4.1. Population-Based Comparisons
Using data from the Counting Ourselves survey, this study explored the extent of mental health inequities that transgender people in Aotearoa/New Zealand face. There was a ninefold increase in the manifestation of high or very high psychological distress symptoms when comparing transgender participants (72%) to the general population (8%). While some studies have found high levels of psychological distress among transgender participants [19
], the other studies we could find using the Kessler Psychological Distress Scale were the United States Trans Survey 2015 using the shortened version—K6 [7
], and an Australian study [29
]. Comparatively, our sample had a higher prevalence of serious psychological distress than that reported in the United States study (44% vs. 39%; measured with K6) (We used same items that are in the K6 scale to compare with the findings of the 2015 U.S. Trans Survey. A serious psychological distress level was identified by a total score of 13 or more on the K6), and high or very high levels of psychological distress compared to the Australian study (72% vs. 46%; measured with K10) community-based studies.
Our transgender participants were also more likely to report having received a mental health diagnosis by a health professional than the general population, with approximately fourfold differences for depression and more than fivefold differences for anxiety disorders. The prevalence of depression (66%) and anxiety disorders (55%) among our Aotearoa/New Zealand transgender participants were also higher than those reported in the United States (47% for depression and 42% for anxiety disorders) [22
] and Australian studies (57% for depression and 40% for anxiety disorders) [11
]. The discrepancy in prevalence could be due to the older average age of transgender participants in the other studies; these warrant further investigation. The mental health inequities between transgender and cisgender participants found in this study are consistent with and add to the body of evidence confirming the deleterious impacts of gender minority stress [16
]. Our questions on depression and anxiety asked about the lifetime prevalences of these diagnoses; we are aware that these might be prone to recall bias, and that we cannot necessarily infer one’s current mental health status from these particular questions in the way that we can from our psychological distress questions. Nevertheless, a strength of our study is that it highlights inequities with the general population for both current mental health status (psychological distress in the past 4 weeks) and lifetime meantal health status (depression and anxiety diagnoses).
4.2. Age Comparisons
Our study also looked at inequities (i.e., comparisons with the general population) for transgender people across different age groups from youth to older adults. Other studies have found that younger transgender participants reported a higher prevalence of mental health diagnoses [11
] and psychological distress symptoms [28
], but we also know that in the general population, youth were at higher risk of mental health difficulties than adults and older adults ([30
]; see also Figure 2
). The 2015 United States Transgender Survey also compared the prevalence of serious psychological distress across age groups relative to the general population [7
]. Similar to our findings, James et al. reported higher inequities for transgender participants aged 18 to 25 (53% vs 10%, RR = 5.3) than those aged 65 and older (8% vs 2%, RR = 4.0) [7
]. We are not aware of any studies that have examined inequities between transgender people and the general population in the prevalence of depression and anxiety diagnoses for younger transgender youth; other studies on this topic only recruited participants of 18 years or older [4
], although other studies have found that adolescent trans youth were more likely to report self-depression and anxiety symptoms than older transgender youth (e.g., [31
]). It is important to note, however, that while mental health inequities faced by older transgender people were less, they still faced substantial mental health inequities compared to the older aged general population.
Examining research on gender minority stressors may help to explain these mental health inequities across different age groups. A United States online survey revealed younger transgender people were more vulnerable to the negative mental health effects of gender minority stressors than their older counterparts [28
]. Jackman et al. in the United States found lower levels of internalised stigma among older transgender people, and suggested that this may be due to them having developed better coping skills and social support systems (maturation effect) in counteracting the effects of gender minority stressors [19
]. Longitudinal research is needed to uncover the ways that transgender people build resilience and support over time that may provide mental health benefits.
While our study has identified age as an important demographic factor in predicting transgender people’s mental health, we could not be certain whether the mental health differences across age groups represented changes as this population grew older (aging effect), their development of the ability to cope with gender minority stressors later in life (maturation effect), or whether they were the result of historical and social contexts that occurred for specific age groups (cohort effects). A comprehensive understanding of the mental health status of transgender people of different age groups would require an examination on how minority stress and resilience for transgender people changes over the life span [14
4.3. Gender Group Comparisons
In our sample, trans women were over-represented in older age groups (aged 55 and above), while the younger participants were more likely to be trans men or non-binary. A population-based study in United States [4
] and community-based studies in United Kingdom [1
], United States [22
], and Canada [6
] demonstrated similar findings, with trans men and non-binary individuals being more common in the trans youth samples of these studies. Because of these differences, we included age as a variable in the regression models that examined gender group differences.
After controlling for the age effect, we found that trans men reported higher prevalences of depression and anxiety diagnoses. This aligns with the findings of other population-based studies [4
] and community-based studies that employed convenience sampling [1
]. Such findings might be explained partly by research on differential experiences of gender minority stressors among gender groups within the transgender population which have found trans men to be more likely to report sexual abuse and domestic violence [1
], and discrimination when accessing employment and healthcare services [28
]. One study in the United Kingdom noted trans men and women were no more or less likely to seek professional help for mental health problems [1
In our sample, non-binary participants were more likely than trans women to have been diagnosed with depression and anxiety disorders. Findings from previous studies of non-binary people’s mental health compared to the other two gender groups have been mixed. Studies of transgender youth [6
] and a population-based study of adults in the United States [4
] found that non-binary participants reported higher levels of mental health concerns. Crissman et al. also found that this difference held after accounting for age differences among the gender groups. This finding, however, was not replicated in a recent United States community-based study which found that non-binary participants had lower odds of reporting depression and anxiety diagnoses by health professionals compared to trans men and trans women, even after adjusting for the effects of demographic variables, such as age [22
]. This discrepancy could be due to Reisner and Hughto’s study having an equal proportion of non-binary participants who were assigned male and female at birth, respectively [22
], whereas our study and the other studies had a higher proportion of non-binary people assigned female at birth.
To extend our knowledge about this topic, we were the first study to also examine the interaction effect between age and gender on transgender people’s mental health outcomes. It is important to examine the interaction of independent variables in regression analyses, because omitting the interaction effect can lead to a biased estimation of model parameters when an interaction effect is present [33
]. Notably, gender differences in mental health diagnoses were no longer statistically significant when we included the age and gender interaction term in the models. This finding suggests that when the interaction effect of age and gender is estimated, trans men and non-binary participants no longer had significantly higher rates of having been diagnosed with depression and anxiety disorders relative to trans women.
Our exploratory finding of an interaction effect on the K10 scale, however, suggested that the relationship between age and psychological distress scores varied across different gender groups. For instance, we found that younger trans women reported less psychological distress compared to trans men and non-binary people of the same age groups. This trend changed for older age groups, where trans women reported more symptoms of psychological distress than other gender groups. This interaction effect remained statistically significant after adjusting for the number of years lived in the affirmed gender (see Table S2
), suggesting that the length of time living in the affirmed gender is not the reason for this difference. Increased rejection and less social support for older trans women may explain this finding. A United States study that examined mental health of trans women across the life span found older trans women were less likely to have stable relationships with family members and friends [32
]. More research is needed to replicate this interaction finding and further explore the reasons for it, but this research suggests a clear need to consider interaction effects when exploring how age and gender are related to mental health for transgender people.
There are other within-group differences that can be assessed of our data that is beyond the scope of this paper, including race/ethnicity, disability status, and cultural connectedness, and future research should consider the variations of mental health outcomes for these different subgroups of transgender people.