Throughout most of the history of autism as recorded within the medical literature, sensory problems have been paid very little attention. These were not unknown phenomena, both Kanner ad Asperger described bizarre reactions to sensory stimuli in their incept cases. Rather, the lack of recognition by the medical profession was probably due to the difficulty found in placing sensory abnormalities within a conceptual and/or mechanistic framework. Still, lone voices were heard calling attention to the significance of sensory abnormalities. Rimland (see https://corticalchauvinism.wordpress.com/2013/02/21/bernard-rimland/) championed research into the field, Lorna Wing included the same within her basic impairments of autistic individuals, and Ornitz tried explaining the sensory phenomena in the context of other abnormalities, e.g. attention.

More recently the notion of sensory problems in autism has gained acceptance within the medical community. Now, they are regarded by some as a core deficit of the condition capable of explaining other autistic manifestations. Sensory abnormalities are now seen at the root of mood disorders (specially anxiety with closely aligned obsessive compulsive traits), socialization problems, and communication difficulties. Thus, the tide has shifted one hundred and eighty degrees in regards to the prevalence and importance of sensory abnormalities in autism. From a seldom-discussed entity, to now the center of a psychological and neurobiological theory trying to explain autism (i.e., sensory integration dysfunction). Curiously enough this theory has been promulgated primarily by occupational therapists.

Sensory integration disorders have been seriously criticized in a metaanalysis by Rogers and Ozonoff (2005). It seems that sensory problems lack specificity for autism and were more prevalent in other disorders such as Fragile X syndrome. Still, more and more studies seem to question the conclusions of Rogers and Ozonoff. Unfortunately many of the positive studies restrict themselves to specific sensory modalities and fail to examine all modalities in conjunction. Furthermore, although age related correlations have been made they have been the result of cross sectional analysis at various stages rather than longitudinal studies. In this regard many questions still remain unanswered. Can sensory phenomena be used in identifying patients at risk (at least one study appears to suggest the same)? Can sensory modalities distinguish subtypes of autism or predict outcome? Are all sensory modalities affected to the same degree in the same patients? How do sensory problems define cognitive difficulties in autistic individuals?

Recently, my group has proposed that sensory abnormalities in autism are the result of aberrantly constructed cortical modules called minicolumns. These abnormalities result in a hyperexcitable cortex with consequent manifestations of seizures and sensory abnormalities (see https://corticalchauvinism.wordpress.com/2013/01/29/what-causes-the-mayor-symptoms-of-autism-part-1/). The overall findings are similar to those exhibited by migraineurs (see https://corticalchauvinism.wordpress.com/2013/02/10/abdominal-pains-and-migraine-in-autism/). Another theory trying to explain the mechanisms of perceptual abnormalities in autism is that of Markram’s hyperconnectivity. The same has been based on an animal model of autism (valproic acid during brain development).

I do believe in the significance of sensory problems in autism and have lost my scientific objectivity to judge both sides of the argument. I have witnessed, and can even predict, the meltdowns sensory overstimulation can provide. I have also seen how repetitive movements seemingly calm them down. In this regard, the best invention ever is the in-house swing that allows you to sit in the same while holding your son or daughter. For my grandson a swing pushed the off switch for his tantrums and allowed you to cuddle him. In another blog we will talk about the closely related squeeze machine.

References

1. Dasha’s Journal: a Cat Reflects on Life, Catness and Autism by T.o. Daria (interesting name, could this be a nom de plume?)
2. Sensory Perceptual Issues in Autism and Asperger Syndrome: Different Sensory Experiences by Olga Bogdashina
3. Autism and the edges of the known world: sensitivities language and constructed reality by Olga Bogdashina
4. Rogers SJ, Ozonoff S Annotation What do we know about sensory dysfunction? A critical review of the empirical evidence. Journal of Child Psychologya and Psychiatry 46(12):1255-68, 2005.