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.
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.
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.
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.