Ageing and Psychological Functioning in Autism Spectrum Disorder

Background: The patterning of cognitive function in individuals with Autism Spectrum Disorder (ASD) is selectively impaired, compared to typical individuals. For example, selective memory and executive function impairments are frequently observed in ASD (Hill, 2004; Howlin et al., 2004; Bowler, 2007; Boucher & Bowler, 2008). However, little is known about the way in which people with ASD age (Mukaetova-Ladinska et al., 2012; Perkins & Berkman, 2012). Relatively few studies have reported poorer outcomes and lifecourse trajectories for older individuals with ASD (Magiati et al., 2014). Declines in cognitive functioning such as dementia, memory decline and impaired executive function have been reliably identified in older typically developed adults (Schaie, 2005; Salthouse, 2009), however, it is unknown whether or not similar changes occur during the course of ageing with autism.   

Objectives: To document the magnitude and patterning of age-related differences in memory and executive function between older and younger adults with ASD compared to matched typical adults.

Methods: Cross-sectional analyses explored age-related differences between younger (18-49 years) and older (50-79 years) adults with (N = 35) and without (N = 35) ASD. Executive function related to working memory, planning and visual learning were assessed on a subset of CANTAB tasks. Self-reported measures of autistic traits (Baron-Cohen et al., 2001) and frequently concomitant conditions such as alexithymia and anxiety (Berthoz & Hill, 2005) were assessed for their potential mediating effects on cognitive performance in later life. Given the patterning of age-related cognitive decline in typical individuals, at least two possible outcomes were expected for older autistic adults: (1) preserved cognitive functioning might be expected, suggesting a ‘buffer’ against further age-related cognitive impairment in older adults with ASD; (2) alternately, the patterning of cognitive functioning in older adults with ASD may parallel that of typically ageing adults, suggesting greater cognitive risks for ageing adults with ASD.  

Results: The results supported the first hypothesis. No age-related differences in executive functioning were observed in older autistic adults compared to older typically ageing adults or younger adults with ASD. Alexithymia was highly comorbid with ASD, and self-reported anxiety was greater in younger adults with ASD. There were no differences in anxiety levels between older adults with and without ASD. The findings suggest that, despite observations of similar cognitive profiles in younger autistic and older typical adults (Bowler, 2007), ASD may provide a ‘buffer’ against further age-related cognitive decline (Geurts & Vissers, 2012). The results should be interpreted with caution as they are based on small sample sizes and cross-sectional analyses. Possible differential participant attrition in the ASD and typical samples may also have affected the results. 

Conclusions: The absence of significant differences on these measures between younger and older adults with ASD suggests that severity of autism and certain concomitant conditions may remain unchanged across the adult lifespan in this population. These preliminary findings suggest potentially optimistic outcomes for ageing adults with ASD. However, the findings represent a small subset of older adults with autism, who might exhibit age-related declines when followed-up longitudinally. Future work will address these issues.