Main

Conversion therapy is based on the unscientific assumption that being from sexual and gender minorities (LGBTQ+) is pathological and should be suppressed or treated. It attempts to change sexual orientation to ‘heterosexual’ or gender identity to ‘cisgender’1,2. Although sexual orientation and gender identity and expression should be viewed as a variation rather than a pathology, conversion therapy has been reported in at least 60 countries worldwide and is closely linked to homophobia and transphobia3. Increasing evidence shows the association between mental health concerns and conversion therapy4,5, and the mental health aftermath is often associated with an elevated rate of self-harm, suicidality, depression and anxiety6,7. However, most studies in the literature have focused on the relationship between sexual minority groups and sexual orientation change efforts8,9,10,11, and insufficient studies have focused on the influence of gender identity conversion efforts (GICE) on TNG individuals7. TNG is an umbrella term used to describe an individual’s gender not aligned with normatively expected assigned sex or within the binary conception of gender12. GICE has been discouraged and labelled as an ineffective and unethical practice by professional organizations, including but not limited to the American Psychiatric Association, the American Academy of Child and Adolescent Psychiatry, the American Medical Association and the American Academy of Paediatrics, and it has been legally banned in several states in the United States of America (USA)7,13. GICE refers to professionals, including psychologists, religious advisors or counsellors, making efforts to alter individuals’ gender identities to their sex assigned at birth7. However, TNG people often also face non-professional efforts to change their gender identity. Specifically in Chinese culture, parents tend to have low tolerance for their children to identify as TNG14. Research in the USA has also showed that family unsupportive of one’s gender identity is associated with a history of ‘detransition’, which discontinues gender affirmation or returns an individual to their birth-assigned sex15.

Researchers have emphasized that the most important thing to support TNG people is to “let them express themselves freely”16. Additionally, affirmation of TNG people’s gender identity has been shown to be related to favourable mental health outcomes17. Nevertheless, GICP continues despite the urge from prominent associations to terminate the practice. Notably, GICP is prevalent among TNG populations, with a lifetime prevalence of 14% in the USA7, 17% in New Zealand18, 19% in Canada1 and 11.5% in South Korea19. Considering approximately 1–2% of the global population identify as TNG12, many individuals may have suffered and will suffer from GICP in the near future.

A recent large-scale cross-sectional survey in the USA covering 27,715 TNG individuals showed that TNG individuals who underwent GICP experienced severe psychological distress, manifested in higher odds of lifetime suicide attempts compared with individuals not exposed to GICP7. This is consistent with general conversion therapy results found in New Zealand and Canada: that the effort to change one’s gender identity is associated with poor mental health outcomes1,18. A landmark study provided evidence on the association between childhood exposure to professional GICP and adverse mental health outcomes in adulthood, with outcome measurements including suicidality, severe psychological distress, binge drinking, cigarette use and illicit drug use7. However, as the study acknowledges, exposure to GICE from other people, such as family members, was not captured. Despite the existing influential research, there is still insufficient information regarding the Asian population, among which family members harbour a crucial negative attitude towards TNG gender identity14. Specifically, under the influence of traditional Chinese culture and a lack of appropriate healthcare services14,20,21,22, it is likely that TNG people in China could face more severe GICP exposure and more devasting consequences compared with those in other developed countries. Mental healthcare for TNG individuals should go beyond practitioners’ clinical competency (for example, clinical knowledge) by also considering practitioners’ cultural competency, such as practitioners’ ability to focus on the TNG-specific social contexts while remaining inclusive regarding gender diversity23. Thus, it is urgent to provide scientific proof of the harmful associations with GICP in the Asian population and to investigate the risk factors associated with GICP in Asia to promote legal prohibition of GICP.

There is also insufficient data on the influence of GICP on different age groups, particularly adolescents ≤17 years old. Research in Canada found that conversion therapy was more prevalent among younger cohorts (15–19 years old) compared with older cohorts (older than 20 years old)1. Research in the southern USA also identified that younger respondents were more likely to experience conversion therapy4. Due to the census age, previous recalled exposure to GICP research did not include participants below 18 years old7. As suggested previously, GICP exposure during childhood showed stronger adverse adult mental health outcomes than GICP exposure during adulthood. Thus, future research should examine the mental health impact resulting from GICP among young people24. In addition, the previous study did not clarify severe psychological distress into specific psychiatric problems, such as depression, anxiety and post-traumatic stress disorder (PTSD)7.

