Clinical, epidemiological, and genetic findings support an overlap between eating disorders, obsessive-compulsive disorder (OCD), and anxiety symptoms. However, little research has examined the role of genetics in the expression of underlying phenotypes. We investigated whether the anorexia nervosa (AN), OCD, or AN/OCD transdiagnostic polygenic scores (PGS) predict eating disorder, OCD, and anxiety symptoms in a large developmental cohort in a sex-specific manner.

Using summary statistics from Psychiatric Genomics Consortium AN and OCD genome-wide association studies, we conducted an AN/OCD transdiagnostic genome-wide association meta-analysis. We then calculated AN, OCD, and AN/OCD PGS in participants from the Avon Longitudinal Study of Parents and Children to predict eating disorder, OCD, and anxiety symptoms, stratified by sex (combined N = 3212–5369 per phenotype).

The PGS prediction of eating disorder, OCD, and anxiety phenotypes differed between sexes, although effect sizes were small. AN and AN/OCD PGS played a more prominent role in predicting eating disorder and anxiety risk than OCD PGS, especially in girls. AN/OCD PGS provided a small boost over AN PGS in the prediction of some anxiety symptoms. All three PGS predicted higher compulsive exercise across different developmental timepoints [β = 0.03 (s.e. = 0.01) for AN and AN/OCD PGS at age 14; β = 0.05 (s.e. = 0.02) for OCD PGS at age 16] in girls.

Compulsive exercise may have a transdiagnostic genetic etiology, and AN genetic risk may play a role in the presence of anxiety symptoms. Converging with prior twin literature, our results also suggest that some of the contribution of genetic risk may be sex-specific.

Family education programs (FEPs) target caregiving-related psychological distress for carers of relatives/friends diagnosed with serious mental health conditions. While FEPs are efficacious in reducing distress, the mechanisms are not fully known. Peer group support and greater mental health knowledge are proposed to reduce carers' psychological distress by reducing stigmatising attitudes and self-blame, and strengthening carers' relationship with their relative.

Adult carers (n = 1016) who participated in Wellways Australia's FEP from 2009 to 2016 completed self-report questionnaires at the core program's start and end, during the consolidation period, and at a 6-month follow-up. Those who enrolled early completed questionnaires prior to a wait-list period. We used linear mixed-effects modelling to assess the program's effectiveness using a naturalistic wait-list control longitudinal design, and multivariate latent growth modelling to test a theory-based process change model.

While there was no significant change over the wait-list period, psychological distress, self-blame and stigmatising attitudes significantly decreased, and communication and relationship quality/feelings increased from the core program's start to its end. Changes were maintained throughout the consolidation period and follow-up. Peer group support significantly predicted the declining trajectory of distress. Peer group support and greater knowledge significantly predicted declining levels of self-blame and stigmatising attitudes, and increasing levels of communication.

This is the first study to quantitatively validate the mechanisms underlying the effect of FEPs on carers' psychological distress. Peer group support is key in modifying carers' appraisals of their friend/relatives' condition. Continued implementation of FEPs within mental health service systems is warranted.