The purpose of this longitudinal investigation is to examine the decline of communication across the course of Alzheimer's Disease (AD) as a manifestation of deterioration in cognitive and neurological status. In addition, relationships between communication and deficits in memory, mortality, and alterations in neural tissue will be examined. As yet, no battery has been developed evaluating the breadth of communication deficits in Alzheimer's dementia. Theoretical views of language have shown a dramatic shift from a formalist linguistic to a functionalist pragmatic perspective. This new view holds that pragmatics rather than syntax is central to the language system. This perspective is particularly relevant to the study of Alzheimer's Disease in that the decline in pragmatics appears critical in loss of communication in these patients. This investigation presents a departure from previous research and offers significance in three ways: 1. Systematically and comprehensively,examines pragmatic communication differences in non-demented and demented persons. 2. It examines communication in the context of a longitudinal protocol that encompasses the breadth of communicative deficits in AD, including phonology, syntax, semantics, and primarily focusing on pragmatics. 3. It allows for examination of associations between communication status and cognitive functioning, rate of mortality, and alterations in neural tissue. Testing will be conducted across an 18 month interval (AD subjects tested at entry and every six months, non-demented subjects tested at entry and at 18 months). Data will be obtained using both standardized language tests paradigms and naturalistic conversation paradigms. Data will be examined both statistically and qualitatively and relationships to other information available from the project will be used to develop a multidimensional perspective of communication deficits in AD.