Down's Syndrome and the Dementia of Alzheimer Disease

The clinical course and expression of dementia in persons with Down's Syndrome (DS) are poorly understood. While longitudinal studies are rare they provide the most accurate data since standardized psychological tests yield performances which show pronounced ‘floor effects’, except with mildly to moderately retarded persons. A review of the main psychological observations is provided along with reference to some of the major problems involved in assessment. A discussion is provided of the relationships between dementia and the Alzheimer disease (AD) process in DS.