Behavioral and Neurophysiological Characteristics of Lewy Body Dementia Implications for Intervention

Abstract:

With the aging of the population, promotion of cognitive health has emerged as a priority in public health. Most notably, Alzheimer's disease (AD) alone remained one of the top 10 causes of mortality throughout the 20th century.1 The public health implications of cognitive status increase dramatically when it is recognized that AD is but one form of cognitive impairment, which, in addition to including several forms of dementia, also encompasses mild cognitive impairment,2 which is often, arguably, a predictor of the emergence of a dementing illness.

Another common form of dementia is Lewy body dementia (LBD). As its name suggests, LBD is characterized by the presence of Lewy bodies— eosinophilic inclusion bodies—in the brainstem and cerebral cortex and has been roughly estimated to comprise about 25% of all dementia cases.3 In this article we examine the behavioral and diagnostic characteristics and neuropathology of LBD, and summarize the latest findings concerning the treatment of this disease.

Studies selected for this review were identified by a search of PubMed for literature referenced to the keywords ‘Lewy body dementia’ or ‘dementia of the Lewy bodies’ and ‘epidemiology.’ In order to ensure the timeliness and clinical relevance of the investigations included, studies selected were limited to those published in the last 10 years featuring human subjects, which were written in English and appeared in core clinical journals (n=39). Furthermore, studies were generally limited to those that largely focused on LBD and provided definitional or diagnostic criteria and a specified interval of observation (n=24), with additional studies being added by expert input.

Results—Behavioral and Diagnostic Characteristics
Although AD is the most common form of dementia in older adults,4 investigators claim that LBD accounts for between 15 and 20% of lateonset cases of dementia.5,6 Part of the prevalence variance may stem from the use of different criteria for the diagnosis of LBD. Diagnostic criteria for LBD have evolved over the years. As summarized by Graham, Ballard, and Saad,7 the Nottingham Criteria for Dementia with Lewy Bodies included dementia having a gradual onset, pronounced deficits in attention or episodes of acute confusion, and parkinsonism (nervous disorders similar to those seen in Parkinson’s disease [PD]), slow or restricted body movements, postural problems, resting tremor, or rigidity.

Contemporary diagnostic criteria delineated in the third report of the Dementia with Lewy Bodies (DLB) consortium include progressive cognitive decline, prominent or persistent memory impairment (typically evident with disease progression), and prominent deficits in tests of attention, visuospatial ability, and executive function as central features essential for the diagnosis of possible or probable DLB. Cognitive fluctuation with marked variations in alertness and attention, recurrent visual hallucinations, and features of parkinsonism are considered core features of DLB, two of which must be present for a diagnosis of probable DLB. Suggestive features of DLB include, among others, rapid eye movement (REM) sleep behavior disorder (RBD) and severe neuroleptic sensitivity. Repeated falls and syncope, severe autonomic dysfunction, and transient, unexplained loss of consciousness are among an array of criteria comprising supportive features of DLB.8

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