Dissociation: Defining the Concept in Criminal Forensic Psychiatry

Historical Roots

At the end of the 19th century, Janet¹³ conceptualized dissociation as a lack of integration of various mental functions when stress or exposure to traumatizing events induced a hysterical reaction, a phenomenon seen only in people with impaired mental or cognitive functioning. Freud's psychodynamic explanation further posited that dissociation was a psychological defense mechanism against negative feelings, conflicts, or experiences.¹⁴ William James¹⁵ and later investigators viewed dissociation as a dimensional construct ranging from daydreaming to severe dissociative disorders.^16,–,18

In response to criticism of the extensive nature of the dissociation concept, Holmes et al.¹⁹ and Brown²⁰ proposed a model of dissociation that includes two distinct categories of dissociative phenomena: detachment and compartmentalization.

“Detachment” is defined as an altered state of consciousness characterized by a sense of separation from aspects of everyday experience.¹⁹ There is often an absence or flattening of emotional experiences during these altered states.²¹ Detachment is thought to arise from intense fear or trauma and includes depersonalization (an altered state of consciousness involving a sense of disconnection from one's mental process or body), derealization (experiencing the external world as strange or unreal), or both.^19,20 In some individuals, dissociative amnesia could arise during detachment related to an encoding and storage deficit.²¹

“Compartmentalization” is defined as a phenomenon that meets the following four criteria: a deficit in the ability to maintain deliberate control of processes or actions that would normally be amenable to such control (including the inability to bring normally accessible information into conscious awareness); the deficit cannot be overcome by an act of will; the deficit is reversible, at least in principle; and it can be shown that the apparently disrupted functions are operating normally and continue to influence cognition, emotion, and action.¹⁹ It includes dissociative experiences such as amnesia. In contrast to detachment, dissociative amnesia representing compartmentalization would thus be due to a memory retrieval deficit.²¹

Dissociation and Trauma

Pathological dissociation has been linked to psychological trauma or overwhelming stress.^12,22,–,28 It may occur more often in people who did not develop effective coping strategies after stressful experiences in childhood.^29,–,31 Individual characteristics, such as cognitive flexibility and emotional processing ability, may affect the likelihood of responding to stress with dissociative symptoms.^32,33

Although dissociation is a core feature of the dissociative disorders, such experiences are also among the criteria for DSM-5 diagnoses of acute stress disorder, posttraumatic stress disorder (PTSD), and borderline personality disorder.¹¹ In the DSM-5, the dissociative disorders are placed next to, but are not part of, the trauma- and stressor-related disorders, indicating the close relationship between these diagnostic classes.¹¹ The symptoms of PTSD reflecting this relationship include dissociative flashbacks, amnesia for some aspects of the trauma, and emotional numbing. The specifier “with dissociative symptoms” can be applied to the PTSD diagnosis if the individual experiences persistent or recurrent symptoms of depersonalization or derealization.

Dissociation is related to a difficult, long-term treatment course. In a recent review, Brand et al.³⁴ noted that symptoms of dissociative disorders are frequently severe and that dissociative disorders are associated with a higher rate of mental health treatment and a substantial economic burden, compared with other psychiatric disorders (e.g., panic disorders, bipolar disorder, and major depressive disorder). Dissociation may also be an important predictor of poor treatment response and high relapse rates, even in patients whose primary diagnosis is not necessarily dissociative disorder.^35,–,37 Patients with dissociative disorders have higher rates of suicidal ideation, suicide attempts, and self-injurious behavior than do people with other disorders.³⁸

Dissociative Disorders in the DSM and Essential Features

The DSM-5 describes the following categories of the dissociative disorders: dissociative identity disorder (DID); dissociative amnesia; depersonalization/derealization disorder; other specified dissociative disorder; and unspecified dissociative disorder.¹¹

Peritraumatic Dissociation and Violence

Peritraumatic dissociation (PTD) refers to dissociative symptoms (e.g., usually depersonalization or derealization) experienced by people during traumatic events. PTD is strongly linked to the development of PTSD over time.^67,–,71 It is related to the severity of PTSD and may predict subsequent amnesia.^38,72,–,74 It is thought that PTD results in insufficient encoding of the traumatic experience, thereby disrupting memory storage and retrieval.⁷⁵

