Dissociative disorders are among the most puzzling forms of mental disorders, both to the observer and to the sufferer. Dissociation means that part of an individual’s personality appears to be separated from the rest. The disorder usually involves memory loss and a complete, though generally temporary, change in identity. Rarely, several distinct personal- ities appear in one person.
Loss of memory without an organic cause can occur as a reaction to an extremely stressful event or period. During World War II, for example, some hospitalized soldiers could not recall their names, where they lived, where they were born, or how they came to be in battle. But war and its horrors are not the only causes of dissociative amnesia. The person who betrays a friend in a business deal or the victim of rape may also forget, selectively, what has happened. Total amnesia, in which people forget everything, is rare, despite its popularity in novels and films. Sometimes an amnesia victim leaves home and assumes an entirely new identity; this phenomenon, known as dissociative fugue, is also very unusual.
In dissociative identity disorder, commonly known as multiple personality disorder, several distinct personalities emerge at different times. In the true multiple personality, the various personalities are distinct people with their own names, identi- ties, memories, mannerisms, speaking voices, and even IQs. Sometimes the personalities are so separate that they don’t know they inhabit a body with other “people.” At other times, the personalities do know of the existence of other “people” and even make dis- paraging remarks about them. Typically, the personalities contrast sharply with one another, as if each one represents different aspects of the same person—one being the more socially acceptable, “nice” side of the person and the other being the darker, more uninhibited or “evil” side.
The origins of dissociative identity disorder are still not understood (Dell, 2006). One theory suggests that it develops as a response to childhood abuse (Lev-Wiesel, 2008). The child learns to cope with abuse by a process of dissociation—by having the abuse, in effect, happen to “someone else,” that is, to a personality who is not con- scious most of the time. The fact that one or more of the multiple personalities in almost every case is a child (even when the person is an adult) seems to support this idea, and clinicians report a history of child abuse in more than three-quarters of their cases of dissociative identity disorder (Kidron, 2008; C. A. Ross, Norton, & Wozney, 1989).
Other clinicians suggest that dissociative identity disorder is not a real disorder at all, but an elaborate kind of role-playing—faked in the beginning and then perhaps gen- uinely believed by the patient (Lilienfeld & Lynn, 2003; H. G. Pope, Barry, Bodkin, & Hudson, 2006). Some intriguing biological data show that in at least some patients, how- ever, the various personalities have different blood pressure readings, different responses to medication, different allergies, different vision problems (necessitating a different pair of glasses for each personality), and different handedness—all of which would be diffi- cult to feign. Each personality may also exhibit distinctly different brain-wave patterns (Dell’Osso, 2003; Putnam, 1984).
A far less dramatic (and much more common) dissociative disorder is depersonalization disorder, in which the person suddenly feels changed or different in a strange way. Some people feel that they have left their bodies, whereas others find that their actions have suddenly become mechanical or dreamlike. This kind of feeling is especially common during adolescence and young adulthood, when our sense of ourselves and our inter- actions with others change rapidly. Only when the sense of depersonalization becomes a long-term or chronic problem or when the alienation impairs normal social func- tioning can this be classified as a dissociative disorder (American Psychological Associa- tion, 2000).