Neuropsychiatric symptoms, functional impairment and executive ability in Thai patients with Alzheimer's Disease

Background: Instrumental activities of daily living (IADL) depend on executive planning and procedural memory mediated by the frontal lobes. Planning and judgment are involved in clock drawing. Neuropsychiatric symptoms are also mediated by frontal lobes, and a relationship between ADL, clock drawing and neuropsychiatric symptoms was hypothesized. Objective: To investigate the relationship between behavioral disturbances, ADL, and executive function. Methods: Seventy-three Thai patients with Alzheimer's disease (AD) were evaluated. Neuropsychiatric symptoms and behaviors were assessed with the Nevropsychiatric Inventory (NPI). The Thai version of the Mini-mental State Examination (TMSE) was utilized as a global cognitive assessment. A clock-drawing test (CDT) and both category (animals) and letter (ko, so in Thai) verbal fluency were used as executive measures. Thai ADL scale, Barthel Index (BI), and Functional Assessment Questionnaire (FAQ) were ADL measures used in this study. Results: There were statistically significant correlations between CDT and the frontally-mediated behaviors of agitation (r=−0.367), apathy (r=−0.273) and disinhibition (r=−0.247). Verbal fluency correlated with agitation (r=−0.341). There were significant correlations between Thai ADL scores and agitation (r=0.350), apathy (r=0.441), and disinhibition (r=0.417). FAQ correlated with the same three behaviors. After controlling for TMSE, a significant correlation remained between Thai ADL scores and agitation (r=0.291) and apathy (r=0.342). Conclusions: We demonstrated correlations between ADL and behavioral changes in Thai elderly with AD. Our results emphasize the important relationships among behavioral changes and impaired ADL.