The relationship between non-cognitive symptoms and functional impairment in Alzheimer's disease.

OBJECTIVE: Cognitive impairment is an important determinant for functional impairment in Alzheimer's disease. The role of non-cognitive symptom is uncertain. The objective of this study was to investigate the role of non-cognitive symptoms as predictive factors for functional outcome in A.D.
METHODS: This was a retrospective study. Subjects were recruited from the Memory Clinic in Queen Mary Hospital over a two years period. Patients with diagnosis of probable A.D. by NINCDS-ADRDA were identified. Demographic data, Folstein Mini-Mental Status Examination (MMSE), Clinical Dementia Rating (CDR), Neuropsychiatric inventory (NPI), Barthel activities of daily living (ADL) as well as Lawton's Instrumental activities of daily living (IADL) were retrieved.
RESULTS: 100 patients were identified. Univariate analysis identified statistically significant correlation between hallucination and disinhibition score with Barthel Index (r=-0.43, p <0.001; r=-0.30, p=0.002 respectively); hallucination and aberrant motor act score with Lawton's IADL (r=-0.21, p=0.038; r=-0.21, p=0.038). MMSE was statistical significantly correlated with the above two functional scores. NPI was not statistical significantly correlated with any one of the functional measures. Multivariate regression analyses showed that hallucination score was an independent predictive factors for the Barthel index but not for the Lawton's IADL. MMSE score was identified to be independent predictive factor for all functional measures.
CONCLUSIONS: Global cognitive impairment and hallucination was an important independent predictive factor for functional outcomes. Screening hallucination during the course of A.D. would be helpful. Further studies are needed to show the benefit of treatment of hallucination on the improvement of functional outcomes.