Naturalistic Study of Ketamine in the Treatment of Depression

Inclusion criteria Having a diagnosis according to DSM-5 for * Major depressive episode as part of either Major depressive disorder, Bipolar I disorder, or Bipolar II disorder according to Fifth Edition of Diagnostic and Statistical Manual for Mental Disorders (DSM-5); * 18 years old or older; * Be able to provide written informed consent.episode; * MADRS scale total score ≥ 12 and score in items 1 (apparent sadness) and 2 (expressed sadness) ≥ 2 during the screening period (baseline); * YMRS scale total score ≤ 11 at baseline; * Having current symptoms of suicidal ideation and/or behavior, according to the C-SSRS scores; * Use of effective contraceptive methods in the case of heterosexual women of childbearing age; * Indication/prescription of the attending physician for the use of ketamine, subcutaneous; * For the patients with Bipolar I disorder: currently using lithium, valproic acid, or atypical antipsychotic at therapeutic doses for at least four weeks prior to initial evaluation. * For patients with Bipolar II disorder: currently using lithium, valproic acid, lamotrigine, or atypical antipsychotic at therapeutic doses for at least four weeks prior to initial evaluation. Exclusion Criteria * Patients with an unstable, defined, or suspected systemic medical condition; * Women who are pregnant, breastfeeding or planning to become pregnant within the next year; * Patients who cannot tolerate the use of ketamine or who have previous adverse effects associated with ketamine; * Inability to comply with informed consent or treatment protocol needs; * Patients currently with psychotic symptoms (according to DSM-5 criteria); * Patients with a current diagnosis of any active substance use disorder according to the MINI/DSM-5 criteria (with the exception of tobacco); * Patients with autoimmune or inflammatory conditions, cancer or active infectious diseases.