Reduced frontal gamma power at 24 months is associated with better expressive language in toddlers at risk for autism.
Carol L Wilkinson, April R Levin, Laurel J Gabard-Durnam and 2 others
PMID 31119899WHAT IT FOUND
High-risk toddlers without later ASD had lower frontal gamma power at 24 months, and lower power was linked to better expressive language.
Toddlers with ASD did not differ from low-risk controls, so this single EEG measure was not a clear ASD marker.
Key findings
01At 24 months, frontal gamma power was lower in high-risk toddlers without ASD than in low-risk toddlers (P = 0.013), while the expected ASD group difference was not seen.
02In high-risk toddlers, frontal gamma power was negatively correlated with expressive language T-scores (r = -0.24, P = 0.01, n = 54), while low-risk toddlers showed no such correlation (expressive r = 0.01, P = 0.94; n = 43).
03At 36 months, low-risk toddlers and high-risk toddlers with ASD differed in how frontal gamma power at 24 months related to later language scores: low-risk toddlers showed a positive association, and high-risk toddlers with ASD showed a negative association.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The analysis used 101 toddlers, although 255 infants were enrolled, because not all had usable EEG data at 24 months. The high-risk toddlers with ASD were few: 16 had usable EEG data at 24 months, so within-group comparisons had limited power. The sample was mostly white and mostly above $75,000 household income, and maternal education differed between groups. Most participants, including those with ASD, generally had age-appropriate language abilities, which reduced variability and may have made language associations harder to detect. EEG equipment and sampling rates changed over the study, and the children's attentional state and behavior could not be fully controlled. Sex subgroup results were based on small numbers, including only 5 high-risk females with ASD. The authors state that the findings do not yet present sufficient evidence for EEG frontal gamma power as a clinical biomarker of language development.
Declared interests
The authors declared no conflicts of interest. The article is listed as supported by NIH and non-U.S. government research funding.
The easy way to misread this
Do not conclude that low frontal gamma power causes better language or can be used to diagnose autism. The study is observational, the ASD group did not differ from low-risk controls on frontal gamma power, and the authors say the measure is not yet a clinical biomarker.