Psychomotor disturbance in depression: Assessment using a driving simulator paradigm

Background: Psychomotor disturbance is an essential feature of Major Depressive Disorder (MDD) and has been associated with impaired functioning on cognitively demanding tasks. Given the psychomotor demands required to navigate a motor vehicle and the disastrous effects of motor vehicles accidents, patients with MDD present a population of clinical interest. The goal of this investigation was to examine the association between MDD and driving ability assessed within a simulated driving paradigm. Methods: 18 outpatients currently meeting diagnostic criteria for MDD and 29 control participants completed four 30-min simulated driving trials at 10:00 am, 12:00 pm, 2:00 pm, and 4:00 pm. Participants also completed the Beck Depression Inventory (BDI) to assess for depression severity and the Epworth Sleepiness Scale (ESS) to assess for everyday sleepiness. Results: After controlling for age and sleepiness, the depressed sample exhibited slower steering reaction times across trials (p <.05) and an increased number of crashes across trials (p <.05) when compared to controls. These differences were characterized by a medium effect size. No significant time-of-day effects were found. Limitations: MDD patients were free of anti-depressant medication and findings may not generalize to medicated populations. Also, a rural highway driving route was used which may not generalize well to urban driving settings. Conclusions: Patients with untreated MDD demonstrate impaired simulated driving performance. Further research into whether these findings translate into on-the-road impairment is important for public health and safety. (c) 2006 Elsevier B.V. All rights reserved.