text: Cognitive and Neuropsychiatric Features in Parkinson's and Lewy Body Dementias.
  Cognitive impairment and neuropsychiatric symptoms affect a substantial number of individuals with Parkinson's disease (PD). These non-motor changes can occur at all stages of disease, often years before motor symptoms manifest in some patients while occurring much later in the disease process for others. Lewy bodies are the hallmark of PD, yet not all patients with PD follow the same course or present in the same way clinically, either from a motor or non-motor standpoint. This has implications on assessment, intervention, and planning for the future. This review will focus on the cognitive and neuropsychiatric features of Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), with emphasis on neuropsychological findings. Differentiation between these dementia syndromes and other atypical parkinsonian syndromes will be mentioned only briefly, as the latter are covered in detail elsewhere in this issue. Neuropathologic, laboratory and radiographic findings will be presented, and recommendations for neurobehavioral assessment and treatment will be provided.