Assessment and Identification of Developmental Dyspraxia in ASD

Background: Both developmental dyspraxia and acquired limb apraxia are disorders of gestural processing. However, in developmental studies, dyspraxia is often referred to as a ‘unitary disorder’, mainly affecting imitation abilities; whereas limb apraxia is usually described as a complex disease, affecting both the production and reception of gestures. To justify the complexity of limb apraxia, recent cognitive models of praxis processing have been devised (Rothi et al., 1991; Cubelli et al., 2000). These models enable the identification of specific patterns of deficits associated to praxis processing in patients with brain damage. Recent findings suggest that dyspraxia in individuals with autism might not be limited to imitation deficits (Mostofsky et al., 2006; Stieglitz Ham, Corley, Rajendran, Carletta, & Swanson, 2008). Therefore, only by employing a complete praxis assessment, as is done in studies of limb apraxia, is it possible to assess dyspraxia in autism in a more comprehensive manner.
Objectives: The aim of this study is to uncover specific praxis profiles in individuals with autism by means of a complete battery of tasks devised to evaluate the different cognitive mechanisms proposed by the cognitive model of praxis processig (Cubelli et al., 2000). Methods: 19 individuals with ASD entered this study. 23 TD controls were tested to gather norms. A battery of tasks has been entirely devised. For the evaluation of the integrity of the lexical route (Cubelli et al., 2000), six tasks assessed the ability to discriminate and comprehend meaningful gestures (transitive, intransitive and pantomimes), and five tasks assessed the ability to produce meaningful gestures across multiple modalities (verbal and visual for pantomimes and intransitive gestures; as well as actual object use. The evaluation of the non-lexical route was carried out with four tasks testing the imitation of meaningful and meaningless gestures. Gesture production was videotaped and coded by two examiners.
Results: Data showed that individuals with autism demonstrated specific patterns of praxis processing. With reference to the cognitive model of praxis processing usually employed in adult lesion patients, results uncovered individuals with ideational dyspraxia (n= 6) of ideomotor dysapraxia (n=4); and of ideational with ideomotor dyspraxia (n=2) as well as individuals with deficits in imitation only (n = 2).
Conclusions: In summary, the cognitive model of praxis processing was useful in identifying specific patterns of praxis processing in individuals with autism