Table 1.

Summary of QEEG studies in autism.

Study	Design	Participants	Measures	Results in ASD
QEEG DURING REST
Cantor et al. (1986)	10/20 System, open eyes	n = 11 ASD (age: 4–12 years, IQ = 37.45 ± 11.4)	PSD, coherence, symmetry	Higher percent delta and less alpha; higher coherence between and within, hemispheres; less asymmetry
		n = 88 TD (age: 5–15 years, IQ = 113.35 ± 9.5)
		n = 18 Intellectually disabled (age: 5–15 years, IQ = 71.1 ± 12.6)
		n = 13 TD toddlers (age: 16 months to 5 years, IQ = 121.0 ± 25.4)
Chan et al. (2007)	10/20 System, open eyes	n = 66 ASD (age: 5–18 years, TONI = 83.36 ± 21.61)	PSD	Higher absolute delta and lower relative alpha; same results for all channel
		n = 90 TD (age: 6–12 years, TONI = 111.42 ± 16.16)
Stroganova et al. (2007)	32 or 24 Electrode system, open eyes	n = 40 ASD (age: 3–8 years, IQ = 111 ± 8.29)	PSD, asymmetry	Higher prefrontal delta; leftward asymmetry at the temporal regions; symmetric mu rhythm in ASD across central sites
		n = 40 TD (age: 3–8 years)
Coben et al. (2008)	10/20 System, closed eyes	n = 40 ASD (age: 6–11 years, IQ = 93 ± 16.8) n = 40 TD (age: 6–11 years, IQ = 98 ± 15.4)	PSD, coherence	Less absolute (left frontal and posterior region) and relative delta (left frontal and vertex regions) and higher absolute beta (midline regions) and relative theta (right posterior regions); less delta and theta intrahemispheric coherence; less inter-hemispheric coherences in delta and theta in frontal regions in delta, theta, and alpha in temporal regions and in delta, theta, and beta bands central/parietal/occipital regions
Murias et al. (2007)	128 Channels, closed eyes	n = 18 ASD (age: 18–38 years, IQ = 107.33 ± 13.96) n = 18 TD (age: 18–38 years, IQ = 106.11 ± 13.56)	PSD, coherence	Higher relative theta in primarily frontal and prefrontal regions, less relative alpha in primarily frontal/prefrontal and occipital/parietal regions and higher relative beta in occipital/parietal regions; higher coherence in theta and less coherence in alpha
Pop-Jordanova et al. (2010)	10/20 System, open eyes and closed eyes	n = 9 ASD (age: 3–6 years) database of TD	PSD, brain rate	Higher delta/theta; higher beta in open eyes than in closed eyes; reduction of brain rate in all regions
Mathewson et al. (2012)	128 Channels, open eyes and closed eyes	n = 15 ASD (age: 19–52 years, IQ = 100.9 ± 18.6) n = 18 TD (age: 18–38 years, IQ = 107.1 ± 11.9)	PSD, coherence, correlation with AQ	Higher alpha in eye opens; less alpha suppression in 01; no difference in coherence; negative correlation between alpha and preferential attention to detail in posterior and frontal regions both in eye open and eye closed; negative correlation between attention to details and coherence in eye opened in the right centro-parietal region and in eye closed in the parieto-occipital regions; negative correlation between alpha coherence in eye-open and social functioning in the right fronto-central region; positive correlation between theta coherence in the left centro-parietal region in eye-closed and social functioning
Sheikhani et al. (2007)	10/20 System, closed eyes	n = 10 ASD (age: 9.3 ± 1.8 years) n = 7 TD (age: 9.2 ± 0.7 years)	PSD (STFT and STFT-BW) and bispectrum	No differences in STFT or bispectrum; significant differences in STFT-BW over Fp1, F3, F7, T3, T5, and O1
QEEG DURING REST
Ahmadlou et al. (2010)	10/20 System, closed eyes	n = 9 ASD (age: 6–13 years) n = 6 TD (age: 7–13 years)	Fractal dimension (HFD and KFD)	Significant difference in HFD in gamma, beta, and alpha and in KFD in gamma, beta, and delta
Thatcher et al. (2009)	10/20 System, open eyes	n = 54 ASD (age: 2.6–10.74 years) n = 241 TD (age: 2.2–11 years)	Phase synchronization analysis	Shorter phase shift durations in ASD in the alpha-1 frequency band (8–10 Hz); longer phase lock durations in ASD in the alpha-2 frequency band (10–12 Hz) and; differences in short and long inter-electrode pairs
Bosl et al. (2011)	64 Channels, open eyes	n = 46 HRA (age: 6–24 months) n = 33 TD (age: 6–24 months)	Multiscale Entropy (MSE) analysis	Reduced MSE in HRA subjects especially in 9–24 months range; discrimination between HRA and controls at 9 months with 80% of accuracy