Here, we investigated the different types of GICP and different referrers (that is, the specific person who suggested GICP or forced the individual into it). We aimed to quantify the prevalence of GICP exposure and the prevalence of different types of GICP among TNG individuals in mainland China, as well as to investigate the GICP-associated mental health concerns. We comprehensively screened mental health outcomes, including PTSD, depression, anxiety, non-suicidal self-injury (NSSI), suicide attempts and substance use (for example, cigarettes and alcohol), and compared age group differences (for example, adolescents ≤17 years old versus adults). We hypothesized that there would be a positive association between exposure to GICP and adverse mental health outcomes, including suicidality, depression, anxiety, substance use, PTSD and NSSI. We also hypothesized that different types of GICP would lead to different levels of mental health damage. Finally, we hypothesized that there could be an age group difference, with adolescents (≤17 years old) suffering more severe mental health concerns associated with GICP.

Results

Sociodemographic characteristics of the participants

Of the 7,576 participants from mainland China included in the analysis, 213 (2.8%) had experienced GICP, in which 34 (16.0%) participants were ≤17-year-olds, 130 (61.0%) participants were 18–24-year-olds and 49 (23.0%) participants were ≥25-year-olds. Of the 213 participants who had experienced GICP, 161 (75.6%) had experienced professional GICP and 52 (24.4%) had experienced non-professional GICP. A comparison between participants with and without experience of GICP revealed significant differences with the following groups more likely to suffer from GICP: male sex assigned at birth, transgender woman or woman gender identity, partnered marital status, father educated to bachelor’s or junior college, father very unsupportive or unsupportive of gender identity, and mother very unsupportive or unsupportive of gender identity (Table 1). Regarding sex assigned at birth, the proportion of participants who had reported GICP who were birth-assigned males was higher, compared with nearly 50% among participants who had not reported GICP (χ2 = 38.47, P = 0.001). As for gender identity, 63.8% of the participants who had reported GICP identified themselves as women or transgender women (χ2 = 72.92, P < 0.001). Regarding marital status, participants who did not report GICP had a higher proportion of being single (χ2 = 38.77, P < 0.001). Participants who reported GICP had fathers with higher education levels than those who did not report GICP (χ2 = 14.28, P = 0.011). Participants who reported GICP had lower paternal support levels (χ2 = 279.61, P = 0.001) and maternal support levels (χ2 = 206.62, P < 0.001) than those who did not report GICP. We also used univariate logistic regression and multivariate logistic regression to analyse the demographic risk factors of GICP (Extended Data Table 1).

Table 1 Characteristics of the study population by GICP response
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As in Extended Data Table 2, the only significant difference between professional and non-professional GICP was that participants who experienced professional GICP revealed higher fear of conversion practice (t = 3.71, P = 0.002). We found no significant difference between groups in all sociodemographic variables.

Description of GICP

According to different conversion methods, GICP was divided into professional GICP and non-professional GICP in the current study. Comparison between two types of GICP on mental health and the effect of age groups difference were examined.

Professional GICP

‘Prescribed psychiatric medication’ had the highest frequency among all professional GICPs, followed by ‘aversion therapy’, ‘hypnotherapy’, ‘hospitalization’, ‘religious rituals’, ‘injection/infusion’ and ‘punishment shock’. There were no significant differences between all three age groups in the frequency of participants suffering from professional GICP (Fig. 1).

Fig. 1: Types of GICP.
figure 1

Asterisks indicate differences between age groups. The analysis used a Pearson’s χ2 test with a statistical significance level of 5% for a two-sided test. Significance levels were adjusted for FDR.

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Non-professional GICP

Of non-professional GICP types, ‘verbal aggression or insult’ had the highest frequency, followed by ‘forced to change physical characteristics and dressing style’, ‘personal insult’, ‘restricting freedom of movement’, ‘hitting’ and ‘forced into marriage’. We found significant differences between age groups. In particular, compared with participants ≥25 years old, those ≤17 years old and those aged 18–24 years old were more likely to suffer from verbal aggression or insult, personal insult and restricted freedom of movement. Participants ≤17 years old were also more likely to be hit than participants ≥25 years old. Forced change to physical characteristics and dressing style was more likely to happen to participants aged 18–24 years old than to participants ≥25 years old (Fig. 1).

