OBJECTIVE: This investigation was undertaken to clarify the neuropathological substrates of key psychiatric symptoms in dementia with Lewy bodies. METHOD: The authors studied 112 autopsy-confirmed cases of dementia with Lewy bodies in patients who had had annual standardized clinical evaluations until their death. The relationships of persistent psychiatric symptoms (visual hallucinations, delusions, depression) to plaques (Consortium to Establish a Registry for Alzheimer's Disease protocol), tangles (Braak staging), and Lewy bodies (consensus Lewy body staging) were evaluated. In addition, symptom frequency and persistent symptoms were compared in the patients with Lewy body dementia and 90 patients with autopsy-confirmed Alzheimer's disease studied prospectively during life. RESULTS: The main neuropathological correlate of persistent visual hallucinations was the presence of less severe tangle pathology, but there was no significant association between tangle pathology and persistent delusions. Lewy body staging was associated with the presence of persistent visual hallucinations and persistent delusions. All baseline psychiatric features were significantly more frequent in dementia with Lewy bodies than in Alzheimer's disease, as were persistent visual hallucinations, but patients who had dementia with Lewy bodies and severe tangle pathology had a clinical symptom profile more similar to that of Alzheimer's disease patients and were less likely to have neocortical Lewy bodies. CONCLUSIONS: The modest proportion of patients with Lewy body dementia and more severe tangle pathology resembled Alzheimer's disease patients clinically. Unlike Alzheimer's disease, dementia with Lewy bodies showed a significant inverse association between tangle burden and psychosis.