Children with neurodevelopmental disorders such as autism spectrum conditions are more likely to move during brain scans, which could distort results in research and diagnosis, according to a new study that assessed data from over 1,400 young people. The findings were published in the journal Biological Psychiatry Global Open Science.
The study, led by researchers at Columbia University and based on the Healthy Brain Network Biobank, evaluated head motion during functional MRI (fMRI) scans in children aged 5 to 21. It investigated whether specific psychiatric diagnoses were associated with movement that might affect brain imaging results. Head movement during scans can introduce artefacts that mimic or obscure true brain activity, complicating efforts to understand the underlying neural mechanisms of psychiatric disorders.
The research team initially hypothesised that children with externalising disorders such as ADHD would show more movement, while those with internalising disorders like anxiety or depression would move less. However, these predictions were not supported by the confirmatory data. Instead, it was neurodevelopmental disorders that consistently emerged as being linked to increased head movement.
Notably, children with autism showed significantly more movement than those without. This could be due to the nature of the condition, which often involves repetitive behaviours and difficulties with motor control. The study also found that the typical pattern of reduced movement with age was less evident in children with neurodevelopmental diagnoses. In other words, while most children move less in the scanner as they grow older, this trend was weaker among those with developmental conditions.
The researchers also examined other factors like intelligence, sex, and body mass index. Children with higher IQs tended to move less, perhaps because they were better able to follow instructions. Girls also generally moved less than boys. Surprisingly, higher body mass index was linked to less movement, contradicting some earlier studies.
Although early findings had suggested possible associations between externalising symptoms and movement, these did not hold up in the follow-up analysis. However, among children without an ADHD diagnosis, those with internalising disorders did show slightly less motion. The researchers suggest that traits such as perfectionism or heightened compliance with instructions might explain this effect.
The findings raise important considerations for researchers using fMRI to study brain development or psychiatric disorders. Since motion can skew the interpretation of brain activity, understanding which groups are more prone to movement can help scientists design more reliable studies. This may involve using mock scanning sessions before the actual scan to train participants or adapting protocols for children with conditions like autism.
The study highlights the complexity of brain imaging in paediatric populations. Movement is influenced by a combination of age, diagnosis, cognitive ability, and perhaps even parental behaviour during preparation. For researchers aiming to map the developing brain, accounting for these variables is essential to ensure that their findings reflect real neural differences rather than movement-related noise.
