Systematic ReviewAutism research : official journal of the International Society for Autism Research2025

Action execution and observation in autistic adults: A systematic review of fMRI studies.

Sara Stillesjö, Hanna Hjärtström, Anna-Maria Johansson and 3 others

PMID 39673256

WHAT IT FOUND

Across 16 fMRI studies of adults with autism, brain activation during action execution and observation occurred in the same regions as non-autistic adults but differed in magnitude and direction.

Results were inconsistent, with no single pattern of atypicality emerging.

Key findings

01Adults with autism showed brain activations in similar locations to non-autistic adults during motor tasks, but the magnitude and direction of these activations deviated.

02Ten brain regions showed overlapping activity between action execution and observation conditions, including the inferior frontal gyrus and precentral gyrus, but the direction of effects varied across studies.

03Most studies did not find significant behavioral differences in task performance between groups, though where differences occurred, they consistently pointed toward less optimal performance in the autism group.

STILL TO COME

How it was doneWhat they found

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What it does not show

Sample sizes were small in many included studies. Participants were predominantly male (88.4%) and had average IQs above 70, limiting generalizability to females or those with intellectual disability. IQ was not controlled for as a covariate in any study. Comorbidities were not reported, so it is unclear if findings are specific to ASD. Statistical procedures and thresholds varied widely between studies. Five studies used 1.5T scanners, which have lower resolution than the 3T scanners used in others. Some studies included child participants despite the review's focus on adults.

Declared interests

The paper does not list specific conflicts of interest or funding sources in the provided text, though it is supported by non-U.S. government funding.

The easy way to misread this

Do not interpret this review as identifying a specific neural marker for motor impairment in autism. The findings are heterogeneous, with studies reporting both higher and lower activation in the same brain regions. No consistent pattern of atypicality was established.

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The study

Participants
233 autistic adults and 238 non-autistic adults across 16 studies (209 and 214 respectively after correcting for assumed identical samples)
Certainty of evidence
Moderate

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    Cite

    Sara Stillesjö, Hanna Hjärtström, Anna-Maria Johansson, et al. Action execution and observation in autistic adults: A systematic review of fMRI studies. Autism research : official journal of the International Society for Autism Research. 2025.

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