SPECIAL SECTION: STRESS AND TRAUMA Dissociation: Defining the Concept in Criminal Forensic Psychiatry Dominique Bourget, MD, Pierre Gagne´, MD, and Stephen Floyd Wood, MD Claims of amnesia and dissociative experiences in association with a violent crime are not uncommon. Research has shown that dissociation is a risk factor for violence and is seen most often in crimes of extreme violence. The subject matter is most relevant to forensic psychiatry. Peritraumatic dissociation for instance, with or without a history of dissociative disorder, is quite frequently reported by offenders presenting for a forensic psychiatric examination. Dissociation or dissociative amnesia for serious offenses can have legal repercussions stemming from their relevance to the legal constructs of fitness to stand trial, criminal responsibility, and diminished capacity. The complexity in forensic psychiatric assessments often lies in the difficulty of connecting clinical symptomatology reported by violent offenders to a specific condition included in the Diagnostic and Statistical Manual of Mental Disorders (DSM). This article provides a review of diagnostic considerations with regard to dissociation across the DSM nomenclature, with a focus on the main clinical constructs related to dissociation. Forensic implications are discussed, along with some guides for the forensic evaluator of offenders presenting with dissociation. J Am Acad Psychiatry Law 45:147–60, 2017 The concept of dissociation is relevant to forensic sault. All recalled the events preceding the violence psychiatry, as illustrated by the fact that amnesia and and most could identify a precise cutoff by which dissociation have frequently been associated with vi- they could not recall subsequent events. Only one olent crimes.1–9 In a review of the literature, Mos- subject had complete amnesia, leading the authors to kowitz4 found that higher levels of dissociation were conclude that complete amnesia is rare. associated with increased violence in a diverse range These considerations and findings merit the atten- of populations, including college students, military tion of the forensic psychiatrist. Little has been said veterans, psychiatric patients, and perpetrators of about the specific implications of dissociation in the sexual/domestic violence and homicide. Amnesia for forensic arena. The scope of this article is three-fold: the violent crime was reported in nearly one-third provide a synthesized review of the definition of dis- (30%) of homicides. Several studies found an associ- sociation and dissociative disorders from a diagnostic ation between amnesia, dissociation and crimes char- and neurobiological perspective; define the concept acterized by lack of planning and lack of premedita- of dissociation in greater detail from a forensic psy- tion, heightened emotional states, emotional ties to chiatric perspective while outlining the legal impli- the victim, and alcohol use.4,6,7,10 Evans et al.10 con- cations; and offer guidance to forensic experts in ducted a systematic and descriptive investigation of their evaluations of offenders who claim amnesia amnesia in a group of 105 young offenders convicted and dissociative experiences in connection with an of violent crimes (lethal and nonlethal bodily harm). offense. Twenty percent reported either partial or complete amnesia for at least the most violent part of the as- The Concept of Dissociation Drs. Bourget and Wood are forensic psychiatrists, Integrated Fo- Dissociation is defined as the disruption of nor- rensic Psychiatric Program, Royal Mental Health Centre, and Dr. mally integrated functions of consciousness, mem- Bourget is Associate Professor of Psychiatry, and Dr. Wood is a ory, identity, perception, body representation, motor lecturer in psychiatry, University of Ottawa, Ottawa, Ontario, 11 Canada. Dr. Gagne´ is Associate Professor of Psychiatry, University control, and behavior. Dissociative symptoms are of Sherbrooke, Sherbrooke, Que´bec, Canada. Address correspon- perceived as intrusive and disruptive and may be clas- dence to: Dominique Bourget, MD, Royal Ottawa Mental Health 12 Centre, 1145 Carling Avenue, Ottawa, Ontario, K1Z 7K4. E-mail: sified as positive or negative. Spiegel et al. defined [email protected]. positive dissociative symptoms (e.g., flashbacks) as Disclosures of financial or other potential conflicts of interest: None. intruding into awareness and accompanied by loss of Volume 45, Number 2, 2017 147 Defining Dissociation continuity in subjective experience, whereas negative compartmentalization would thus be due to a mem- dissociative symptoms (e.g., amnesia) result in an ory retrieval deficit.21 inability to access information or to control normally readily accessible mental functions. Dissociation