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Objective: Limb apraxia is a common early sign of Alzheimer’s disease (AD) and is thought to occur specifically in early-onset (before the age of 65) AD. The Dementia Apraxia Test (DATE), a test of limb and face praxis developed to support the differential diagnosis of dementia, has shown good diagnostic accuracy in detecting AD in older patients, but it has not been validated for younger age groups. We investigated how accurately DATE can detect AD in middle-aged individuals and whether apraxia is a distinctive feature in early-onset AD. Method: A sample of mild-stage AD patients (n = 24; Mage = 61, SD = 4) was drawn from a prospective consecutive series of individuals referred to our neurology clinic for dementia investigations. A healthy comparison group (HC) of comparable age (n = 22; Mage = 61, SD = 7), sex distribution, and education was recruited. DATE was administered as a blinded experimental measure, and a receiver operating characteristic (ROC) analysis was used to define the optimal diagnostic cutoff point. Results: The DATE classified 93% of the participants correctly as AD or HC (sensitivity 0.88, specificity 1.00, area under curve 0.968). The optimal diagnostic cutoff point was higher (49 points) than in a previous sample of older patients (45 points). Early onset did not seem to be associated with worse praxis performance in AD. Conclusions: DATE is an accurate tool for detecting early-onset AD within 2 years of symptom onset. The diagnostic cutoff point should be higher for middle-aged populations than for late-onset AD.

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