Cognitive and Cerebral Aging Research in Autism: A Systematic Review on an Emerging Topic

Aging in autism is an emerging and under-explored area of research. This systematic review provides a comprehensive overview of studies on cognitive and both structural and functional cerebral aging in autism. A systematic search of PubMed and APA PsycInfo was conducted up to and including January 2024. Two researchers independently screened and identified relevant English studies on cognitive (i.e., processing speed, executive function, working memory, episodic memory) and/or cerebral (i.e., structural and functional aspects) aging in autism. Study quality was assessed using the QualSyst quantitative scale to minimize bias. Thirty-six studies met the inclusion criteria, with nine focusing on cerebral mechanisms, 19 on cognitive function, and eight addressing both. We examined cerebral and cognitive aging profiles in autism within the context of three hypotheses: accelerated aging, parallel aging, and the safeguard hypothesis. The synthesis does not reveal a consistent pattern with respect to any of the three hypotheses, as results varied across methodology types (cross-sectional vs. longitudinal) and studies, even with similar measures of cerebral or cognitive function. This systematic review highlights the ongoing lack of consensus in this area, which may be attributed to various internal or external factors (e.g., participants age, co-occurring conditions, lifestyle, cognitive reserve). Despite divergent findings, this review suggests that cross-sectional studies on cerebral and cognitive autistic aging predominantly align with the parallel or safeguard hypothesis. In contrast, the few longitudinal studies, which are the only ones capable of directly informing the aging process, are more consistent with the parallel or accelerated hypothesis. Further research is crucial to understand how cerebral and cognitive aging impact autistic symptomatology, enabling tailored support.