Invisible Threads: Mapping the Brain Connectivity in Autism

While there is evidence suggesting alterations in functional connectivity within the autistic brain, the findings have often been inconsistent. The existing body of literature provides a myriad of diverse and at times contradictory findings on how brain regions synchronize and interact differently in those with autism compared to neurotypical individuals.

This inconsistency could largely be attributed to small sample sizes, with prior studies often relying on fewer than 70 participants per study. This can increase the risk of false positive results and inflated effect sizes, potentially compromising the replicability and reliability of the findings.

Another contributor to these divergent results could be head movement during scanning. Individuals with autism tend to move significantly more than neurotypical individuals during scans, and such movement is known to generate artifactual connectivity patterns, resembling those reported in previous studies as characteristic of autism.

To address these challenges, a joint study was conducted by Radboudumc and Monash University in Melbourne, Australia. This research published in Biological Psychiatry integrated data from the large autism initiatives EU-AIMS LEAP (European Autism Interventions Longitudinal European Autism Project) and ABIDE (Autism Brain Imaging Data Exchange). Under the guidance of Jan Butelaar and Alex Fornito, the study, led by Iva Ilioska and Marianne Oldehinkel, analysed resting state brain scans from 1824 participants aged 5 to 58 - the largest fMRI sample of autistic individuals studied to date.

The team implemented rigorous quality control and meticulously removed artifacts caused by head motion contamination. This facilitated a more reliable comparison of functional connectomes between the groups of autistic and neurotypical people.

They identified weaker connectivity primarily in brain networks related to sensory processing and attention, whereas stronger connectivity was found in higher order processing systems linked to introspection and social cognition. Interestingly, these changes did not show a significant dependence on age or sex, suggesting that these connectivity patterns might be a stable trait-like feature of autism. These results replicate in the two independent samples separately and are not sensitive to medication use, ADHD comorbidity or different data preprocessing pipelines.

figure 1.

This research highlights a complex pattern of altered functional connectivity in autism that relates to clinical symptoms and helps to reconcile prior mixed findings. The authors see their findings as a groundwork for future development of targeted interventions and biomarkers discovery in autism.

Read the study here

Ilioska I, Oldehinkel M, Llera A, Chopra S, Looden T, Chauvin R, Van Rooij D, Floris DL, Tillmann J, Moessnang C, Banaschewski T, Holt RJ, Loth E, Charman T, Murphy DGM, Ecker C, Mennes M, Beckmann CF, Fornito A, Buitelaar JK. Connectome-wide Mega-analysis Reveals Robust Patterns of Atypical Functional Connectivity in Autism. Biol Psychiatry. 2023 Jul 1;94(1):29-39. doi: 10.1016/j.biopsych.2022.12.018. Epub 2022 Dec 23. PMID: 36925414.