Table 2.
Summary of EEG asymmetry analysis in patients with major depressive disorder.
| Researchers | Aim | Material and methods | Results |
|---|---|---|---|
| Barros et al. (2022) | To compare frontal alpha asymmetry (FAA) in younger and older adults | Resting-state EEG analysis of 57 younger adults and 39 older adults. Regression analyses assessed the relationship between FAA and loneliness, depression, and anxiety. | Both groups showed greater left than right cortical activity. Older adults had higher FAA than younger adults. |
| Monni et al. (2022) | To assess frontal alpha asymmetry (FAA) using a latent factor approach, improving reliability and discriminant validity of resting-state EEG FAA measurements. | FAA was assessed at broad, low, and high alpha bands (8–13 Hz; 8–10.5 Hz; 11–13 Hz), using mastoid references and Current Source Density (CSD). | Both factor and raw scores showed excellent reliability, but only FAA demonstrated full discriminant validity. FAA at low alpha band was negatively associated with depression symptoms. |
| Dharmadhikari et al. (2019) | To evaluate the usefulness of frontal alpha asymmetry (FAA) as a potential biomarker for depression in both resting and activated EEG conditions. | 24 patients with depression and 17 healthy controls were compared. EEG was recorded in resting, activated and post-activation phases. Alpha power at FP1, FP2, F3, F4, F7, and F8 was analyzed to assess FAA. | Significant FAA differences were found between groups at the F7–F8 pair and at F7 specifically. FAA varied across conditions, with the most pronounced differences during the activation phase. |
| Luo et al. (2025) | To assess frontal alpha asymmetry (FAA) as a potential resting-state diagnostic biomarker for major depressive disorder (MDD). | 23 studies were included, with 1928 MDD patients and 2604 controls. FAA measurements were taken from EEG electrodes (F3/F4, F7/F8, or Fp1/Fp2). | FAA (F4 – F3) showed a small but significant overall effect size, suggesting limited diagnostic utility. |
| Stewart et al. (2014) | To test whether frontal EEG asymmetry during emotional challenge better reflects depression vulnerability than resting-state asymmetry. | EEG was recorded during rest and during a facial emotion task (approach emotions: anger, happiness; withdrawal emotions: fear, sadness). Asymmetry was analyzed using average, Cz, mastoid references | EEG asymmetry during the emotional challenge better distinguished MDD status than resting FAA for most references, supporting the capability model |
| Périard et al. (2024) | To investigate whether relative frontal alpha asymmetry (FAA) can serve as a biomarker for somatoform disorders (SFD) and its relationship with chronic stress and depressive symptoms. | Resting-state EEG was recorded using 64 electrodes (10-10 system) in 26 patients with primary SFD, 23 with major depressive disorder (MDD), and 25 healthy controls. FAA was calculated as alpha power in the right frontal cortex minus left. | No significant group differences in FAA were found. However, across all participants, lower relative left frontal activity was associated with higher chronic stress and depressive symptoms. |
| Arns et al. (2016) | Investigating EEG alpha asymmetry as a predictor of antidepressant treatment effectiveness. | EEG analysis in a randomized trial of treatment for depression (iSPOT-D) | Alpha asymmetry predicted treatment response |
| Bruder et al. (1997) | Investigate differences in EEG asymmetry between depressed patients with and without anxiety disorder. | Resting traditional EEG (eyes open and closed) in 44 patients with MDD (19 with anxiety, 25 without) and 26 healthy subjects | Depression with and without anxiety shows different brain activity patterns – in line with the model of hemispheric asymmetry |
| Hinrikus et al. (2010) | Study of EEG spectral characteristics in depression. | EEG spectral analysis in patients with depression. | EEG spectral characteristics showed significant differences between people with and without depression. |
| Graae et al. (1996) | Investigating alpha asymmetry in the traditional EEG of people who have attempted suicide | EEG analysis of people after a suicide attempt vs. a control group | Alpha asymmetry in the EEG may be a biomarker for suicide risk. |
| Rasouli et al. (2024) | Investigating EEG activity in the frontal regions during cognitive tasks in people who have recently attempted suicide. | Power spectrum analysis of EEG during Raven's task | Frontal EEG can be a useful indicator of suicide risk in people with depression. |
| Roh et al. (2020) | Investigating the role of frontal alpha asymmetry moderated by suicidal thoughts in MDD. | EEG analysis in MDD patients with and without suicidal thoughts | Frontal alpha asymmetry can help predict suicide risk in MDD |