Infant Neuroconnectivity Is a Predictor of Social Responsiveness Deficits at Age Four
The ability to identify infants who are at increased risk of developing Autism Spectrum Disorder (ASD) would facilitate referral to early intervention, which has been shown to lead to improved outcomes. Biomarkers offer one method to attain that possibility. Hyperconnectivity between brain regions is seen in animal models of ASD and in human neuroimaging studies. A noninvasive way to assess neuroconnectivity in very young populations is via the electroencephalogram (EEG), a measure of neuroelectrical activity. EEG coherence is the squared cross-correlation between two electrodes and is conceptualized as a measure of functional connectivity between underlying neural networks.
The association between hyperconnectivity and social deficits in the literature led to our a priori hypothesis that early frontotemporal connectivity would predict later levels of poor social responsiveness and engagement (positive beta weights) in typically developing children.
At five-months of age, 58 infant-parent dyads participated in a research study; baseline EEG was recorded while the infant watched multicolored balls spin in a toy. When the children were four years old, parents completed the Social Responsiveness Scale (SRS) about their child’s social impairments. The SRS produces a total score, as well as five subscales: social awareness, social cognition, social communication, social motivation, and restricted and repetitive behaviors, with a higher score indicating increased impairment in each domain. All children were born full term with no complications, representing a typically developing sample.
Five-month EEG coherence at baseline between bilateral frontal and temporal scalp locations predicted SRS total score at four years (p=.03, F=3.64), with right hemisphere electrodes (F4-T8) providing unique variance (p=.012, b=.332). This measure of connectivity at five-months accounted for 12% of the variance in SRS total seen at four years. Based on this finding, we conducted post hoc analyses to determine which of the subscales may be driving the effect. Social communication (p=.028, F=3.835) and social motivation (p=.038, F=3.477) were the only two subscales predicted by five-month frontotemporal EEG coherence. Again, the right hemisphere electrodes (F4-T8) contributed unique variance for social communication (p=.011, b=.337) and social motivation (p=.039, b=.271)
These findings suggest that right frontotemporal hyperconnectivity is associated with later social behaviors that may contribute to the social deficits seen in disorders like ASD. This hyperconnectivity seems to result in diminished social motivation and communication, but not in restricted and repetitive behaviors or social cognition and awareness. Currently, there are no empirically supported methods to diagnose children with ASD as young as five-months of age; however, this measure of hyperconnectivity could serve as a predictor for reduced social responsiveness at age four. This could lead to early screening techniques and allow for targeted interventions for children who are at risk for developing ASD or other difficulties with social engagement.