multiple personality disorder

Multiple Personality Disorder 

Definition

Multiple personality disorder, or MPD, is a mental disturbance classified as one of the dissociative disorders in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). It has been renamed dissociative identity disorder (DID). MPD or DID is defined as a condition in which "two or more distinct identities or personality states" alternate in controlling the patient's consciousness and behavior. Note: "Split personality" is not an accurate term for DID and should not be used as a synonym for schizophrenia.

Description

The precise nature of DID (MPD) as well as its relationship to other mental disorders is still a subject of debate. Some researchers think that DID may be a relatively recent development in western society. It may be a culture-specific syndrome found in western society, caused primarily by both childhood abuse and unspecified long-term societal changes. Unlike depression or anxiety disorders, which have been recognized, in some form, for centuries, the earliest cases of persons reporting DID symptoms were not recorded until the 1790s. Most were considered medical oddities or curiosities until the late 1970s, when increasing numbers of cases were reported in the United States. Psychiatrists are still debating whether DID was previously misdiagnosed and underreported, or whether it is currently over-diagnosed. Because childhood trauma is a factor in the development of DID, some doctors think it may be a variation of post-traumatic stress disorder (PTSD). DID and PTSD are conditions where dissociation is a prominent mechanism. The female to male ratio for DID is about 9:1, but the reasons for the gender imbalance are unclear. Some have attributed the imbalance in reported cases to higher rates of abuse of female children; and some to the possibility that males with DID are underreported because they might be in prison for violent crimes.

The most distinctive feature of DID is the formation and emergence of alternate personality states, or "alters." Patients with DID experience their alters as distinctive individuals possessing different names, histories, and personality traits. It is not unusual for DID patients to have alters of different genders, sexual orientations, ages, or nationalities. Some patients have been reported with alters that are not even human; alters have been animals, or even aliens from outer space. The average DID patient has between two and 10 alters, but some have been reported with over one hundred.

Causes and symptoms

The severe dissociation that characterizes patients with DID is currently understood to result from a set of causes:

• An innate ability to dissociate easily
• Repeated episodes of severe physical or sexual abuse in childhood
• The lack of a supportive or comforting person to counteract abusive relative(s)
• The influence of other relatives with dissociative symptoms or disorders

The relationship of dissociative disorders to childhood abuse has led to intense controversy and lawsuits concerning the accuracy of childhood memories. The brain's storage, retrieval, and interpretation of childhood memories are still not fully understood.

The major dissociative symptoms experienced by DID patients are amnesia, depersonalization, derealization, and identity disturbances.

Amnesia

Amnesia in DID is marked by gaps in the patient's memory for long periods of their past, in some cases, their entire childhood. Most DID patients have amnesia, or "lose time," for periods when another personality is "out." They may report finding items in their house that they can't remember having purchased, finding notes written in different handwriting, or other evidence of unexplained activity.

Depersonalization

Depersonalization is a dissociative symptom in which the patient feels that his or her body is unreal, is changing, or is dissolving. Some DID patients experience depersonalization as feeling to be outside of their body, or as watching a movie of themselves.

Derealization

Derealization is a dissociative symptom in which the patient perceives the external environment as unreal. Patients may see walls, buildings, or other objects as changing in shape, size, or color. DID patients may fail to recognize relatives or close friends.

Identity disturbances

Identity disturbances in DID result from the patient's having split off entire personality traits or characteristics as well as memories. When a stressful or traumatic experience triggers the reemergence of these dissociated parts, the patient switches—usually within seconds—into an alternate personality. Some patients have histories of erratic performance in school or in their jobs caused by the emergence of alternate personalities during examinations or other stressful situations. Patients vary with regard to their alters' awareness of one another.

Diagnosis

The diagnosis of DID is complex and some physicians believe it is often missed, while others feel it is over-diagnosed. Patients have been known to have been treated under a variety of other psychiatric diagnoses for a long time before being re-diagnosed with DID. The average DID patient is in the mental health care system for six to seven years before being diagnosed as a person with DID. Many DID patients are misdiagnosed as depressed because the primary or "core" personality is subdued and withdrawn, particularly in female patients. However, some core personalities, or alters, may genuinely be depressed, and may benefit from antidepressant medications. One reason misdiagnoses are common is because DID patients may truly meet the criteria for panic disorder or somatization disorder.

