WordNet
n. a state of depression for which there is no apparent precipitating cause
Wikipedia
Endogenous depression (melancholia) is an atypical sub-class of the mood disorder, major depressive disorder (clinical depression). 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.
Usage examples of "endogenous depression".
One of the psychotherapists, not Sue Raudsley this time, but probably encouraged by her, had argued for the reintroduction of electroconvulsive therapy in place of the monoamine oxidase inhibitor drugs for endogenous depression.