Major Depressive Disorder (MDD) is one of the most prevalent mental diagnosis within the worldwide population. Although there is evidence about relationship between MDD and cognitive dysfunction, still the correlations between biomarkers and the severity of the disorder or the level of cognitive dysfunction need further research. Therefore, the aim of the study is to determine such relationships in Ukrainian population.

Inclusion Criteria:

• Outpatient 18 to 65 years of age
• Meets DSM-5 criteria for MDD
• Depressive episode duration ≥ 2 months
• The participant has MARDS total score ≥ 7
• Free of psychotropic medications for at least 5 half-lives before baseline
• Fluent in Russian/Ukrainian

Exclusion Criteria:

• Current diagnosis or history of manic/hypomanic episode
• Any other psychiatric diagnosis that is considered the primary diagnosis
• Any significant personality disorder diagnosis
• High suicidal risk, defined by clinician judgment
• Substance dependence/abuse in the past year
• Significant neurological disorders, head trauma, or other unstable medical conditions
• History of endocrinological diseases
• Pregnant or breastfeeding
• Psychosis in the current episode
• High risk for hypomanic switch
• Cognitive or language impairment of such severity as to adversely affect the performance of tests