Declarative memory and structural language impairment in autistic children and adolescents

Two experiments tested the hypothesis that a plausible contributory factor of structural language impairment in Autism Spectrum Disorder (ASD) is impaired declarative memory. We hypothesised that familiarity and recollection (subserving semantic and episodic memory, respectively) are both impaired in autistic individuals with clinically significant language impairment and learning disability (ASDLI/LD); whereas recollection is selectively impaired in autistic individuals with typical language (ASDTL). Teenagers with ASDLI/LD (n = 19) and primary school age children with ASDTL (n = 26) were compared with teenagers with learning disability (LD) (n = 26) without autism, and primary school aged typically developing (TD) children (n = 32). Both experiments provided strong support for the hypothesised links between declarative memory processes and lexical-semantic facets of language in the two autistic groups, but not in the TD group. Additional findings of interest were that declarative memory processes and lexical-semantic knowledge were also linked in the LD group and that the ASD groups –and to a lesser extent the LD group – may have compensated for declarative memory impairments using spared visual-perceptual abilities, a finding with potential educational implications. Relative difficulties with familiarity and recollection in ASDLI/LD and LD may help explain structural language impairment, as investigated here, but also the broader learning disabilities found in these populations.