Adolescents with early-onset-schizophrenia (EOS) and with autism spectrum disorder (ASD) exhibit similar cognitive impairments which may be related to different neurocognitive processes.

The present study aimed to compare the semantic memory structure and function in adolescents with EOS and ASD in order to highlight some fundamental similarity or distinctions between the two disorders.

Adolescents with EOS (n = 16), with ASD (n = 14) and with typical development (n = 24) matched on general, verbal and performance IQ, participated to a verbal fluency task. A quantitative analysis (number of words correctly reported) was made in letter and category fluency task. Qualitative analysis (number of clusters and switches and cluster size) was made using the CFT. The semantic memory structure was derived from a multidimensional scaling analysis (MDS) using sequential word outputs from the CFT.

Adolescents with EOS and with ASD exhibited performance reduction compared to control group. EOS and ASD exhibited similar quantitative performance and produced similar number of clusters on CFT. In contrast, qualitative analysis showed that EOS produced more switches and smaller cluster size compared to ASD. MDS analysis of the semantic memory structure revealed atypical associations of category members in EOS compared to ASD and to healthy adolescents.

Despite quantitatively similar results, EOS and ASD appear to use different sematic strategies of memory search which may results from qualitative differences of the functional organization of the semantic memory. Semantic memory disorganization appear to be specific to schizophrenia and may be a considered as specific marker to the disorder.