Differential neuropsychiatric symptom responses to tacrine in Alzheimer's disease: relationship to dementia severity.

Neuropsychiatric symptom responses to tacrine were investigated in an open-label study of Alzheimer's outpatients. Forty subjects were stratified into three groups (Mild, Moderate, and Severe) based on Mini-Mental State Examination scores. A significant reduction in total Neuropsychiatric Inventory score across all subjects was principally attributable to changes in the Moderate group. Apathy and disinhibition symptoms were significantly reduced overall. Whereas other symptoms showed differential responses in Mild and Severe subjects, all symptoms improved in Moderate subjects. These findings suggest that disease severity may significantly influence neuropsychiatric symptom responses to tacrine. Putative mechanisms underlying the observed pattern of responses are explored.