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Dissociative Amnesia

by Helen Farrell, MD
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    00:00 Let’s talk now about Dissociative Amnesia. Dissociative amnesia, a potentially reversible memory impairment that primarily affects autobiographical information. The dissociative amnesia cannot be explained by ordinary forgetfulness, and while the patient is aware that they are having trouble remembering, they are actually, oddly not that concerned by it. That's a key feature of the disorder. So, there are different types of memory that are important to know about, which you can read about here including autobiographical, semantic, there is also episodic memory and finally we also have procedural memory. So, these are 4 different types of memory to familiarize yourselves with. When it comes to dissociative amnesia, this is a common dissociative disorder.

    00:57 The prevalence is around 10% and there is an increased incidence of comorbid major depression and also anxiety disorder that comes along with it. Females tend to be more affected than males and also younger adults are more likely to be affected than older adults. Dissociative disorders result from genes and environmental factors that influence their expression. So this is what we think of in terms of the pathology of dissociation. So, in other words, when an overwhelming traumatic experience occurs, maybe during childhood or later in life, it can actually trigger the expression of a genetic vulnerability that otherwise might have gone unnoticed throughout the duration of someone’s life. Environmental factors that can trigger this gene to be expressed are things like serious trauma, trauma like sexual trauma, military trauma, something very considerable. Also neurobiological factors can influence the expression of a gene that can cause dissociation to occur. We tend to think of the temporal, hippocampal, and also occipital areas of the brain as being associated with autobiographical memory and if any of these brain regions are actually affected, it can lead to dissociation. Then genetic vulnerability, we see there is about a 50% variance in dissociation disorders. So, how do you diagnose a dissociative amnesia? Well, you want to go about your assessment looking for these points. It's an inability to recall important autobiographical information that is not consistent or inconsistent with ordinary forgetfulness. The symptoms cause marked distress or impairment in social and occupational functioning. The disturbance is not due to the effects of a substance and you have ruled out, of course, all other general medical conditions and the disturbance is not better accounted for by any other psychiatric disorder and it's very important to specify whether or not the dissociative amnesia is associated with a dissociative fugue, and we’ll talk about that in more detail coming up. So, the differential diagnosis for dissociative amnesia is going to include dementia. What’s the difference between the two? Well, there are different ways to separate them. So, in one of these illnesses, the patient is going to be very upset by their memory loss.

    03:44 Do you know which one that is? That’s dementia. Because in dissociative amnesia despite the inability to recall information, people tend not to be too upset by that. How about which disorder has people really trying to recall their memories? That’s usually seen in dementia, whereas in dissociative amnesia, patients will appear as quite aloof even when you’re asking them to recall details about their life. What other diagnosis must be ruled out when considering dissociative amnesia? So, in other words, what’s your differential diagnosis and what other illnesses are you going to rule out? Well you're going to look for alcohol abuse, anxiety, factitious disorders, depression, other general medical disorders and also malingering. Also, there’s something interesting called Ganser syndrome, which you’re going to want to rule out. So, what’s Ganser syndrome? Well, that is a reaction to extreme stress and the patient will actually give approximations of answers or they'll give absurd answers that make absolutely no sense.

    04:57 Dissociative fugue, which I mentioned earlier, is actually a subtype of dissociative amnesia and we’ll talk again a little bit more about that coming up. So, characteristics of trauma can lead different forms of dissociation and there are a lot of different types of trauma that one can experience and depending on the depth and degree of the trauma, patient may be more or less likely to dissociate later. So, some examples of trauma types are human assault or natural disaster, repeated traumatizations, having endured trauma over a long period of time, consider someone like a prisoner of war, fear of death or significant harm during the trauma where one really felt like their life was at risk, and a traumatic event that is perpetuated by gangs or multiple people can be very, very distressing. Also, other types of trauma include when there is a trauma between a close partner or someone you have an intimate relationship with, betrayal by a caretaker such as a doctor who induces trauma on a patient, threats of death, again very important, so worth repeating, and whether or not there was violence that actually in fact led to physical injury and harm, and people who endured trauma at an early, early age might be more susceptible later to having a form of dissociation. So, the types and subtypes of amnesia we'll go through. We talked a little bit about different memory types and when assessing somebody, you really want to know kind of what memory is in fact available to them, like if they aren’t recalling their autobiographical memory, you want to ask them a little bit about what can they recall. What was happening before you met them, before an isolated event, how did they think, what were they feeling? So, you are looking for different subtypes of amnesia, things like localized amnesia, selective amnesia, generalized amnesia. There can also be overt amnesia and covert amnesia. The definitions of all of these were listed out for you and will be important for you to review. So, when I go back to this case that we introduced in the overview of dissociation, this woman, Alice, who has appeared in an emergency room after being found in a clothing store where she thought she was working but wasn't actually employed there. She can’t remember anything about herself but she’s telling you all these odd details about her nephew’s birthday party. So, what type of amnesia is Alice experiencing among these various subsets? So, based off of your knowledge now, can you take a guess at the type of amnesia that she has? So, right, so she has a generalized amnesia. There’s a lot of information she cannot recall, and it’s actually overt dissociative amnesia, so type 1. That’s the overview of dissociative amnesia and you now know a little bit about its definition, epidemiology, diagnostic criteria and assessment. We're going to keep going forward in talking about more forms of dissociation coming up.


    About the Lecture

    The lecture Dissociative Amnesia by Helen Farrell, MD is from the course Dissociative Disorders and Somatoform Disorders . It contains the following chapters:

    • Dissociative Amnesia
    • Dissociative Amnesia Assessment
    • Trauma

    Included Quiz Questions

    1. Autobiographical information.
    2. Procedural memory.
    3. Geographical information.
    4. Episodic memory.
    5. Semantic memory.
    1. Episodic memory.
    2. Semantic memory.
    3. Autobiographical memory.
    4. Procedural memory.
    5. Geographical memory.
    1. It is a potentially reversible memory impairment where the patient is not bothered by it.
    2. The prevalence is around 40% in the general population.
    3. Co-morbid conditions include bipolar disorder type 2 and anorexia nervosa.
    4. Older males are more affected.
    5. It results due to sudden health deterioration due to general medical conditions.
    1. Ganser syndrome.
    2. PTSD.
    3. Malingering.
    4. Normal grief.
    5. Schizophrenia.
    1. Generalized amnesia.
    2. Selective amnesia.
    3. Localized amnesia.
    4. Covert amnesia.
    5. Overt dissociative amnesia.
    1. Present with dramatic, profound loss of memory for personal history and loss of personal identity.
    2. A common type of amnesia which is often not uncovered unless clinical probes for it.
    3. Lack of autobiographical memory for a specific time period.
    4. Partial memory for a period of time.
    5. Inability to recall the entirety of the life history usually accompanied by loss of memory for the person’s identity.

    Author of lecture Dissociative Amnesia

     Helen Farrell, MD

    Helen Farrell, MD


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