L-dopa does not add to the success of high-intensity language training in aphasia

Purpose: L-dopa has been shown to improve outcome of moderate-intensity language training after stroke in acute aphasia. Given the critical role of training intensity we probed the effect of l-dopa in combination with high-intensity language training in chronic post-stroke aphasia. Methods: In this prospective, randomized, placebo-controlled, double-blind study, aphasia patients (>1 year post stroke) were administered 100/25 mg of l-dopa/carbidopa or placebo daily prior to four hours of language training for two weeks. Conditions were crossed-over after a wash-out period of 4 weeks. Results: An a-priori planned interim analysis (n = 10) showed that naming performance and verbal communication improved significantly and persistently for at least 6 months in every patient, but l-dopa had no incremental effect to intensive training. Conclusion: High-intensity language training in chronic aphasia may take learning to a ceiling that precludes additive benefits from l-dopa. Effects of l-dopa on post-stroke recovery during less intense treatment in chronic aphasia remain to be evaluated.