Olfactory functions are not associated with autism severity in autism spectrum disorders

Changes in olfactory functions have been found in many neurodegenerative and psychiatric disorders, including autism spectrum disorders (ASDs). The aim of the present study was to evaluate the relationship between olfactory functions (odor-detection thresholds, odor identification, and odor preference) and autism severity and sensory-related behavior in children and adolescents with ASD.

Our sample consisted of 35 high-functioning patients with ASD (mean age 10.8±3.6 years, 31 boys). Olfactory testing (threshold and identification) used the Sniffin' Sticks test. Odor pleasantness was assessed on a 5-point scale using the Identification part of the Sniffin' Sticks test. The severity of autistic psychopathology was measured using the Childhood Autism Rating Scale (CARS).

Using Spearman's correlation, we found no significant correlations between autism severity (as expressed by total CARS score) and odor-detection thresholds (R=0.144, P=0.409), odor identification (R=0.07, P=0.966), or odor pleasantness (R=-0.046, P=0.794). There was also no significant relationship between CARS item 9 ("Taste, smell, and touch response and use") and odor-detection thresholds (R=0.170, P=0.330), odor identification (R=0.282, P=0.100), or odor pleasantness (R=0.017, P=0.923).

We did not find any significant relationship between the severity of autistic psychopathology and olfactory functions.