The lack of elaboration of the memory is proposed to be related to high emotion and dissociation during the traumatic experience.⁷⁶ Longstanding dissociation after the experience prevents memory elaboration, resulting in fragmentation of the trauma memory and PTSD. The memory disturbance that can accompany high levels of dissociation may serve to protect the individual from becoming overwhelmed by aspects of the trauma before being able to deal with it.⁷⁷

Some have advanced the notion that peritraumatic dissociation may represent a normative reaction. In a retrospective study, Rivard et al.⁷⁸ examined the prevalence of acute traumatic dissociation in a small convenient sample of 115 law enforcement officers involved in critical shooting incidents. It was found that 90 percent had experienced an acute traumatic dissociation. Close to one-fifth described some form of memory impairment.⁷⁸

Moskowitz and Evans⁷⁷ reported that a notable proportion of violent offenders experience PTD and amnesia and that dissociative experiences are more likely to occur when the violence is more extreme.^77,79 They explored three theoretical possibilities as to the significance of PTD and amnesia in violent offenders, in that PTD may reflect:

• Traumatic reaction to one's violent actions (in the absence of a preexisting dissociative disorder). Some violent offenders develop symptoms of PTSD in response to their own violence (with no prior evidence of a dissociative disorder).^80,81 This suggests that the source of the trauma is the individual's own violent behavior.

• A preexisting dissociative disorder. Some violent individuals who report PTSD or amnesia have a preexisting dissociative disorder (often DID). Moskowitz and Evans⁷⁷ suggested that the violent crime may be an expression of a violent or homicidal alter. A recent review of medicolegal challenges associated with DID noted that this area is an important consideration in many legal cases, as defendants claiming that their alter committed the crime have pleaded not guilty by reason of insanity.⁸² A few studies have assessed the frequency of violent and homicidal behavior in individuals diagnosed with DID. Putnam et al.⁸ found violent alters in 70 percent of patients with DID, most of whom were female. In contrast, Loewenstein and Putnam⁸³ reported that male DID patients had a greater percentage of violent but not homicidal alters compared with a sample of female DID patients from the study by Putnam et al. (90% compared with 74%). Homicidal alters were present in about one-third of both sexes. In other research, more than one-third of alters in adolescents with DID had been violent or threatened violence.⁸⁴ Homicide remained a rare event, however.

• The emergence of a dissociative disorder through the act of violence, with limited to no evidence afterward. Moskowitz and Evans⁷⁷ suggested that some individuals may not have a dissociative disorder before an act of violence but would have met criteria for a dissociative disorder at the time of violence. This pattern is similar to that seen in studies of homicide and first-episode psychosis that found that 30 to 61 percent of homicides committed during psychotic illness took place during first-episode psychosis.^85,–,90

Dissociative symptoms have also been linked to violence in individuals diagnosed with other disorders. Although the concept of dissociation was first introduced in the context of hysteria, it was eventually applied to symptoms seen in schizophrenia, as they relate to the disruption of thinking and emotions.⁹¹ In psychotic patients, delusions of control and of thought insertion have been identified as predictive of violence.^92,93 These types of delusions are also reported often in people with DID, and are interpreted as arising from alters influencing the “host” personality.^94,95 The distinction between DID and schizophrenia may pose a challenge as these conditions share several psychopathological symptoms and impairment. Using the dissociative experience scale, a controlled-group study concluded that patients with schizophrenia have significantly more dissociative symptoms than do nonclinical controls. In particular, dissociative symptoms correlated with the so-called positive or productive symptoms, such as delusions and hallucinatory behavior.⁹¹ Such findings have challenged the notion that dissociative symptoms belong to the neurotic sphere rather than the psychotic sphere.

