Neuropsychological predictors of dependency in patients with Alzheimer disease

Objective: To determine whether specific cognitive deficits can predict the progression of Alzheimer disease (AD). Methods: Two hundred fifty-two patients with AD enrolled in the Predictors Study were followed at 6-month intervals for up to 4.5 years with neurologic, cognitive, and psychiatric examinations. Neuropsychological functions were assessed by the Modified Mini-Mental State Examination (mMMSE). Items of mMMSE were divided into five cognitive domains: temporospatial orientation, short-term memory, long-term memory, language, and visuoconstructive functions. Loss of autonomy was assessed by both the Dependency Scale (DS) and the Equivalent Institutional Care (EIC) rating. Cox proportional hazards models, adjusted for age, sex, estimated duration of illness at entry into the study, and presence of extrapyramidal signs and behavioral disturbances, were used to determine the predictive value of each neuropsychological domain on dependency outcomes. Results: Global mMMSE, temporospatial orientation, and short-term memory scores were associated with a greater relative risk of moderate or severe dependency. The visuoconstructive score predicted the development of severe dependency. Long-term memory and language scores were not predictive of the EIC or DS endpoints. Conclusions: The presence of certain neuropsychological deficits at a patient's initial visit, such as short-term memory, temporospatial orientation, and constructive apraxia, predict more rapid dependency in patients with Alzheimer disease. Neuropsychological items have different weights in term of predictive power, and these effects are independent of the influence of age and disease duration at baseline.