Summary: A recent meta-analysis reveals a significant connection between early-onset neurodevelopmental disorders that include language symptoms and left- or mixed-handedness. Disorders such as dyslexia, autism, and schizophrenia were notably linked to higher instances of non-right-handedness, unlike conditions like depression that emerge later in life.
Researchers believe this correlation stems from shared early brain development processes, since both handedness and language abilities are established during formative years. This underscores how the timing and nature of developmental disruptions can influence handedness in those affected.
Key Facts:
- Increased Left/Mixed-Handedness: Dyslexia, autism, and schizophrenia show significantly higher rates of left-handedness and mixed-handedness.
- Importance of Early Onset: The strongest connections are found in disorders manifesting early in life with language impairments.
- No Connection in Later Disorders: Disorders with later onset, such as depression, do not exhibit this association.
Source: RUB
Linguistic symptoms and early onset: Several neurological disorders, particularly autism spectrum disorders, are often linked with left- or mixed-handedness.
The strong prevalence of left- or mixed-handedness in individuals with specific neurological disorders is a well-documented observation in healthcare.
The reasoning behind this link likely stems from early brain development affecting both handedness and these disorders. Previous studies have examined this connection for various conditions, with mixed results.
An international research team’s meta-analysis—including contributors from Bochum, Hamburg, Nijmegen, and Athens—found that left and mixed-handedness are especially common in individuals facing early-onset disorders with linguistic symptoms, like dyslexia, schizophrenia, and autism.
The team shared their findings in the journal Psychological Bulletin on May 2, 2025.
Symptoms as a Starting Point
The researchers revisited earlier meta-analyses from a fresh viewpoint.
“We wondered if left- and mixed-handedness might be linked to disorders associated with language,” said Dr. Julian Packheiser from the Institute of Cognitive Neuroscience at Ruhr University Bochum.
“Both language and handedness have specific brain locations, suggesting that the development of each, along with their disorders, could be interrelated.”
The team also believed that handedness could correlate with conditions manifesting very early in life, as handedness itself develops at a young age.
“Both of these hypotheses were supported,” noted Professor Sebastian Ocklenburg from the Medical School Hamburg.
For instance, left-handedness and mixed-handedness are statistically more prevalent in dyslexic individuals than in those without the disorder.
Conditions like autism, often accompanied by communication challenges, and schizophrenia, characterized by symptoms like auditory hallucinations, also show a connection to linguistic issues alongside a greater frequency of left-handedness and mixed-handedness.
Relationship Between Handedness and Neurodevelopmental Disorders
Supporting the initial hypothesis, the researchers found that earlier symptom onset correlates with a higher frequency of left and mixed-handedness.
The findings suggest that both handedness and various neurodevelopmental disorders are influenced by overlapping early brain developmental processes.
About This Research on Handedness and Neurodevelopment
Original Research: “Handedness in Mental and Neurodevelopmental Disorders: A Systematic Review and Second-Order Meta-Analysis.” This research highlights that several meta-analyses have explored hand preference across mental and neurodevelopmental disorders over the last decade.
Diagnoses like schizophrenia have shown an association with increased rates of atypical hand preference, while others, including depression, have not exhibited this link.
The study utilized extensive data from previously published meta-analyses, encompassing 402 datasets and over 202,000 individuals.
Results demonstrated that atypical hand preference was considerably more common among cases than controls. Further analysis revealed that differences varied across diagnoses.
Conditions like schizophrenia presented a higher frequency of atypical hand preferences. Moderator analyses indicated that neurodevelopmental disorders and those with early onset and language-related symptoms correlated with increased atypical hand preferences.
This suggests that the association between handedness and clinical conditions is best understood from a developmental and symptom-focused perspective.
