Worldwide, there is high prevalence of depressive disorder. Pharmacological treatment strategies to manage depression are limited by effectiveness as well as tolerability issues apart from the late onset of action. Extent of antidepressant medication response often differs with individual variation and surrogate markers predicting non-response at the earliest possible time are needed to avoid leaving patients under an inefficient medication/ treatment. The use of brain imaging techniques like fNIRS/qEEG can depict the cortical activity associated with the changes in symptoms of depression. Literature has reported lower levels of BDNF in depression that improves with response to treatment.  BDNF Val66Met polymorphism may help in predicting treatment responders.

The study hypothesizes that individuals with MDD differ from healthy individuals for prefrontal hemodynamic activity assessed using fNIRS and cortical electrical activity assessed using qEEG and that individuals with MDD after treatment with antidepressant medications demonstrate changes in depressive symptoms, Prefrontal hemodynamic activity assessed using fNIRS, cortical electrical activity assessed using qEEG and serum BDNF levels. The study also hypothesizes that the presence of Val66Met BDNF gene polymorphism is associated with change in depressive symptoms after antidepressant treatment in individuals with MDD.

Consultants and Senior Residents in the outpatient department (OPD) and inpatient department (IPD) of Psychiatry, AIIMS, New Delhi shall be requested to refer all the patients with depression. Out of the referred patients, those with HAMD score >17 (moderate depression) will be chosen by a purposive method for participation in the study. Diagnosis of severe depression will be confirmed using DSM-5 criteria by clinical interview and participants fulfilling the inclusion and exclusion criteria will be recruited. Participants will be screened for psychiatric comorbidities using clinical interview. Physical, neurological and substance use comorbidity as well as pregnancy/lactation will be ruled out by history and clinical examination. Written consent will be taken prior to participation in the study. Healthy controls will also be recruited similarly from the outpatient department (OPD) and inpatient department (IPD) of Psychiatry, AIIMS, New Delhi, who are meeting inclusion and exclusion criteria.

For both the groups baseline assessment will be done within 2 days of assessments by sociodemographic and clinical data using semi structured datasheet and outcome parameters by fNIRS and qEEG for both the group. For other outcome parameters will also be assessed namely HAMD, HAMA, BDNF and BDNF gene polymorphism.

Only the MDD group will be reassessed at 4 and 8 weeks (±2-3 days) using HAMD, HAMA, BDNF level, fNIRS, qEEG.