Mental disorders were generally attributed to an excess of black bile in the body, which caused an imbalance or flux of noxious humour to the brain, resulting in melancholia.

Mental diseases. Medieval medical texts distinguished five types of mental disease: phrenitis (acute inflammation of the brain), delirium (abnormal reactions accompanied by fever), mania (violent behavior), melancholia (depression and lack of interest in people and events), and amentia (lack or loss of mental faculties). Other recognized mental illnesses included epilepsy and lycanthropy, which was characterized by wandering through cemeteries and woods at night imitating wolves and wild animals.