Dementia can occur in a substantial number of patients with Parkinson's disease with a point prevalence close to 30%. The cognitive profile is characterized by predominant deficits in executive, visuospatial functions, attention and memory. Behavioral symptoms are frequent such as apathy, visual hallucinations and delusions. The most prominent associated pathology is Lewy body-type and biochemical deficit is cholinergic. Placebo-controlled randomized trials with cholinesterase inhibitors demonstrated modest but significant benefits in cognition, behavioral symptoms and global functions. (C) 2017 Elsevier B.V. All rights reserved.