Caffeine for Motor Manifestations of Parkinson's Disease

Numerous epidemiological studies have linked lifelong use of caffeine to a lower risk of Parkinson's disease (PD) - prospective studies have estimated that non-coffee drinkers have an approximately 1.7-2.5 fold increased risk of developing PD compared to coffee drinkers. This is an extremely important finding which deserves further more in depth investigations. The exact pathophysiological mechanism remains elusive, but multiple hypotheses do exist: Caffeine antagonizes adenosine receptors directly yielding an improvement on motor systems and even on Levodopa serum concentrations (when on therapy). An additional explanation is that adenosine antagonism has neuroprotective properties by acting locally on basal ganglia circuits and the substantia nigra. The current study aims to identify the optimal caffeine dose with maximal motor benefit and the least amount of undesirable adverse effects.