ACQ_Vol_11_no_3_2009

Mental health

Differentiating between childhood communication disorders Implications for language and psychosocial outcomes Andrew Whitehouse

Specific language impairment and autism are considered distinct developmental disorders. However, while “textbook” cases of these conditions can be differentiated with little difficulty, there is a substantial proportion of children who display “intermediate” characteristics. One such example is the group of children who exhibit pragmatic language difficulties in the absence of other autism-like behaviours, so called pragmatic language impairment. There is contention as to whether the difficulties of these children are best considered a mild form of autism, or whether they represent a diagnostic category in their own right (so-called pragmatic language impairment). This paper highlights current thinking in the diagnostic differentiation of these disorders, using evidence from a longitudinal study investigating the language, psychosocial, and mental health outcomes in adulthood of children with each condition. The findings reinforce the validity of the pragmatic language impairment diagnosis, and suggest that adult psychosocial outcomes can be predicted from their childhood language profile. Mental ill-health was one outcome that was relatively common among the adults with a history of a communication disorder, suggesting that a good working knowledge of psychiatric conditions is beneficial for speech pathology practice. C ommunication disorders are, by their very nature, heterogeneous; it is rare to find two individuals with identical difficulties. Part of the issue here is that communication is a broad category, encompassing both structural (e.g., phonology, morphology, and semantics) and pragmatic aspects of language (i.e., how language is used in context). One of the goals of research in this area has been to provide “order”, by identifying diagnostic categories into which children can be grouped. Differential diagnosis has benefits for both research (e.g., helping to elucidate the

underlying aetiology of each condition) and clinical practice (identifying interventions that may be more effective with different groups of individuals). Differential diagnosis The current diagnostic approach is to differentiate “specific language impairments” (SLI) from “non-specific language impairments”. The former category includes those children whose difficulties are restricted to the language domain, whereas the latter category includes difficulties that are associated with a broader condition, such as autism. “Textbook” cases of SLI and autism are relatively easy to identify and differentiate. The broad communicative difficulties of individuals with autism (affecting both structural and pragmatic aspects of communication) contrast with SLI, in which there is a relatively specific deficit in the development of linguistic skills. However, research over the past decade has raised concerns over the validity of this diagnostic divide. For example, many children have behavioural characteristics that could be considered “intermediate” between SLI and autism. Autism, in particular, is widely recognised as a broad spectrum of disorders, ranging from autism at the severe end of the continuum, to pervasive developmental disorder – not otherwise specified (PDD-NOS; behaviours characteristic of autism, but not at a quantitative and/or qualitative severity to reach full criteria for autism) and Asperger syndrome (behaviours characteristic of autism, without any clinically significant delay in language or cognitive development) at the less severe end. The spectrum-nature of this condition has led to the now widely used term autism spectrum conditions (ASC), which refers to individuals with either a diagnosis of autism or PDD-NOS. It is also not uncommon to observe a child with pragmatic difficulties, but without the repetitive behaviours and marked social deficits that are required to meet criteria for an ASC. Such children have led to the additional diagnostic category of pragmatic language impairment (PLI). Originally referred to as semantic-pragmatic disorder, there has been a transition to the alternative label of PLI, particularly in the United Kingdom, due to findings that semantic and pragmatic deficits do not always occur in combination (Bishop, 1998). Although the current paper will adopt ASC and PLI to refer to the syndromes described above, it is important to note that the terms are not currently recognised in international diagnostic guidelines. The jury is still out on the ecological validity of the PLI diagnostic category. Perhaps the most comprehensive

Keywords AUTISM SPECIFIC LANGUAGE IMPAIRMENT PRAGMATIC LANGUAGE IMPAIRMENT DIAGNOSIS ADULT OUTCOME

Andrew Whitehouse

149

ACQ Volume 11, Number 3 2009

www.speechpathologyaustralia.org.au