Oral microbiota as biomarker for early autism

Iveta Ramonaite, Dental Tribune International

Thu. 1 May 2025

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HONG KONG: Autism spectrum disorder (ASD) is a global public health concern. Early identification and timely support for children with ASD can significantly enhance their likelihood of independent living and improved social functioning. However, this neurodevelopmental disorder is often diagnosed later in life, and screening methods mostly rely on subjective teacher and parent assessments. In a new study, researchers at the University of Hong Kong have found that oral microbiota could serve as an effective early screening tool for ASD, potentially improving both diagnostic accuracy and intervention outcomes.

Dentists could play a pivotal role in the early identification of autism spectrum disorder by incorporating oral microbial sampling into routine dental check-ups. (Image: University of Hong Kong)

Approximately one in 100 children worldwide have autism, according to a systematic review, and in Hong Kong, the figure is even higher, affecting one in 49 children in the educational system. According to multiple studies, the global prevalence rates for ASD are rising. Previous research has shown a strong association between gut microbiota and ASD; however, research on the link between oral microbiota and autism is limited.

“Emerging evidence on the brain–gut axis shows that gut microbiota composition is altered among individuals with ASD compared with their neurotypical counterparts. Considering that the digestive system begins with the mouth, it is possible that oral microbiota may differ between children with ASD and their typically developing peers. If such alterations exist, they might potentially serve as biomarkers for screening and aid in the early detection of ASD in young children,” lead author Jacqueline Wai-yan Tang, senior lecturer in the Department of Psychology at the University of Hong Kong, told Dental Tribune International.

The study analysed oral bacterial samples from 25 children with ASD and from 30 neurotypical children aged 3–6 to identify microbial differences and potential biomarkers for early diagnosis. The results showed lower bacterial diversity in children with ASD compared with the control group and distinct microbial compositions in both groups. In total, the researchers identified 11 bacterial species with strong potential as biomarkers for distinguishing between children with ASD and neurotypical children—six more strongly associated with the ASD group and five with the controls.

A new model for non-invasive autism screening

Based on the findings, the researchers developed a predictive model which demonstrated an accuracy rate of 81% in identifying ASD based on oral swab samples. “These findings suggest that oral bacteria patterns could potentially serve as biological markers for autism screening, providing a new direction for early detection tools that do not solely rely on behavioural observations. This innovative collaboration across disciplines adds to the growing body of evidence linking microorganisms and brain development in autism,” Tang noted.

The findings may have practical implications for dental professionals, who could play a pivotal role in early autism detection by incorporating microbial screening into regular check-ups. As a non-invasive screening method, it could effectively complement current behavioural assessments. Tang emphasised that the approach may be particularly valuable for young children, who often benefit the most from early intervention.

In addition, given the increased oral sensitivities often found in children with ASD, introducing early and consistent dental check-up routines provides dual benefits. Tang explained: “Beyond detecting potential biomarkers, these visits help to gradually desensitise children to oral examinations and dental procedures, thereby reducing anxiety and sensory discomfort associated with dental care. This proactive approach can help to prevent the development of dental phobias that may otherwise compromise oral health throughout life.”

Lead author Jacqueline Wai-yan Tang (middle) believes that her study on employing oral microbiome analysis to identify children with autism spectrum disorder will pave the way for a more accessible and objective method of early autism screening. (Image: University of Hong Kong)

Towards a multidisciplinary approach to autism care

In addition to the direct clinical findings, this study highlights the significant importance of interprofessional collaboration in the care of individuals with autism. “By bringing together educational psychologists and dentists, the research demonstrates how crossing traditional disciplinary boundaries can yield innovative approaches to complex health challenges,” Tang noted.

“This research opens up possibilities for a more accessible and objective screening method that respects the unique sensory needs of children on the autism spectrum while still providing valuable clinical information,” she concluded.

Future research will focus on expanding the sample size and refining the screening technology. The authors recommended further study of the mechanistic association between the oral bacterial compositions that they identified and ASD pathophysiology.

The study, titled “Alterations of oral microbiota in young children with autism: Unraveling potential biomarkers for early detection”, was published online in the January 2025 issue of the Journal of Dentistry.