Sexual minority (e.g., gay, lesbian, bisexual) individuals are more likely to meet criteria for mental and substance use disorders compared to their heterosexual counterparts (Bränström, 2017; Gmelin et al., 2022; Kidd et al., 2016; King et al., 2008; Plöderl and Tremblay, 2015; Sandfort et al., 2014). These disparities have also been found among other non-LGB (lesbian, gay, bisexual) sexual minority groups (e.g., heterosexual-identified individuals with same-gender attraction, questioning, asexual; Borgogna et al., 2019; Gattis et al., 2012; Krueger et al., 2018; Lhomond et al., 2014). Similar mental health disparities across sexual orientation have been found among college student samples (Oswalt and Wyatt, 2011; Przedworski et al., 2015). This increased risk for mental disorders has been partly attributed to stress based on minoritized identities (Hatzenbuehler and Pachankis, 2016; Meyer, 2003), including societal-level stigma and prejudice (e.g., negative attitudes, lack of acceptance; Hatzenbuehler, 2016; Hatzenbuehler et al., 2018). Gender may also interact with sexual orientation given evidence suggesting that mental health disparities may be greater between sexual minority women and men compared to heterosexual women and men, respectively (Batchelder et al., 2021; Kerridge et al., 2017; Krueger et al., 2018; Schuler and Collins, 2020) though differences in gender disparity have been less explored for mental disorders diagnosed by criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Little research has examined how gender and societal-level stigma interact with mental health disparities among sexual minority college students. Furthermore, most of the empirical studies on college mental health are focused on Western countries (Hernández-Torrano et al., 2020), limiting generalizability to broader global college mental health. College students are at a unique stage of identity development characterized by a relative increase in autonomy and independence that allows for further personal exploration (Arnett, 2000; Hatano et al., 2022; Jones and Abes, 2013). This period may also provide opportunities to explore sexual attractions and identities beyond the heterosexual norm, including same-gender attractions and/or sexual minority identities (Dillon et al., 2011; Morgan, 2013). College age and emerging adulthood have also been noted as a crucial period for experiencing a high prevalence of mental disorders (Auerbach et al., 2018), and college students with a sexual minority identity or orientation may be at greater risk due in part to prejudice-related stress in a heteronormative context (Bissonette and Szymanski, 2019; Busby et al., 2020).

Sexual orientation has been conceptualized as a multidimensional construct comprised of sexual identity, sexual attractions, and sexual behaviors (Dillon et al., 2011; Korchmaros et al., 2013). Sexual identity refers to one's self-identification within a group (i.e., heterosexual, gay/lesbian, etc.) while sexual attraction refers to the “direction” towards the gender to which someone experiences sexual arousal (e.g., women, men, non-binary, or neither). Utilizing a multidimensional approach to measure sexual orientation through self-identification and attraction has been effective at identifying health disparities among understudied sexual minority populations. For example, individuals who identify as heterosexual and report same-gender attraction (SGA), or identify as “mostly heterosexual” (Igartua et al., 2009; Savin-Williams and Vrangalova, 2013), may also be at greater risk for negative mental health symptoms and substance use compared to heterosexual individuals with no SGA (Hughes et al., 2015; Krueger et al., 2020; Maheux et al., 2021; Rentería et al., 2021). Still, there remains a research gap on the prevalence of DSM-5 disorders among emerging sexual orientations (e.g., asexual, questioning, mostly heterosexual) and how gender may interact with sexual identity. This is a critical gap considering research suggesting that mental health risk is greater among bisexual women relative to lesbian/gay women (Schuler and Collins, 2020). The use of a large sample will capture sufficient numbers of sexual minority subgroups enabling the investigation of these interaction effects, which typically cannot be done in smaller samples.

Minority stress theory (Brooks, 1981; Meyer, 2003) posits that disparities in mental disorders among sexual minority populations may be attributed to exposure to hostile environments due to prejudice, rejection, and discrimination on the basis of sexual orientation. Minority stress includes external (e.g., physical assault, slurs) and internal processes (e.g., expectations of rejection, internalized negative schemas; Borgogna and Aita, 2023; Douglass and Conlin, 2022; Walch et al., 2016) and may affect individuals with sexual minority experiences that do not fit the normative heterosexual identity (e.g., heterosexual with SGA or questioning; Gattis et al., 2012; Rentería et al., 2021; Williams et al., 2003). Stigma and prejudice may also include social-structural factors, for example, social attitudes towards sexual minority populations. In fact, sexual minority individuals living in countries with higher structural stigma (i.e., discriminatory laws, policies, and negative social attitudes) report lower levels of life-satisfaction compared to those living in countries with lower structural stigma (Pachankis and Bränström, 2018; van der Star et al., 2021). Social attitudes of acceptance towards the LGBTQ+ community have previously been used as a component in measuring structural stigma towards sexual minority individuals, and the evidence suggests that increased structural stigma is associated with poorer health outcomes (Hatzenbuehler et al., 2018; Pachankis et al., 2014; Pachankis and Bränström, 2018). These studies utilized an index of structural stigma composed of population attitudes towards LGBTQ+ populations and an index of discriminatory legislation and policies using data collected by the International Lesbian, Gay, Bisexual, Trans and Intersex Association on European laws and policies (Annual Review of the Human Rights Situation of Lesbian, Gay, Bisexual, Trans and Intersex People in Europe, 2015) thus the scope of such research only included European member states. A World Mental Health Surveys study (Gmelin et al., 2022) that examined the relative risk of twelve-month disorders among LGB groups compared to heterosexual adults found no differences in relative risk across country-level social acceptance as measured by the Global Acceptance Index (GAI; Barrientos and González, 2022; Flores, 2021). However, this study was exploratory and did not investigate the interaction between social acceptance and sexual orientation in predicting twelve-month disorders.

The current study, which included cross-national samples of college students from 13 countries (N = 53,175), examined the twelve-month prevalence of five common DSM-5 disorders across sexual orientation groups. These disorders are major depressive disorder (MDD), generalized anxiety disorder (GAD), panic disorder (PD), and alcohol (AUD) and drug use (DUD) disorders. Additionally, we tested the interaction effects of gender and the Global Acceptance Index (GAI) with sexual orientation for twelve-month mental disorders to assess differences based on gender and country-level social acceptance. Informed by prior sexual minority health research (Bränström and Pachankis, 2018; Gmelin et al., 2022; Krueger et al., 2020), we hypothesized that sexual minority groups (heterosexual with SGA, gay/lesbian, bisexual, questioning, and asexual) would present greater risk for mental disorders compared to heterosexual students without SGA, although we expected that disparities would vary across sexual orientation. We expected bisexual students would present greatest odds based on prior research indicating bisexual individuals present greater health disparities relative to heterosexual and gay/lesbian individuals (Oswalt and Wyatt, 2011; Shokoohi et al., 2022).We expected a significant interaction effect between sexual orientation and gender, such that the difference in prevalence between sexual minority women and men would be greater than between heterosexual women and men with no SGA. Finally, we expected a significant interaction effect between sexual orientation and GAI, such that the odds of a disorder among sexual minority groups would decrease relative to the heterosexual group at higher levels of GAI.