Objectives: (1) To disentangle the relative importance of information-processing deficits from self- and social-processing deficits in ASD using episodic and semantic memory tasks matched for level of complexity. (2) To determine whether deficits in memory in autism can be traced to abnormalities in the hippocampus or amygdala.
Methods: Participants included 34 8-18 year-old subjects with ASD and 35 age, sex and IQ-matched controls. Autism diagnoses were confirmed using ADOS (Lord et al., 1999) and ADI-R assessments (Lord et al., 2003), and all subjects completed the Social Responsivity Scale (SRS) (Constantino, 2000) and Social Communication Questionnaire (SCQ) (Berument et al., 1999). Sub-tests from the NEPSY-II were used to obtain standardized measures of social and non-social semantic memory and organizational ability. The experimental tasks included a Levels-of-Processing task (based on Toichi et al., 2002) and a narrative recall task (based on Crane and Goddard, 2008) comparing memory for self, mother and favorite fictional character. A subset of 20 ASD subjects and 19 TD controls were scanned using Magnetic Resonance Imaging, and hippocampi and amygdalae region of interest volumes were measured using voxel-based morphometry.
Results: The TD group performed overall higher than the ASD group in all memory conditions (p=0.009); with post-hoc tests revealing a significant difference in semantic memory (p=0.001), memory for self (p=0.013), and memory for mother (p=0.015). Further, memory for self was found to be positively correlated with a test for organizational ability (r=0.353; p=0.003), yet did not correlate with a test for social memory (r=0.208; p=0.087)
Further analyses are underway to determine the relation between these behavioral results and anatomical regions of interest.
Conclusions: These preliminary results suggest that the pattern of memory abilities in autism may be driven by a broad deficit in information-processing, rather than a specific deficit in social information-processing. Further analyses will determine the relation between these behavioral memory patterns and brain structure.
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