When a person's consciousness, sense of identity, or behavior are found to be seriously disrupted, they may be entering the range of the continuum of dissociation where a disorder is present. In addition, there is a catch-all category covering atypical dissociative presentations. The completeness of the amnesia and the time period involved may vary widely. There is often the assumption of a new identity. Depersonalization is only considered to be a diagnosable disorder when it occurs in the absence of one of these other conditions, and is severe enough to cause social or occupational impairment or marked distress.
Depersonalization involves an alteration in the individual's sense of self.
The person feels unreal, as if in a dream, like a machine, dead, self-estranged, or otherwise significantly changed from normal. Sensory disturbances such as anesthesias, paresthesias, a change in the sense of body size or body parts, macroscopia or microscopia, or the experience of being outside of one's body and watching one's self from a distance or looking down from above are often present. There must still be found to be present a dissociative alteration in the normally unified functions of identity, memory, or consciousness. MPD is a complex and chronic condition in which all of the elements of the other dissociative disorders may be found. Individuals with MPD will, at times, manifest psychogenic amnesia, fugue episodes, and profound depersonalization.