Comparison between professional and non-professional GICP

It can be seen from Fig. 1 that most participants experienced various kinds of non-professional GICP, and the proportion who experienced professional GICP is lower. Among all types of GICP, the five most frequently experienced are all non-professional GICPs. Additionally, only non-professional GICPs showed significant differences between age groups. We found a common result in all age groups: TNG individuals were most likely to be suggested or forced to participate in GICP by their parents or guardians, followed by psychiatrists, friends of parents, relatives and counsellors (Extended Data Fig. 1).

Effect of GICP on mental health outcomes and substance use

After controlling for socio-demographic variables, we found that GICP is a risk factor for multiple mental health conditions, including depression (B = 0.59; 95% confidence interval (CI), 0.31–0.87; P < 0.001), anxiety (B = 0.64; 95% CI, 0.38–0.89; P < 0.001) and PTSD symptoms (adjusted odds ratio (aOR) = 2.36; 95% CI, 1.72–3.24; P < 0.001). GICP would also increase the risk of suicidality, which was reflected in the fact that participants who have experienced GICP had a higher risk of suicidal ideation in the previous 12 months (aOR = 1.91; 95% CI, 1.33–2.74; P < 0.001), suicidal plan in the previous 12 months (aOR = 2.29; 95% CI, 1.68–3.13; p < 0.001), suicide attempts in lifetime (aOR = 3.16; 95% CI, 2.26–4.40; P < 0.001) and suicide attempts in the previous 12 months (aOR = 2.89; 95% CI, 2.13–3.92; P < 0.001) than participants who had no GICP. Similarly, we found that GICP was also a risk factor for NSSI in the previous 12 months (aOR = 2.21; 95% CI, 1.64–2.98; P < 0.001), frequency of NSSI in the previous 12 months (B = 0.57; 95% CI, 0.37–0.77; P < 0.001) and alcohol use (aOR = 1.68; 95% CI, 1.19–2.37; P = 0.004) (Table 2).

Table 2 Mental health and substance use outcomes for those with exposure to GICP
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In addition, after controlling socio-demographic variables, conversion practice in previous 12 months, and fear of conversion practice, we also found that professional GICP had greater impact on suicidality than non-professional GICP, including suicidal plan in previous 12 months (aOR = 4.61, 95%CI [1.53–13.84], p = 0.023), suicide attempts in lifetime (aOR = 12.42, 95% CI [3.89–39.63], p < 0.001), and suicide attempts in previous 12 months (aOR = 5.46, 95%CI [1.82–16.38], p = 0.010) (see Table 3). A visual comparison between professional and non-professional GICP experiences’ impacts on mental health and substance use is shown in Fig. 2.

Table 3 Mental health and substance use outcomes for those with exposure to professional and non-professional conversion practice
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Fig. 2: Comparison of mental health problems between professional GICP and non-professional GICP.
figure 2

The proportion of participants who experienced Professional GICP and Non-professional GICP in Mental Health, Suicide, and NSSI was presented.

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Age group differences

Our results showed that compared with the other two age groups, participants ≤17 years old with GICP demonstrated higher rates of suicidal plans in the previous 12 months (χ2 = 17.83, P < 0.001) and higher risk of suicide attempts in the previous 12 months (χ2 = 19.87, P < 0.001). Compared with participants ≥25 years old, those ≤17 years old with GICP revealed more severe depression (χ2 = 12.70 P = 0.015), more severe PTSD symptoms (χ2 = 11.56, P = 0.005), higher risk of suicidal ideation in the previous 12 months (χ2 = 25.69, P < 0.001), higher risk of suicide attempts in lifetime (χ2 = 27.54, P < 0.001), higher risk of NSSI in the previous 12 months (χ2 = 13.41, P = 0.002), and more frequent NSSI in the previous 12 months (χ2 = 18.29, P = 0.008) (Extended Data Table 3). Extended Data Fig. 2 presents a visual comparison of differences between age groups.

