A 65-year-old man has had symptoms of progressive cognitive dysfunction over a 1-year period. Memory and calculation ability are worsening. The patient has also had episodes of paranoia and delusions. Antipsychotic medication resulted in extrapyramidal signs and was stopped. The patient has recently complained of several months of visual hallucinations. There is no history of alcohol abuse.
Which of the following is the most likely diagnosis?
A. Lewy body dementiaLewy body dementia has been recently recognized as a specific type of dementia different from Alzheimer disease or Parkinson disease. On autopsy Lewy bodies are present throughout the brain, including the cortex. Mild Parkinsonism may or may not be present. Paranoia and delusions are more common than in Alzheimer disease, and treatment with antipsychotic drugs characteristically worsens the underlying condition. Visual hallucinations are characteristic of Lewy body dementia and uncommon in Alzheimer disease. Parkinson disease causes dementia late in its course, when the characteristic tremor, bradykinesia, and balance disturbance are easily recognized. Delirium is an acute confusional state that would not present with progressive cognitive deterioration or repeated hallucinations over time. Vascular dementia is characterized by stepwise progression (due to numerous lacunar strokes) and upper motor neuron signs.