Endogenous depression

Endogenous depression is an atypical subclass of major depressive disorder (clinical depression). It could be caused by genetic and biological factors. Endogenous depression occurs due to the presence of an internal (cognitive, biological) stressor instead of an external (social, environmental) stressor. Endogenous depression includes patients with treatment-resistant, non-psychotic, major depressive disorder, characterized by abnormal behavior of the endogenous opioid system but not the monoaminergic system. Symptoms vary in severity, type, and frequency and can be attributed to cognitive, social, biological, or environmental factors that result in persistent feelings of sadness and distress. Since symptoms are due to a biological phenomenon, prevalence rates tend to be higher in older adults. Due to this fact, biological-focused treatment plans are often used in therapy to ensure the best prognosis. Endogenous depression was part of the Kraepelinian dichotomy system.