Misdiagnoses include schizophrenia, borderline personality disorder, and, as noted, somatization disorder and panic disorder. DID patients are often frightened by their dissociative experiences, which can include losing awareness of hours or even days of time, meeting people who claim to know them by another name, or feeling "out of body." Persons with the disorder may go to emergency rooms or clinics because they fear they are going insane.

When a doctor is evaluating a patient for DID, he or she will first rule out physical conditions that sometimes produce amnesia, depersonalization, or derealization. These conditions include head injuries; brain disease, especially seizure disorders; side effects from medications; substance abuse or intoxication; AIDS dementia complex; or recent periods of extreme physical stress and sleeplessness. In some cases, the doctor may give the patient an electroencephalograph (EEG) to exclude epilepsy or other seizure disorders. The physician also must consider whether the patient is malingering and/or offering fictitious complaints.

If the patient appears to be physically normal, the doctor will next rule out psychotic disturbances, including schizophrenia. Many patients with DID are misdiagnosed as schizophrenic because they may "hear" their alters "talking" inside their heads. If the doctor suspects DID, he or she can use a screening test called the Dissociative Experiences Scale (DES). If the patient has a high score on this test, he or she can be evaluated further with the Dissociative Disorders Interview Schedule (DDIS) or the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D). The doctor may also use the Hypnotic Induction Profile (HIP) or a similar test of the patient's hypnotizability.

Treatment

Treatment of DID may last for five to seven years in adults and usually requires several different treatment methods.

Psychotherapy

Ideally, patients with DID should be treated by a therapist with specialized training in dissociation. This specialized training is important because the patient's personality switches can be confusing or startling. In addition, many patients with DID have hostile or suicidal alter personalities. Most therapists who treat DID patients have rules or contracts for treatment that include such issues as the patient's responsibility for his or her safety. Psychotherapy for DID patients typically has several stages: an initial phase for uncovering and "mapping" the patient's alters; a phase of treating the traumatic memories and "fusing" the alters; and a phase of consolidating the patient's newly integrated personality.

Most therapists who treat multiples, or DID patients, recommend further treatment after personality integration, on the grounds that the patient has not learned the social skills that most people acquire in adolescence and early adult life. In addition, family therapy is often recommended to help the patient's family understand DID and the changes that occur during personality reintegration.

Many DID patients are helped by group as well as individual treatment, provided that the group is limited to people with dissociative disorders. DID patients sometimes have setbacks in mixed therapy groups because other patients are bothered or frightened by their personality switches.

Medications

Some doctors will prescribe tranquilizers or antidepressants for DID patients because their alter personalities may have anxiety or mood disorders. However, other therapists who treat DID patients prefer to keep medications to a minimum because these patients can easily become psychologically dependent on drugs. In addition, many DID patients have at least one alter who abuses drugs or alcohol, substances which are dangerous in combination with most tranquilizers.

Hypnosis

While not always necessary, hypnosis is a standard method of treatment for DID patients. Hypnosis may help patients recover repressed ideas and memories. Further, hypnosis can also be used to control problematic behaviors that many DID patients exhibit, such as self-mutilation, or eating disorders like bulimia nervosa. In the later stages of treatment, the therapist may use hypnosis to "fuse" the alters as part of the patient's personality integration process.

Alternative treatment

Alternative treatments that help to relax the body are often recommended for DID patients as an adjunct to psychotherapy and/or medication. These treatments include hydrotherapy, botanical medicine (primarily herbs that help the nervous system), therapeutic massage, and yoga. Homeopathic treatment can also be effective for some people. Art therapy and the keeping of journals are often recommended as ways that patients can integrate their past into their present life. Meditation is usually discouraged until the patient's personality has been reintegrated.

Prognosis

Some therapists believe that the prognosis for recovery is excellent for children and good for most adults. Although treatment takes several years, it is often ultimately effective. As a general rule, the earlier the patient is diagnosed and properly treated, the better the prognosis.

Prevention

Prevention of DID requires intervention in abusive families and treating children with dissociative symptoms as early as possible.

Resources

Books

Eisendrath, Stuart J. "Psychiatric Disorders." In Current Medical Diagnosis and Treatment, 1998, edited by Stephen McPhee, et al., 37th ed. Stamford: Appleton & Lange, 1997.

Key terms

Alter — An alternate or secondary personality in a patient with DID.

Amnesia — A general medical term for loss of memory that is not due to ordinary forgetfulness. Amnesia can be caused by head injuries, brain disease, or epilepsy as well as by dissociation.

Depersonalization — A dissociative symptom in which the patient feels that his or her body is unreal, is changing, or is dissolving.

