Depression is one of the most common forms of mental illness. In Germany, an estimated 4.9 million people suffer from unipolar depression, andabout 19 % of the population suffer from depression at least once in their lifetime. Due to the frequency of the disease and its impact on the lives of those affected, depression is one of the most socially burdensome diseases,ranking even higher than common diseases such as diabetes or coronary heart disease.

A clinically relevant depression (depressive episode or major depression) is characterized by the occurrence of the core symptoms of dejection/sadness and loss of interest and pleasure over a period of at least two weeks. In addition to these symptoms, other complaints may include loss of energy, insomnia, restlessness or slowing down, weight changes, feelings of worthlessness or guilt, disturbances in thinking, concentration, or decision-making, and suicidal thoughts.

Many factors interact in the development of depression: genetic, neurobiological (e.g. altered function of neurotransmitters between neurons), and psychosocial (e.g. loss of loved ones, job stress). Depressive disorders are treated with medication and/or psychotherapeutic procedures, depending on their severity. In severe depression, which accounts for about 30 % of all depressive disorders, the therapy guidelines provide for a combination of drug therapy with antidepressants and psychotherapy.

The DELTA study explores the course of illness, treatment, and outpatient care of patients over several years, and will identify factors influencing the course of illness. Influencing factors will include physical activity, handgrip strength and diet. In order to document drug treatment, drug levels in the blood are determined on an ongoing basis. In addition, the study will investigate the role of biomarkers measured in blood, stool and urine in the course of the disease. The study will also help to identify disease groups that benefit insufficiently from antidepressant therapy. Overall, the study will provide a comprehensive overview of the course of the disease and the health care of patients between the ages of 18 and 65 who were treated as inpatients for major depression.

The study is conducted by the Chair of Epidemiology, Medical Faculty of the University of Augsburg, Augsburg University Hospital (Head: Prof. Dr. Jakob Linseisen) in collaboration with the Bezirkskrankenhaus Augsburg, Chair of Psychiatry and Psychotherapy of the University of Augsburg (Head: Univ. Prof. Dr. A. Hasan).