Spontaneous Beta Oscillations Are a Biomarker of Duplication 15q11.2-q13.1 Syndrome
Objectives: Herein, we sought to quantify SBOs in resting-state EEG recordings from children and compare a cohort of children with Dup15q syndrome with (A) a comparison group of age-matched typically developing (TD) children and (B) another comparison group of age and intelligence quotient (IQ) matched children with nonsyndromic ASD.
Methods: We measured SBOs from resting-state EEG recordings of children with Dup15q syndrome (n = 11) using 129 channel high-density EEG nets and compared these recordings to those from TD children (n = 9) and children with nonsyndromic ASD (n = 10). Because beta is traditionally examined as two frequency bands, we quantified SBOs as both low beta and high beta power. Relative power in delta (1 – 4 Hz), theta (4 – 8 Hz), alpha (8 – 12 Hz), low beta (12 – 20 Hz), high beta (20 – 30 Hz), and gamma (30 – 48 Hz) frequency bands was computed for 9 scalp regions of interest (ROIs). Any child being treated with benzodiazepines—drugs which induce beta oscillations and enhance inhibitory currents through GABAA receptors—was excluded from analysis.
Results: High beta power was significantly higher in children with Dup15q syndrome compared with both the TD (p < 1.0 x 10-4, FDR corrected) and ASD (p < 1.0 x 10-4, FDR corrected) comparison groups. Similarly, resting low beta power was significantly higher in children with Dup15q syndrome than in either comparison group (TD, p = 0.0108, FDR corrected; ASD, p = 6.5 x 10-3, FDR corrected). Delta power was also significantly lower in children with Dup15q syndrome than in either comparison group (TD, p = 8.1 x 10-3, FDR corrected; ASD, p= 0.0126, FDR corrected).
Conclusions: SBOs represent a clear diagnostic biomarker of a genetically distinct subgroup of children with neurodevelopmental disorders. Given evidence that beta oscillations relate to GABAergic tone [Gaetz et al., 2011; Van Lier et al., 2004], these SBOs represent a potential biomarker of cortical inhibition in this population that may facilitate not only the diagnosis but also treatment monitoring in a subgroup of children within the autism spectrum. Our finding of lower delta power in children with Dup15q syndrome may relate to a shift in spectral energy from slow to fast frequencies (i.e., delta to beta) resulting from GABAA receptor gene upregulation in this disorder.