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Dissociative disorders (DDs) have been associated with considerable controversy in the mental health field. While limitations in funding have hampered research about DDs, studies are emerging that can inform the discussions about DDs. The purpose of this column is to review the extant and emerging literature to clarify if several commonly held beliefs about dissociative disorders (DDs) are empirically supported. The beliefs to be explored are:

Belief 1: DDs are primarily North American phenomena.
Belief 2: DDs are overdiagnosed.
Belief 3: The most severe form of dissociative disorder, dissociative identity disorder (DID) is not a separate disorder, but rather a variation of borderline personality disorder (BPD).
Belief 4: DID is the most common type of dissociative disorder.

True or False: DDs are primarily North America phenomena.

False. A recent study using structured interviews with a large community sample of women in Turkey (N = 628; Sar, Akyuz, & Dogan, 2006) found that DDs are common, albeit underdiagnosed in Turkey. Sar et al. found a lifetime prevalence rate of 18.3% among Turkish women. In the first study of pathological dissociation among a community sample in Europe (Maaranen, 2006), the rate of pathological dissociation was almost identical to the rate found in a Canadian sample (3.2% vs. 3.3%, respectively; Canadian sample from Waller & Ross, 1997). In a sample of 459 Filipino college students (Gingrich, 2005), participants who scored high on self-report measures of dissociation were administered a structured interview of dissociation. Thirty-two percent of the interviewed sample and 4.1% of the entire sample met criteria for a DD. Data from clinical samples in the Netherlands, Turkey, Switzerland and Germany have also found high rates of DDs (4.3% - 13.8% for any DD; .4% - 5.4% for DID; see Sar, 2006 for a review). While research is needed from a wider range of countries using large samples and structured interviews for DDs, the current data suggest that DDs are common among the general population and psychiatric samples in Europe. It is a misconception that DDs are primarily a North American phenomena.

True or False: DDs are overdiagnosed.

False. Two studies have found that few of the individuals meeting criteria for DDs have been diagnosed with a DD, while none have found contradictory evidence. Among 110 consecutive admissions to a state psychiatric hospital, Saxe et al. (1993) found that 15% met criteria for a DD. However, only 21% of those patients received either an admission or discharge diagnosis of a DD, as recorded in their medical record.  Sar et al. (2006) found that 18.3% of the women in their representative community sample met criteria for lifetime prevalence of a DD. However, only one third of those with DD had ever received psychiatric treatment. Data were not available for the disorders these women had been diagnosed with by their treatment providers. These preliminary studies suggest that DDs are under-diagnosed as well as under-treated, although more research is needed to see if this pattern is replicated.

True or False: DID is a severe variation of BPD.

False but more research is needed.  Studies that investigate the underlying personality features of DDs typically show that DDs differ from BPD. For example, a study (Brand et al., 2005) comparing the Rorschachs of 100 dissociative disorder patients to 40 BPD patients found that the dissociative patients were significantly different from the BPD patients on 9 out of 11 variables tested. Some of the significant differences were that the DD patients were better able to modulate affect and had better reality testing and more organized thinking than did the BPD patients. Given that affective instability and brief episodes of psychotic symptoms are DSM-IV (APA, 2004) criteria for BPD, and that DD patients show relative strengths in these areas compared to BPD patients, these findings suggest important differences between the two disorders.

Nonetheless, comorbidity with these disorders is to be expected given that there is large phenomenological overlap between BPD and DDs including the DSM-IV criteria for BPD of “transient dissociative phenomena” and identity disturbance. Furthermore, patients with both disorders often report experiencing childhood abuse (APA, 2004), suggesting possible similarities in some of the etiological factors for the disorders. Indeed, epidemiological studies have found high comorbidity between the disorders. For example, a survey of a random national U.S. sample of experienced clinicians determined that more than half (53.3%) of the BPD patients also met criteria for a DD (Zittel et al., 2005). One possibility is that there are subtypes of BPD, one of which may be a highly traumatized, highly dissociative variation.

