The study was undertaken to evaluate the nature of sensory dysfunction in persons with autism. The cross-sectional study examined auditory, visual, oral, and touch sensory processing, as measured by the Sensory Profile, in 104 persons with a diagnosis of autism, 3-56 years of age, gender-and age-matched to community controls. Persons with autism had abnormal auditory, visual, touch, and oral sensory processing that was significantly different from controls. This finding was also apparent when the high and low thresholds of these modalities were examined separately. At later ages for the group with autism, lower levels of abnormal sensory processing were found, except for low threshold touch, which did not improve significantly. There was a significant interaction in low threshold auditory and low threshold visual, suggesting that the two groups change differently over time on these variables. These results suggest that sensory abnormalities in autism are global in nature (involving several modalities) but have the potential to improve with age.

This study examined the relationship between auditory, visual, touch, and oral sensory dysfunction in autism and their relationship to multisensory dysfunction and severity of autism. The Sensory Profile was completed on 104 persons with a diagnosis of autism, 3 to 56 years of age. Analysis showed a significant correlation between the different processing modalities using total scores. Analysis also showed a significant correlation between processing modalities for both high and low thresholds, with the exception that auditory high threshold processing did not correlate with oral low threshold or touch low threshold processing. Examination of the different age groups suggests that sensory disturbance correlates with severity of autism in children, but not in adolescents and adults. Evidence from this study suggests that: all the main modalities and multisensory processing appear to be affected; sensory processing dysfunction in autism is global in nature; and sensory processing problems need to be considered part of the disorder.

The prevalence of neurodevelopmental disorders, including autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), and Tourette syndrome (TS), has increased over the past two decades. Currently, about one in six children in the United States is diagnosed as having a neurodevelopmental disorder. Evidence suggests that ASD, ADHD, and TS have similar neuropathology, which includes long-range underconnectivity and short-range overconnectivity. They also share similar symptomatology with considerable overlap in their core and associated symptoms and a frequent overlap in their comorbid conditions. Consequently, it is apparent that ASD, ADHD, and TS diagnoses belong to a broader spectrum of neurodevelopmental illness. Biologically, long-range underconnectivity and short-range overconnectivity are plausibly related to neuronal insult (e.g., neurotoxicity, neuroinflammation, excitotoxicity, sustained microglial activation, proinflammatory cytokines, toxic exposure, and oxidative stress). Therefore, these disorders may a share a similar etiology. The main purpose of this review is to critically examine the evidence that ASD, ADHD, and TS belong to a broader spectrum of neurodevelopmental illness, an abnormal connectivity spectrum disorder, which results from neural long-range underconnectivity and short-range overconnectivity. The review also discusses the possible reasons for these neuropathological connectivity findings. In addition, this review examines the role and issue of axonal injury and regeneration in order to better understand the neuropathophysiological interplay between short- and long-range axons in connectivity issues.

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