Persistent Dissociation and PTSD

Dissociation that occurs in response to trauma usually dissipates over time. However, some individuals have recurring trauma-related dissociative symptoms, including depersonalization and derealization, for months or years after the event. Persistent dissociation, dissociative symptoms that occur after a traumatic experience and continue over time, may contribute to the development and maintenance of PTSD symptoms.^96,–,99 Clinical and neurobiological evidence of dissociative symptoms lend support to a dissociative subtype of PTSD, which is now included in the DSM-5.^{11,100,–,103}

Using epidemiologic data from 16 countries in the World Health Organization World Mental Health Survey, Stein et al.¹⁰⁴ reported that 14.4 percent of respondents diagnosed with PTSD met criteria for the dissociative subtype, a proportion within the range noted in prior studies. Dissociation was associated with heightened PTSD symptom counts, severe impairment in role functioning, and suicidality.

PTSD has been strongly associated with violent behavior.^105,106 This violence may be driven by dissociative flashbacks from traumatic experiences, among the most common of PTSD symptoms.^80,106,107

Neurobiological Basis

Chronic psychosocial stresses could lead to dissociative disorders via dysregulation of hormonal stress responses. Neurobiological findings and imaging techniques have provided evidence that changes in brain structure or metabolism underlie several psychiatric disorders, including DID and dissociative amnesia.^47,108

Repeated exposure to stress may result in widespread alterations in neurotransmission with direct effects on brain function.^109,–,111 The model for dissociative amnesia described by Staniloiu and Markowitsch⁴⁷ suggests that traumatic experiences may change how specific neurotransmitters are activated and result in altered processing of incoming information. The nature and extent of these changes are affected by how the traumatic experiences (particularly those with early onset) interact with an individual's genetic disposition, environmental factors, and the developmental window. Subsequent stress may lead to dissociation of the usual synchronization between emotion-processing areas of new information (e.g., amygdala and septal region and basal forebrain) and cognitive-processing areas, leading to the block of autobiographical information processing. Such a model is consistent with evidence indicating that early life experiences can lead to changes in stress responses and neuroanatomical changes affecting brain connectivity, structures, and volume, including changes in the right hemispheric uncinate fascicle, a fiber bundle essential in the retrieval of episodic-autobiographical memory (e.g., personal context-based events).^{11,47,113,–,115}

The release of glucocorticoids and other stress hormones negatively impacts the function of brain structures necessary for the encoding or retrieval of information. Elevated glucocorticoid levels reduce traumatic memory retrieval by inhibiting activity in the medial temporal lobe.^116,–,120 In patients with dissociative amnesia after stressful or traumatic experiences, Brand et al.¹²¹ found significantly decreased glucose utilization in the right inferolateral prefrontal cortex, known to play an important role in the retrieval of autobiographical memories. The right prefrontal cortex is strongly involved in synchronizing emotional and factual elements related to the self.^122,–,125 Brand et al.¹²¹ posited that such hypometabolism in the inferolateral prefrontal cortex in patients with dissociative amnesia could indirectly compromise executive functioning associated with retrieval deficits.

In a review of research investigating a neurobiological basis for dissociation, Brand et al.³⁴ suggested that different aspects of emotion dysregulation contribute to the subtypes of PTSD. They hypothesized that hyperarousal symptoms and experiencing flashbacks after traumatic events could represent emotional undermodulation that is mediated by failure of prefrontal inhibition of activity in limbic regions. In contrast, the dissociative subtype involving symptoms of depersonalization and derealization could be seen as emotional overmodulation, accompanied by increased activation of medial prefrontal structures and hyperinhibition of limbic regions. Long-term childhood abuse and military combat trauma are associated with the overmodulation characterizing the dissociative subtype.^{72,102,126,127}

Vignette 1

A man's marriage had recently broken up and he suspected his wife of having a lover. He reported vague depressive symptoms and a history of domestic violence. One evening, he went out with friends and used alcohol and cocaine and returned home, becoming increasingly paranoid. He confronted his wife and a verbal fight ensued. His wife pushed him and he became furious. He regained consciousness in a nearby swamp with his wife unconscious beside him. He was charged with first-degree murder and found guilty. This description exemplifies peritraumatic dissociation triggered by anger, in the context of cocaine and alcohol-induced paranoid state.

