CohortAutism research : official journal of the International Society for Autism Research2026

Behavioral Phenotype Associations With Resting State EEG Signal Complexity and Power Spectral Density in Fragile X Syndrome.

Mélodie Proteau-Lemieux, Inga S Knoth, Saeideh Davoudi and 12 others

PMID 41657078

WHAT IT FOUND

In Fragile X syndrome, higher brain signal complexity linked to better cognition, and more alpha power linked to less social avoidance.

More high gamma power linked to less hyperactivity, but only in those not taking stimulants. These are brain markers, not treatments.

Key findings

01Higher complexity in the EEG signal was associated with better non-verbal cognitive functioning in two brain regions.

02Higher alpha power was associated with lower scores for social avoidance behaviors.

03Higher high gamma power was associated with lower hyperactivity scores, but this link survived correction only in participants not taking psychostimulants.

STILL TO COME

How it was doneWhat they found

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What it does not show

The sample size was small (41 participants), which limits how confident we can be in the findings. ADHD symptoms were assessed using the SNAP-IV, which has not been validated for people with intellectual disabilities, so these scores may not accurately reflect true symptom severity. The study excluded individuals with non-verbal IQ scores above 85, so the results do not apply to those with Fragile X who have average or above-average cognitive abilities. Many participants were on medication, which complicates the interpretation of brain-behavior links, particularly for hyperactivity. This is a cross-sectional study, so it shows associations at one point in time, not that brain activity causes these behaviors or vice versa.

Declared interests

The authors declared no conflicts of interest. The work was funded by the Azrieli Foundation, Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council of Canada, and the UC Davis MIND Institute.

The easy way to misread this

Do not interpret these EEG patterns as diagnostic tools or predictors of treatment response. The study found statistical associations in a small group, but these markers are not yet validated for clinical use, and the link between brain activity and hyperactivity was unclear in patients already taking stimulant medication.

Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →


The study

Participants
41
Certainty of evidence
Low

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    Cite

    Mélodie Proteau-Lemieux, Inga S Knoth, Saeideh Davoudi, et al. Behavioral Phenotype Associations With Resting State EEG Signal Complexity and Power Spectral Density in Fragile X Syndrome. Autism research : official journal of the International Society for Autism Research. 2026.

    Read the original — we summarise, we never replace the paper.