Altered GABA Concentration in Brain Motor Area Is Associated with the Severity of Motor Disabilities in Individuals with Autism Spectrum Disorder.

The sample sizes were 21 ASD and 20 TD, and the paper states these were not enough for the correlation analysis even with prior-study assumptions. GABA+ concentrations did not differ between groups, so the positive results are within-group associations, not group-level differences. Eight ASD participants were taking medical treatments, and medication was not controlled, so its effect on GABA+ or motor scores cannot be ruled out. The MRS voxel was 2 × 2 × 2 cm, smaller than the 3 × 3 × 3 cm voxels used in several previous studies, which may reduce signal-to-noise ratio. Motor skills and MRS were not completed on the same day for all participants; the average gap was 68 ± 119 days in ASD and 138 ± 287 days in TD. One ASD participant's SMA GABA+ value was excluded from subsequent analyses because it exceeded three times the SD of the mean. The BOT-2 tasks may be relatively easy for TD individuals, so low variability may explain absent TD correlations.

Funders named: Japan Society for the Promotion of Science and Meiji Yasuda Life Foundation of Health and Welfare.

Do not conclude that individuals with ASD have altered brain GABA+ levels or that GABA+ changes cause motor disability. The study found no significant group difference in GABA+ in M1 or SMA, and the motor associations were observational.