The progression of cognition, psychiatric symptoms, and functional abilities in dementia with Lewy bodies and Alzheimer disease

Background: Although dementia with Lewy bodies (DLB) may be one of most common forms of dementia, relatively little is known about its cognitive and functional course. Objective: To compare change over time in general cognitive status,memorytest performance, psychiatric symptoms, neurological signs,andfunctional abilities in patients with probable DLB and probable Alzheimer disease (AD). Design: Twenty-eight patients who met diagnostic criteria for DLB were recruited into the study from 3 sites. Patients with AD (n=55) were selected from a larger cohort and matched 2 to 1 to the patients with DLB on age and baseline global cognitive status. Patients were followed up at 6-month intervals for an average of 6.2 visits and assessed at each visit with tests of global cognitive functioning and verbal learning and memory and measures of psychiatric, neurological, and functional status. Results: At the baseline evaluation, patients with DLB performed more poorly on a measure of constructional praxis and all measures of functional status. They also had more severe psychiatric symptoms and neurological signs than the AD group. Despite these initial differences, generalized estimating equations applied to regression analyses with repeated measures determined that the only difference between the 2 groups in change in cognitive test performance was on a measure of recognition memory; patients with AD declined, while patients with DLB remained relatively stable. Patients with DLB had relatively stable behavioral symptoms and visual illusions, whereas patients with AD had a significant increase in these symptoms over time. Neurological and functional changes over time were similar in the 2 groups. Conclusions: Both baseline and longitudinal differences between patients with DLB and patients with AD were noted; these have implications for clinical diagnosis and treatment.