As I was prepping for my journey into the Mecca for doctors, IFM training, I was halted in my review of the PDFs by a fascinating article.
According to HealthDay, “The sense of smell is in fact a major component of human social interaction,” said lead author Liron Rozenkrantz, a Ph.D. student at the Weizmann Institute of Science in Israel. “Given that olfaction is probably altered in autism, could it be that this is a part of the social challenge in autism?” 1
This quote was referencing a recent study in which children with autism spectrum disorders appeared to respond to unpleasant odors differently than children without autism. In fact, researchers were able to tell who had autism about 80% of the time based only on “sniff responses.” This supports that a difference in how children with autism process odors exists. 1-2
“Since we know that many children with autism are hypersensitive to touch, sound, taste and visual stimuli, it is especially interesting that they seem not to be responsive to odor in the same fashion,” said Elliott, who was not part of the research. 1
This is not the first study to evaluate olfaction differences in autistic children. In a 2011 trial with 35 highly functioning autistic children vs. control, researchers reported, “We found impaired odor detection and almost normal odor identification in children with autism.” 3
Several other studies have also reported a link in the sense of smell and children with autism. A small 2 part study sought to determine differences in higher-order olfactory processing (assessing olfactory identification) and low-level olfactory processing (odor detection thresholds and discrimination) among controls, autistic, and Asperger participants. Olfactory identification was impaired in autistic children; whereas detection and discrimination were not different. The authors believed this signified a difference to other enhanced perceptions in autistic children. 4
In a similar study, “Patients with ASD, compared to healthy controls, perceived the smell of cinnamon and pineapple as significantly less pleasant (p < 0.05); at the trend level, the same was true of cloves (p < 0.1).” 5
Another study found no association in relation to ASD and olfaction; however, there was diversity in age amongst the participants and was another small sample size study. 6
I’ve written several articles on the perception of pain and olfaction and the processing networks involved. In my former blog, the Smell of Emotions, I discussed how odor was linked to emotional processing and how the sense of smell could relate to survival and reactionary patterns. It’s interesting that autistic children have a different response to odors.
Of course, there are many complex patterns in neurological connectivity, receptivity, and brain stem feedback involved in sensory processing, but the studies are intriguing relating to the consideration of olfaction in diagnosis and the implications in treatment for autism. Autism has many other intricate factors to be explored such as SNPs, toxicant exposure, the microbiome and gut-brain axis, mitochondrial health, intestinal health, stealth infections, and all the other complex matrix of interactions which I discussed previously.
Furthermore, nutritional interventions can have impact. One study reported the following, “Recent trials involving gluten-free diets, casein-free diets, and pre- and probiotic, and multivitamin supplementation show contradictive but promising results. It can be concluded that nutrition and other environmental influences might trigger an unstable base of genetic predisposition, which may lead to the development of autism, at least in a subset of ASD patients. Clear directions for further research to improve diagnosis and treatment for the different subsets of the disorder are provided.”
It will be interesting to see if researchers begin to examine interventions such as essential oils and use of various scents to determine if these can effect various symptoms or behavior in children with ASD.
In my love for the microbiome, I wanted to share this amazing video with you that I came across during the Future of Healing Series.
- Haelle, T. Children with Autism Respond Differently to Smells: Study. Health Day. July 2, 2015. http://consumer.healthday.com/cognitive-health-information-26/autism-news-51/children-with-autism-respond-differently-to-smells-study-700983.html
- Rozenkrantz et al. A Mechanistic Link between Olfaction and Autism Spectrum Disorder. Current Biology. 2015. DOI: 10.1016/j.cub.2015.05.048
- Dudova I, Vodicka J, Havlovicova M, Sedlacek Z, Urbanek T, Hrdlicka M. Odor detection threshold, but not odor identification, is impaired in children with autism. Eur Child Adolesc Psychiatry. 2011 Jul;20(7):333-40. doi: 10.1007/s00787-011-0177-1. Epub 2011 Apr 29.
- Galle SA, Courchesne V, Mottron L, Frasnelli J. Olfaction in the autism spectrum. Perception. 2013;42(3):341-55.
- Hrdlicka M, Vodicka J, Havlovicova M, Urbanek T, Blatny M, Dudova I. Brief report: significant differences in perceived odor pleasantness found in children with ASD. J Autism Dev Disord. 2011 Apr;41(4):524-7. doi: 10.1007/s10803-010-1084-x.
- Dudova I, Hrdlicka M. Olfactory functions are not associated with autism severity in autism spectrum disorders. Neuropsychiatric Disease and Treatment. 2013;9:1847-1851. doi:10.2147/NDT.S54893.