In several retrospective post-mortem studies, patients meeting clinical criteria for Alzheimer's disease (AD) who gained the greatest cognitive benefit from treatment with an acetylcholinesterase (AChE) inhibitor were found to have neocortical Lewy bodies accompanying classical AD neuropathology. This 'dementia with Lewy bodies' (DLB) subtype manifests both parkinsonian and psychopathologic features that set it apart from 'pure' AD (hereafter called AD). In the present preliminary study, 16 dementia patients were prospectively categorized as having DLB versus AD. Subjects were also categorized according to their profile on surface electromyographic (EMG) measures demonstrated in prior work to be analogues of clinically observed parkinsonian extrapyramidal signs (EPS). All patients were prescribed the AChE inhibitor donepezil (5 mg per day). At baseline and at 6 months, patients underwent cognitive testing with the Mini-Mental State Examination (MMSE) while caregivers assessed their psychopathologic status using the Behavioral Symptoms in Alzheimer's Disease (BEHAVE-AD) scale. The tester was blinded to the AD versus DLB classification of the patients. AD cases (N=12) had only a slight increase in cognitive scores, while DLB patients' (N=4) mean MMSE scores increased to a significantly greater degree. Furthermore, patients categorized by EMG as EPS positive (N=8) attained an increase in their mean MMSE score from baseline to 6 months that differed significantly from a decline in MMSE observed among their EPS negative (N=4) counterparts. For all subjects, an increase in MMSE scores across 6 months of treatment correlated with a decline in BEHAVE-AD scores.
Copyright 2000 John Wiley & Sons, Ltd.