ABSTRACT
THE NEUROPSYCHOLOGY OF DOWN SYNDROME Down syndrome (DS) is the most prevalent genetic cause of mental retardation, affecting 1 in 700 live births (Stoll, Alembik, Dott, & Roth, 1990). It is caused by the presence of all or part of an extra copy of the 21st chromosome. Although this disorder has been recognized for more than a century (Down, 1866), the cognitive phenotype, with the exception of the language deficit and early onset dementia, is not well described. In addition, the mechanisms by which extra copies of normal (indeed, essential) genes produce the cognitive phenotype are not understood. This chapter reviews the known cognitive phenotype of DS and the contribution of existing animal models to the understanding of DS, providing an overview of the various types of animal models followed by a detailed analysis of the segmental trisomies.
