Dissociative Disorders

Depersonalization disorder (DPD) is a dissociative disorder in which the sufferer is affected by persistent or recurrent feelings of depersonalization and/or derealization.
Occasional moments of mild depersonalization are normal: strong, severe, persistent, or recurrent feelings are not.
Depersonalization disorder is marked by a feeling of detachment or distance from one's own experience, body, or self. These feelings of depersonalization are recurrent. Of the dissociative disorders, depersonalization is the one most easily identified with by the general public; one can easily relate to feeling as they in a dream, or being "spaced out." Feeling out of control of one's actions and movements is something that people describe when intoxicated. An individual with depersonalization disorder has this experience so frequently and so severely that it interrupts his or her functioning and experience. A person's experience with depersonalization can be so severe that he or she believes the external world is unreal or distorted.

Depersonalization disorder is a psychiatric disorder affecting emotions and behavior. It is characterized by an alteration in how an affected individual perceives or experiences his or her unique sense of self. The usual sense of one's own reality is temporarily lost or changed. A feeling of detachment from, or being an outside observer of, one's mental processes or body occurs such as the sensation of being in a dream.

Derealization (sometimes abbreviated as DR) is an alteration in the perception or experience of the external world so that it seems strange or unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional coloring and depth.
Terms commonly used to describe Derealisation spaceyness... like looking through a grey veil... a sensory fog... being trapped in a glass bell jar... in a disney-world dream state... withdrawn... feeling cut off or distant from the immediate surroundings... like being a spectator at some strange and meaningless game... objects appear diminished in size, flat, dream-like, cartoon like, artificial... objects appear to be unsolid, to breathe, or to shimmer...

A fugue state, formally dissociative fugue or psychogenic fugue is a rare psychiatric disorder characterized by reversible amnesia for personal identity, including the memories, personality and other identifying characteristics of individuality. The state is usually short-lived (hours to days), but can last months or longer. Dissociative fugue usually involves unplanned travel or wandering, and is sometimes accompanied by the establishment of a new identity. After recovery from fugue, previous memories usually return intact, but there is complete amnesia for the fugue episode.

Dissociative identity disorder (DID) is a psychiatric diagnosis and describes a condition in which a person displays multiple distinct identities or personalities (known as alter egos or alters), each with its own pattern of perceiving and interacting with the environment.
Psychogenic amnesia, also known as functional amnesia or dissociative amnesia, is a memory disorder characterized by extreme memory loss that is caused by extensive psychological stress and that cannot be attributed to a known neurobiological cause. Psychogenic amnesia is defined by (a) the presence of retrograde amnesia (the inability to retrieve stored memories leading up to the onset of amnesia), and (b) an absence of anterograde amnesia (the inability to form new long term memories). Dissociative amnesia is due to psychological rather than physiological causes and can sometimes be helped by therapy.

There are two types of psychogenic amnesia, global and situation-specific. Global amnesia, also known as fugue state, refers to a sudden loss of personal identity that lasts a few hours to days, and is typically preceded by severe stress and/or depressed mood. Fugue state is very rare, and usually resolves over time, often helped by therapy. In most cases, patients lose their autobiographical memory and personal identity even though they are able to learn new information and perform everyday functions normally. Other times, there may be a loss of basic semantic knowledge and procedural skills such as reading and writing. Situation-specific amnesia occurs as a result of a severely stressful event, as in post-traumatic stress disorder, child sex abuse, military combat[8] or witnessing a family member's murder or suicide, and is somewhat common in cases of severe and/or repeated trauma