Self-paced and reprogrammed saccades: Differences between melancholic and non-melancholic depression

Motor disturbances in major depressive disorder (MDD) are increasingly recognized and may differentiate melancholic, from non-melancholic depression. Motor impairments in melancholic depression have been likened to Parkinson's disease and proposed to have a frontostriatal basis. This study investigated self-pacing and reprogramming skills, thought to rely on frontostriatal functioning, in groups of healthy individuals (n = 15), non-melancholic depression patients (n = 10) and melancholic depression patients (n = 9) using ocular motor tasks. Self-paced saccades were requested to be performed at a rhythm of I Hz between two continuously illuminated targets, before and after external cueing. Saccade reprogramming, for direction and amplitude, was explored using a saccadic "oddball" task. Results indicated no group differences for accuracy, intersaccadic intervals (during the self-paced task), latency or peak velocity. However, the melancholic group showed greater intrasubject variability of latencies than the control group, lower peak saccade velocities compared to the non-melancholic group, and reduced accuracy of the primary saccade when compared to the control and the non-melancholic groups. These findings provide further support for distinct motor impairments associated with melancholia that may reflect frontostriatal abnormalities. (c) 2006 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.