Legal Perspectives on Dissociative Amnesia

Dissociation and dissociative amnesia for serious offenses can have legal repercussions, because of their relevance to the legal constructs of fitness to stand trial and criminal responsibility. Regarding fitness or competency to stand trial, as per the competency standard set by Dusky v. United States (1960),¹³⁶ dissociative amnesia could render a defendant incompetent to stand trial because memory loss for the events would prevent him from having a reasonable degree of rational understanding and restrict his ability to assist counsel in the preparation of his defense. Fitness to stand trial was addressed in Wilson v. United States (1968).¹³⁷ The U.S. Court of Appeals D.C. Circuit ruled that lack of memory for an alleged offense is not a sufficient factor alone to negate competency. The Court concluded that the following factors must be addressed in an evaluation of the impact of amnesia on a defendant's ability to stand trial: the defendant's ability to consult with and assist counsel; the extent to which the memory loss affected the defendant's ability to testify and to reconstruct evidence extrinsically; the extent to which the government assisted in that reconstruction; the strength of the prosecution's case; and any other general factors pertinent to the case.

Although no convincing case law could be found regarding dissociative amnesia and fitness to stand trial, Smith and Resnick¹³⁸ provided a summary of United States v. Andrews,¹³⁹ which involved an individual with a drug-induced amnesia surrounding a count of bank robbery. In essence, Mr. Andrews was found guilty of robbing the bank in a bench trial, which he appealed, based on his claim that his amnesia for the relevant period of the robbery had rendered him unable to assist in his own defense at trial. The Court affirmed Mr. Andrews' conviction and found that the district court did not err in its finding that Mr. Andrews was fit to stand trial. Smith and Resnick provided the reasoning for this determination, which relied heavily on the precedent set in United States v. Stevens,¹⁴⁰ stating that “amnesia is not a bar to prosecution of an otherwise competent defendant.” The appeals court also cited the standard laid out in Dusky v. United States¹³⁶ and identified the factors listed above when applying this standard to an amnestic defendant. However, the court also acknowledged the importance of not trying individuals who are unfit to stand trial, and that it is possible that amnesia could impair fitness.¹³⁸ An example of this could be a person with an ongoing dissociative disorder with significant periods of amnesia and dysfunctional mental states keeping him from productively conferring with a lawyer (i.e., not able to discuss a traumatic index offense due to ongoing dissociations, or dissociations during the trial or when taking the stand).

Dissociative states are legally relevant because of the equating of memory loss with lack of intent and involuntariness of behavior, when appropriate. Careful consideration is needed, because these situations call for different possible legal outcomes. Possible verdicts include automatism, not criminally responsible, and diminished responsibility.

Verdict of Automatism

In the context of criminal responsibility, amnesia for serious offenses has particular relevance, because it may indicate automatism: criminal behavior that is not voluntarily controlled and is executed without intent. In Canada in 1971 the automatism defense was extended from physical trauma to include psychological trauma, a state of dissociation also referred to as “psychological blow” automatism.¹⁴¹ In Canada, dissociative states fall within the defense of mental disorder; the automatism defense is either noninsane (nonmental disorder) or insane (mental disorder) automatism. Noninsane automatism is rare. The crime is attributed to involuntary action caused by a temporary impairment of mental functioning that does not stem from a disease of the mind (leading to full acquittal, if the defense is successful). A classic example is sleepwalking.¹⁴² Insane automatism applies to a crime arising from organic brain dysfunction, that is, involuntary action resulting from a “disease of the mind” (falling under the defense of mental disorder leading to a verdict of not criminally responsible by reason of mental disorder).

In the landmark Supreme Court of Canada case of R. v. Stone,¹⁴³ a man accused of murdering his wife raised the defenses of provocation and noninsane automatism, claiming a dissociative state triggered by a psychological blow. The jury ruled that the accused did not have a disease of the mind and rejected the defense of automatism. The accused was convicted of manslaughter, based on the provocation defense. Yeo¹⁴⁴ pointed out that in Stone, the Court clarified that unconsciousness need not be present in a state of automatism and that the important element in automatism is whether criminal behavior is involuntary or not.

Insane and noninsane automatisms are distinguished by a test of internal versus external cause. The defendant's automatistic reaction to the psychological trauma is evaluated from the perspective of a normal individual who experiences the same stressful circumstances. If it is determined that a normal individual would have reacted in a similar manner by experiencing an automatistic state, a defense of noninsane automatism would be supported, as the cause of the automatism would be considered to be an external event and not due to the psychological or emotional character of the defendant.

