EEG In psychiatric disorders
From Newson and Thiagarajan 2019
ADHD
- Age-dependent (significant in children) increase in theta and decrease in beta under eyes closed conditions (increase in theta/beta ratio)
- Approved as a biomarker by the FDA
- But there’s a general pattern of increase in theta or decrease in beta in other disorders incl. OCD, SCZ, internet addiction — reduced theta/beta ratio is a general marker for shared symptoms across a number of disorders rather than specific to ADHD
Schizophrenia
- Consistent and reliable increases in the absolute delta and theta band power, decreases in absolute alpha band power with eyes closed
- In eyes open, increase in theta, alpha, beta
- Differences are higher in magnitude relative to differences reported for other disorders (avg theta increase 50%, alpha decrease 58%)
Depression
- Increase in absolute power in theta and beta for both eyes open and closed, but nonsignificant when considering relative power
- Large study of 1,344 participants using a different methodology than other studies identified increases in theta across frontal regions of the brain
Addiction
- No significant difference across addictions (opioid, alcohol, internet) except beta which has an increase for opioid/alcohol addiction & decrease for internet addiction
- Increase in theta power for alcohol addiction & decrease in alpha for opioid addiction
OCD
- Similar to ADHD & SCZ: increase in delta & theta bands and decrease in alpha band
- High consistency for absolute, but low for relative power
- Often comorbid with other disorders & these changes are unlikely to reflect changes purely attributable to OCD. There may be overlap in symptoms with ADHD and schizophrenia.
PTSD
- Generally, no significant differences in spectral bands (reasonable consistency)
- When differences reported, they suggest decrease in all bands in disorder group for eyes open conditions, and increases/decreases for eyes closed conditions
Autism
- Little or no significant difference in the majority of bands, with exception of delta/beta eyes closed & alpha eyes open. Highly inconsistent results, no patterns can be inferred.