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

Abstract

Several meta-analyses on hand preference in mental and neurodevelopmental disorders have been published in the last decade. Some disorders, like schizophrenia, have been associated with increased rates of atypical hand preference (i.e., non-right-, left-, or mixed-hand preference)—but others, like depression, have not. To identify overarching patterns between hand preference and psychopathology and estimate the influence of potential moderators independent of diagnosis, we need to leverage rich information in the databases of these meta-analyses and conduct a higher level of analysis of meta-analytic data across diagnoses. To this end, we performed a second-order meta-analysis after reviewing, updating, and reanalyzing previously published meta-analyses on hand preference in various mental and neurodevelopmental disorders. In total, this study includes 402 data sets totaling 202,434 individuals. On average, atypical hand preference had a significantly higher frequency in cases compared to controls (nonright odds ratio [OR]: 1.46, 95% CI [1.35, 1.59]; left OR: 1.34, 95% CI [1.22, 1.48]; mixed OR: 1.63, 95% CI [1.38, 1.93]). Further analyses indicated that case–control differences varied with diagnosis. Some diagnoses, like schizophrenia, are associated with a high frequency of atypical hand preference (nonright OR: 1.50, 95% CI [1.32, 1.70]; left OR: 1.37, 95% CI [1.17, 1.61]; mixed OR: 1.70, 95% CI [1.19, 2.44]). Moderator analyses showed that neurodevelopmental conditions, nonneurodevelopmental conditions with an early age of onset, and conditions that include symptoms related to language were all associated with higher rates of atypical hand preference. This finding suggests that the association between handedness and clinical conditions is best understood from a transdiagnostic, developmental, and symptom-focused perspective.