Colin A. Ross

Childhood trauma, psychosis and schizophrenia: a literature review with theoretical and clinical implications.

Objective:  To review the research addressing the relationship of childhood trauma to psychosis and schizophrenia, and to discuss the theoretical and clinical implications.

Patterns of dissociation in clinical and nonclinical samples

Research has consistently found elevated mean dissociation scores in particular diagnostic groups. In this study, we explored whether mean dissociation scores for different diagnostic groups resulted from uniform distributions of scores within the group or were a function of the proportion of highly dissociative patients that the diagnostic group contained. A total of 1566 subjects who were psychiatric patients, neurological patients, normal adolescents, or normal adult subjects completed the Dissociative Experience Scale (DES). An analysis of the percentage of subjects with high DES scores in each diagnostic group indicated that the diagnostic groups mean DES scores were a function of the proportion of subjects within the group who were high dissociators. The results contradict a continuum model of dissociation but are consistent with the existence of distinct dissociative types.

Multiple Personality Disorder: An Analysis of 236 Cases:

The authors collected a series of 236 cases of multiple personality (MPD) reported to them by 203 psychiatrists, clinical psychologists and other health care professionals. MPD patients experienced extensive sexual (79.2%) and physical (74.9%) abuse as children. They had been in the health care system for an average of 6.7 years before being diagnosed with MPD and had an average of 15.7 personalities at the time of reporting. The most common alter personalities were a child personality (86.0%), a personality of a different age (84.5%), a protector personality (84.0%), and a persecutor personality (84.0%). Patients MPD are highly suicidal with 72% attempting suicide and 2.1% being successful. The patients frequently received diagnoses for other mental disorders. The most common previous diagnoses were for affective disorders (63.7%), personality disorders (57.4%), anxiety disorders (44.3%), and schizophrenia (40.8%).

Paranormal experiences in the general population

The Dissociative Disorders Interview Schedule was administered to a random sample of 502 adults in the general population of Winnipeg, a midwestern Canadian city. Results showed that paranormal/extrasensory experiences were common in the general population. They were linked to a history of childhood trauma and to other dissociative symptom clusters. A factor analysis of the paranormal experiences identified three factors which together accounted for 44.0% of the combined variance of the scores. A model is proposed in which paranormal experiences are conceptualized as an aspect of normal dissociation. Like dissociation in general, paranormal experiences can be triggered by trauma, especially childhood physical or sexual abuse. Such experiences discriminate individuals with childhood trauma histories from those without at high levels of significance.

Lifetime Axis I and II Comorbidity and Childhood Trauma History in Dissociative Identity Disorder

According to DSM-IV, dissociative identity disorder is characterized by the existence within the person of two or more distinctly different identities or personality states that from time to time take executive control of the persons body and behavior, with accompanying amnesia (American Psychiatric Association, 1994). By retrospective patient report, dissociative identity disorder usually occurs in conjunction with severe childhood trauma (Kluft 1985; Putnam et al. 1986; Ross 1989; Ross et al. 1989a, 1990a). The disorder appears to be the most severe form of disturbance on the dissociative disorders continuum (Boon and Draijer 1993; Coons 1992; Ross 1985; Ross et al. 1992). There is evidence that dissociative identity disorder may be more prevalent than once believed in the general population (Ross 1991) and among general adult psychiatric inpatients (Latz et al. 1995; Ross et al. 1991; Saxe et al. 1993).

Differences between multiple personality disorder and other diagnostic groups on structured interview

The Dissociative Disorders Interview Schedule was administered to 20 subjects with multiple personality disorder, 20 with schizophrenia, 20 with panic disorder, and 20 with eating disorders. The findings showed that multiple personality can be differentiated from the other groups on variables such as history of physical abuse, sexual abuse, substance abuse, sleepwalking, childhood imaginary playmates, secondary features of multiple personality and extrasensory and supernatural experiences. Those with multiple personality also differ from the other groups on DSM-III criteria for multiple personality, psychogenic amnesia, and psychogenic fugue. The groups did not differ on the number of subjects who had had a major depressive episode.

Schneiderian symptoms in multiple personality disorder and schizophrenia

We report structured interview data from a series of 102 cases of multiple personality disorder (MPD) diagnosed in four centers. Schneiderian first-rank symptoms of schizophrenia were equally common in all four centers. The average MPD patient had experienced 6.4 Schneiderian symptoms. When these 102 cases are combined with two previously reported series of MPD cases, an average of 4.9 Schneiderian symptoms in 368 cases of MPD is noted. This compares with an average of 1.3 symptoms acknowledged by 1,739 schizophrenics in 10 published series. Schneiderian symptoms are more characteristic of MPD than of schizophrenia.

Schneiderian symptoms and childhood trauma in the general population

The Dissociative Disorders Interview Schedule (DDIS) was administered to a sample of 502 adults in the city of Winnipeg, Manitoba, Canada. Findings indicate that Schneiderian symptoms are highly related to childhood trauma and other dissociative symptoms clusters in the general population, as they are in clinical populations. Implications of the findings are discussed.

Dissociation and Schizophrenia

ABSTRACT The authors administered the Dissociative Experiences Scale (DES), the Dissociative Disorders Interview Schedule (DDIS), the Scale for the Assessment of Positive Symptoms, and the Scale for Assessment of Negative Symptoms to 60 participants with schizophrenia. Participants were divided into two groups: those with scores below 10 on the DES and no dissociative disorder on the DDIS; and those with scores above 25 on the DES and/or a dissociative disorder on the DDIS. The dissociative participants had more severe trauma histories, more comorbidity and higher scores for both positive and negative symptoms. The authors interpret their findings as evidence in support of a trauma-dissociation subgroup within schizophrenia.

Prevalence, reliability and validity of Dissociative Disorders in an inpatient setting

Abstract The authors studied the prevalence and concurrent validity of the dissociative disorders in a private psychiatric hospital inpatient setting over a period of 8 months. All consenting patients admitted over a period of 8 months were administered the 8-item taxometric subscale of the Dissociative Experiences Scale (DES-T) and the Dissociative Disorders Interview Schedule (DDIS) by one interviewer. A second interviewer then administered the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D). Subsequently, a third interviewer conducted clinical diagnostic interviews on subjects positive and negative for dissociative disorders according to the previous interviewers. The second and third interviewers were blind to the results of the preceding interviews. A total of 407 individuals were admitted; of these, 201 completed the DES-T and DDIS; of these, 110 completed the SCID-D; and of these, 50 completed a clinical interview. The lifetime prevalences of dissociative disorders among the interviewed subjects were: DDIS, 40.8%; SCID-D, 44.5%; and clinician, 28.0%. The lifetime prevalences of dissociative identity disorder were: DDIS, 7.5%; SCID-D, 9.1%; and clinician, 10.0%. Kappas for presence of dissociative identity disorder or dissociative disorder not otherwise specified versus no dissociative disorder were: DDIS-DES-T, 0.81; SCID-D-DES-T, 0.76; clinician-DES-T, 0.74; DDIS-SCID-D, 0.74; DDIS-clinician, 0.71; and SCID-D-clinician, 0.56. Kappas for dissociative amnesia and depersonalization disorder were not significant. Dissociative disorders, including dissociative identity disorder, are common in inpatient settings. Chronic, complex dissociative disorders have good concurrent validity. Dissociative fugue is too rare for reliability data to be accumulated. Dissociative amnesia and depersonalization disorder did not demonstrate validity in this study.