Autism Spectrum Disorder (ASD) is a complex, highly heritable neurodevelopmental disorder that is characterized by challenges with language, social behavior and interaction, and restricted activities or repetitive behavior patterns. It is also associated with behaviors such as strong fact recall or detail-oriented. Sometimes this is associated with exceptional skills in art, math, memory, etc. known as “savant” skills.
ASD is known to affect approximately 1.5% of the population in developed countries around the world (1). It is more common in males than females, with reported ratios ranging from 2:1 to 5:1 and an average estimate of about 4:1 (2).
ASD is known to affect approximately 1.5% of the population in developed countries around the world (1). It is more common in males than females, with reported ratios ranging from 2:1 to 5:1 and an average estimate of about 4:1 (2).
At the level of neurocircuitry, many brain regions have been found to be affected by ASD. The most affected regions tend to be those involved in emotional and social reasoning as well as those involved in cognitive flexibility. Such regions include the PFC subregions, cerebellum, hippocampus, and amygdala (3). These regions typically contribute to increased attention, salience attribution, and emotional response to sensory stimulus.
Autistic individuals often struggle when responding to sensory stimuli; an issue associated with ASD since first described in 1943 by Kanner (4).
- The display of differences in sensitivity can exist as
- Hypo-sensitivity, where meaningful stimuli do not receive preferential attention
- Hyper-sensitivity, where stimuli cause an aversive over arousal (5).
- Examples of Sensory Over Responsivity (SOR) behaviors include withdrawing from or crying after certain visual or physical stimuli.
- When unable to communicate distress, in the case of ASD, the experienced distress frequently leads to self-injury and aggressive behavior
SOR And The Five Different Senses
Over-reactivity to sensory stimuli can manifest in all 5 major senses: tactile, visual, auditory, olfactory, and gustatory. Tactile issues include being bothered by tags or seams on clothing or being touched unexpectedly. This can even manifest through daily tasks like hair brushing or tooth brushing. Visual issues include increased neural responses to conditions of increasing visual contrast and covering eyes to protect eyes from light. Auditory issues include distraction when there is a lot of noise around or crying at loud noises. Olfactory issues and gustatory issues include consuming a narrow range of food variety and reluctance to eat new foods due to taste, texture, smell, etc. (6). Sensory processing differences mirror and likely contribute to much of the social and higher order cognitive challenges in ASD.
Brain Regions Involved in SOR
Previous studies suggest a role for the PFC, thalamus, and amygdala in sensory over responsivity (SOR) in ASD individuals (7). More specifically, the PFC plays a top-down, regulatory role in relation to other cortical and subcortical structures. The thalamus plays a central role in adjusting attention and coordinating sensory information response and connects with cortical and subcortical regions.
|
The amygdala plays a role in assigning emotional prominence to stimuli and reward learning (8). Differences in these three regions, either in anatomical structure or metabolic activity have been observed in individuals with and without ASD.
Furthermore, such differences are a potential source for SOR prevalence in those with ASD. There is consistent evidence that dysregulated connectivity exists for ASD brain regions compared to neurotypical. Diffusion Tensor Imaging (DTI) has revealed changes in functional connectivity between the PFC, thalamus, and amygdala, though results remain mixed across all three pathways (7,9). DTI has also revealed structural connectivity hindrance or impaired white matter structural integrity between the PFC-amygdala, PFC-thalamus, and thalamus-amygdala in ASD individuals (10, 11, 12). Together dysregulation between these three regions can be attributed to the decreased ability to regulate emotional response to sensory stimuli.
Furthermore, such differences are a potential source for SOR prevalence in those with ASD. There is consistent evidence that dysregulated connectivity exists for ASD brain regions compared to neurotypical. Diffusion Tensor Imaging (DTI) has revealed changes in functional connectivity between the PFC, thalamus, and amygdala, though results remain mixed across all three pathways (7,9). DTI has also revealed structural connectivity hindrance or impaired white matter structural integrity between the PFC-amygdala, PFC-thalamus, and thalamus-amygdala in ASD individuals (10, 11, 12). Together dysregulation between these three regions can be attributed to the decreased ability to regulate emotional response to sensory stimuli.
The increasing prevalence of ASD is associated with a growing population of autistic individuals who require adequate healthcare to accommodate their specific needs. However, the current healthcare system is not sufficiently equipped to meet the needs of ASD individuals.
Sensory-Related Health Barriers and Solutions
As a result of overwhelmed sensory experiences in ASD, autistic individuals face significant sensory-related healthcare barriers. A community based study revealed that sensory issues caused by facilities were a top 3 barrier for autistic adults seeking care (13). Imagine stepping into a beeping elevator then into the buzzing noise of the waiting area, which is lighted by bright fluorescent lights, filled with the smell of rubbing alcohol, but quiet enough where you can still detect the beeping of a heart rate monitor. This is all before the heightened anxiety of seeing the doctor.
