Foot Dominance and Minor Physical Anomalies in Schizophrenia. Relations Between Two Biological Markers of Aberrant Neurodevelopment

Abstract

Abstract Background The aim is to investigate the frequency of left foot dominance and minor physical anomalies (MPAs) in patients with schizophrenia and control subjects and to determine the relations between these two biological markers of neuronal dysontogenesis in schizophrenia. Methods A Combined Foot Dominance Scale consisting of two subscales - Chapman & Chapman Foot Dominance Subscale, supplemented with a new Complex Tasks Subscale, containing tasks for measuring spontaneity, precision, strength, and balance - and 7 MPAs were assessed in a sample of 180 subjects (98 schizophrenia patients and 82 controls). We introduced mean left-footedness as a new, more sensitive measure of left foot dominance in detecting a difference between subjects with schizophrenia and control subjects and enabling comparison of the important mean left-footedness sum of a whole foot set. Results Left foot dominance is significantly higher in subjects with schizophrenia. Left foot dominance subjects are more often associated with MPAs. There is a significant positive correlation between left-footedness and MPAs. Dextrality vs. sinistrality is not a categorical variable, but is rather expressed on a continuum due to the very complex bio-psycho-social-cultural influence on its genesis. Conclusions As hand dominance is under cultural pressure, left foot dominance is a useful, reliable, culturally independent indicator of altered hemispheric lateralization. Significant positive correlations between left-footedness and MPAs are an important additional evidence of the neuronal dysontogenesis in schizophrenia. The higher co-occurrence of two biological markers of dysontogenesis - left-footedness and MPAs - in one subject becomes a stronger reliable index of underlying aberrant neurodevelopment.