Cognitive control and episodic memory in adolescents with autism spectrum disorders

To further investigate manifestations of episodic memory impairments in adolescents, we examined the role of encoding on recognition of stimuli in conditions designed to emphasize their item-specific versus relational characteristics in a group of 12-18 year olds with autism spectrum disorders (ASD). We also examined how strategic learning and memory processes, verbal abilities, attention, and age were associated with recognition in this group.

Twenty two high functioning adolescents with ASD (mean age=15 years; SD=1.8; range=12.2-17.9), and 26 age, gender, and IQ-matched adolescents with typical development (TYP) (mean age=14.7 years; SD=1.9; range=12.3-17.8) completed the Relational and Item-Specific Encoding task (RiSE), the California Verbal Learning Test-Children's Version (CVLT-C), the Wechsler Abbreviated Scales of Intelligence, and the Connors' Parent Rating Scale-Revised. Univariate statistical analyses were performed.

The ASD group showed poorer performance on strategic memory assessed by the CVLT-C. Surprisingly, on the RiSE, ASD showed poorer discriminability for objects encoded in item-specific versus relational encoding conditions and were more impaired in familiarity (after relational encoding) than in recollection. ASD also did not show the hypothesized association between item and associative recognition and CVLT-C performance found in TYP. Instead, in the ASD group recognition was associated with increased age.

Findings from the RiSE task demonstrated that adolescents with ASD do not always exhibit impaired memory for relational information as commonly believed. Instead, memory was worse when cognitive control demands were high, when encoding focused on specific item features, and when familiarity was used to retrieve relational information. Recognition also was better in older participants. This suggests that learning and memory deficits in adolescents with ASD, may not be due primarily to failed relational binding processes in the hippocampus but, rather to disrupted strategic memory and familiarity processes associated with the prefrontal and perirhinal cortices. These findings demonstrate the importance and utility of using well-validated cognitive neuroscience tasks and of considering the ages of participants when comparing the neural underpinnings of different memory processes in both typical and atypical populations.