CONSENSUS GUIDELINES FOR THE CLINICAL AND PATHOLOGICAL DIAGNOSIS OF DEMENTIA WITH LEWY BODIES (DLB) - REPORT OF THE CONSORTIUM ON DLB INTERNATIONAL WORKSHOP

Recent neuropathologic autopsy studies found that 15 to 25% of elderly demented patients have Lewy bodies (LB) in their brainstem and cortex , and in hospital series this may constitute the most common pathologi c subgroup after pure Alzheimer's disease (AD). The Consortium on Deme ntia with Lewy bodies met to establish consensus guidelines for the cl inical diagnosis of dementia with Lewy bodies (DLB) and to establish a common framework for the assessment and characterization of pathologi c lesions at autopsy. The importance of accurate antemortem diagnosis of DLB includes a characteristic and often rapidly progressive clinica l syndrome, a need for particular caution with neuroleptic medication, and the possibility that DLB patients may be particularly responsive to cholinesterase inhibitors. We identified progressive disabling ment al impairment progressing to dementia as the central feature of DLB. A ttentional impairments and disproportionate problem solving and visuos patial difficulties are often early and prominent. Fluctuation in cogn itive function, persistent well-formed visual hallucinations, and spon taneous motor features of parkinsonism are core features with diagnost ic significance in discriminating DLB from AD and other dementias. App ropriate clinical methods for eliciting these key symptoms are describ ed. Brainstem or cortical LB are the only features considered essentia l for a pathologic diagnosis of DLB, although Lewy-related neurites, A lzheimer pathology, and spongiform change may also be seen. We identif ied optimal staining methods for each of these and devised a protocol for the evaluation of cortical LB frequency based on a brain sampling procedure consistent with CERAD. This allows cases to be classified in to brainstem predominant, limbic (transitional), and neocortical subty pes, using a simple scoring system based on the relative distribution of semiquantitative LB counts. Alzheimer pathology is also frequently present in DLB, usually as diffuse or neuritic plaques, neocortical ne urofibrillary tangles being much less common. The precise nosological relationship between DLB and AD remains uncertain, as does that betwee n DLB and patients with Parkinson's disease who subsequently develop n europsychiatric features. Finally, we recommend procedures for the sel ective sampling and storage of frozen tissue for a variety of neuroche mical assays, which together with developments in molecular genetics, should assist future refinements of diagnosis and classification.