QEEG AS AN ASSESSMENT TOOL FOR AUTISTIC SPECTRUM DISORDER
Natasha Nesic, Ph.D. student, Psychophysiology Department
College of Integrative Medicine & Health Sciences Saybrook University
One of the features of autism spectrum disorder (ASD) is abnormal neural connectivity. Connectivity abnormalities often are manifested in cortical excitability, which can be recorded with QEEG. EEG abnormalities frequently correspond to behavioral symptoms associated with the disorder. EGG measurements serve as biomarkers for early risk assessment as well as prognosis. QEEG uses methods such as functional connectivity analyses, spectral analyses, coherence analyses, correlation, synchronization, information dynamics, etc., to identify quantitative features associated with behaviors characteristic of ASD. ASD is usually related to reduced long-range connections between the frontal lobe and other regions in the alpha band and short-range connectivity in the theta band. This underconnectivity is also supported by fMRI studies (Gurau et al., 2017).
ASD QEEG Characteristics
Summary
Early Detection and Biomarkers
Introduction
References
ASD affects 8.8 % of children, and 5.4 are males. ASD is highly heritable 70-90 %; other etiologies, epigenetic abnormalities, and mechanisms might be involved. The main characteristics of ASD are related to communicational and social impairments and stereotypical and restricted behaviors. ASD has high heterogeneity in presentation (Wang et al., 2013). Rewarding processes to social stimuli are dampened early in the development; this causes complex cognitive and social processes to develop later and has altered trajectories and shifts towards restricted interest (RI). (Carter et al., 2020)
Abnormal power: power profile pattern is “U “shaped; extremes of the power spectrum are increased while power in the middle frequencies is reduced. GABAergic interneurons are responsible for excitatory activity in pyramidal cells are involved.
Abnormalities in hemispheric asymmetry - there is greater power in the left hemisphere compared to the right across all frequency bands. Increased resting power in the left hemisphere may contribute to executive task performance deficits.
Hyperconnectivity is often noted in the left hemisphere and reduced power in the right.
Abnormal coherence – reduced long-range coherence patterns present in ASD. Deficits in frontal lobe connectivity led to a wide range of abnormalities in cognitive, sensory, and motor processes. Findings in short-range coherence/connection patterns deficits are inconsistent in ASD. Few studies proposed excessive short-range connectivity in ASD due to the increased density of cortical matter (Wang et al., 2013).
Figure 3 Crater et al. (2020)
Figure 1 Medical daily (n.d.)
Figure 2 : Brain Hyperconnectivity in Children with Autism and its Links to Social Deficits
Figure 1 Medical daily (n.d.) https://www.medicaldaily.com/kids-autism-have-hyperconnected-brain-areas-could-brain-imaging-one-day-diagnose-disorder-262261
Figure 2 : Brain Hyperconnectivity in Children with Autism and its Links to Social Deficits - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Higher-Levels-of-Amplitude-of-BOLD-Oscillations-Are-Associated-with-Functional-Brain_fig1_258427674 [accessed 28 Feb, 2022]
Figure 3 Crater et al. (2020) retrieved from https://doi.org/10.3389/fnhum.2020.00212
Gurau, O., Bosl, W. J., & Newton, C. R. (2017). How useful is electroencephalography in the diagnosis of autism spectrum disorders and the delineation of subtypes: A systematic review. Frontiers in Psychiatry, 8. https://doi.org/10.3389/fpsyt.2017.00121
Wang, J., Barstein, J., Ethridge, L. E., Mosconi, M. W., Takarae, Y., & Sweeney, J. A. (2013). Resting state EEG abnormalities in autism spectrum disorders. Journal of Neurodevelopmental Disorders, 5(1). https://doi.org/10.1186/1866-1955-5-24
Carter, R. M. K., Jung, H., Reaven, J., Blakeley-Smith, A., & Dichter, G. S. (2020). A Nexus model of restricted interests in autism spectrum disorder. Frontiers in Human Neuroscience, 14. https://doi.org/10.3389/fnhum.2020.00212
Studies of resting state EEG suggest that we can identify selective alterations typical for ASD as early as in 6 months old baby. High-risk infants have been found to have globally reduced the power of delta, theta, alpha, beta, and gamma frequency bands. Differences in hemispheric asymmetry were also found; there was midline, and right temporal cortex gamma increased power in infants at high risk. Development lag becomes more prominent in late childhood and adolescence.