Decreased daytime motor activity associated with apathy in Alzheimer disease: an actigraphic study.

Objective: Across all stages of Alzheimer disease (AD), apathy is the most common neuropsychiatric symptom. Studies using the Neuropsychiatric Inventory (NPI) have found that apathy is present in up to 70% of individuals with Alzheimer disease. One of the main difficulties in assessing apathy and other neuropsychiatric symptoms is the absence of reliable, objective measures.