Language Profiles and Memory Components in Specific Language Impairment and Autism Spectrum Disorders in Relation to the Broader Phenotype

Background: Phenotypic overlap between autism spectrum disorder (ASD) and specific language impairment (SLI) is currently debated in the literature. One aspect of controversy is related to whether children’s phonological short term memory (PhSTM) performance is a possible clinical marker in both SLI and ASD.

Objectives: To assess memory abilities including PhSTM in children with SLI compared to children with SLI and additional significant ASD traits with standardised memory tests designed for clinical use with children. These profiles are then related to their own and their parents’ PhSTM.  

Methods: 61 children with current SLI but without autistic traits (SLI-) are compared with 31 children with SLI plus additional autistic traits (SLI+) (assessed by the family history questionnaire) as well as 52 unimpaired siblings all aged 5-16.9 years on measures of language, IQ, memory and learning (using the Wide Ranging Assessment of Memory and Learning – WRAML). They came from 75 families. Their parents’ nonword repetition data were also analysed.

Results: Both SLI+ and SLI- groups (by definition) showed impairment in receptive and expressive language compared with unimpaired siblings. Group comparisons showed equal impairment in verbal memory for SLI- and SLI+ groups. Visual memory and learning were comparative strengths for both groups. The SLI+ group showed a mixed pattern of impairment in PhSTM. In the SLI+ group, if PhSTM was impaired, verbal memory was also impaired and receptive language impairment greater than in the SLI- group.  Parental PhSTM was impaired if their children had poor PhSTM, a finding only in the SLI- group.

Conclusions: Verbal memory skills are significantly impaired in children with SLI regardless of whether or not they have additional autistic traits with SLI+. The significant component of memory appears to be PhSTM. Impairment in parental nonword repetition is correlated with NWR in children with SLI- suggesting familiality.