Purpose of review: While the distinctive motor symptoms of Parkinson disease (PD) have been described for centuries, cognitive impairment has only recently been recognized as a central feature. Studies have yielded clues to the etiology and natural history of cognitive impairment in PD, but much remains unclear and effective therapies are needed. Recent findings: Longitudinal cohort studies demonstrate that almost all patients with PD will develop dementia if they live long enough. New CSF biomarker and genetic studies suggest that it may soon be possible to forecast and track the progression of dementia in PD. Sleep and sleep disturbance appear to be intrinsically linked with PD, although the implications for individual outcomes and opportunities for intervention are unclear. Multidisciplinary treatment approaches incorporating cognitive training may help to improve outcomes. Summary: We review several recent advances in understanding the pathophysiology, genetics, and management of cognitive impairment in PD. Neurol Clin Pract 2016;6:452-458 C ognitive impairment is a disabling comorbidity for many patients with Parkinson disease (PD) and represents a major challenge for physicians, caregivers, and the health care system.Prevalence and natural history of PD dementia: Near-universal prevalence and progression Clinical features of cognitive impairment in PD involve a wide range of cognitive domains, including executive function, visuospatial reasoning, memory, and language function, and can include additional features including visual hallucinations, paranoia, and fluctuations in attention.1 PD is often marked primarily by visuospatial and executive deficits, in contrast to Alzheimer disease (AD), where memory impairment predominates. Cognitive impairment in PD encompasses a spectrum of severity from relatively mild symptoms to end-stage