Dehydroepiandrosterone (DHEA) as Augmentation of Standard Antidepressants in Treatment-resistant Depression.

Inclusion Criteria: * Patient provided written informed consent -,The patient is capable of giving consent (has sufficient knowledge of German and clearly understands the nature, significance and scope, including risks, of the medical procedure) * The patients is aged between 18 and 75 years (≥ 18 and ≤ 75) * The patient has an episode of major depression according to DSM 5 (Diagnostic and Statistical Manual of Mental Disorders, 5th edi-tion) * The patient has treatment-resistant depression (TRD), defined as non-response to at least one 4-week antidepressant treatment trial (including the current treatment) in the index episode (correspond-ing to level 1 resistance to treatment failure according to the Maudsley staging method) * The patient has a Montgomery-Asberg Depression Rating Scale (MADRS) score of ≥ 20 * The patient is receiving antidepressant medication (SSRI or SNRI or tricyclic antidepressant or mirtazapine or bupropion) for at least 4 weeks, the dosage is at least at the approved minimum thera-peutic dosage and has been unchanged for at least 14 days prior to screening visit. * The patient had less than three (\<3) treatment attempts with anti-depressants in the current MDE (current treatment attempts not in-cluded). Exclusion Criteria: * Exclusion Criteria Related to psychiatric diagnosis * The patient has current clinically significant suicidal ideation with intent, corresponding to a score of 4 or 5 for ideation on the C-SSRS, or a suicidal attempt within the past 6 months, as indicated by the C-SSRS at screening visit * The patient fulfills the criteria for psychotic depression according to DSM-5 * The patient meets the criteria for schizophrenia, schizoaffective disorder or bipolar disorder in M.I.N.I according to DSM-5 * The patient meets the criteria for a dependency disorder in the M.I.N.I. for DSM-5 * The patient has dementia or moderate to severe cognitive impair-ment. Exclusion Criteria Related to IMP * The Patient is currently taking DHEA or has taken it within the last 14 days prior to screening visit. * The patients is currently taking hormone replacement therapy with sex hormones (other than contraceptives) * The patient has undiagnosed genital bleeding * The patient has untreated endometrial hyperplasia The patient has or has had sex hormone-dependent cancer (e.g. breast cancer, ovarian cancer, endometrial cancer, prostate can-cer) * The patient is allergic or has contraindication to DHEA or lactulose and cellulose * The patient has previous diagnosis of chronic kidney disease stage G3b (or higher) or GFR \< 30 ml/min. * The patient has diagnosis of prostatic hyperplasia. Exclusion Criteria Related to standard antidepressant medication (AxMP) * The Patient is taking antidepressants other than those listed as in-clusion criterion (SSRI, SNRI, tricyclic antidepressants, bupropion, mirtazapine) * The patient is taking psychotropic medication, e.g. antipsychotics, anticonvulsants, lithium or Johannis herbs. Allowed substances in-clude benzodiazepines, non-benzodiazepines (Zopiclon, Zolpidem or Eszopiclon) and antidepressants listed under inclusion criteria. * The patient is using non-selective, irreversible MAO inhibitors (e.g. tranylcypromine) or selective, reversible MAO-A inhibitors (e.g. moclobemide) or the reversible non-selective MAO inhibitor line-zolid * The patient has insulin-dependent diabetes mellitus General Safety Exclusion Criteria * The patient has an untreated and unstable general medical condi-tion (e.g. hypertension with end organ damage or hypertensive de-railment) * The patient has a medical history of liver failure and/or bilirubin above 3 times the normal range and reduced total protein * The patient is pregnant or breastfeeding. * The patient of childbearing age shows an unwillingness to use an effective contraceptive method (defined as a Pearl Index \< 1) * The patient currently has or has a history of venous thromboembo-lism (VTE) (deep vein thrombosis, pulmonary embolism) * The patient currently has or has a history of arterial thromboem-bolic disease (e.g. angina pectoris, myocardial infarction, stroke) * The patient has a thrombophilic disease (e.g. protein C, protein S or antithrombin deficiency) * The patient has porphyria * The patient has clinically significant untreated hypothyroidism * The patient has clinically significant abnormalities in the 12-lead ECG (e.g. prolongation of the QTc interval ≥ 500 ms) as performed during screening visit * The patient is a vulnerable person (defined as: persons deprived their liberty, confined to an institution by court or administrative or-der, persons that may have Insufficient power, intelligence, educa-tion, resources, strength, or other needed attributes to protect their own interests, or unable to explicitly give consent) * The patient might be dependent on representative of the sponsor, the investigator or the trial site The patient is currently participating in another interventional clini-cal trial. Laboratory Exclusion Criteria * The patient's laboratory values show clinically significant abnor-malities * The patient currently has liver disease with liver-specific levels out-side the age- and gender-specific reference intervals \[elevations of GOT or GPT above 3 times the upper normal value (ULN)\]