Endogenous anxiety: implications for nosology and treatment.

Clinical and research findings are reviewed in relation to the distinction between endogenous and exogenous anxiety. The single most potent discriminating symptom between the two subtypes is the presence or absence of spontaneous (anxiety) symptom attacks. This concept avoids the diagnostic difficulties that can arise under current systems when patients present with symptoms that fulfill the criteria for multiple anxiety-related diagnosis. Patients in the endogenous category differ from those whose anxiety is reactive in age of onset, clinical course, and response to psychotherapy and medication. Thus, this distinction appears to have clinical merit.