Cognitive impairment in Down syndrome
Cognitive functioning refers to multiple mental abilities, including learning, thinking, reasoning, remembering, problem solving, decision making, flexibility or attention.
Individuals with Down syndrome (DS) commonly present unique neurocognitive profiles that emerge within specific developmental periods. For example, they show more difficulties while processing verbal information than visual information. Children with DS continue to make gains in nonverbal cognitive abilities but the development of verbal abilities tends to decelerate throughout adolescence and into adulthood.1
Individuals with Down syndrome show more difficulties while processing information than visual information.
Children with DS also show impairment in many aspects of attention (e.g., auditory sustained attention, visual selective attention), some of which persist through adulthood limiting the ability to consistently responding in the same manner to certain situations, thus affecting function and independency.2
However, most cognitive difficulties are observed in the executive functions, mainly in working memory and memory flexibility.3
But what are executive functions?
Executive functions are mental skills that include working memory, flexible thinking, or decision making. We use these skills every day to learn, work, and manage daily life. Problems with executive function can make it hard to focus, follow directions or planning, among other issues.
Overall, individuals with Down syndrome show impairments in executive functions, and these deficits appear even in youngchildren. For example, individuals with Down syndrome show persistent deficits across modality in working memory and planning (six to seven times more likely to experience problems), and parents also endorse significant problems with inhibitory control.4
Working memory is a basic mental skill. It is important for both learning and doing many everyday tasks. Working memory allows the brain to briefly hold new information while it is needed in the short term. It may then help to transfer it into long-term memory.
An example of a working memory task could be listening to a sequence of events in a story while trying to understand what the story means.
Auditory working memory is less developed than visuospatial working memory in DS children. In school aged children and adolescents, further studies have suggested that reduced verbal working memory may reflect the absence of active rehearsal.5
Inhibitory control or response inhibition, allows to inhibit our impulses and our natural or dominant behavioral responses, to select a more appropriate behavior consistent with our goals. Self-control is an important aspect of inhibitory control. Poor response inhibition is evident across the lifespan of DS individuals, emerging in toddlers and continuing through adulthood.6
What happens if we do not have good impulsivity control? We make risky decisions, driven by immediate reward rather more than by the potential negative consequences of our choices. In short, “we act before we think.”
Two of the ICOD project goals are to develop adequate tools for diagnosis and appropriate treatments to improve executive function.
1. Naess KB, Lyster SH, Hulme C, Melby-Lervag M (2011). Language and verbal short-term memory skills in children with Down syndrome: A meta-analytic review. Res Develop Disabil 32:2225–2234.
2. Trezise KL, Gray KM, Sheppard DM (2008). Attention and vigilance in children with Down syndrome. J Appl Res Intellect 21:502–508.
3. Rowe J, Lavender A, Turk V (2006). Cognitive executive function in Down’s syndrome. Br J Clin Psychol 45:5–17.
4. Lee NR, Fidler DJ, Blakeley-Smith A, Daunhauer L, Robinson C, Hepburn S (2011). Caregiver report of executive functioning in a population-based sample of young children with Down syndrome. Am J Intel Devel Disabil 116:290–304.
5. Frenkel S, Bourdin B (2009). Verbal, visual, and spatio-sequential short-term memory: Assessment of the storage capacities of children and teenagers with Down’s syndrome. J Intellect Disabil Res 53:152–160.
6. Lanfranchi S, Jerman O, Dal Pont E, Alberti A, Vianello R (2010). Executive function in adolescents with Down syndrome. J Intel Disabil Res 54:308–319.