Scientists have uncovered a potential link between left-handedness and a higher risk of certain neurological and developmental disorders, according to a new study published in Psychological Bulletin. The research, which analyzed data from over 200,000 individuals, found that people who are left-handed are 3.5 times more likely to be diagnosed with autism compared to right-handed individuals. This study also suggests associations between left-handedness and schizophrenia, intellectual disability, and other neurodevelopmental conditions.
The lead author, Dr. Julian Packheiser of Ruhr University Bochum in Germany, explained that the findings highlight how variations in hand preference from the typical right-handed norm may be connected to psychiatric and neurological conditions. For example, dyslexia and schizophrenia are also more common in left-handed individuals. However, he emphasized that the study’s results are correlational, not causal. In other words, while there is a connection between left-handedness and certain conditions, it does not mean that being left-handed causes these disorders.
Dr. Earnest Lee Murray, a neurologist at West Tennessee Medical Group, noted that the brain’s dominant side is typically where language and motor control are processed, and that left-handedness or mixed-handedness may indicate a less centralized language function. He explained that the early development of these brain functions, such as thumb-sucking in the womb, may play a role in determining handedness and its potential links to neurological conditions. However, he added that the study’s results should not be overinterpreted, and more research is needed to understand these connections fully.
The study also examined whether atypical handedness is more common in clinical populations with specific health conditions. In particular, it observed that disorders linked to early language development, such as autism, were more frequently associated with left- or mixed-handedness. The researchers suggested that the connection may be due to the fact that language and handedness are both primarily located in the left hemisphere of the brain. As such, disruptions in this area could affect both developmental processes.
While the study raises important questions about the relationship between handedness and neurological conditions, Dr. Jonathan Alpert, a psychotherapist and author not involved in the research, cautioned that correlation does not imply causation. He stressed that being left-handed does not mean a person is more likely to develop autism or schizophrenia, and that these findings should be interpreted with caution to avoid stigmatization or unnecessary concern. Nonetheless, the study opens up new avenues for research into the ways the brain develops and how these processes might be affected in individuals with certain conditions.