Cognitive differences in dementia patients with autopsy-verified AD, Lewy body pathology, or both

Abstract

Objective: To examine the neuropsychological profile of dementia patients from a community-based autopsy sample of dementia, comparing Alzheimer disease (AD), Lewy body pathology (LBP) alone, and LBP with coexistent AD (AD/LBP).

Methods: The authors reviewed 135 subjects from a community-based study of dementia for whom autopsy and brain tissue was available. Diagnostic groups were determined according to standard neuropathologic methods and criteria, and the presence of LBs was determined using alpha-synuclein immunostaining. Neuropathologically defined diagnostic groups of AD, AD/LBP, and LBP were examined for differences on neuropsychological test performance at the time of initial study enrollment.

Results: There were 48 patients with AD alone, 65 with LB and AD pathology (AD/LBP), and 22 with LBP alone (LBP alone). There were no significant differences between groups demographically or on performance of enrollment Mini-Mental State Examination (MMSE) or Dementia Rating Scale (DRS). AD patients performed worse than the LBP patients on memory measures (Fuld Object Memory Evaluation Delayed Recall, Wechsler Memory Scale Logical Memory Immediate and Delayed Recall; p < 0.05) and a naming task (Consortium to Establish a Registry for Alzheimer's Disease Naming; p < 0.05). LBP patients were more impaired than AD patients on executive function (Trail Making Test Part B; p < 0.05) and attention tasks (Wechsler Adult Intelligence Scale-Revised Digit Span; p < 0.05). Decline in MMSE and DRS scores over time were greatest in the patients with AD/LBP.

Conclusions: In a community-based sample of older, medically complicated patients with dementia, there are neuropsychological differences between dementia subtypes at the time of diagnosis. In particular, patients with Alzheimer disease (AD) alone and AD/Lewy body pathology (LBP) had more severe memory impairment than patients with LBP. LBP alone was associated with more severe executive dysfunction. Patients with AD/LBP had the most rapid rate of cognitive decline.

Figure

(A) Repeated follow-up change in cognitive testing scores (Dementia Rating Scale [DRS]). Change in DRS scores over time. Decline (points/year) was calculated by subtracting final scores from initial scores and dividing by the number of years the patient was followed. Patients with Alzheimer disease (AD)/Lewy body pathology (LBP) had a significantly greater rate of decline (p < 0.05) than both AD and LBP patients. *p < 0.05. (B) Repeated follow-up change in cognitive testing scores (Mini-Mental State Examination [MMSE]). Change in MMSE scores over time. Decline (points/year) was calculated by subtracting final scores from initial scores and dividing by the number of years the patient was followed. AD/LBP patients had a significantly greater rate of decline (p < 0.05) than both AD and LBP patients. *p < 0.05. †This finding is reduced to p < 0.07 with the removal of patients in the AD/LBP group who have LBP restricted to the amygdala.