Treatment with the drug amantadine hydrochloride improved functional recovery compared with placebo in a clinical trial that involved 184 patients who were in a vegetative or minimally conscious state. Compared with placebo, amantidine treatment resulted in a 0.24 point improvement on the Disability Rating Scale (DRS) during the 4-week active treatment arm. However, in the 2 weeks following treatment, the rate of improvement in the amantadine group was significantly slower than in the placebo group, and no difference was observed in DRS scores between the two groups at the end of the 6-week study.