By comparing the impact of professional and non-professional GICP on mental health outcomes in different age groups, we found that the proportion of participants who attempted suicide in their lifetime was higher for those who experienced professional GICP compared with non-professional GICP both in 18–24-year-olds (χ2 = 14.38, P = 0.002) and ≥25-year-olds (χ2 = 8.39, P = 0.050). In addition, our results also show that in the ≥25 years old age group, participants who had experienced professional GICP were more likely to have attempted suicide in the previous 12 months than those who had experienced non-professional GICP (χ2 = 8.65, P = 0.050).

Discussion

This Chinese national health survey on the well-being of TNG people utilized multi-dimensional mental health measurements. The prevalence of GICP among TNG individuals was 2.8%, for ≤17-year-olds it was 2.6%, for 18–24-year-olds it was 2.8%, and for ≥25-year-olds it was 3.0%. Results proved that exposure to GICP was significantly associated with all measured mental health concerns, including depression, anxiety, PTSD, suicidality and NSSI.

Research on TNG individuals has emphasized that non-professional GICP from family members can lead to detrimental mental health consequences14. However, no study had systematically measured non-professional GICP and compared the influence of professional and non-professional GICP. Our national-scale study comprehensively measured and compared both types of GICP. We found that although professional GICP was prevalent, constituting over three-quarters of the proportion of GICP, non-professional GICP accounted for an alarming proportion of almost one-quarter. Abundant research has provided empirical evidence on the harmful consequences of professional GICP, however, this study has revealed the high proportion of non-professional GICP. Importantly, we found that, as with professional GICP, non-professional GICP also led to significant mental health problems, warranting urgent attention. Compared with professional GICP, there is no significant difference across the detrimental mental health measurement in non-professional GICP, despite professional GICP leading to a higher risk of lifetime suicidal attempts. That is, the neglected research area of non-professional GICP produces almost equivalent destructive consequences to TNG individuals.

Previous research found that recalled lifetime exposure to GICP was 14.0% for all the transgender participants and 19.6% for those who discussed their gender identity with a professional7. Between 2010 and 2015, the prevalence of transgender participants reporting exposure to professional GICP in the USA was 5% nationally (range, 1.2–16.3%)24. The prevalence of GICP found in the Chinese population was much lower than in Western countries. It is possible that religious beliefs and religious refusals are prominent rationales underlying conversion therapy in Western societies25. Conversion therapy was most common in religious and faith-based settings (67%), followed by licensed healthcare provider offices (20%) in Canadian sexual and gender minority groups1. GICP in American TNG individuals followed a similar pattern, with the most prevalent type being through religious leaders and clergies (10.0%), followed by mental health practitioners (9.1%)4. Connecting to the current study, to some extent, we consider that the low religious belief prevalence may lead to the low rate of GICP in the Chinese population. A previous study found that individuals who experienced GICP were twice as likely to report attempted suicide7,26. Here, we found that GICP exposure resulted in 3.09-fold increase in suicide attempts, which is much higher than previous reports. Accordingly, although the prevalence of GICP in the Chinese population is relatively low, the suicidality risk for those who experienced GICP is much higher. Notably, our results show that compared with non-professional GICP, professional GICP leads to an even more severe risk of lifetime suicidal attempt. This is the only significant difference we recorded in mental health outcomes between professional and non-professional GICP. For TNG individuals who suffered from professional GICP, it is urgent to provide suicide prevention intervention.

TNG individuals assigned male sex at birth and fathers with higher education levels were significantly more likely to report exposure to GICP. Unlike previous research in the USA, which found that TNG individuals who were assigned female sex at birth showed higher odds of GICP exposure7, our sample showed that individuals assigned male sex at birth showed higher odds of GICP exposure. Past research also showed that lower education levels were correlated with a higher likelihood of TNG individuals receiving GICP4. A previous study showed that respondents from socioeconomically disadvantaged groups, such as low educational backgrounds, tended to report exposure to professional GICP7. In our sample, participants’ education levels did not show significant differences between GICP and non-GICP groups, while participants with fathers with higher educational levels were significantly more likely to report exposure to GICP. This indicated that, unlike in the USA, participants with higher socioeconomic backgrounds might suffer more commonly from GICP in China. This may be because disadvantaged families do not have access to professional GICP due to financial constraints. Nevertheless, owing to the cross-sectional nature of the study, we cannot offer a solid causal interpretation.

