Subjective and objective cognitive differences in adults in mid-life and older age with autism or high autistic traits: a systematic review and meta-analysis.

Background

Research examining ageing in autistic populations, once largely neglected, has expanded in recent years. Cognitive decline and dementia are key public health concerns, and it remains unclear whether autism is related to atypical cognitive ageing. A synthesis of quantitative evidence on cognition in autistic adults in mid- to later-life is needed. This systematic review and meta-analysis is the first to do this.

Methods

Studies comparing objective and subjective cognition in autistic and neurotypical adults aged 50+ were included. Given the underdiagnosis of autism in this age group, autistic samples defined using validated measures of autistic traits were included alongside formally diagnosed samples. Online databases (PubMed, Scopus, CINAHL, PsychINFO) were searched. Risk of bias was assessed using AXIS.

Results

Fifteen cross-sectional studies were included, examining 13 cognitive constructs. Additional analyses compared effect sizes between diagnosed and trait-defined populations. Autistic individuals reported significantly greater subjective cognitive difficulty (d = 0.90), although this was not reflected in objective performance. Small group differences were observed in processing speed, verbal fluency, and working memory (d = -0.28 - -0.38), across which autistic samples performed more poorly. Other cognitive domains did not significantly differ. Heterogeneity was high across several analyses.

Discussion

Results suggest broadly similar cognitive ageing in autistic and neurotypical adults. However, interpretation is limited by underrepresentation of participants over 65, and the absence of longitudinal studies. The discrepancy between objective and subjective cognition was a striking finding, with implications for clinical investigation of self-reported cognitive concerns amongst adults on the autism spectrum.