By using a marker for dopamine D2-receptor availability and synaptic dopamine function (11C-raclopride, or RAC), Sawamoto et al. studied subjects with early symptomatic PD and age-matched controls during a spatial working memory task and visuomotor task to determine whether the cognitive impairment in PD results from frontal lobe or striatal dopaminergic dysfunction (37). This evidence concerns the gene DRD2 and Parkinson disease.