These results highlight the importance of recognition of gender diversity and stress the adverse associations of GICP. This study is validation and expansion of landmark research, which consistently showed GICP was associated with psychological distress and suicidality7, although this study further details measured psychological distress in terms of depression, anxiety and PTSD. In addition, the previous study showed that early exposure to GICP was associated with worse mental health outcomes and indicated that rejection of gender identity at earlier stages could elevate lifetime suicide attempts7. However, owing to a lack of adolescents ≤17 years old, they did not investigate the GICP impacts on different age groups. Compared with other age groups who suffered from GICP, participants ≤17 years old who suffered from GICP demonstrated more severe depression, suicidal ideation, suicidal plans, suicide attempts (both in the previous 12 months and lifetime) and NSSI. Our results demonstrate that TNG adolescents ≤17 years old tended to have more severe mental health associations with GICP. Researchers have warned that it is critical to focus on younger generations, because half of received conversion therapy is during childhood or adolescence10,13.

Researchers have proposed that GICP exposure might elevate stigma-related minority stress, which could lead to general emotional dysregulation and mental health concerns7. Aside from emotional abuse, GICP could encompass rejection based on gender identity and produce internalized stigma, all risks that are strongly associated with suicidality26. Conversion therapy was also associated with poor self-esteem, internalized stigma and discrimination5,6,14,20. In our current findings, regarding TNG individuals who reported GICP, higher self-esteem was shown to be a protective factor for the three primary outcomes (mental health, suicidality and NSSI), while fear of GICP was shown to be the risk factor for the three primary outcomes. It was also worth noting that internalized transphobia was a risk factor for the mental health of TNG people.

We found that most TNG individuals who suffered from GICP were referred by their parents. Such a finding is consistent with results from two previous Chinese studies, which suggested that parents tend to avoid and reject the gender identity of their TNG children14,27. Thus, it is crucial to psychoeducate parents to support rather than suppress their children’s gender identity. We propose providing parents of TNG individuals with psychoeducation sessions on the diversity of gender identity, the negative consequences of GICP, as well as supportive techniques for their TNG children’s mental health. More importantly, supporting families with understanding the adverse and destructive consequences of GICP on TNG adolescents’ mental health. Considering the aftermath of GICP, healthcare providers should stand firmly against conversion therapy on a personal level. Previous research found that recalled lifetime exposure to GICP of those who discussed gender identity with a professional was higher than for the total transgender participants (14.0% versus 19.6%)7. This might indicate that professionals may not act according to their ethical doctrine as they are supposed to. It is essential for healthcare providers to self-educate, advocate for TNG individuals’ rights to not undergo GICP and offer gender affirmative therapy to improve the mental health of TNG individuals28. Moreover, we recommended that TNG communities provide consulting hotlines to support individuals who suffered from GICP. There is a long way to go for the prohibition of GICP, which will require efforts from policymakers. We hope that our research findings could move things forward.

There are several limitations that need to be addressed. Firstly, the cross-sectional nature of this study limits the study’s ability to infer and establish causality between GICP and adverse mental health outcomes. Future longitudinal studies are needed to investigate causal relationships of GICP on mental health outcomes. Secondly, we did not measure the intensity of GICP, including the frequency, duration or date of GICP. We recommend further studies to collect detailed information about GICPs to measure the potential mental health variations caused by different GICPs on victims. Thirdly, the survey used a convenience sample collected through online and offline advertisements. Thus, the sample may not be representative of all TNG individuals in the nation, especially those who are not frequent social media users.

Conclusions

In conclusion, based on a large sample size of the TNG individuals, we repoted that GICP increased risk for multiple mental health problems including suicidality. Compared with non-professional GICP, professional GICP demonstrated more severe harm. Compared with other age groups, GICP tended to associate with more severe mental health problems in TNG people aged ≤17 years old. Our results support the standpoint that GICP should be avoided and banned urgently. GICP is an unethical practice that elevates the risks of mental health concerns in a population already facing severe mental health risks. Despite its pervasive nature and lack of scientific credibility, our findings add to the substantial evidence suggesting that GICP is associated with various mental health concerns and substance use, including suicidality and NSSI. It is necessary for the public to become more aware of the devastating impact of GICP on the TNG population.

