Interconnection between Mixed-Handedness, Digit Ratios and Hand and Foot Minor Anomalies in Predicting Schizophrenia

According to the neurodevelopmental theory, brain structuring early markers could be seen in different body parts as minor physical anomalies. Alongside minor physical anomalies, handedness and index to ring finger ratio are brain development indicators, specifically brain lateralization. Studies are consentient about the association of these findings with schizophrenia, though there is inconsistency about individual anatomical regions' contribution. We proposed that handedness in combination with morphological indicators of early brain development could be sensitive and specific in predicting schizophrenia status.

Within the list for the assessment of schizophrenia patients and normal controls of the Caucasian race were seven categorical minor physical anomalies of hand and feet, handedness, and index to ring finger ratio. In this cross-sectional study the examinees were recruited from January 2012 to December 2015.

Forced-entry binary logistic regression model correctly classified 86.5% of patients and 99.2% of the comparison subjects with a 92.8% overall accuracy. Mixed-handedness, hyperconvex fingernails, big gap between 1^st and 2^nd toe, and partial syndactyly of 2^nd and 3^rd toe made a significant independent contribution to the patient-control prediction group status. Furthermore, these items showed a significant correlation with the predictors of the head from the previous study.

Briefly, the limb components, assessed independently of other body regions, proved to be worthy as schizophrenia predictors.