Major depressive disorder (MDD) is a multidimensional disorder characterized by the changes in the mood, cognitive capacity, sensorimotor and homeostatic functions. Approximately half of the patients diagnosed with MDD do not respond to treatments. New methods are being sought in order to estimate the characteristics that separate the treatment-responsive patients from non-treatment-responsive patients.
Electroencephalography (EEG) is frequently used in order to research the electrophysiological variables associated with mood disorders. Moreover, it is a non-invasive technique that allows for the provision of neurophysiological data to determine the treatments and to predict the responses to treatment.
In the studies made with EEG on MDD patients, a specific amount of lateralization was found in the electrical activity of the brain as well as some differences in the alpha and theta rhythms. Mood and cognitive status of MDD patients are associated with a decrease in the left frontal-cortical activation.
These findings could be helpful in determining individuals with high risk of depression, in understanding the differences between those who respond and do not respond to various treatments (pharmacological, electroconvulsive treatment, etc.), and in determining in which phase the treatment would be more effective. Although the data are still insufficient and the need for more studies is still ongoing, neurophysiological indicators in alpha and theta help make an early diagnosis and treat mood disorders in a better and more accurate manner.
Fernández-Palleiro, P., Rivera-Baltanás, T., Rodrigues-Amorim, D., Fernández-Gil, S., del Carmen Vallejo-Curto, M., Álvarez-Ariza, M., … Spuch, C. (2019). Brainwaves Oscillations as a Potential Biomarker for Major Depression Disorder Risk. Clinical EEG and Neuroscience.