A rare disorder in which the patient complains spontaneously that his or her mental activity, body, and surroundings are changed in their quality, so as to be unreal, remote, or automatized. Among the varied phenomena of the syndrome, patients complain most frequently of loss of emotions and feelings of estrangement or detachment from their thinking, their body, or the real world. In spite of the dramatic nature of the experience, the patient is aware of the unreality of the change. The sensorium is normal and the capacity for emotional expression intact. Depersonalization-derealization symptoms may occur as part of a diagnosable schizophrenic, depressive, phobic, or obsessive-compulsive disorder. In such cases the diagnosis should be that of the main disorder.