Derealization — A dissociative symptom in which the external environment is perceived as unreal.

Dissociation — A psychological mechanism that allows the mind to split off traumatic memories or disturbing ideas from conscious awareness.

Dissociative identity disorder (DID) — Term that replaced Multiple Personality Disorder (MPD). A condition in which two or more distinctive identities or personality states alternate in controlling a person's consciousness and behavior.

Hypnosis — An induced trance state used to treat the amnesia and identity disturbances that occur in dissociative identity disorder (DID).

Multiple personality disorder (MPD) — The former, though often still used, term for dissociative identity disorder (DID).

Primary personality — The core personality of an DID patient. In women, the primary personality is often timid and passive, and may be diagnosed as depressed.

Trauma — A disastrous or life-threatening event that can cause severe emotional distress. DID is associated with trauma in a person's early life or adult experience.

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disorder /dis·or·der/ (dis-or´der) a derangement or abnormality of function; a morbid physical or mental state.

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acute stress disorder  an anxiety disorder characterized by development of anxiety, dissociative, and other symptoms within one month following exposure to an extremely traumatic event. If persistent, it may become posttraumatic stress disorder.

adjustment disorder  maladaptive reaction to identifiable stress (e.g., divorce, illness), which is assumed to remit when the stress ceases or when the patient adapts.

affective disorders  mood d's.

amnestic disorders  mental disorders characterized by acquired impairment in the ability to learn and recall new information, sometimes accompanied by inability to recall previously learned information.

anxiety disorders  mental disorders in which anxiety and avoidance behavior predominate, i.e., panic disorder, agoraphobia, social phobia, specific phobia, obsessive-compulsive disorder, posttraumatic stress disorder, acute stress disorder, generalized anxiety disorder, and substance-induced anxiety disorder.

attention-deficit/hyperactivity disorder  a controversial childhood mental disorder with onset before age seven, and characterized by inattention (e.g., distractibility, forgetfulness, not appearing to listen), by hyperactivity and impulsivity (e.g., restlessness, excessive running or climbing, excessive talking, and other disruptive behavior), or by a combination of both types of behavior.

autistic disorder  autism; a severe pervasive developmental disorder with onset usually before three years of age and a biological basis; it is characterized by qualitative impairment in reciprocal social interaction, verbal and nonverbal communication, and capacity for symbolic play, by restricted and unusual repertoire of activities and interests, and often by cognitive impairment.

behavior disorder  conduct d.

binge-eating disorder  an eating disorder characterized by repeated episodes of binge eating, as in bulimia nervosa, but not followed by inappropriate compensatory behavior such as purging, fasting, or excessive exercise.

bipolar disorders  mood disorders with a history of manic, mixed, or hypomanic episodes, usually with present or previous history of one or more major depressive episodes; included are bipolar I d., characterized by one or more manic or mixed episodes, bipolar II d., characterized by one or more hypomanic episodes but no manic episodes, and cyclothymic disorder. The term is sometimes used in the singular to denote either bipolar I disorder, bipolar II disorder, or both.

body dysmorphic disorder  a somatoform disorder characterized by a normal-looking person's preoccupation with an imagined defect in appearance.

breathing-related sleep disorder  any of several disorders characterized by sleep disruption due to some sleep-related breathing problem, resulting in excessive sleepiness or insomnia.

brief psychotic disorder  an episode of psychotic symptoms with sudden onset, lasting less than one month.

catatonic disorder  catatonia due to the physiological effects of a general medical condition and neither better accounted for by another mental disorder nor occurring exclusively during delirium.

character disorders  personality d's.

childhood disintegrative disorder  pervasive developmental disorder characterized by marked regression in various developmental skills, including language, play, and social and motor skills, after two to ten years of initial normal development.

circadian rhythm sleep disorder  a lack of synchrony between the schedule of sleeping and waking required by the external environment and that of a person's own circadian rhythm.

collagen disorder  an inborn error of metabolism involving abnormal structure or metabolism of collagen, e.g., Marfan syndrome, cutis laxa. Cf. collagen disease.

communication disorders  mental disorders characterized by difficulties with speech or language, severe enough to interfere academically, occupationally, or socially.

conduct disorder  a type of disruptive behavior disorder of childhood and adolescence marked by persistent violation of the rights of others or of age-appropriate societal norms or rules.