Duffy and Als (2012)	32 Channels, open eyes	n = 463 ASD (age: 1–18 years) n = 571 TD (age: 1–18 years)	Coherence	High classification success between ASD and TD groups. decrease in short–distance coherence and increase in long-distance coherence in ASD group within a wide spectral range
QEEG DURING SPECIFIC TASKS
Oberman et al. (2005)	10/20 System, tasks: (1) moving their own hand, (2) watching a video of a moving hand, (3) watching a video of two bouncing balls (non-biological motion), and (4) watching visual white noise	n = 10 ASD (age: 9–14 years, IQ > 80) n = 10 TD (age: 9–14 years)	PSD mu	Decreased mu only during the self-initiated hand movement
Orekhova et al. (2007)	10/20 System, sustained visual attention	n = 40 ASD (age: 3–8 years) n = 40 TD (age: 3–8 years)	PSD in high frequency bands	Higher power especially in gamma1 in midline, central, and parietal regions
Sheikhani et al. (2009)	10/20 System, tasks: (1) eye-closed condition, (2) eye-opened condition, (3–5) looking at three samples of Kanizsa shapes, (6) looking at mother’s picture upright and (7) inverted, (8) looking at stranger’s picture upright, and (9) inverted in frequency bands	n = 15 ASD (age: 6–11 years, IQ > 85) n = 11 TD (age: 6–11 years, IQ > 85)	PSD, spectrogram	Lower spectrogram criteria at Fp1, Fp2, and T6 in gamma and higher spectral power at FP1 and FP2 in open-eyes condition; difference in alpha at T3, F7, and C3 in looking at the inverted mother’s picture; difference in alpha and beta at F7, F4, F8, C4, Pz. In looking at a stranger’s picture inverted
Sheikhani et al. (2012)	128 Channels (reduced to 10/20), sustained visual attention	n = 17 ASD (age: 6–11 years, IQ > 85) n = 11 (age: 6–11 years, IQ > 85)	Spectrogram criteria	Lower spectrogram criteria in alpha, beta, and gamma especially in temporal and frontal regions in left hemisphere
Chan et al. (2011a)	Object recognition (OR) task	n = 21 ASD (age: 5–14 years, TONI = 101.86 ± 16.09) n = 21 TD (age: 5–14 years, TONI = 106 ± 14.59)	Coherence in theta	Elevated fronto-posterior coherences in left hemisphere; higher coherence in the left than in the right hemisphere; negative correlations between memory performance and the inter-hemispheric coherence
QEEG DURING SPECIFIC TASKS
Chan et al. (2011b)	10/20 System, Go/No-Go task	n = 20 ASD (age: 7–14 years) n = 20 TD (age: 7–14 years)	PSD in theta source localization with LORETA	In the “Go” condition theta decreased in the anterior cingulate cortex (ACC), in the “No-Go” condition in the ACC and in the precuneus
Lushchekina et al. (2012)	10/20 System, tasks: (1) eye-closed condition, (2) counting during eye closed	n = 27 ASD (age: 5–7 years) n = 19 TD (age: 5–7 years)	PSD, coherence	Higher gamma in baseline condition; right-sided predominance of spectral power in alpha both at rest and during counting
Catarino et al. (2011)	10/20 System, detection tasks: (1) faces, (2) chairs	n = 15 ASD (age: 23.79–42.34 years, IQ = 119 ± 13)	MSE, PSD	Reduced MSE in ASD especially in parietal regions; higher MSE in response to faces in both groups; no differences in PSD
		n = 15 TD (age: 21.50–37.77 years, mean IQ = 119 ± 14)
QEEG FOR THE IDENTIFICATION OF AUTISTIC SUBGROUPS
Dawson et al. (1995)	10/20 System, open eyes	n = 28 ASD (age: 5–19 years, IQ = 119 ± 13)	PSD	Reduced delta and theta in the passive group in all brain regions and reduced alpha in the frontal regions
		n = 28 Chronological-age-matched TD (age: 5–19 years)
		n = 24 Language-age-matched TD (age: 2–7 years)
Sutton et al. (2005)	10/20 System, open eyes and closed eyes	n = 23 ASD (age: 9–14 years, IQ: 110.13 ± 21.21) n = 20 TD (age: 9–14 years IQ: 116.80 ± 11.69)	PSD	Higher alpha in anterior, central, and posterior cortical regions; more left-sided mid-frontal and central regions; subgroups with greater left-sided mid-frontal activity had greater social anxiety, greater general anxiety, greater social stress, and less satisfaction with interpersonal relations

ASD, autism-spectrum disorder; TD, typical developing; HRA, “high risk” of autism.