Definition and diagnosis of dementia with Lewy bodies

Significant advances have been made in neuropathologic identification procedures for dementia with Lewy bodies (DLB), but difficulties remain in clinical diagnosis. Consensus criteria state that the core features of DLB are fluctuating cognition with pronounced variation in attention and alertness, recurrent visual hallucinations and spontaneous motor features of parkinsonism. At least two of these features must be present for the diagnosis of probable DLB. Assessments of the validity of the consensus criteria against autopsy generally indicate high specificity but varying sensitivity. More detailed assessments of core diagnostic features or better operationalization, particularly of fluctuating cognition, may help improve the diagnostic guidelines. Greater utilization of some features described as supporting the diagnosis (such as auditory hallucinations) and the potential inclusion of additional symptoms (such as REM sleep behavioral disorder) also may be useful. In addition, the potential role of more detailed neuropsychology and neuroimaging in the diagnostic process needs to be evaluated, although it is important that changes to the diagnostic criteria are based on empirical evidence. Other key issues pertain to the classification of DLB patients with concurrent Alzheimer's disease and the differentiation of DLB and Parkinson's disease dementia based on less than a 1-year history of parkinsonism preceding the dementia.