This 6-month, naturalistic cohort study examines male and female inpatients aged 18 to 75 years i) with any form of unipolar depressive episode (cohort 1); ii) clinical diagnosis of a moderate or severe unipolar depressive episode and suicidal tendencies who agree to participate in a prospective study (cohort 2); and moderate or severe unipolar depressive episodes validated by research interviews and and suicidal tendencies that persist for at least 48 hours after admission who are followed up for 6 months (cohort 3).

Epidemiological cross-sectional study in over 3000 inpatients with a clinical diagnosis of major depressive disorder, validation of the clinical diagnosis in 520 patients, and prospective naturalistic 6-month follow-up study of 260 adults with a research interview-confirmed major depressive disorder, with data collection at the following points: at T0 = time of hospitalization (epidemiological study population 1 with data from clinical routine practice), at time T1 of baseline survey in patients with persistent suicidal tendencies, i.e. at least 48 hours after T0 (study population 2 as a subgroup of study population 1, with study information and consent), and in study population 3 (subgroup of study population 2, with study information and consent) at the time of discharge (T2), 3 months after admission to hospital (T3/ by telephone) and 6 months after inpatient admission (T4).

The aim of the study is to characterize the remission or recurrence of suicidal symptoms in the context of a depressive episode. It is expected that the results will help to improve the understanding of the disease process and the further development of effective intervention options.

Inclusion Criteria:

For Population 1

1.any form of unipolar depressive episode

For Population 2

1. clinical diagnosis of a moderate or severe unipolar depressive episode
2. clinically diagnosed suicidal tendencies that persist for at least 48 hours after admission to hospital
3. Written consent to participate in the study

For Population 3

1. Diagnosis of a moderate or severe unipolar depressive disorder through the structured research interview "Mini International Neuropsychiatric Interview" (M.I.N.I.)
2. Suicidality with a value > / = 1 for item 2 (passive suicidality) OR item 3 (active suicidality) based on the research interview "Sheehan Suicidality Tracking Scale" (S-STS)
3. Written consent to participate in the study

Exclusion Criteria:

• Patients younger than 18 years or older than 75 years
• No clinical diagnosis of a depressive episode
• Depressive episode in the context of a bipolar disorder- secondary depression as a result of physical illness or substance use
• severe physical symptoms of disease that make participation in the study impossible
• Pregnancy
• not being able to understand the study processes
• incapable of giving informed consent
• no authorization to give consent due to (limited) incapacity

All patient are gonna be recruited from 7 different psychiatric clinics. For population 1, only clinically available data is extracted from patient records population 2 and 3: Patients who meet the inclusion criteria and are in psychiatric hospital treatment in the study centres