Cognition in down syndrome: A developmental cognitive neuroscience perspective

Down syndrome (DS) is the most common genetic form of intellectual disability. DS results in a characteristic profi{ligature}le of cognitive and neurological dysfunction. The predominant theory of the pattern of neural defi{ligature}cits in this syndrome suggests that DS aff{ligature}ects 'late-developing' neural systems, including the function of the prefrontal cortex and hippocampus. In order to evaluate the validity of this theory, in this review, I highlight data addressing the neurological and cognitive phenotype in DS across development. In particular, I address the evidence suggesting that DS may impact late-developing neural systems and end with the conclusion that some cognitive diffi{ligature}culties in DS must result from poor communication between late-developing regions. Analogous to recent theories of cognitive processing in autism, cognitive defi{ligature}cits in DS may be substantially impacted by less effi{ligature}cient interregional communication. Finally, I discuss some ways in which understanding the impact of altered neurodevelopment in DS has the potential to inform our understanding of species-typical trajectories of cognitive development.