Intelligence trajectories in adolescents and adults with down syndrome: Cognitively stimulating leisure activities mitigate health and ADL problems

Abstract

Goals This study examined: (a) crystallized/fluid intelligence trajectories of adolescents and adults with Down syndrome; and (b) the contribution of endogenous (health, activities of daily living—ADL) and exogenous (cognitively stimulating leisure activities) factors on adults’ intelligence with age. Method Four cohorts (N = 80) with Down syndrome participated: adolescents (ages 16–21) and adults (ages 30–45, 46–60 and 61+). All completed Vocabulary and Similarities (crystallized) and Block Design and Raven (fluid) intelligence tests (WAIS‐IIIHEB, Wechsler, 2001). Results The 30–45 cohort significantly outperformed the 16–21 cohort. Except for Vocabulary, which remained stable, onset of decline was at 40–50. Age‐related declining health and ADL correlated with participants’ lower fluid intelligence, but cognitive leisure activities mitigated this influence. Conclusions Intelligence development into adulthood supported the continuous trajectory and compensation age theory, rather than accelerated or stable trajectories. Not only endogenous factors but also exogenous factors determined intelligence levels in adults with Down syndrome, supporting cognitive activity theory.

Brain reserve theory: Are adults with intellectual disability more vulnerable to age than peers with typical development?

“…Even adults with Down syndrome may now experience good health and successful aging, without cognitive deterioration (Krinsky‐McHale et al, 2008; Wiseman et al, 2015). In our country, adults with intellectual disability are busy in meaningful activities in employment and satisfying cognitive leisure activities (Lifshitz et al, 2021). Participation in leisure activities holds a potential for improving cognitive functioning and mitigates cognitive deterioration among adults with intellectual disability (Lifshitz‐Vahav et al, 2016) and with Down syndrome (Lifshitz et al, 2021).…”

“…IQ was calculated according to three subscales of the WAIS III HEB (Wechsler, 2001): Vocabulary, Similarities, Matrix and Block Design, which are indicators of general intelligence according to the WASI ™ (Wechsler Abbreviated Scale of Intelligence, Wechsler, 1999). This procedure was used in a population with typical development (Canivez et al, 2009) and in a population with intellectual disability (Gawrylowicz et al, 2012; Lifshitz et al, 2021). We used the raw scores in all tests, since the process of converting them to scaled scores conceals a hidden assumption that age‐related differences across the lifespan in the research group is similar to that of the control group.…”

“…Brain imaging has demonstrated that brain maturation in the general population appears to peak in late adolescence (Cromer et al, 2015;Crone & Ridderinkhof, 2011). Our previous studies show that intelligence of adults with intellectual disability (age 20-45) was higher than that of adolescents with intellectual disability (age 16-21) with the same basic cognitive level (Chen et al, 2017;Lifshitz et al, 2021). Adults also gained more from mediation aimed to ameliorate cognitive skills than adolescents (Lifshitz et al, 2005(Lifshitz et al, , 2011, supporting the Compensation Age Theory in adults with intellectual disability (Lifshitz, 2020).…”

“…Wechsler, 1999). This procedure was used in a population with typical development (Canivez et al, 2009) and in a population with intellectual disability (Gawrylowicz et al, 2012;Lifshitz et al, 2021). We used the raw scores in all tests, since the process of converting them to scaled scores conceals a hidden assumption that age-related differences across the lifespan in the research group is similar to that of the control group.…”

“…The Rey-AVLT (Vakil et al, 2010;Vakil & Blachstein, 1997) (Vakil & Blachstein, 1997). Our experience in assessing cognitive tests among individuals with intellectual disability (Lifshitz et al, 2021;Shnitzer-Meirovich et al, 2018) indicates that adults with intellectual disability can concentrate between 1 and 1.5 h with a break in the middle. Based on this, and to prevent mental fatigue, the tests battery was divided into two sessions.…”