conversion disorder  a somatoform disorder characterized by conversion symptoms (loss or alteration of voluntary motor or sensory functioning suggesting physical illness) with no physiological basis and not produced intentionally or feigned; a psychological basis is suggested by exacerbation of symptoms during psychological stress, relief from tension (primary gain), or gain of outside support or attention (secondary gains).

cyclothymic disorder  a mood disorder characterized by alternating cycles of hypomanic and depressive periods with symptoms like those of manic and major depressive episodes but of lesser severity.

delusional disorder  a mental disorder marked by well-organized, logically consistent delusions of grandeur, persecution, or jealousy, with no other psychotic feature. There are six types: persecutory, jealous, erotomanic, somatic, grandiose, and mixed.

depersonalization disorder  a dissociative disorder characterized by intense, prolonged, or otherwise troubling feelings of detachment from one's body or thoughts, not secondary to another mental disorder.

depressive disorders  mood disorders in which depression is unaccompanied by manic or hypomanic episodes.

developmental coordination disorder  problematic or delayed development of gross and fine motor coordination skills, not due to a neurological disorder or to general mental retardation, resulting in the appearance of clumsiness.

disruptive behavior disorders  a group of mental disorders of children and adolescents consisting of behavior that violates social norms and is disruptive.

dissociative disorders  mental disorders characterized by sudden, temporary alterations in identity, memory, or consciousness, segregating normally integrated parts of one's personality from one's dominant identity.

dissociative identity disorder  a dissociative disorder characterized by the existence in an individual of two or more distinct personalities, with at least two of the personalities controlling the patient's behavior in turns. The host personality usually is totally unaware of the alternate personalities; alternate personalities may or may not have awareness of the others.

dream anxiety disorder  nightmare d.

dysthymic disorder  a mood disorder characterized by depressed feeling, loss of interest or pleasure in one's usual activities, and other symptoms typical of depression but tending to be longer in duration and less severe than in major depressive disorder.

eating disorder  abnormal feeding habits associated with psychological factors, including anorexia nervosa, bulimia nervosa, pica, and rumination disorder.

expressive language disorder  a communication disorder occurring in children and characterized by problems with the expression of language, either oral or signed.

factitious disorder  a mental disorder characterized by repeated, intentional simulation of physical or psychological signs and symptoms of illness for no apparent purpose other than obtaining treatment.

factitious disorder by proxy  a form of factitious disorder in which one person (usually a mother) intentionally fabricates or induces physical (Munchausen syndrome by proxy) or psychological disorders in another person under their care (usually their child) and subjects that person to needless diagnostic procedures or treatment, without any external incentives for the behavior.

female orgasmic disorder  consistently delayed or absent orgasm in a female, even after a normal phase of sexual excitement and adequate stimulation.

female sexual arousal disorder  a sexual dysfunction involving failure by a female either to attain or maintain lubrication and swelling during sexual activity, after adequate stimulation.

functional disorder  a disorder of physiological function having no known organic basis.

gender identity disorder  a disturbance of gender identification in which the affected person has an overwhelming desire to change their anatomic sex or insists that they are of the opposite sex, with persistent discomfort about their assigned sex or about filling its usual gender role.

generalized anxiety disorder  (GAD) an anxiety disorder characterized by excessive, uncontrollable worry about two or more life circumstances for six months or more.

hypoactive sexual desire disorder  a sexual dysfunction consisting of persistently or recurrently low level or absence of sexual fantasies and desire for sexual activity.

impulse control disorders  a group of mental disorders characterized by repeated failure to resist an impulse to perform some act harmful to oneself or to others.

induced psychotic disorder  shared psychotic d.

intermittent explosive disorder  an impulse control disorder characterized by multiple discrete episodes of loss of control of aggressive impulses resulting in serious assault or destruction of property that are out of proportion to any precipitating stressors.

learning disorders  a group of disorders characterized by academic functioning that is substantially below the level expected on the basis of the patient's age, intelligence, and education.

lymphoproliferative disorders  a group of malignant neoplasms arising from cells related to the common multipotential lymphoreticular cell, including lymphocytic, histiocytic, and monocytic leukemias, multiple myeloma, plasmacytoma, and Hodgkin's disease.

lymphoreticular disorders  a group of disorders of the lymphoreticular system, characterized by the proliferation of lymphocytes or lymphoid tissues.

major depressive disorder  a mood disorder characterized by the occurrence of one or more major depressive episodes and the absence of any history of manic, mixed, or hypomanic episodes.

male erectile disorder  a sexual dysfunction involving failure by a male to attain or maintain an adequate erection until completion of sexual relations.