To address sensory related issues, sensory-friendly items like stress balls, pop tubes, or lap pad can be used to redirect and calm ASD patients during hospital visits. Also, headphones or sunglasses can be used to block noise or light. Directly addressing the over-stimulating environments can also be helpful for sensory processing, such as using natural light as much as possible, informing the patient before touching him or her, seeing the patient in a quiet room with soft colors, or wearing less visually arousing clothing or jewelry (14). It is important to obtain individualized information about a patient’s needs that can be easily accessed by physicians, for example in a patient’s Electronic Medical Record.
Generally speaking, interventions target toward improving healthcare accessibility for disabled all individuals would be transferrable and helpful towards autistic individuals as well.
To address sensory related issues, sensory-friendly items like stress balls, pop tubes, or lap pad can be used to redirect and calm ASD patients during hospital visits. Also, headphones or sunglasses can be used to block noise or light. Directly addressing the over-stimulating environments can also be helpful for sensory processing, such as using natural light as much as possible, informing the patient before touching him or her, seeing the patient in a quiet room with soft colors, or wearing less visually arousing clothing or jewelry (14). It is important to obtain individualized information about a patient’s needs that can be easily accessed by physicians, for example in a patient’s Electronic Medical Record.
Generally speaking, interventions target toward improving healthcare accessibility for disabled all individuals would be transferrable and helpful towards autistic individuals as well.
Sources
(1) Lyall, K., Croen, L., Daniels, J., Fallin, M. D., Ladd-Acosta, C., Lee, B. K., Park, B. Y., Snyder, N. W., Schendel, D., Volk, H., Windham, G. C., & Newschaffer, C. (2017). The Changing Epidemiology of Autism Spectrum Disorders. Annual Review of Public Health, 38(1), 81–102. https://doi.org/10.1146/annurev-publhealth-031816-044318
(2) Lord, C., Brugha, T. S., Charman, T., Cusack, J., Dumas, G., Frazier, T., Jones, E. J. H., Jones, R. M., Pickles, A., State, M. W., Taylor, J. L., & Veenstra-VanderWeele, J. (2020). Autism spectrum disorder. Nature Reviews Disease Primers, 6(1), 1–23. https://doi.org/10.1038/s41572-019-0138-4
(3)Smith, B., Rogers, S. L., Blissett, J., & Ludlow, A. K. (2020). The relationship between sensory sensitivity, food fussiness and food preferences in children with neurodevelopmental disorders. Appetite, 150, 104643. https://doi.org/10.1016/j.appet.2020.104643
(4) Kanner, L. (1943). Autistic disturbances of affective contact. Nervous Child, 2, 217–250.
(5) Liss, M., Saulnier, C., Fein, D., & Kinsbourne, M. (2006). Sensory and attention abnormalities in autistic spectrum disorders. Autism: The International Journal of Research and Practice, 10(2), 155–172. https://doi.org/10.1177/1362361306062021
(6) Smith, B., Rogers, S. L., Blissett, J., & Ludlow, A. K. (2020). The relationship between sensory sensitivity, food fussiness and food preferences in children with neurodevelopmental disorders. Appetite, 150, 104643. https://doi.org/10.1016/j.appet.2020.104643
(7) Green, S. A., Hernandez, L., Bookheimer, S. Y., & Dapretto, M. (2017). Reduced modulation of thalamocortical connectivity during exposure to sensory stimuli in ASD. Autism Research: Official Journal of the International Society for Autism Research, 10(5), 801–809. https://doi.org/10.1002/aur.1726
(8) Adolphs, R. (2010). What does the amygdala contribute to social cognition? Annals of the New York Academy of Sciences, 1191, 42–61. https://doi.org/10.1111/j.1749-6632.2010.05445.x
(9) Green, S. A., Hernandez, L., Tottenham, N., Krasileva, K., Bookheimer, S. Y., & Dapretto, M. (2015). Neurobiology of Sensory Overresponsivity in Youth With Autism Spectrum Disorders. JAMA Psychiatry, 72(8), 778–786. https://doi.org/10.1001/jamapsychiatry.2015.0737
(10) Nair, A., Carper, R. A., Abbott, A. E., Chen, C. P., Solders, S., Nakutin, S., Datko, M. C., Fishman, I., & Müller, R. (2015). Regional specificity of aberrant thalamocortical connectivity in autism. Human Brain Mapping, 36(11), 4497–4511. https://doi.org/10.1002/hbm.22938
(11) Solso, S., Xu, R., Proudfoot, J., Hagler, D. J., Campbell, K., Venkatraman, V., Barnes, C. C., Ahrens-Barbeau, C., Pierce, K., Dale, A., Eyler, L., & Courchesne, E. (2016). Diffusion Tensor Imaging Provides Evidence of Possible Axonal Overconnectivity in Frontal Lobes in Autism Spectrum Disorder Toddlers. Biological Psychiatry, 79(8), 676–684. https://doi.org/10.1016/j.biopsych.2015.06.029
