disorders that occur without the influence of any significant external pathogenic cause. They develop due to internal causes, among which heredity (hereditary factor) is distinguished in the first place. Endogenous disorders are characterized by: 1) spontaneous nature of occurrence;2) external factors can be triggering – only the cause, but not the cause of the development of the disease;3) the course of the disease depends little on external conditions, is determined by the logic of the development of the disease (pathogenesis).Schizophrenia can be considered a typical example of an endogenous mental disorder. The opposite term is exogenous disorder (see Exogenous disorders in Chapter 2.1. Key Psychological Concepts in Clinical Psychology).