Antithetical asymmetry in schizophrenia and bipolar affective disorder: a line bisection study

Rao NP, Arasappa R, Reddy NN, Venkatasubramanian G, Gangadhar BN. Antithetical asymmetry in schizophrenia and bipolar affective disorder: a line bisection study. Bipolar Disord 2010: 12: 221–229. © 2010 The Authors. Journal compilation © 2010 John Wiley & Sons A/S. Objective: Evolutionary theories link the pathogenesis of psychosis with anomalous brain asymmetry. Research shows that aberrant lateralization is linked to schizophrenia with elevated rates of left‐handedness and reversal of normal cerebral asymmetries. However, lateralization is underexamined in bipolar affective disorder (BPAD) and the available literature suggests the possibility of greater lateralization, which is diametrically opposite to what is observed in schizophrenia. For the first time, we report concurrent analyses of asymmetry in BPAD and schizophrenia using a line bisection task. Methods: We examined 164 subjects (31 patients with BPAD in remission, 30 patients with schizophrenia, and 103 healthy controls) using a two‐hand line bisection task with established methodology. Raters with good inter‐rater reliability (intraclass correlation coefficient > 0.8) measured deviation from the center. Task performance was compared using analysis of covariance with age, sex, and education as covariates. Results: Study groups did not differ significantly on age, sex, and handedness (p > 0.06). Patients (both schizophrenia and BPAD) had significantly more errors in identifying the center than controls (p