Serum vitamin D levels as a potential risk factor for olfactory abnormalities in children with autism spectrum disorders: a case-control study

Abstract

Abstract Objective To explore the relationship between blood 25-hydroxyvitamin D (25(OH)D) levels and olfactory abnormalities in patients with autism spectrum disorder (ASD). Methods A pathology-controlled study method was used to enroll 115 children with ASD who were admitted to the HITS Dahealth Children's Rehabilitation Center in Haikou City, Hainan Province, China, from August 2022 to August 2023. The children with ASD were divided into an abnormal olfactory group and a normal olfactory group according to the SPSRC scale. 32 children with ASD with abnormal olfaction were used as the case group, and 1:1 age- and sex-matched children with normal olfaction with ASD were used as the control group, and the differences in 25(OH)D levels and clinical phenotypic data between the two groups were compared. Serum 25(OH)D levels were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Clinical characterization of the children in the two groups was assessed using the short version of the Sensory Processing Proficiency Scale (SSP), the Revised Stereotyped Repetitive Behavior Scale (RBS-R), the Social Reactivity Scale, Second Edition (SRS-2), and the Autism Spectrum Questionnaire Scale (AQ). Results Blood 25(OH)D levels, SSP scores, and SRS-2 scores were lower in the olfactory abnormality group than in the control group, and the difference was statistically significant (t = 4.460, P < 0.001). Logistic regression analysis showed that 25(OH)D < 25 ng/mL (β = 1.433, OR = 4.192) and SSP < 115 (β = 1.838, OR = 6.286) were independent risk factors for the disease (all P < 0.05). Conclusion Blood 25(OH)D levels were lower in children with ASD associated with olfactory abnormalities and correlated with olfaction and some clinical phenotypes, but the specific mechanisms need further investigation.