Working memory and secondary memory deficits in Alzheimer's disease.

The memory loss associated with Alzheimer's Disease (AD) may have multiple cognitive components. Working Memory appears to be impaired due to failures of a Central Executive System. Secondary Memory, on the other hand, is affected due to poor encoding or mediational processes. An analysis of the performance of 71 AD patients on tests related to these neuropsychological constructs revealed that they could indeed be dissociated. In fact, individual patients were identified with significantly different, and unique, patterns of impairment which were consistent with the two-component model. These data, therefore, lend preliminary support for the notion of multiple cognitive impairments being responsible for the memory loss in AD.