A kinematic analysis of manual aiming control on euthymic bipolar disorder

Motor deficits in tasks that require force steadiness or scaling of movement velocity have been found in bipolar disorder (BD). A potential explanation for these results is the abnormal functioning of the frontostriatal circuitry. We designed this study to investigate the possible impairments in a manual aiming task. Participants comprised 15 euthymic BD patients and 15 healthy controls, who performed 100 trials of a goal-directed manual movement with a non-inking pen on a digitizing tablet. Four different conditions of execution were required. The control condition appeared on the computer screen in 70% of the trials, and the other three conditions, (a) distractor, (b) inhibition of response and (c) higher index of difficulty, each appeared in 10% of the trials. Compared to the controls, the BD patients were less fluent in their movements, relied more heavily on visual feedback to control their manual movements and presented a lower spatial accuracy. We found that motor deficits in euthymic BD were observed in the kinematic analysis of manual aiming. Our findings are consistent with the hypothesis of abnormal functioning of the frontostriatal circuitry in euthymic BD.