jueves, 21 de febrero de 2019

What is Dissociative Amnesia?

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By Jennifer Logan, MD, MPHReviewed by Chloe Bennett, B.Sc.

Dissociative amnesia is a psychological disorder whereby an individual has a marked deficit in the ability to recall information, usually following a traumatic or stressful event. The development of the disorder is thought to be influenced by a combination of personality traits, genetics, adverse childhood experiences, and psychiatric comorbidities.

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What is Dissociation?

Dissociation is linked to the autobiographical memory system, personal identity, and consciousness. Dissociation is a psychological state which often occurs in response to high levels of stress or traumatic experiences. People going through periods of dissociation may feel a sense of disconnection between themselves and their environment.

What is Dissociative Amnesia?

Derived from Greek, the term amnesia is used to describe memory impairment that is characterized by the inability to successfully recall previously learned information and learn new information. To be diagnosed with amnesia, the impairment shown must not be due to dementia or other psychological disorders. Furthermore, a worsening of functioning compared to a previously attained level of functioning must be seen. Dissociative amnesia, in particular, is a term that has been used in recent years to describe a category of amnestic disorders that don’t have evidence of significant brain damage due to disease or injury. Those with dissociative amnesia typically exhibit the following symptoms.

Inability to recall essential personal information, which is usually traumatic or stressful in nature
Memory recall issues that are not associated with other psychological disorders including dissociative identity disorder and posttraumatic stress disorder, substance abuse or other medical conditions
Symptoms experienced cause a significant impact on the individual’s functionality

Unlike other amnesia disorders, those with dissociative disorder show anterograde amnesia, whereby they struggle to recall information following the trauma; however, are able to learn new information. The majority of those with dissociative amnesia are partly or completely unaware that they have gaps in their memory until they are made aware of the fact.

What Causes Dissociative Amnesia?

There are several proposed theories regarding causes of dissociative amnesia. For many patients, identifying the underlying causal and maintaining mechanisms is a difficult task. Current theories center around executive dysfunction, stressful and psycho-traumatic events, memory suppression, and socio-cognitive changes.

Dissociative Amnesia and Stress

Individuals might develop the impairment in episodic memory seen in dissociative amnesia due to a stress hormone-triggered-and-mediated memory blockage. This is thought to be underpinned by desynchronization between the frontal lobe and temporo-amygdalar systems. The latter is considered to play a role in emotional processing, whereas the former is important in autonoetic consciousness, which is the ability to mentally reenact previous events, or place ourselves in future events or counterfactual situations. The impairment is considered to be precipitated by adverse childhood events or life conditions and influenced by a range of other factors such as personality, genetics and psychiatric comorbidities.

The stress experienced in association with these events can lead to a surge in the release of stress hormones, which bind to neurons in the hippocampus and amygdala, which have large numbers of glucocorticoid receptors and play a role in encoding and retrieving episodic memories. This, in turn, can cause changes to the connectivity in the aforementioned systems resulting in memory problems.

Comorbid Psychological Disorders

Like many other psychological disorders, dissociative amnesia has been found to be comorbid with a range of psychiatric conditions such as obsessive-compulsive disorder. In a specific case study, a patient presented symptoms of dissociation and experienced spells of being mute but was unable to recall why. After undergoing a drug-assisted interview, the patient was able to recall a pattern of obsessive thoughts which were followed by compensatory mental compulsions aimed to remove those thoughts. The distress caused by those thoughts was argued to be the trigger of the subsequent period of dissociative amnesia.

Furthermore, a growing body of research has highlighted links between dissociative amnesia and personality disorders. Specifically, the symptoms experienced have been found to be most commonly associated with Cluster B personality disorders, as individuals with the disorder typically have a history of psychological or physical trauma. Also, there is a separate branch of research which has demonstrated potential links with Cluster C personality disorders, in particular, avoidant and dependent personality disorders.

Treatment Options for Dissociative Amnesia

Treatment methods for dissociative amnesia aim to recover memory and typically involve the use of psychotherapy to address the issues associated with the stressful or traumatic event that triggered the onset of the condition.