Snapshot A 67-year-old man is brought to the neurologist by his wife for bizarre behaviors. She said that at times he would be difficult to understand and disorganized. He also said that he has seen animals on top of the television which was disturbing for him. He would speak in his sleep. Physical examination is notable for postural instability and upper extremity rigidity. Introduction Definition progressive dementia characterized by fluctuating cognition visual hallucinations parkinsonism REM sleep disorder Epidemiology Incidence second most common type degenerative dementia Etiology Lewy bodies Pathogenesis accumulation of Lewy bodies and α-synuclein Presentation Symptoms/physical exam cognitive dysfunction early findings impaired attention, executive, and visuospatial function flucuating cognition visual hallucinations people, animals, shapes, or colors REM sleep behavior disorders dream enactment parkinsonism bradykinesia and akinesia rigidity gait disorder resting tremor is rare antipsychotic sensitivity taking antipsychotics lead to severe parkinsonism and unresponsiveness autonomic dysfunction Studies Making the diagnosis this is a clinical diagnosis Histology eosinophilic intracytoplasmic inclusions (Lewy bodies) also contain aggregated α-synuclein Differential Alzheimer disease differentiating factors memory loss is an early, prominent feature Treatment Medical acetylcholinesterase inhibitors indication recommended for vascular dementia medications donepezil galantamine rivastigmine Complications Major depression