• Left- and mixed-handedness are more prevalent in individuals with early-onset neurodevelopmental disorders characterized by language impairments.
• The association is strongest in disorders like autism, dyslexia, and schizophrenia, suggesting a shared developmental origin in the brain.
• No significant correlation was found between handedness and later-onset disorders such as depression.

A recent meta-analysis conducted by an international research team has revealed a significant association between left- and mixed-handedness and the occurrence of early-onset neurodevelopmental disorders that involve language impairments. The study, published in the journal Psychological Bulletin on May 2, 2025, analyzed numerous datasets and found that conditions like autism, dyslexia, and schizophrenia are more common in individuals who are not right-handed. Researchers suggest that this connection stems from overlapping processes during early brain development that influence both handedness and language skills. The findings offer insights into the neurodevelopmental origins of these disorders.

• What: A meta-analysis found that left- and mixed-handedness are more common in individuals with early-onset neurological disorders characterized by language impairments, such as autism, dyslexia, and schizophrenia.
• Who: The research team included members from Ruhr University Bochum, Medical School Hamburg, Radboud University Nijmegen, and National and Kapodistrian University of Athens, led by Dr. Julian Packheiser and Professor Sebastian Ocklenburg.
• When: The meta-analysis was published in the journal Psychological Bulletin on May 2, 2025. The research considered disorders with symptom onset early in life.
• Where: The research was conducted by an international team from Bochum, Hamburg, Nijmegen, and Athens.

The meta-analysis provides a comprehensive overview of the connection between handedness and neurodevelopmental disorders. The research suggests that the association is primarily driven by early-onset disorders with language impairments, indicating a shared developmental pathway in the brain. This finding challenges previous assumptions and highlights the importance of considering the timing and nature of developmental disruptions when studying handedness and psychopathology. The research did not find a correlation between handedness and late-onset disorders, which further supports the theory of shared early brain development processes.

We suspected that left- and mixed- handedness could be associated with disorders whose symptoms are related to language. Language, like handedness, has a very one-sided location in the brain, so it stands to reason that the development of both and their disorders could be linked.

Both hypotheses have been confirmed.

In people with depression, which on average occurs around the age of 30, we couldn’t show any connection.

The meta-analysis provides strong evidence for a link between left- and mixed-handedness and early-onset neurodevelopmental disorders with language impairments. The findings suggest that shared developmental processes in the brain contribute to this association. While the study clarifies the relationship between handedness and certain disorders, further research is needed to fully understand the underlying mechanisms and potential implications for diagnosis and treatment. The absence of a link with later-onset disorders further emphasizes the importance of early brain development in shaping handedness and its relationship to neurological conditions. Future studies could explore the specific genetic and environmental factors that influence both handedness and brain development.