DEMENTIA WITH LEWY BODIES - A DISTINCT NON-ALZHEIMER DEMENTIA SYNDROME

Lewy body formation is central to the pathological phenotype of a spec trum of disorders, The most familiar of these is the extrapyramidal sy ndrome of idiopathic Lewy-body Parkinson's disease (PD), Studies of de mentia in the elderly suggest that another manifestation of Lewy body pathology is equally or more common than Parkinson's disease, This syn drome of Dementia with Lewy bodies (DLB) has been given a number of di agnostic labels and is characterised by dementia, relatively mild park insonism, visual hallucinations, and fluctuations in conscious level, Although many of these features can arise in Parkinson's disease, the patients with DLB tend to have early neuropsychiatric features which p redominate the clinical picture, and the diagnosis of the syndrome in practice is more concerned with the differential diagnosis of Alzheime r's disease (AD). Distinction from AD has clinical importance because of potentially differing therapeutic implications. Diagnostic guidelin es for the clinical diagnosis and pathological evaluation of DLB are r eviewed, Research into the disorder has centered around characterising the clinical, neuropsychological, pathological, neurochemical and gen etic relationships with Alzheimer's disease on the one hand, and Parki nson's disease on the other, Many cases of DLB have prominent patholog ical features of AD and there are some shared genetic risk factors, Di fferences from the pathology of PD are predominantly quantitative rath er than qualitative and evidence is discussed which suggests that DLB represents a clinicopathological syndrome within the spectrum of Lewy body disorders. The possibility that the syndrome represents a chance association of PD and AD is not supported by published studies.