Polygenic Scores Clarify the Relationship Between Mental Health and Gender Diversity

BACKGROUND: Gender -diverse individuals are at increased risk for mental health problems, but it is unclear whether this is due to shared environmental or genetic factors. METHODS: In two SPARK samples, we tested for associations of 16 polygenic scores (PGSs) with quantitative measures of gender diversity and mental health. In study 1, 639 independent adults (59% autistic) reported their mental health with the Adult Self -Report and their gender diversity with the Gender Self -Report (GSR). The GSR has 2 dimensions: binary (degree of identification with the gender opposite that implied by sex designated at birth) and nonbinary (degree of identification with a gender that is neither male nor female). In study 2 (N = 5165), we used a categorical measure of gender identity. RESULTS: In study 1, neuropsychiatric PGSs were positively associated with Adult Self -Report scores: externalizing was positively associated with the attention-deficit/hyperactivity disorder PGS (3 = 0.10 [0.03-0.17]), and internalizing was positively associated with the PGSs for depression (3 = 0.07 [0-0.14]) and neuroticism (3 = 0.10 [0.03-0.17]). Interestingly, GSR scores were not significantly associated with any neuropsychiatric PGS. However, GSR nonbinary was positively associated with the cognitive performance PGS (3 = 0.11 [0.05-0.18]), with the effect size comparable in magnitude to the associations of the neuropsychiatric PGSs with the Adult Self -Report. Additionally, GSR binary was positively associated with the nonheterosexual sexual behavior PGS (3 = 0.07 [0-0.14]). In study 2, the cognitive performance PGS effect replicated; transgender and nonbinary individuals had higher PGSs (t316 = 4.16). CONCLUSIONS: We showed that while gender diversity is phenotypically positively associated with mental health problems, the strongest PGS associations with gender diversity were with the cognitive performance PGS, not the PGSs.