Methods

Study design

The data used in this study are from the 2021 Chinese Transgender Health Survey. This cross-sectional health survey was conducted from 6 May to 26 December 2021, covering all province-level administrative divisions in mainland China (Extended Data Figs. 3 and 4). It is larger than previous health survey on the TNG population in China29,30,31. The Chinese Transgender Health Survey protocol was reviewed and approved by the ethics committee of the Second Xiangya Hospital of Central South University, Changsha, Hunan, China.

Participants

A total of 9,390 responses were received: 9,161 respondents completed all components of the survey and 229 participants declined consent. Therefore, the response rate was 97.6%. To ensure the authenticity and reliability of the data, data cleaning was conducted according to the following criteria: (1) participants correctly answered two of the three attention detection questions; (2) a combination of IP (Internet Protocol) address and contact information did not indicate a repeated submission; (3) the answers to ‘sex assigned at birth’ and ‘gender identity’ indicated TNG identity (for example, those questions were not answered randomly or illogically); (4) the participant lives or grew up in mainland China. This excluded 1,585 respondents leaving 7,576 participants (mean age was 21.61 years ± 5.15) in the final sample for analysis, with an effective rate of 82.7%. To find out the differences between age groups, we divided the participants into three: ≤17 years old, 18–24 years old and ≥25 years old. The cut-off values of these three age groups were based on the legal definition of minors in China and guidelines published by the World Health Organization (WHO). We classified ≤17 years old as adolescence because this is a legal age boundary for adults and adolescents in China32. This group represented adolescents who did not have legal and medical autonomy. We further set the other age groups as 18–24 years old (adolescents with legal and medical autonomy) and ≥24 (adults), as WHO sets 24 years old as the upper limit for young adults33,34,35.

Defining the TNG population

Participants’ sexes assigned at birth and gender identities were each measured by a self-report item, which was used to define the TNG population. Sex assigned at birth was measured by asking each participant, ‘Which sex were you assigned at birth?’ The options included male, female and other (to be filled in by participants). Gender identity was measured by asking each participant, ‘If only one item can be chosen, which of the following is a better description of you?’ The options included man, woman, transgender man, transgender woman, non-binary/genderqueer, cross-dresser, questioning and none of the above. According to participants’ choices on these two items, we divided the participants into six categories (Table 1).

Recruitment

Owing to the COVID-19 restrictions, convenient sampling and snowball sampling were employed for online participant recruiting. The promotion of online recruitment advertising has been promoted by many LGBTQ+ community organizers. Online posters and links have been released through multiple social media channels and platforms, such as WeChat or QQ groups, which are popular in the Chinese TNG community. The online questionnaire was prepared on the ‘Wenjuanxing’ platform, and a QR (quick response) code was automatically generated for distribution. TNG individuals who agreed to participate in this survey were provided with the QR code for online survey entry. Participants who completed the entire survey had a chance to win a cash reward in a prize draw. All questionnaires were anonymous and online informed consent was acquired prior to the study. Participants were informed of the right to withdraw from the study at any time. Participants were also provided with information on accessing mental health support should they become upset at any point during or after the study.

Measures

Sociodemographic characteristics

Participants’ sociodemographic characteristics, including age group, sex assigned at birth, gender identity, sexual orientation, ethnicity, education level, religious belief, marital status, family category, annual family income, education level of father or male guardian, and education level of mother or female guardian were collected.

Measurements of GICP

In this study, we focus on any treatments or other practices enforced with the purpose of changing a person’s gender identity36. We defined GICP as practices with the purpose of changing one’s gender identity conducted by any person with authority, including both professional and non-professional personnel. In the current study, non-professional GICP were measured separately to professional GICP (that is, GICE, as described previously, in which conversion therapy was conducted by professionals)1,7. Furthermore, non-professional GICP is defined in this study as measures conducted by non-professional personnel (for example, parents, guardians, relatives, teachers, education practitioners and partners). The definition of non-professional GICP is rooted in the notion of the existing non-professional practice of gender identity change efforts from previous studies1. A previous study37 measured and reported that gender identity and expression conversion attempts come from ‘parent(s), family member(s)’, ‘friends or acquaintances’, ‘relationship (ex-)partner(s)’, which corresponds to the non-professional GICP defined in the current study.