male orgasmic disorder  consistently delayed or absent orgasm in a male, even after a normal phase of sexual excitement and stimulation adequate for his age.

manic-depressive disorder  former name for a mood disorder now known as bipolar I d. or bipolar II d. and often called bipolar d. (q.v.).

mendelian disorder  a genetic disease showing a mendelian pattern of inheritance, caused by a single mutation in the structure of DNA, which causes a single basic defect with pathologic consequences.

mental disorder  any clinically significant behavioral or psychological syndrome characterized by the presence of distressing symptoms, impairment of functioning, or significantly increased risk of suffering death, pain, or other disability.

minor depressive disorder  a mood disorder closely resembling major depressive disorder and dysthymic disorder but intermediate in severity between the two.

mixed receptive-expressive language disorder  a communication disorder involving both the expression and the comprehension of language, either spoken or signed.

monogenic disorder  mendelian d.

mood disorders  mental disorders characterized by disturbances of mood manifested as one or more episodes of mania, hypomania, depression, or some combination, the two main subcategories being bipolar disorders and depressive disorders.

motor skills disorder  any disorder characterized by inadequate development of motor coordination severe enough to restrict locomotion or the ability to perform tasks, schoolwork, or other activities.

multifactorial disorder  one caused by the interaction of genetic and sometimes also nongenetic, environmental factors, e.g., diabetes mellitus.

multiple personality disorder  dissociative identity d.

myeloproliferative disorders  a group of usually neoplastic diseases possibly related histogenetically, including granulocytic leukemias, myelomonocytic leukemias, polycythemia vera, and myelofibroerythroleukemia.

neurotic disorder  neurosis.

nightmare disorder  repeated episodes of nightmares that awaken the sleeper, with full orientation and alertness and vivid recall of the dreams.

obsessive-compulsive disorder  (OCD) an anxiety disorder characterized by recurrent obsessions or compulsions, which are severe enough to interfere significantly with personal or social functioning. Cf. obsessive-compulsive personality disorder, under personality .

obsessive-compulsive personality disorder  see under personality.

oppositional defiant disorder  a type of disruptive behavior disorder characterized by a recurrent pattern of defiant, hostile, disobedient, and negativistic behavior directed toward those in authority.

organic mental disorder  a term formerly used to denote any mental disorder with a specifically known or presumed organic etiology. It was sometimes used synonymously with organic mental syndrome.

orgasmic disorders  sexual dysfunctions characterized by inhibited or premature orgasm; see female orgasmic d., male orgasmic d., and premature ejaculation.

pain disorder  a somatoform disorder characterized by a chief complaint of severe chronic pain which is neither feigned nor intentionally produced, but in which psychological factors appear to play a major role in onset, severity, exacerbation, or maintenance.

panic disorder  an anxiety disorder characterized by attacks of panic (anxiety), fear, or terror, by feelings of unreality, or by fears of dying, or losing control, together with somatic signs such as dyspnea, choking, palpitations, dizziness, vertigo, flushing or pallor, and sweating. It may occur with or, rarely, without agoraphobia.

paranoid disorder  older term for delusional d.

personality disorders  a category of mental disorders characterized by enduring, inflexible, and maladaptive personality traits that deviate markedly from cultural expectations and either generate subjective distress or significantly impair functioning. For specific disorders, see under personality.

pervasive developmental disorders  disorders in which there is impaired development in multiple areas, including reciprocal social interactions, verbal and nonverbal communications, and imaginative activity, as in autistic disorder.

phagocytic dysfunction disorders  a group of immunodeficiency conditions characterized by disordered phagocytic activity, occurring as both extrinsic and intrinsic types. Bacterial or fungal infections may range from mild skin infection to fatal systemic infection.

phobic disorders  see phobia.

phonological disorder  a communication disorder characterized by failure to use age- and dialect-appropriate sounds in speaking, with errors occurring in the selection, production, or articulation of sounds.

plasma cell disorders  see under dyscrasia.

postconcussional disorder  see under syndrome.

posttraumatic stress disorder  (PTSD) an anxiety disorder caused by an intensely traumatic event, characterized by mentally reexperiencing the trauma, avoidance of trauma-associated stimuli, numbing of emotional responsiveness, and hyperalertness and difficulty in sleeping, remembering, or concentrating.

premenstrual dysphoric disorder  premenstrual syndrome viewed as a psychiatric disorder.

