Italian Multicentre Study on Dementia (SMID): a neuropsychological test battery for assessing Alzheimer's disease.

For the Italian Multicentre Study on Dementia, a longitudinal survey on Alzheimer's disease (AD) initiated in 1982, we developed a neuropsychological test battery for screening, staging and monitoring cognitive impairment in AD patients and for delineating their pattern of cognitive decline. The tests measured higher cortical functions primarily involved in AD, such as short- and long-term memory, orientation, language, and praxis, and spanned a large enough range of difficulty to minimize ceiling and floor effects. We administered this battery to 143 clinically diagnosed AD patients and 146 hospital controls whose scores were corrected for age and educational level. Interrater and test-retest reliability were substantial, as were content and concurrent validity. Five of the battery's subtests proved capable of accurately screening early demented from non-demented elderly subjects and of staging mild, moderate, severe and very severe mental impairment. The mean performance of subjects classified into these categories differed significantly on all cognitive functions tested. Follow-up studies are in progress.