities 2001-2022: population-level evidence from an Australian cohort study

Trans, non-binary and gender-diverse (TGD) people experience poorer mental health relative to cisgender populations. However, we know little on how TGD mental health inequalities are changing over time. With newly available information on gender identity within Australia's largest longitudinal household survey, we aimed to provide the first nationally representative estimates of temporal trends in TGD mental health inequalities.

We used the 2001-2022 Household, Income and Labour Dynamics in Australia Survey, a national probability sample of Australian adults. Using questions about sex at birth and gender identity, asked in the 2022 wave, we compared temporal trends in mental health among TGD and cisgender respondents. Mental health was measured using the five-item Mental Health Inventory (MHI). Adjusting for age, income and other observable characteristics, we calculated annual population-weighted estimates of mean MHI Scores for TGD and cisgender respondents and corresponding TGD mental health inequalities.

Across the 22-year period, TGD respondents consistently reported poorer mental health than cisgender respondents. Prior to 2010, differences in MHI Scores were more variable, but TGD MHI Scores were generally lower than cisgender respondents. From 2010 onwards, there was a trend of widening inequalities, with TGD-cisgender MHI inequalities ranging from -5.1 (95% CI -10.6, 0.3) in 2010 to -7.6 (95% CI -10.8, -4.4) in 2022, indicating clinically relevant differences in mental health. Effects were driven by younger populations.

TGD-cisgender mental health inequalities are increasing in Australia, with inequalities more apparent between 2010 and 2022. Policy action and greater protections for gender-diverse Australians are urgently needed.