psychoactive substance use disorders  substance use d's.

psychosomatic disorder  one in which the physical symptoms are caused or exacerbated by psychological factors, as in migraine headaches, lower back pain, or irritable bowel syndrome.

psychotic disorder  psychosis.

reactive attachment disorder  a mental disorder of infancy or early childhood characterized by notably unusual and developmentally inappropriate social relatedness, usually associated with grossly pathological care.

rumination disorder  excessive rumination of food by infants, after a period of normal eating habits, potentially leading to death by malnutrition.

schizoaffective disorder  a mental disorder in which symptoms of a mood disorder occur along with prominent psychotic symptoms characteristic of schizophrenia.

schizophreniform disorder  a mental disorder with the signs and symptoms of schizophrenia but of less than six months' duration.

seasonal affective disorder  (SAD) depression with fatigue, lethargy, oversleeping, overeating, and carbohydrate craving recurring cyclically during specific seasons, most commonly the winter months.

separation anxiety disorder  prolonged, developmentally inappropriate, excessive anxiety and distress in a child concerning removal from parents, home, or familiar surroundings.

sexual disorders 

1. any disorders involving sexual functioning, desire, or performance.

2. specifically, any such disorder that is caused at least in part by psychological factors; divided into sexual dysfunctions and paraphilias.

sexual arousal disorders  sexual dysfunctions characterized by alterations in sexual arousal; see female sexual arousal d. and male erectile d.

sexual aversion disorder  feelings of repugnance for and active avoidance of genital sexual contact with a partner, causing substantial distress or interpersonal difficulty.

sexual desire disorders  sexual dysfunctions characterized by alteration in sexual desire; see hypoactive sexual desire d. and sexual aversion d.

sexual pain disorders  sexual dysfunctions characterized by pain associated with intercourse; it includes dyspareunia and vaginismus not due to a general medical condition.

shared psychotic disorder  a delusional system that develops in one or more persons as a result of a close relationship with someone who already has a psychotic disorder with prominent delusions.

sleep disorders  chronic disorders involving sleep, either primary (dyssomnias, parasomnias) or secondary to factors including a general medical condition, mental disorder, or substance use.

sleep terror disorder  a sleep disorder of repeated episodes of pavor nocturnus.

sleepwalking disorder  a sleep disorder of the parasomnia group, consisting of repeated episodes of somnambulism.

social anxiety disorder  social phobia.

somatization disorder  a somatoform disorder characterized by multiple somatic complaints, including a combination of pain, gastrointestinal, sexual, and neurological symptoms, and not fully explainable by any known general medical condition or the direct effect of a substance, but not intentionally feigned or produced.

somatoform disorders  mental disorders characterized by symptoms suggesting physical disorders of psychogenic origin but not under voluntary control, e.g., body dysmorphic disorder, conversion disorder, hypochondriasis, pain disorder, somatization disorder, and undifferentiated somatoform disorder.

somatoform pain disorder  pain d.

speech disorder  defective ability to speak; it may be either psychogenic (see communication d. ) or neurogenic. See also aphasia, aphonia, dysphasia, and dysphonia.

stereotypic movement disorder  a mental disorder characterized by repetitive nonfunctional motor behavior that often appears to be driven and can result in serious self-inflicted injuries.

substance-induced disorders  a subgroup of the substance-related disorders comprising a variety of behavioral or psychological anomalies resulting from ingestion of or exposure to a drug of abuse, medication, or toxin. Cf. substance use d's.

substance-related disorders  any of the mental disorders associated with excessive use of or exposure to psychoactive substances, including drugs of abuse, medications, and toxins. The group is divided into substance use d's and substance-induced d's .

substance use disorders  a subgroup of the substance-related disorders, in which psychoactive substance use or abuse repeatedly results in significantly adverse consequences. The group comprises substance abuse and substance dependence.

undifferentiated somatoform disorder  one or more physical complaints, not intentionally produced or feigned and persisting for at least six months, that cannot be fully explained by a general medical condition or the direct effects of a substance.

unipolar disorders  depressive d's.

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multiple personality disorder

n.

Abbr. MPD A dissociative disorder in which two or more distinct personalities exist in the same person, each of which prevails at a particular time. Also called dissociative identity disorder.

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multiple personality disorder.

See dissociative identity disorder.

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multiple personality disorder

Split personality Psychiatry The 'presence of two or more distinct identities or personality states…that recurrently take control of behavior.' See Dissociate, Fugue, Personality, Schizophrenia.