Question: Do children with autism and children with other developmental problems experience sensory symptoms, and if so, do the rates differ between groups?

Background: Many parents report that their children with autism have unusual responses to sounds, touch, or taste/smell. Some children may show little or no response to certain sounds, while others may cover their ears and cry or scream on hearing sounds that other people do not react to. The goals of this study were to 1) look at the mothers' reports of sensory symptoms in their small children with autism or other developmental problems; 2) to look at the relationships of the sensory problems with intelligence, age, the severity of autistic symptoms and the severity of symptoms associated with autism; 3) to compare the consistency of the mothers' and the observers' reports on symptoms of sensory problems using a variety of instruments; and 4) to look at whether sensory symptoms interfere with the development of adaptive behaviours.

Participants: The participants were 102 children, 26 with autism, 20 with Fragile X syndrome, 32 with developmental disabilities of different origin and 24 who were typically developing children, and their mothers. The children with autism had a strict diagnosis of their condition made and were free from other medical conditions. The children with Fragile X were recruited from specialty clinics, and the typically developing children were recruited from the University of Denver research subject pool. The children ranged in age from 21 to 50 months of age. The groups of children were matched on mental age rather than their chronological age.

Study Design: Symptom prevalence study.

Method: The Short Sensory Profile was administered to the mothers prior to the first home visit to elicit reports of sensory symptoms in their young children. The mothers of the children with autism completed the ADI-R and the children were administered Module 1 of the ADOS-G. Both tests elicit autistic symptoms. All of the children were given developmental testing using the MSEL (the Mullen) and were tested for adaptive behaviour using the Vineland Scales of Adaptive Behaviour. Each of the four groups of children were later observed by assessors unaware of their diagnosis to look for behavioural indicators of either under-reactivity or over-reactivity to sound or touch or to taste/smell.

Main Results: Children with autism and Fragile X had generally higher scores than the developmentally delayed and typically developing children on tests of sensory reactivity. Children with autism had higher scores on taste/smell sensitivity, tactile sensitivity and auditory filtering than did children of all the other groups. The children with Fragile X had significantly higher scores on low energy/weak muscles and in the areas of tactile sensitivity, underreactive or stimulation seeking, as well as auditory filtering (the ability to discern meaningful speech from background noise). There was no relationship between the severity of the sensory problem and the level of developmental delay. In the children with autism there was a significant relationship seen between the sensory problems and repetitive/restrictive behaviours, but not with social communication. The children with Fragile X who also had symptoms of autism tended to have more sensory problems than did children without the dual diagnosis, meaning that the sensory problems seem to be more related to the autistic symptoms than to the degree of mental handicap. Another significant finding was that there was a relationship between the incidence of sensory symptoms and poor adaptive behaviours (i.e., activities of daily living that demonstrate personal and social skills).

The study demonstrated that the parents' report of their child's sensory problems more or less agreed with the more objective tests used by the researchers. There was strong merging of findings amongst the different methods used to detect sensory problems in the children, suggesting that the tests used were all able to discern sensory problems.

Conclusions: It appears that sensory problems are found more frequently in children with autism than in other groups of children but are not exclusive to children with autism. There was no correlation found between the children's intelligence level and the presence or severity of sensory problems. There was no relationship found between the sensory symptoms and the level of social-communication deficits in the children with autism. Children with coexisting autism and Fragile X syndrome seemed to have the most severe sensory symptoms. The repetitive behaviours more frequently seen in children with autism did not seem to be related to the sensory symptoms. The authors caution that this finding is based on a very small number of children and must be reproduced in a much larger group.