A review of the research to identify the most effective models of practice in early intervention for children with autism spectrum disorders
Sensory Integration Therapy
Sensory integration is the ability to process, immediately and simultaneously, the many different sensory messages that result from even the simplest action. It has been established that children with autism frequently have problems in dealing with complex sensory stimuli and that they may be sensitive to particular kinds of stimuli such as noise or texture (Howlin, 1997). Children with autism appear to have difficulties modulating their response to sensory input and maintaining optimal arousal and focused attention (Prior & Ozonoff, 2006). Poor sensory processing may contribute to the development of maladaptive behaviours and difficulties with social relating which are common in children with autism (Schaaf & Miller, 2005.
As many as 40% of children with autism are reported to have some form of sensory difficulty (Attwood, 1998; Rimland, 1990; Taley-Ongan & Wood, 2000). The sensory motor theory of autism proposes that motor problems in autism are related to praxis, the formation of a motor goal, the motor planning to carry out the goal and the execution of the motor movement to complete the goal. The cognitive and sensory characteristics of autism affect the first two steps in particular and can result in significant motor problems, or dyspraxia (Anzalone & Williamson, 2000). Developmental dyspraxia relates to fine and gross motor performance and in turn affects sensorimotor exploration, play and functional tasks. Oral/verbal dyspraxia interferes with the proper development of speech and eating skills. The issue of the co-occurrence of autism and dyspraxia remains unresolved. In a recent study of imitation and autism no evidence was found relating imitation deficits in young children with autism to dyspraxia (Rogers, in press).
Sensory Integration Therapy aims to improve the sensory processing capabilities of the brain through the provision of vestibular, tactile, and/or proprioceptive stimulation (Ian Dempsey & Foreman, 2001; Schaaf & Miller, 2005). The treatment is commonly delivered by occupational therapists and may involve activities such as swinging in a hammock, balancing on beams, and brushing or stroking the child's body (Dempsey & Foreman, 2001). Therapists select activities for each child based on his or her 'sensory needs.' Sensory Integration Therapy is believed to work directly on a child's nervous system functioning, capitalizing on plasticity within his or her nervous system, and resulting in the development of adaptive behaviours and an increased ability to learn (MADSEC, 2000).
Despite recommendations for use of Sensory Integration therapy with children with autism (e.g., Mailloux, 2001; Richards, 2000) and anecdotal reports (e.g., Cook, 1991; Sachs, 1995), little experimental evidence of its benefits have been reported in the literature. Dawson and Watling (2000) reviewed the evidence regarding sensory integration, auditory integration and traditional occupational therapy and found only poor quality evidence providing either no, or at best equivocal, support for Sensory Integration therapy and found no empirical evidence on the practice of occupational therapy in autism. The MADSEC Autism Task Force (2000) reported similar findings following a review of the literature. They concluded that SI cannot be considered to be an effective treatment for children with autism on the basis of current research and that caution is called for on the basis of one study reporting an increase in self injurious behaviour.
Despite the lack of randomised controlled trials, Schaaf and Miller (2005) noted that over 80 studies, measuring some aspect of the effectiveness of Sensory Integration Therapy, have been conducted. However, they also noted several key limitations which impact on the validity of the research conducted to date. These limitations include
- the heterogeneous nature of the populations studied,
- the failure of researchers to identify a consistent independent variable (treatment) in their studies to date,
- the fact that dependent variables (outcomes measures) were often not clearly related to the purpose of the intervention provided or too many dependent variables were measured, and
- the implementation and evaluation of Sensory Integration Therapy in isolation rather than as part of a comprehensive occupational therapy program (Schaaf & Miller, 2005).
It is important to distinguish between sensory integration therapy (SI) and the management of the sensory characteristics frequently associated with autism. Intervention to manage sensory issues may consist of environmental management or involve the person with autism directly. Clearly the effective management of sensory issues in autism is of potentially great benefit and more research is needed to evaluate this type of intervention.