Nonverbal memory tasks in early differential diagnosis of Alzheimer's disease and unipolar depression

We examined whether there are selective deficits in early-stage Alzheimer's disease (AD; n = 27) and in unipolar depression (UD; n = 17) patients on recall and recognition of spatial and visual components of nonverbal memory (NVM) and whether the two groups can be differentiated based on their performance on such tasks. We also investigated which NVM measures had the best discrimination power. We tested spatial, visuospatial, and visuoconstructive abilities in AD and UD patients. AD patients' scores on NVM tasks were significantly lower than those of healthy subjects (HS; n = 30) and consistently lower than those of the UD group. Z-scores suggested that AD patients suffered from a generalized impairment. Clear differences between AD and UD patients were found on abstract design tasks.