Non-right-handedness and psychiatric disorders: A synthesis of epidemiological, genetic, and neurobiological evidence

Non-right-handedness (NRH), encompassing left-handedness and mixed-handedness, has been frequently reported at elevated rates in individuals with various psychiatric disorders. The consistency of this association across multiple conditions and its underlying mechanisms is the subject of ongoing investigation. This review synthesized current evidence to explore the association between NRH and psychiatric disorders from epidemiological, genetic, and neurobiological perspectives. We systematically identified and appraised relevant literature investigating NRH prevalence in psychiatric populations and potential explanatory mechanisms. Epidemiological evidence indicates an elevated prevalence of NRH, particularly within neurodevelopmental disorders. Potential contributing mechanisms identified include early developmental disruptions, shared genetic predispositions, and atypical patterns of brain lateralization. While the association between NRH and psychiatric conditions, especially neurodevelopmental disorders, is evident, the causal pathways and relative contributions of identified mechanisms are complex and debated. This review highlighted key areas requiring further research to elucidate these relationships.