Effects of caffeine on the freezing of gait in Parkinson's disease.

Caffeine is a nonselective competitive blockade of adenosine A1 and A2A receptors. In this report, we studied the efficacy of 100 mg of caffeine per day on the freezing of gait (FOG) for patients with Parkinson's disease. Different subtypes of FOG showed different therapeutic responses to caffeine. Caffeine improved "total akinesia" type of FOG, but had no effect on "trembling in place." Tolerance developed to the beneficial effect of caffeine on FOG within a few months, but a 2-week caffeine withdrawal period could restore the effect of caffeine.