DISTIMIA. - An abnormal variation in the affective life of psychopathic individuals, oscillating between manic exaltation (v. MANIA) and melancholic depression (v. MELODIA), not motivated by external circumstances (endogenous causes). Dysthymias constitute, in particular, the building elements of manic-depressive psychosis. On the other hand, distinct clinical pictures may occur in the course of the most varied nervous and mental diseases, in which variations in the individual’s mood represent one of the symptoms or transient and non-specific episodes of the disease.
Thus in epilepsy, with a tendency to irritability and to gloomy, sad, pessimistic, anxious, and lasting forms, the patient assuming a suspicious and violent demeanour; in progressive paralytic dementia, with manic exaltation, euphoria, psychomotor excitability; in senile dementia and dementia of the climacteric age (v. CLIMATERICA ETÀ), with a tendency toward melancholic depressive forms; alcoholism (v.); schizophrenia (v.); in hysteria. With regard to certain distinctive forms, doubt may remain as to how much belongs to external causes of the family and social environment and how much to endogenous constitutional causes; we often observe in individuals an almost serial variability between cycloid temperament (v. INDOLE), with an easily unstable and poorly motivated mood, and the actual forms of dysthymia to be classified among pathological morbid conditions.