Handedness in mental and neurodevelopmental disorders: A systematic review and second-order meta-analysis

Area of Science:

• Psychiatry and Neuroscience
• Developmental Psychology
• Human Genetics

Background:

• Atypical hand preference, including non-right, left, or mixed-hand preference, has been inconsistently linked to various mental and neurodevelopmental disorders.
• Previous meta-analyses have examined specific disorders, but a comprehensive, cross-diagnostic analysis is needed to identify overarching patterns and moderators.

Purpose of the Study:

• To conduct a second-order meta-analysis to synthesize existing data on hand preference across a wide range of mental and neurodevelopmental disorders.
• To estimate the prevalence of atypical hand preference in affected individuals compared to controls.
• To investigate potential moderators, such as diagnosis type, age of onset, and symptom clusters, influencing the association between hand preference and psychopathology.

Main Methods:

• A systematic review and re-analysis of published meta-analyses on hand preference in mental and neurodevelopmental disorders.
• Inclusion of 402 datasets comprising 202,434 individuals.
• Second-order meta-analysis to pool effect sizes and conduct moderator analyses.

Main Results:

• Atypical hand preference was significantly more frequent in individuals with mental and neurodevelopmental disorders compared to controls (nonright OR: 1.46, left OR: 1.34, mixed OR: 1.63).
• The frequency of atypical hand preference varied by diagnosis, with conditions like schizophrenia showing particularly high rates.
• Moderator analyses revealed that neurodevelopmental conditions, early-onset non-neurodevelopmental conditions, and disorders with language-related symptoms were associated with increased atypical hand preference.

Conclusions:

• The association between handedness and clinical conditions is best understood through a transdiagnostic lens, considering developmental trajectories and specific symptom profiles.
• Findings support a developmental and symptom-focused perspective on the relationship between atypical hand preference and psychopathology.
• This research highlights the importance of considering hand preference as a potential indicator within a broader framework of neurodevelopmental and psychiatric conditions.