Introduction

“Lewy bodies” are proteinaceous intraneuronal inclusions that were first described by F. H. Lewy in 1912 in neurons of the basal forebrain and thalamus of patients with Parkinson's disease (PD) (Lewy, 1913). More than eight decades after Dr. Lewy's original report, international consensus criteria (see Table 33.1) were created that formally acknowledged the existence of a syndrome of dementia with parkinsonism associated with LBs in other brain areas such as the limbic system and neocortex (McKeith et al., 1996). This condition, known as Dementia with Lewy bodies (DLB), is now recognized to be the second most common cause of neurodegenerative dementia in older adults. Lewy body neuropathology is found in the brains of 15% to 28% of dementia patients that undergo autopsy (Jellinger, 2003; Rahkonen et al., 2003), and DLB accounts for nearly half as many cases of dementia as Alzheimer's disease (Barker et al., 2002). Despite its considerable prevalence and morbidity, DLB is a relatively unknown entity to a large segment of the general public as well as many physicians.

In its most recognizable form, DLB presents as a hypokinetic movement disorder associated with progressive cognitive decline. Other core features include delirium-like fluctuations of attention/arousal, autonomic and sleep disturbances as well as idiosyncratic delusions and hallucinations. While the clinical features of DLB can resemble those of Alzheimer's and Parkinson's disease, possible demographic distinctions have been reported among these disorders. In one autopsy series, DLB was found to be over-represented in men relative to women (Rahkonen et al., 2003), the reverse of the gender ratio generally observed for Alzheimer's disease.