Dichotic listening asymmetry: A Potential Neuro-Behavioural Marker of Depression.

Depression has often been linked with anomalous pattern of hemispheric asymmetry and recent studies provide support that neuro-behavioural measures of hemispheric asymmetry may potentially be used as a marker of depression. With this background the present study examines the nature of hemispheric asymmetry in depression using dichotic listening test. The rhymed fused alphabets were presented in dichotic listening paradigm to clinically, sub-clinically, previously depressed individuals as well as on age and gender matched healthy controls. The findings revealed that all the four groups showed a significant right ear (i.e., left hemispheric) advantage. However, this left hemispheric advantage was less pronounced in depressed groups (clinically and sub-clinically depressed) as compared to depression free groups (previously depressed and normal controls). The observed gradient in the magnitude of left hemispheric asymmetry from depression to no-depression suggests that with increasing severity of depression the individuals tend to show reduced left hemispheric performance and as the symptoms of depression gradually becomes less severe or disappear the left hemispheric performance tend to recover. The findings imply that reduced left hemispheric asymmetry may serve as a potential neuro-behavioural marker of depression. [ABSTRACT FROM AUTHOR]