The California Verbal Learning Test and other standard clinical neuropsychological tests to predict conversion from mild memory impairment to dementia

This study describes the neuropsychological assessment of 34 patients with questionable Alzheimer's disease (QAD) followed up for 3 years. Several measures were selected from the California Verbal Learning Test (CVLT) and compared to other cognitive tasks to assess the best neuropsychological indices for (a) detecting early memory impairment in QAD and (b) predicting conversion to AD. Concerning detection, the results indicated that a recall measure depending on semantic categorization (short-delay cued recall) signaled a memory deficit in stable QAD patients, suggesting that episodic and semantic memory problems are involved in the early cognitive impairments of stable QAD patients. However, the conversion to AD was best predicted by the initial performance at the recency index (score reflecting high reliance on working memory), corroborating the idea that AD patients (even at the questionable stage) essentially rely on preserved phonological loop functioning in memory tasks. Finally, an additional impairment in visuospatial memory (Rey's figure) provided a good discriminant value to distinguish converters from stable QAD patients, showing that various cognitive disabilities deteriorate in AD.