Episodic memory impairment and its influencing factors in individuals with autism spectrum disorder: systematic review and meta-analysis

Individuals with autism spectrum disorders (ASD) are considered to experience difficulties with episodic memory (EM), while studies on EM in ASD have shown inconsistent results. A meta-analysis of 65 episodic memory studies with a combined sample size of 1652 individuals with ASD and 1626 typically developing individuals was conducted to analyze factors that may affect EM in ASD. The results showed that ASD had a significant medium to large effect size decrease in EM ability. Age period, task type, and reporting method significantly reduced the observed heterogeneity while EM type did not reduce the observed heterogeneity. The results of the meta-regression revealed that it was verbal IQ rather than full-scale IQ that was significantly correlated with EM in individuals with ASD. These findings suggest that individuals with ASD have reduced EM abilities and the potential factors is still needed to be explored.