Reviewing his series of studies utilizing a structured interview to diagnose DDs, Ross (1997) concluded that a concomitant BPD diagnosis is more of a severity indicator in DID, indicating greater posttraumatic disturbance, rather than being a true co-morbid disorder. To better clarify the relationships between dissociative and borderline symptomatology, studies need to compare groups of patients diagnosed with DD without BPD, BPD without DD, and comorbid DD and BPD.  It is important that future studies use structured diagnostic interviews for both disorders as well as other standardized measures.

True or False: DID is the most common type of dissociative disorder.

False. In a longitudinal study utilizing a representative sample of residents in New York state (N = 658), Johnson and colleagues (2006) found 9.1% of the sample met criteria for a DD. The most prevalent DD was DDNOS at 5.5% while only 1.5% of the sample met criteria for DID. The first methodologically sound large sample (N = 231; Foote et al., 2006) of consecutive admissions in an inner city outpatient in the United States found very high rates of DDs with DDNOS (9%) being more prevalent than DID (6%), depersonalization disorder (5%) and dissociative fugue (0%). Similarly, studies in Holland, Turkey, Germany, Canada and the Philippines have found that DDNOS is more common than DID among clinical and general population samples (Gast et al., 2001; Gingrich, 2005; Friedly & Draijer, 2000; Sar et al., 2006; Waller & Ross, 2001). The high prevalence of DDNOS suggests that further clarification of the criteria for the DDs are needed because “NOS” categories are intended to be rare.

References
American Psychiatric Association (2004). Diagnostic and Statistical Manual of Mental Disorders (4th ed.). Washington, DC: Author.

Brand, B., Armstrong, J. , Lœwenstein, R.J. (November 2005). The unique Rorschach profile of severely dissociative patients: Results of 100 cases. Paper presented at the 22nd Fall International Society for the Study of Dissociation Conference, Toronto, Canada.

Foote, B., Smolin, Y., Kaplan, M., Legatt, M.E., & Lipschitz, D. (2006). Prevalence of dissociative disorders in psychiatric outpatients. American Journal of Psychiatry, 163, 623-629.

Johnson, J.G., Cohen, P., Kasen, S. & Brook, J. (2006). Dissociative disorders among adults in the community, impaired functioning, and axis I and II comorbidity. Journal of Psychiatric Research, 40, 131-140.

Gast U, Rodewald F, Nickel V, Emrich HM. (2001). Prevalence of dissociative disorders among psychiatric inpatients in a German university clinic. J Nerv Ment Dis. 2001 Apr;189(4):249-57.

Gingrich, H. (2005). Trauma and dissociation in the Philippines. Journal of Trauma Practice, 4 (3/4), 245-269.

Maaranen, P., Tanskanen, A., Honkalampi, K., Haatainen, K, Hintikka, J., & Viinamaki, H. (2005). Factors associated with pathological dissociation in the general population. Australian and New Zealand Journal of Psychiatry, 39, 387-394.

Ross, C.A. (1997). Dissociative Identity Disorder: Diagnosis, Clinical Features, and Treatment of Multiple Personality. New York: John Wiley & Sons.

Sar, V. (2006). The scope of dissociative disorders: An international perspective. Psychiatric Clinics of North America, 29, 227-244.

Sar, V., Akyuz, G., & Dogan, O. (2006). Prevalence of dissociative disorders among women in the general population. Psychiatry Research, 149, 169-176.

Saxe, G.N., van der Kolk, B.A., Berkowitz, R., Chinman, G., Hall, K., Lieberg, G., & Schwartz, J. (1993). Dissociative disorders in psychiatric inpatients. American Journal of Psychiatry, 150, 1037-1042.

Steinberg, M., Rounsaville, B., & Cicchetti, D. V. (1990). The Structured Clinical Interview for DSM-III-R Dissociative Disorders: Preliminary report on a new diagnostic instrument. American Journal of Psychiatry, 147(1), 76-82.

Waller, N.G., & Ross, C.A. (1997). The prevalence and biometric structure of pathological dissociation in the general population: taxometric and behavior genetic findings. Journal of Abnormal Psychology, 106, 499-510.

Zittel Conklin, C & Westen, D. (2005). Borderline personality disorder in clinical practice. American Journal of Psychiatry, 162, 867-975.