The authors declare that there are no commercial or financial involvements that might present an appearance of a conflict of interest in connection with this paper.
Antithetical asymmetry in schizophrenia and bipolar affective disorder: a line bisection study
Article first published online: 10 MAY 2010
© 2010 The Authors. Journal compilation © 2010 John Wiley & Sons A/S
Volume 12, Issue 3, pages 221–229, May 2010
How to Cite
Rao, N. P., Arasappa, R., Reddy, N. N., Venkatasubramanian, G. and Gangadhar, B. N. (2010), Antithetical asymmetry in schizophrenia and bipolar affective disorder: a line bisection study. Bipolar Disorders, 12: 221–229. doi: 10.1111/j.1399-5618.2010.00811.x
- Issue published online: 10 MAY 2010
- Article first published online: 10 MAY 2010
- Received 17 July 2009, revised and accepted for publication 14 January 2010
- bipolar disorder;
- line bisection;
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 < 0.001). Patients with schizophrenia bisected fewer lines at center than controls and BPAD subjects (p < 0.001). Using their right hand, schizophrenia patients had significant rightward deviation and BPAD patients had leftward deviation (p = 0.001). A significant interaction between diagnosis and direction of deviation (p = 0.01) was noted, with significant rightward deviation in schizophrenia and a trend toward leftward deviation in BPAD.
Conclusions: Study findings suggest attenuation of normal pseudoneglect in schizophrenia and accentuation of normal pseudoneglect in BPAD, indicating lesser lateralization in schizophrenia and possibly greater lateralization in BPAD. From an evolutionary perspective, schizophrenia and BPAD might have antithetical origins.