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Dec 8, 2022
Electroencephalography (EEG) is a non-invasive and painless procedure that can record electrical activity along the scalp produced by firing neurons within the brain. EEG reflects the synchronized and de-synchronized oscillations of the overall cortical activity in the brain. Brain patterns commonly form sinusoidal wave shapes, and the brain state may make certain frequencies more dominant. Brain waves have been categorized into four basic groups (delta waves, less than 3.5 Hz; theta waves which are 4-7 Hz; alpha waves which are 8-12 Hz; and beta waves which are 13-30 Hz). Each wave signifies the consciousness of the person’s brain state. Delta waves are seen in deep sleep states, theta waves are seen during the stages of falling asleep, alpha waves are seen during awake and resting states, and beta waves are seen when someone is awake with mental activity.
EEG could be useful in determining the presence of mood disorders, sleep disorders, and eating disorders. Psychiatrists and neurologists will often order an EEG for their patients to evaluate the person’s brain activity in certain states. Clinicians evaluate event-related potentials (ERP) to recognize mental processes such as perception, selective attention, and language processing, which occur in milliseconds. Changes in sleep can be closely related to disturbances and changes in nutritional status. Weight gain can increase the length of sleep and REM sleep (Jauregui-Lobera, 2011). Therefore, the relationship between insomnia and low body weight may hold for various psychiatric and other disorders with impaired nutritional status and weight loss. Sleep disturbances have been reported in over 80% of patients with depression (Armitage, 2007). However, these sleep disturbances can vary in recognition using EEG based on gender and age. Melancholic features of depression correlated significantly with low slow-wave activity in depressed men but not in depressed women (Armitage, 2007). Women with depression showed low temporal coherence of sleep EEG rhythms, but the presence or absence of melancholic features did not influence correlations (Armitage, 2007).
According to Kim et al. (2022), resting-state EEGs of people with bipolar disorder (BD), people with major depressive disorder (MDD), and people who were considered healthy controls (HC) were conducted to investigate functional cortical networks. The BD and MDD patient groups showed significantly higher strength and clustering coefficients than the HC group (Kim et al., 2022). Also, the BD and MDD groups showed a lower path length in six frequency bands compared to the HC group (Kim et al., 2022). Therefore, resting-state EEG may be a useful tool for clinicians evaluating people with various mood disorders by analysis of the high beta band, which may indicate that regions of the brain have become more connected with their neighbors with depressive and anxious states.
- Armitage, R. (2007). Sleep and circadian rhythms in mood disorders. Acta Psychiatrica Scandinavia, 115(433), 104-115.
- Jauregui-Lobera, I. (2011). Electroencephalography in eating disorders. Neuropsychiatric Disease and Treatment, 8(1), 1-11. DOI: 10.2147/NDT.S27302
- Kim, S., Baek, J., Shim, S., Kwon, Y., Lee, H., Yoo, J., & Kim, J. (2022). Alteration of functional cortical networks in mood disorders with resting-state electroencephalography. Scientific Reports, 12(5920), 1-7. DOI: 10.1038/s41598-022-10038-w
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