Major depressive disorder (MDD) is a prevalent disease that affects approximately 14% of the world population. MDD is a psychiatric disorder that causes discomfort in the individual through symptoms, such as depressive mood, impairment of concentration, difficulty in making decisions, a sense of worthlessness or guilt, sleep deprivation or hypersomnia, being incapable of enjoying life, and it requires certain treatment.
Recent neuroimaging studies draw attention to the physiological causes of the disorder by stating that there is an abnormal connectivity between the cerebral networks of major depressive disorder patients. Moreover, the EEG results of the disorder manifest themselves through an increase in the alpha rhythm.
The most up-to-date treatment of the disorder is performed through pharmacological treatment (antidepressant drugs) or psychotherapy. Nevertheless, two-thirds to one-third of the patients do not respond to pharmacological treatments or psychotherapy.
ECT (electroshock) is generally considered an option following a failure in one or multiple drug interventions or when a fast and strong healing is required (e.g. in life-threatening cases of physical exhaustion that are related to depressive delusions, hallucinations or mania) (for detailed information about ECT, please watch our video titled “What is ECT?”). Nonetheless, the patient can be negatively affected by adverse effects, such as post-treatment cognitive dysfunctions (short-term memory loss) or post-treatment dizziness. When it is possible to predict whether a patient can respond to ECT based on the electroencephalography (EEG) results, other methods of MDD treatment can be preferred or the adverse risks of the treatment can be diminished.
In a previous study, the EEG data of the MDD patients, who received ECT treatment, were analyzed. There was a striking difference found following the comparison of the EEG data of the patients who responded to ECT treatment and those of the patients who did not respond to ECT treatment. It was observed that the MDD patients, who responded to ECT, had a lower connection in the frontal and left hemispheric networks on the EEG alpha 2 band, compared to those who did not respond to it.
The connectivity on the Alpha 2 (10-12 Hz) band, which is obtained in the pre-treatment EEG procedure, has a predictive value for its effectiveness in the ECT treatment. As ECT is the most advanced treatment option in MDD patients that are resistant to treatment, it is still one of the most invasive treatment options in psychiatry. Consequently, the correlation between ECT and EEG alpha 2 band can help clinicians, and thus patients, in terms of regulating the MDD treatment.
– DSM-V, Amerika Psikiyatri Birliği, Ruhsal Bozuklukların Tanısal ve Sayımsal Elkitabı, 5. Baskı, Tanı Ölçütleri Başvuru Elkitabı, Çev. Köroğlu E, Hekimler Yayın Birliği, Ankara, 2014.
– Kirsten, A., Seifritz, E., & Olbrich, S. (2019). Electroencephalogram Source Connectivity in the Prediction of Electroconvulsive Therapy Outcome in Major Depressive Disorder. Clinical EEG and Neuroscience.