Studies comparing chronic fatigue syndrome (CFS) and major depressive disorder (MDD) reported similarities as well as differences between the two disorders. However, whereas psychomotor symptoms have been studied extensively in MDD, such research in CFS is more limited. Moreover, the few studies that compared cognitive and motor performance in MDD and CFS yielded inconsistent results. This study hence directly compares fine psychomotor functioning in both syndromes.
Thirty-eight patients diagnosed with CFS without a current major depressive episode (MDE), 32 MDD patients with a current MDE and 38 healthy controls performed two computerized copying tasks differing in complexity: a line-copying task that mainly requires motor effort and a figure-copying task requiring additional cognitive efforts. All participants were female. A multivariate general linear model was used to compute group differences.
Overall, both patient groups performed more slowly than the controls. Compared to CFS patients, patients with MDD needed significantly more time to copy the single lines but no such between-group performance difference was observed for the figure reproductions. In this latter copying task, the increasing complexity of the figures resulted in prolonged reaction times for all three participant groups with the effect being larger and the magnitude similar for the two patient groups.
All patients were female and most were on psychotropic medication.
Both the MDD and CFS patients tested demonstrated an overall fine motor slowing, with the motor component being more affected in the MDD patients than in the CFS patients while both patient groups showed similar cognitive impairments.