A quantitative neuromotor predictor of antidepressant non-response in patients with major depression

Predicting response to antidepressant medication has been a challenge to clinicians and researchers for decades. Attention has been paid to the role of motor retardation as a putative indicator of treatment response, yet previous findings have been mixed. One reason for this inconsistency may be related to the subjective nature of motor retardation and how it is assessed. In the present study, we adopted a measure of motor programming previously shown to characterize parkinsonian bradykinesia to test whether neuromotor function could predict response to antidepressant treatment. Twenty-eight patients (14 males and 14 females with a mean age of 42.0 years) meeting DSM-IV criteria for a depressive disorder were randomized to receive 8 weeks of treatment with one of three antidepressant medications (sertraline, phenelzine, or bupropion). Treatment outcomes were assessed using the 17-item version of the Hamilton Rating Scale for Depression (HRSD). Patients were considered asymptomatic if their post-treatment HRSD total score was equal to or less than 7. Treatment responders (n=15) had significantly less baseline impairment (P=0.01) on the neuromotor measure than non-responders (n=13). There was a significant relationship between amount of improvement on the HRSD and severity of baseline neuromotor function (r=-0.51; P=0.006). No significant group effects were found for baseline psychomotor slowing or clinical ratings of motor retardation. These results demonstrate that a quantitative measure of motor programming may be a useful predictor of antidepressant non-response.