Mild cognitive deficits in Parkinson disease

Abstract

In this issue of Neurology ®, Aarsland et al.1 demonstrate that among patients with Parkinson disease (PD) without dementia, mild cognitive impairment (MCI) is common. These data are consistent with recent investigations emphasizing the nonmotor aspects of PD. When James Parkinson2 first described PD as the “shaking palsy” in 1817, he focused on motor symptoms and described the “intellects” as “uninjured.” Approximately 10 years later, Wilhelm von Humboldt began writing detailed descriptions of his own PD symptoms that included micrographia and veiled references to fluctuating attention.3 When he died, his doctors described his intellect as “undisturbed.” It was not until the latter part of the 20th century that investigators began to address nonmotor symptoms of PD, including specific cognitive changes.4 Most clinicians in current practice acknowledge the possibility of cognitive changes in PD, but focus on motor manifestations until more severe decline, or dementia, cannot be ignored. Studies addressing mild cognitive changes have emphasized deficits in complex attention, executive functions (e.g., initiation, planning, speed of processing),5,6 visuoconstructive skills, and memory, prompting use of the term MCI to characterize a predementia stage. Recognizing these relatively mild …