In this article we are continuing with the series of memory disorders in cognitive psychology. Specifically understanding dissociative disorders of memory; what they are and how they affect cognition. We’ll also discuss memory disorders influenced by childhood trauma, alcohol addiction and ageing.
Discover all previous articles on memory here.
WHAT ARE DISSOCIATIVE DISORDERS?
Dissociative disorders are a state of psychological distance from typically traumatic ongoing or past events. Dissociative Experience is the experience of a traumatic event as if outside of ones body, e.g. “This isn’t happening”, “This is all a dream”.
Extreme forms of dissociation:
- Dissociative fugue
- Dissociative amnesia
- Dissociative Identity Disorder (DID)
- Cause: psychologically traumatic experience
- Symptoms: Inability to recall period of life or entire past including identity. Semantic and procedural memory intact
- Distinct from retrograde amnesia as unable to remember identity
- Duration: Typically lasts <1 week
- Recovery: Occurs after shock from trauma subsides.
- Outwardly appears normal, but has extensive amnesia and identity confusion.
- Travels away from home; adopts new identity
- Extended, current form of Dissociative Amnesia
- Cause: Severe stress or psychological trauma
- Duration: days, months, (extreme cases) years.
- Recovery: No physical trauma. Requires psychological recovery from trauma.
* A bonk on the head does not help (whatever Hollywood may claim!)
DISSOCIATIVE IDENTITY DISORDER (DID)
- Previously, Multiple Personality Disorder (MPD)
- Sufferer acts as if 2 or more personalities inhabit same body
- May be of different, age, gender, sexuality, have different habits, tastes, knowledge, memory, etc.
- Sufferers often experience traumatic abuse as child, often sexual
- Extreme and rare and controversial form of dissociation
- <1975 = 200 cases reported
- Now = thousands
- Increase may be due to media exposure of DID, diagnostic fad, suggestive therapy
Dissociative Disorders are controversial and generally psychological in nature (not neurological – may co-occur with retrograde amnesia). Typically dissociative disorders are diagnosed and treated by therapist. Although as it can be seen in False Memory, therapy can be unintentionally suggestive. A large number of individuals are susceptibility to dissociation, which may correlate with susceptibility to hypnosis (Bliss, 1980).
Children adept at self-hypnosis may develop dissociation as a strategy of dealing with trauma.
Excessive drinking can lead to a black out; consciousness without memory. Due to a failure to consolidate memories during the black out. By product, memories shortly before black out are remembered better than normal. There is a lack of consolidation; lack of new memories interfering with the old ones.
- Cause: alcohol abuse and malnutrition
- Mechanism: Thiamine (vitamin B1) deficiency blocking formation of new memories
- Symptoms: Short-term memory may be normal, but cannot form new memories
- anterograde and retrograde amnesia
- Other neurological problems: loss of executive control, feeling in fingers and toes, etc
- Location: Damage to frontal lobes, forebrain, Hippocampus and Amygdala
- Recovery: None but thiamine treatment may help
ALZHEIMER’S DISEASE (AD)
Alzheimer’s disease is associated with a gradually progressive loss of memory and executive function often occurring in old age.
- Early signs = anterograde memory
- Degeneration =confusion, irritability, aggression, mood swings, language, retrograde amnesia, general withdrawl as senses decline
- Terminal: mean life expectancy from diagnosis 7 years
Due to increasing life-span, prevalence is increasing, by 2020, 1 in 85 people predicted to have Alzheimer’s disease.
- Neurophysiological = plaques and neuro-fibrillary tangles throughout brain
- Neurochemical = loss of acetylcholine, a neurotransmitter in the limbic system
- Acetycholine is produced by the basal forebrain
- Required for consolidation of memories
Currently there is no chemical or therapeutic treatment to halt or reverse degeneration. Most treatments deal with symptoms such as aggression and confusion. Given the rapidly increasing prevalence, treatment of Alzheimer’s disease and other age related degenerations is a major priority.