Taste processing in autism spectrum disorder: A translational scoping review.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by persistent challenges in social communication and restricted/repetitive behaviors, including sensory atypicalities. Taste processing is critical for assessing the sensory and hedonic properties of food; however, it remains understudied in ASD, which may limit our understanding of the disorder's links to selective eating and nutritional deficits. This scoping review on autistic gustatory functioning followed a predefined protocol. We conducted searches across four databases and identified 37 studies involving human participants, categorized into three methodologies: questionnaires, neuroimaging, and psychophysical tests. Additionally, eight studies on ASD animal models were included to offer cross-species insights. Questionnaire data generally indicate that individuals with ASD exhibit differences in taste reactivity compared to those without ASD. Neuroimaging studies suggest potential involvement of specific brain regions, including hippocampal volume and anterior superior temporal sulcus (aSTS) connectivity in atypical taste processing. Psychophysical assessments and animal studies further reveal variability in basic taste preferences, with individuals with ASD showing particular aversion to bitterness and showing either no difference or a decreased preference for sweetness compared to typically developing peers. This review also highlights research gaps regarding specific qualitative tastes such as saltiness, sourness, and umami in ASD, limiting a comprehensive understanding of ASD's chemosensory profile and emphasizing the need for further research in these areas.