Summary

Recent clinico-neuropathological studies have shown that approximately 25% of patients who manifest a syndrome similar to dementia of the Alzheimer type during life have diffuse Lewy body disease (DLBD), a condition characterized by neocortical and subcortical Lewy body pathology that occurs, in many cases, along with the typical cortical distribution of senile plaques and neurofibrillary tangles associated with Alzheimer's disease (AD). Studies of the neuropsychology of this disorder demonstrate that DLBD, without concomitant AD, can produce a global dementia characterized by particularly pronounced deficits in memory (i.e. retrieval), attention, visuospatial abilities and psychomotor speed. When both DLBD and AD pathology is present, patients exhibit severe deficits in memory, language, and executive functions, most likely due to the severe hippocampal and neocortical damage that occurs in AD, as well as particularly severe deficits in visuospatial abilities, attention, and psychomotor processes, which may reflect the additive effects of Lewy body pathology. This pattern of neuropsychological deficits has also been observed in recent prospective studies of patients with clinically diagnosed DLBD, and may prove to be an important addition to the diagnostic criteria for DLBD.

Introduction

Recent clinico-neuropathological studies have shown that approximately 25% of patients who manifest a syndrome similar to dementia of the Alzheimer type during life have Lewy bodies diffusely distributed throughout the neocortex (for review, see Hansen & Galasko, 1992). This cortical Lewy body pathology occurs along with the typical subcortical changes of Parkinson's disease (i.e. Lewy bodies and cell loss) in the substantia nigra and other pigmented brainstem nuclei, and in many cases with the typical cortical distribution of senile plaques and neurofibrillary tangles associated with Alzheimer's disease (AD) (Hansen et al., 1990).