The Effects of Repetition on Memory Performance in Cognitively Impaired Patients

Patients diagnosed with Alzheimer's disease (AD; n = 37), alcohol amnestic disorder (AMD; n = 9), major depression (n = 16), as well as elderly normal volunteers (n = 48), are differentially sensitive to the effects of repetition on memory. Three learning and memory procedures were used to demonstrate that repeated words were more likely to be recalled by elderly normal volunteers than by AD patients. This insensitivity to repetition effects in AD is attributed to an impairment in generating information from semantic memory, which forms the basis of the cognitive context that is used to rehearse and encode to-be-remembered words. In contrast, depressed patients were particularly sensitive to the effects of repetition on recall. AMD patients also recalled more words that were repeated than words that were presented only once, but this effect was attenuated compared with the response expressed in normal volunteers.