Dementia with Lewy bodies (DLB) is increasingly recognized clinically as the second most common type of degenerative dementia after Alzheimer disease (AD). In addition to dementia, distinctive clinical features include: visual hallucinations, parkinsonism, cognitive fluctuations, dysautonomia, sleep disorders, and neuroleptic sensitivity.
First described in the 1960s, DLB has a varied clinical presentation that shares features with other degenerative dementias. It was often overlooked pathologically because of the difficulty in identifying cortical Lewy bodies with routine cellular stains. With the advent of immunohistochemical stains for constituents of Lewy bodies, the prevalence of this disorder began to be recognized. However, challenges remain in defining this as an entity distinct from other degenerative dementias.
DLB may represent several diseases with the shared common finding of cortical Lewy bodies, or it may be a single disease with a spectrum of additional pathological features. This is reflected by the varied names by which it has been called, including diffuse Lewy body disease, Lewy body dementia, Lewy body variant of Alzheimer disease, cortical Lewy body disease, and senile dementia of the Lewy body type.
This topic will describe the epidemiology, neuropathologic findings, and potential pathogenic mechanisms of dementia with Lewy bodies. The clinical features, diagnosis, prognosis, and treatment are discussed separately. (See "Clinical features and diagnosis of dementia with Lewy bodies" and "Prognosis and treatment of dementia with Lewy bodies".)
In population-based and clinic-based studies, dementia with Lewy bodies (DLB) accounts for approximately 4 to 30 percent of dementia cases [1,2]. DLB was likely underrepresented in many of these studies, however, most of which were not specifically designed to identify the prevalence of DLB and did not include mention in the methods of the evaluation of signs and symptoms, such as extrapyramidal signs or fluctuations, that would have increased the likelihood of diagnosing DLB . Autopsy series have also found DLB to represent a greater percentage of dementia cases than is typically reported in clinical series, with DLB comprising as much as 31 percent of cases in one study [3,4].