An estimated 26.7% of patients with Parkinson’s disease experience mild cognitive impairment (MCI), according to a Movement Disorder Society task force report (Litvan et al. Mov Disord 2011; 26: 1814-1824). The estimated point prevalence of MCI is 30%; the estimated cumulative prevalence is >75% for PD patients surviving more than 10 years (Hely et al. Mov Disord 2008; 60: 387-392; Bronnick et al. J Neurol Neurosurg Psychiatry 2006; 77: 1136-1142).