Background Childhood maltreatment, bullying, and discrimination are more prevalent among Lesbian, Gay, and Bisexual (LGB) youths, correlating with increased risk of mental disorders and suicide ideation or attempts. This study aims to evaluate the role of childhood maltreatment, bullying, and mental disorders on the risk for suicidal thoughts and behaviours (STB); and the role of mental disorders on the association between discrimination and STB, among LGB youths.
Methods A longitudinal observational study was conducted on first-year university students from five public Spanish universities, representing diverse geographic regions. Eligible participants were freshmen aged 18 to 24, enrolled in the universities for the first time. Baseline and 12-month follow-up online surveys, using validated scales, assessed mental disorders (mood, anxiety, and alcohol/substance disorders [abuse or dependence]), suicidal thoughts and behaviors (STB), childhood maltreatment (emotional, physical, sexual, neglect), bullying (physical, verbal, cyber), and discrimination. Descriptive analyses were conducted, and multivariable logistic regression models assessed the effects of childhood maltreatment, bullying, and discrimination on the risk for mental disorders and STB among LGB youths.
Results A total of 1,224 students were included (16,4% LGBs). Prevalence of any form of childhood maltreatment ranged from 35.1% (homosexuals) to 59.7% (asexual/other), emotional maltreatment was the most common maltreatment (from 22.2% for unsure respondents, to 56.3% for asexual/other). Most common form of bullying among LGBs was verbal form (from 27.2% for asexual/other, to 69.9% for homosexuals). Risk factors of lifetime suicidal ideation (SI) were sexual orientation (OR 2.4), any bullying (OR 2.4), any childhood maltreatment (OR 4.0), and any mental disorders (OR 3.8). Final model Area Under the Curve (AUC) 0.78. Among homosexual and bisexual students, discrimination showed increased risk of 12-month SI (OR 2.2), but this effect was no longer statistically significant when any 12-month mental disorder was added (OR 7.8). Final model AUC 0.72.

Conclusions Childhood maltreatment, bullying, discrimination and mental disorders interact in the risk for SI among LGB youths. Mental disorders may mediate the association between discrimination and SI. Further research using larger samples and causal modelling approach assessing the mediators for STB risk among LGBs is needed.