Handedness patterns in autism suggest subtypes

Area of Science:

• Neurodevelopmental Disorders
• Cognitive Neuroscience
• Behavioral Genetics

Background:

• Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition.
• Handedness variations have been observed in ASD, but require further investigation.
• Understanding these variations may offer insights into underlying brain structure and function.

Purpose of the Study:

• To investigate the incidence of non-right-handedness in autistic individuals.
• To characterize handedness phenotypes (e.g., left-handedness, ambiguous handedness) in ASD.
• To explore the association between handedness phenotypes and cognitive functioning in autism.

Main Methods:

• Utilized a comprehensive assessment procedure with numerous items for autistic subjects (children and adults).
• Administered assessments across multiple sessions, spaced one week apart, accommodating lower-functioning individuals.
• Analyzed handedness distribution and correlated phenotypes with intellectual scores in two autistic samples.

Main Results:

• A significant shift away from right-handedness was observed in both autistic samples.
• Increased incidences of manifest left-handedness and ambiguous handedness were identified.
• Ambiguously handed individuals exhibited significantly lower intellectual scores in one sample, suggesting potential bilateral central nervous system (CNS) pathology.

Conclusions:

• Autism Spectrum Disorder is characterized by a notable deviation in handedness distribution towards non-right-handedness.
• Manifest left-handedness and ambiguous handedness are key phenotypes in this shift.
• Ambiguous handedness may serve as a marker for impaired cognitive functioning and potential early brain injury in some autistic individuals.