There may be shared genetic risk between schizophrenia and binge eating behaviors, according to research published in the British Journal of Psychiatry. Previous studies have suggested comorbidities between psychotic and eating disorders and that the two could have a shared genetic liability, but this has been overlooked in epidemiologic literature.
To test whether polygenic risk scores (PRS) for schizophrenia are associated with disordered eating behaviors and body mass index (BMI), researchers collected genetic data from the Avon Longitudinal Study of Parents and Children. Using random-effects logistics and linear regression models, they investigated the association between PRS for schizophrenia and self-reported disordered eating behaviors, including binge eating, purging, fasting, and excessive exercise, as well as BMI at 14, 16, and 18 years of age.
Of 6920 children, 4473 (64.6%) had at least one disordered eating outcome and 5069 (73.3%) had one BMI outcome measurement. Increases in PRS were associated with higher rates of binge eating behaviors and lower BMIs. Impaired social cognition and irritability, which have previously been found to have positive correlations in this sample with schizophrenia PRS, may also denote risk factors for both phenotypes. Additionally, shared genetic liability between schizophrenia and binge eating could clarify higher rates of metabolic syndrome in individuals with schizophrenia.
The study was limited by its broad definitions of disordered eating, as well as by significant attrition.
“Future research should investigate the presence of shared intermediate phenotypes across these disorders, including the role of metabolic abnormalities, to improve early identification of at-risk children,” researchers wrote. “From a clinical viewpoint, these findings further highlight the need to consider the co-occurrence of disordered eating behaviors, particularly binge eating, in individuals with psychotic illnesses, as this might account for the weight gain observed in this population.”
Solmi, F, Mascarell, M, Zammit, S, Kirkbride, J, Lewis, G. Polygenic risk for schizophrenia, disordered eating behaviours and body mass index in adolescents [published online March 6, 2019]. Br J Psychiatry. doi:10.1192/bjp.2019.39