(12) Noriuchi, M., Kikuchi, Y., Yoshiura, T., Kira, R., Shigeto, H., Hara, T., Tobimatsu, S., & Kamio, Y. (2010). Altered white matter fractional anisotropy and social impairment in children with autism spectrum disorder. Brain Research, 1362, 141–149. https://doi.org/10.1016/j.brainres.2010.09.051
(13) Raymaker, D. M., McDonald, K. E., Ashkenazy, E., Gerrity, M., Baggs, A. M., Kripke, C., Hourston, S., & Nicolaidis, C. (2017). Barriers to healthcare: Instrument development and comparison between autistic adults and adults with and without other disabilities. Autism: The International Journal of Research and Practice, 21(8), 972–984. https://doi.org/10.1177/1362361316661261
(14) O’Hagan, B., Bays-Muchmore, C., Friedman, A., Bartolotti, L., & King, S. (2019, December 18). AUCD - Building an Autism Friendly Hospital: How we started, what we have accomplished, and where we go from here. https://www.aucd.org/template/news.cfm?news_id=14472&id=17
(2) Lord, C., Brugha, T. S., Charman, T., Cusack, J., Dumas, G., Frazier, T., Jones, E. J. H., Jones, R. M., Pickles, A., State, M. W., Taylor, J. L., & Veenstra-VanderWeele, J. (2020). Autism spectrum disorder. Nature Reviews Disease Primers, 6(1), 1–23. https://doi.org/10.1038/s41572-019-0138-4
(3)Smith, B., Rogers, S. L., Blissett, J., & Ludlow, A. K. (2020). The relationship between sensory sensitivity, food fussiness and food preferences in children with neurodevelopmental disorders. Appetite, 150, 104643. https://doi.org/10.1016/j.appet.2020.104643
(4) Kanner, L. (1943). Autistic disturbances of affective contact. Nervous Child, 2, 217–250.
(5) Liss, M., Saulnier, C., Fein, D., & Kinsbourne, M. (2006). Sensory and attention abnormalities in autistic spectrum disorders. Autism: The International Journal of Research and Practice, 10(2), 155–172. https://doi.org/10.1177/1362361306062021
(6) Smith, B., Rogers, S. L., Blissett, J., & Ludlow, A. K. (2020). The relationship between sensory sensitivity, food fussiness and food preferences in children with neurodevelopmental disorders. Appetite, 150, 104643. https://doi.org/10.1016/j.appet.2020.104643
(7) Green, S. A., Hernandez, L., Bookheimer, S. Y., & Dapretto, M. (2017). Reduced modulation of thalamocortical connectivity during exposure to sensory stimuli in ASD. Autism Research: Official Journal of the International Society for Autism Research, 10(5), 801–809. https://doi.org/10.1002/aur.1726
(8) Adolphs, R. (2010). What does the amygdala contribute to social cognition? Annals of the New York Academy of Sciences, 1191, 42–61. https://doi.org/10.1111/j.1749-6632.2010.05445.x
(9) Green, S. A., Hernandez, L., Tottenham, N., Krasileva, K., Bookheimer, S. Y., & Dapretto, M. (2015). Neurobiology of Sensory Overresponsivity in Youth With Autism Spectrum Disorders. JAMA Psychiatry, 72(8), 778–786. https://doi.org/10.1001/jamapsychiatry.2015.0737
(10) Nair, A., Carper, R. A., Abbott, A. E., Chen, C. P., Solders, S., Nakutin, S., Datko, M. C., Fishman, I., & Müller, R. (2015). Regional specificity of aberrant thalamocortical connectivity in autism. Human Brain Mapping, 36(11), 4497–4511. https://doi.org/10.1002/hbm.22938
(11) Solso, S., Xu, R., Proudfoot, J., Hagler, D. J., Campbell, K., Venkatraman, V., Barnes, C. C., Ahrens-Barbeau, C., Pierce, K., Dale, A., Eyler, L., & Courchesne, E. (2016). Diffusion Tensor Imaging Provides Evidence of Possible Axonal Overconnectivity in Frontal Lobes in Autism Spectrum Disorder Toddlers. Biological Psychiatry, 79(8), 676–684. https://doi.org/10.1016/j.biopsych.2015.06.029
(12) Noriuchi, M., Kikuchi, Y., Yoshiura, T., Kira, R., Shigeto, H., Hara, T., Tobimatsu, S., & Kamio, Y. (2010). Altered white matter fractional anisotropy and social impairment in children with autism spectrum disorder. Brain Research, 1362, 141–149. https://doi.org/10.1016/j.brainres.2010.09.051
(13) Raymaker, D. M., McDonald, K. E., Ashkenazy, E., Gerrity, M., Baggs, A. M., Kripke, C., Hourston, S., & Nicolaidis, C. (2017). Barriers to healthcare: Instrument development and comparison between autistic adults and adults with and without other disabilities. Autism: The International Journal of Research and Practice, 21(8), 972–984. https://doi.org/10.1177/1362361316661261
(14) O’Hagan, B., Bays-Muchmore, C., Friedman, A., Bartolotti, L., & King, S. (2019, December 18). AUCD - Building an Autism Friendly Hospital: How we started, what we have accomplished, and where we go from here. https://www.aucd.org/template/news.cfm?news_id=14472&id=17