Which disorder includes parkinsonism without tremor, vivid visual hallucinations, Capgras syndrome, REM sleep behavior disorder, fluctuating attention, and antipsychotic hypersensitivity?

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Lewy body dementia is characterized by a distinctive mix of motor, cognitive, and perceptual symptoms that often overlap with Parkinson’s disease and other dementias. A hallmark is parkinsonism that can appear without prominent tremor, along with well-formed visual hallucinations and fluctuations in attention or alertness. Another common feature is REM sleep behavior disorder, where dream enactment during sleep occurs. Capgras syndrome, a delusion of misidentification, can also appear in Lewy body dementia, reflecting its broad impact on perception and reality testing. In addition, patients tend to be unusually sensitive to antipsychotic medications, with these drugs often causing worsening motor symptoms or confusion.

These features together point to Lewy body dementia rather than a single symptom or a different disorder. Capgras syndrome by itself is just a misidentification syndrome and can occur in various conditions. REM sleep behavior disorder by itself is a sleep disorder and not the defining illness. Antipsychotic hypersensitivity describes a drug reaction pattern, not a disease. Put together, the cluster of parkinsonism without tremor, vivid visual hallucinations, REM sleep behavior disorder, fluctuating attention, and antipsychotic sensitivity best fits Lewy body dementia.