Contribution of lewy body inclusions to dementia in patients with and without Alzheimer disease neuropathological conditions

Context: Lewy bodies (LBs) are intraneuronal inclusions in the brain that h ave been increasingly recognized as neuropathological lesions with relevanc e not only to Parkinson disease but also to Alzheimer disease. However, the degree to which the density of LBs in the brain contributes to the severit y of dementia has not been clear. Objective: To determine the degree to which LB "burden" contributes to deme ntia. Design: Brain specimens were examined from 273 consecutive autopsies of eld erly subjects residing in a nursing home. The numbers and densities of LBs were determined in multiple brain regions, and their correlation with a mea sure of cognition and functional status (Clinical Dementia Rating) during t he 6 months preceding death was determined. Setting and Patients: Postmortem study of nursing home residents. Results: The severity of dementia correlated significantly and positively w ith the density of LBs. These correlations were independent of other neurop athological disorders commonly associated with dementia, including Alzheime r disease. The density of LBs correlated significantly with dementia severi ty whether or not the diagnostic criteria for Alzheimer disease were met an d after the contribution of classical Alzheimer disease lesions, neuritic p laques, and neurofibrillary tangles had been accounted for by partial corre lation analysis. Conclusion: Lewy body inclusions appear to contribute significantly to cogn itive deficits in the elderly in a manner that is independent of other neur opathological disorders.