A Mechanistic Link between Olfaction and Autism Spectrum Disorder

Area of Science:

• Neuroscience
• Developmental Psychology
• Sensory Processing

Background:

• Internal action models (IAMs) are neural templates for sensory-motor coordination.
• Impaired IAMs are hypothesized to underlie autism spectrum disorder (ASD).
• The role of IAMs in olfaction and their link to ASD phenotypes remain unclear.

Purpose of the Study:

• To investigate olfactory IAMs in children with ASD by analyzing the sniff response.
• To determine if olfactory IAM dysfunction correlates with social communication impairments in ASD.
• To explore the sniff response as a potential biomarker for ASD.

Main Methods:

• Measured non-verbal, non-task-dependent sniff responses to pleasant and unpleasant odors in 18 children with ASD and 18 typically developing (TD) controls.
• Analyzed sniff magnitude modulation relative to odor onset and valence.
• Correlated sniff response patterns with ASD severity and social/motor impairments.

Main Results:

• TD children exhibited typical adult-like sniff modulation within 305 ms.
• Children with ASD showed a profoundly altered sniff response, lacking valence-based modulation.
• The altered sniff response accurately classified 81% of ASD cases and correlated significantly with social, but not motor, impairment.

Conclusions:

• Olfactory IAMs are impaired in children with ASD.
• Aberrant sniffing is a novel, objective marker for ASD.
• This finding suggests a mechanistic link between olfactory processing, IAMs, and social communication deficits in ASD.