and Trauma Pathological dissociation has been linked to psy- Historical Roots chological trauma or overwhelming stress.12,22–28 It At the end of the 19th century, Janet13 conceptu- may occur more often in people who did not develop alized dissociation as a lack of integration of various effective coping strategies after stressful experiences mental functions when stress or exposure to trauma- in childhood.29–31 Individual characteristics, such as tizing events induced a hysterical reaction, a phe- cognitive flexibility and emotional processing ability, nomenon seen only in people with impaired mental may affect the likelihood of responding to stress with 32,33 or cognitive functioning. Freud’s psychodynamic ex- dissociative symptoms. planation further posited that dissociation was a psy- Although dissociation is a core feature of the dis- chological defense mechanism against negative feel- sociative disorders, such experiences are also among ings, conflicts, or experiences.14 William James15 the criteria for DSM-5 diagnoses of acute stress dis- order, posttraumatic stress disorder (PTSD), and and later investigators viewed dissociation as a di- 11 mensional construct ranging from daydreaming to borderline personality disorder. In the DSM-5, the severe dissociative disorders.16–18 dissociative disorders are placed next to, but are not In response to criticism of the extensive nature part of, the trauma- and stressor-related disorders, 19 indicating the close relationship between these diag- of the dissociation concept, Holmes et al. and 11 Brown20 proposed a model of dissociation that in- nostic classes. The symptoms of PTSD reflecting cludes two distinct categories of dissociative phe- this relationship include dissociative flashbacks, am- nomena: detachment and compartmentalization. nesia for some aspects of the trauma, and emotional numbing. The specifier “with dissociative symp- “Detachment” is defined as an altered state of con- toms” can be applied to the PTSD diagnosis if the sciousness characterized by a sense of separation from individual experiences persistent or recurrent symp- aspects of everyday experience.19 There is often an toms of depersonalization or derealization. absence or flattening of emotional experiences dur- 21 Dissociation is related to a difficult, long-term ing these altered states. Detachment is thought to treatment course. In a recent review, Brand et al.34 arise from intense fear or trauma and includes dep- noted that symptoms of dissociative disorders are fre- ersonalization (an altered state of consciousness in- quently severe and that dissociative disorders are as- volving a sense of disconnection from one’s mental sociated with a higher rate of mental health treat- process or body), derealization (experiencing the ex- 19,20 ment and a substantial economic burden, compared ternal world as strange or unreal), or both. In with other psychiatric disorders (e.g., panic disor- some individuals, dissociative amnesia could arise ders, bipolar disorder, and major depressive disor- during detachment related to an encoding and stor- 21 der). Dissociation may also be an important predic- age deficit. tor of poor treatment response and high relapse rates, “Compartmentalization” is defined as a phenom- even in patients whose primary diagnosis is not nec- enon that meets the following four criteria: a deficit essarily dissociative disorder.35–37 Patients with dis- in the ability to maintain deliberate control of pro- sociative disorders have higher rates of suicidal ide- cesses or actions that would normally be amenable to ation, suicide attempts, and self-injurious behavior such control (including the inability to bring nor- than do people with other disorders.38 mally accessible information into conscious aware- ness); the deficit cannot be overcome by an act of Dissociative Disorders in the DSM and Essential will; the deficit is reversible, at least in principle; and Features it can be shown that the apparently disrupted func- The DSM-5 describes the following categories of tions are operating normally and continue to influ- the dissociative disorders: dissociative identity disor- ence cognition, emotion, and action.19 It includes der (DID); dissociative amnesia; depersonalization/ dissociative experiences such as amnesia. In contrast derealization disorder; other specified dissociative to detachment, dissociative amnesia representing disorder; and unspecified dissociative disorder.11 148 The Journal of the American Academy of Psychiatry and the Law Bourget, Gagne´, and Wood Dissociative Identity Disorder Spiegel et al.12 noted several types of dissociative Dissociative identity disorder (DID; formerly amnesia, including “localized amnesia,” the inability termed multiple-personality