Autism, primary pragmatic difficulties, and specific language impairment: can we distinguish them using psycholinguistic markers?

Three groups of children with communication disorders were examined using a series of psycholinguistic markers to explore whether the tasks could identify children with impairments other than specific language impairment (SLI), and to examine whether the different groups within this clinical population could be distinguished reliably from one another. The groups comprised children with autistic spectrum disorders (ASD; n = 13, all males; mean age 10 years 10 months, range 10 years 2 months to 12 years 6 months); children with primary pragmatic language impairment (PLI) but who did not have definite ASD diagnoses (n = 25, 22 males, three females; mean age 11 years 3 months, range 10 years 2 months to 12 years 5 months); and children with specific language impairment (SLI) without marked pragmatic language difficulties (n = 29, 25 males, 4 females; mean age 10 years 10 months, range 10 years 2 months to 11 years 9 months). Clinical markers examined were: the Children's Non-Word Repetition (CNRep), the Past Tense Task (PTT), and the Clinical Evaluation of Language Fundamentals, Recalling Sentences. First, it was found that the a priori groupings were not sufficiently defined and that four groups were actually present. The PLI group was in fact two separate samples: those with PLI pure and those with some autistic-like behaviours (referred to here as PLI plus, following Bishop 1998). Second, group comparisons indicated that CNRep was significantly lower for children with SLI than all other groups (although this measure was not such a good discriminator using a specificity analysis). Third, the markers were able to discriminate between all types of communication impairment in normal control participants (n = 100; 51 females, 49 males; mean age 11 years, range 10 years 5 months to 11 years 6 months) with sensitivity levels of at least 75% and specificity of 80%. Recalling Sentences was the most efficient marker for all groups. Finally, analysis showed that children with PLI plus could be accurately distinguished from all others, scoring most favourably overall on communication markers and on performance IQ scores.