Professional GICP included hypnotherapy, aversion therapy, religious rituals, punishment shock, hospitalization, injection or infusion and prescribed psychiatric medication38. In these conversion practices, hypnotherapy and aversion therapy belong to psychological intervention techniques39, which need to be conducted by professional psychotherapists. In addition, punishment shock, hospitalization, injection or infusion and prescribed psychiatric medication need to be implemented by doctors or mental health practitioners in psychiatric hospitals or psychiatric departments of comprehensive hospitals5. Besides, religious rituals are usually carried out by church leaders40. Therefore, we defined these conversion practices conducted by personnel who have received professional medical or psychological training as professional GICPs. Non-professional GICP experience measured in this study included verbal aggression or verbal insult, being forced to change one’s physical characteristics and dressing style, facing personal insult, facing restrictions on freedom of movement, facing physical abuse and being forced into marriage41.

All of the participants answered the screening item, ‘Have you ever experienced gender identity conversion?’ Because conversion therapy includes sexual orientation, gender identity and gender expression37, and we focused on the negative influences of GICP on the TNG population, if participants chose ‘no’, they would skip this section. Otherwise, participants answered four more detailed questions: (1) ‘Which types of GICP did you experience?’, (2) ‘Who forced or suggested you participate in gender identity conversion?’, (3) ‘Did the conversion therapy occur within the last 12 months?’, and (4) ‘What degree of fear did you feel towards gender identity conversion?’ The first question assessed participants according to the definitions of professional and non-professional GICP. The degree of fear of gender identity conversion assessed the overall fear of participants’ gender identity conversion experience, including both fears of professional and non-professional GICP.

Mental health outcomes and substance use

We compared differences between participants who reported GICP and who did not report GICP in the following outcome variables: mental health, including the level of depression in the past week (a short version of the Center for Epidemiologic Studies depression scale (CES-D-9), Cronbach’s alpha = 0.92)29,42, the level of anxiety in the past week (Generalized Anxiety Disorder 7-item (GAD-7), Cronbach’s alpha = 0.92)29,43, and PTSD symptoms (Trauma Screening Questionnaire (TSQ), Cronbach’s alpha = 0.87)44; suicidality31, including suicidal ideation in the previous 12 months, suicide plan in the previous 12 months, suicide attempt in the previous 12 months, and lifetime suicide attempt; NSSI, including whether there was NSSI in the previous 12 months and the times of NSSI behaviours in the previous 12 months, and substance use, including use of alcohol (Alcohol Use Disorder Identification Test (AUDIT), Cronbach’s alpha = 0.76), cigarettes (Fagerstrӧm test for nicotine dependence (FTND), Cronbach’s alpha = 0.85) and e-cigarettes (e-FTND, Cronbach’s alpha = 0.79)45,46.

Statistical analysis

The sample characteristics were presented using mean and standard deviation (s.d.) for continuous variables and percentages for categorical variables. Firstly, we compared differences between participants with GICP and participants without GICP in sociodemographic characteristics, mental health, suicidality, NSSI and substance use. Secondly, we divided participants into two groups (professional GICP versus non-professional GICP) according to the types of GICP experienced. Participants who reported experiencing hypnotherapy, aversion therapy, religious rituals, punishment shock, hospitalization, injection or infusion and prescription of psychiatric medication were allocated to the professional GICP group, and the others were allocated to the non-professional GICP group. We compared the differences between these two groups regarding participants’ sociodemographic characteristics, conversion practice in the previous 12 months and fear of conversion practice.

Chi-squared tests were performed to verify whether there was any significant difference in categorical variables. If the variable was continuous, an independent sample t test was performed. The proportion of GICP types and who suggested or forced participants into GICP were described for different age groups, and mental health variables were also compared for different GICP groups. Logistic regression analysis and linear regression analysis were conducted to explore the effect of GICP on mental health, suicidality, NSSI and substance use outcomes by adjusting for sociodemographic variables. Furthermore, we compared the effects of professional GICP and non-professional GICP on all the above outcomes by adjusting the sociodemographic variables, conversion practice in the previous 12 months and fear of conversion practice. Adjusted OR and beta with 95% CI were used to show the degree of effects. Data were analysed using SPSS (v. 26.0), with a P-value lower than 0.05 (two-tailed) considered to be statistically significant. All P-values were respectively adjusted for FDR in each analysis, using R (v. 4.1.0).

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.