Phenomenologically, anxiety may refer to an emotion, a feeling, a symptom, or a cluster of cognitive and somatic symptoms. Etiologically, it may describe reactions to danger, stress, or conflict, the results of trauma or frightening memories, the toxic withdrawal reactions to many drugs and illnesses, a habit (a persistent pattern of maladaptive behavior acquired by learning), or the symptomatic expression of a genetically inherited metabolic disease. The prevailing opinion in psychiatry views anxiety as a cluster of symptoms that impairs normal functioning.