Verdict of Not Criminally Responsible

In Canada, criminal responsibility is related to the ability of the accused to know that the act was wrong. To establish criminal responsibility, it is necessary to show an element of criminal intent (mens rea) and that the actions of the accused were conscious and voluntary.¹⁴⁵ In Canada, dissociative states are viewed generally as giving rise to insane automatism, akin to not criminally responsible (NCR).¹⁴⁶ For the purpose of the defense of NCR, the accused is determined to have been in a dissociative state at the time of the criminal act.

Vignette 2

A married female with a teenage daughter entertained an ambivalent relationship with the victim, a man with high influence in their community. They engaged in sexual intimacy without intercourse. They met in an isolated place to have sex. He became violent and abusive, raped her, and threatened to do the same to her daughter. The woman remembered removing a weapon from the glove compartment of the car. She was charged with murdering her assailant. She had anterograde amnesia with only partial and blurred visual memories. She had no prior history of psychiatric illness or dissociative experience. Clinical evaluation revealed nothing out of the ordinary except for a high level of anxiety, although it was also understandable in the context of her legal case. This illustrates an acute dissociation triggered by sexual abuse and direct threat to integrity of her daughter. A jury found her not criminally responsible by reason of a mental disorder.

Berger et al.¹⁴⁷ provided an excellent review of case law for PTSD-related dissociative symptoms, as a criminal defense in the United States. Some examples of successful insanity defenses included State of New Jersey v. Cocuzza (1981), State v. Heads (1980), State v. Wood (1982), and Commonwealth v. Tracy (1989). In his first trial, Heads was found guilty of murder, but in a second trial, he was found not guilty by reason of insanity after an expert testified about PTSD.¹⁴⁸ All of these cases seemingly involved Vietnam veterans committing an offense while in a dissociative state. Dissociative flashbacks have been suggested by some to be the only legitimate basis for insanity and other exculpating defenses, although criminal defenses of hyperarousal symptoms and sensation-seeking behaviors have also been presented.¹⁴⁷ Berger et al.¹⁴⁷ indicated that PTSD has received mixed treatment when offered as a basis for insanity, being met with skepticism in several jurisdictions. However, it appears that the main reason for the rejection of PTSD as an insanity defense often stemmed from a lack of demonstrating how PTSD (and dissociative phenomena) could lead to insanity due to the difficult-to-verify nature of DSM's PTSD and dissociative disorder criteria.^147,148 Although there is a perception that individuals could abuse PTSD as a defense, Appelbaum et al.¹⁵⁰ found that defendants in the United States had no more success with PTSD than with other mental disorders and that insanity pleas based on PTSD made up a small proportion of all insanity pleas. PTSD has been determined to meet both the Frye standard and the Daubert standard, governing the admissibility of expert witness testimony in courts.¹⁴⁷

Farrell¹⁵¹ provided a review of medicolegal challenges with DID and determined that most DID defenses did not hold up after State v. Milligan,¹⁵² in response to which public outrage occurred after a serial rapist was not held culpable for his actions. It was opined that defendants who claim DID are usually viewed as having limited credibility because of the perception of malingering.

Diminished-Capacity Defense

Certain jurisdictions have allowed the defense of diminished capacity or diminished responsibility. The criteria for a verdict of diminished capacity require that the defendant has an underlying condition, an abnormality of mental functioning (e.g., a major mood disorder or psychotic illness), that substantially impairs his or her ability for rational judgment, understanding of his or her actions, and self control. A mental disorder short of insanity may interfere with an individual's capacity to form a specific intent to carry out actions, such as killing. If diminished capacity is proven on a charge of murder, the accused is convicted instead of manslaughter, a crime of general intent.

In State v. Warden,¹⁵³ a woman charged with first-degree murder, raised the diminished capacity defense. At trial, an expert testified that she had PTSD with dissociation and that she lacked the capacity to form a specific intent at the time of the crime. The trial judge did not instruct the jury on manslaughter. On appeal, the Washington Supreme Court overturned the conviction and found guilt on the lesser charge of manslaughter. A similar situation arose in State v. Bottrell,¹⁵⁴ where the same court of appeal reversed a prior ruling.