A Literature Review of Gustatory Over-Responsivity Among the Population with Autism Spectrum Disorders

Introduction Atypical response to sensory stimuli is common in the autism spectrum disorder (ASD) population. While sensory over-responsivity in the gustatory domain (GOR) among ASD has been frequently reported, previous reviews were not solely focused on GOR in the ASD population. This review sheds light on pertinent sensory functions in ASD, differences in GOR between those with and without ASD, and concepts related to GOR in ASD. Results Neurobiological mechanisms in GOR were less studied in the population with ASD. Also, it is not clear if GOR is from difficulties of differentiation, detection threshold, and multisensory integration. Among thirty-six studies using behavioral questionnaires, a greater proportion of ASD (36-72%) had GOR compared to typically developing (TD, 20%) individuals. Furthermore, the ASD population repeatedly showed severe GOR scores relative to the TD cohort. Brain imaging studies suggested aberrant neural responses to oral stimuli as a contributing factor. It is posited that GOR contributes to food selectivity and poor dental care among ASDs. Poor nutritional outcomes among ASDs are controversial. However, severe GOR and food selectivity in reported cases present life-threatening events like pulmonary hypertension mediated by vitamin deficiencies. In addition, being underweight or overweight was associated with GOR in youths with ASD, raising a chronic health concern for general health and well-being. Another emerging consideration is the role of gut microbiome disruption in individuals with ASD and its relationship with GOR. Finally, the ASD population showed more common gastrointestinal problems than their TD counterparts, implying that GOR could be a consequence of anxiety from prior gastrointestinal experiences. Conclusion To provide families with ASD with an environment that promotes healthy development and growth, we need further research, development of clinical management, and policy changes. Thus, we recommend the targeted study of the neural mechanisms, microbiome consequences, and evidence-based intervention for GOR in ASDs.