Increased persuadability and credulity in people with corpus callosum dysgenesis.

Corpus callosum dysgenesis is one of the most common congenital neurological malformations. Despite being a clear and identifiable structural alteration of the brain's white matter connectivity, the impact of corpus callosum dysgenesis on cognition and behaviour has remained unclear. Here we build upon past clinical observations in the literature to define the clinical phenotype of corpus callosum dysgenesis better using unadjusted and adjusted group differences compared with a neurotypical sample on a range of social and cognitive measures that have been previously reported to be impacted by a corpus callosum dysgenesis diagnosis. Those with a diagnosis of corpus callosum dysgenesis (n = 22) demonstrated significantly higher persuadability, credulity, and insensitivity to social trickery than neurotypical (n = 86) participants, after controlling for age, sex, education, autistic-like traits, social intelligence, and general cognition. To explore this further, we examined the covariance structure of our psychometric variables using a machine learning algorithm trained on a neurotypical dataset. The algorithm was then used to test whether these dimensions possessed the capability to discriminate between a test-set of neurotypical and corpus callosum dysgenesis participants. After controlling for age and sex, and with Leave-One-Out-Cross-Validation across 250 training-set bootstrapped iterations, we found that participants with a diagnosis of corpus callosum dysgenesis were best classed within dimension space along the same axis as persuadability, credulity, and insensitivity to social trickery, with a mean accuracy of 71.7%. These results have implications for a) the characterisation of corpus callosum dysgenesis, and b) the role of the corpus callosum in social inference.