Working memory and everyday cognition in adults with Down's syndrome.

A number of previous studies have suggested that young people with Down's syndrome (DS) have a specific deficit of the phonological loop component of the working memory. However, there have also been studies which have proposed a specific deficit of the central executive component of working memory and suggested similarities of working memory functioning with patients with Alzheimer's disease. Fifteen middle-aged people with DS were matched for their individual scores of non-verbal intelligence to 15 individuals with mixed aetiology of intellectual disability. A versatile range of tasks was used in order to evaluate the functioning of working memory components. In addition, several everyday cognition skills were assessed. The subjects with DS performed significantly more poorly in all tasks assessing the phonological loop. Performance in other working memory tasks and compound variables representing different working memory components was equal in the groups. In addition, both groups had equal everyday cognition skills. The functioning of the phonological loop seems to be clearly deficient in people with DS. Interestingly, the deficit does not seem to affect the vocabulary or other everyday cognition skills in individuals with DS. No signs of specific deficit of the central executive component of working memory were found.