Psyco 350 Lec #22– Slide 1
Lecture 22 – Psyco 350, B1Winter, 2011
N. R. Brown
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Outline• Memory Issues in PTSD
• Background• Dual-representation Theory (& Data)
Holmes, Brewin, & Hennessy, 2003• The Mnemonic Model (& Data)
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Post-traumatic Stress Disorder:Background
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DSM-IV Criterion A The person has been exposed to a traumatic event in
which both of the following have been present:
(1 – The Event) The person experienced, witnessed, or was confronted with an event or events that involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others
(2 – Peritraumatic Reaction) the person's response involved intense fear, helplessness, or horror.
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DSM-IV Criteria B-FB. reexperiencing of the traumatic event C. avoidance of stimuli associated w/ trauma and
numbing of general responsivenessD. increased arousal E. symptoms present for more than 1 monthF. clinically significant impairment in social,
occupational, or other important areas of functioning
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Dual- Representation Theory (DRT)
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DRT: Holmes, Brewin, & Hennesy (2004)
Two type of event information1. Verbally Accessible Memory (VAM)
“ordinary autobiographical memory”requires “high-level of conscious processing”
2. Situationally Accessible Memory (SAM)“stores sensory information, mostly… in the form of visual images”
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DRT: SAM on Its OwnSAM Retrieval:
triggered by exposure to “relevant” cues accessed automatically
Reaction to SAM:re-experience eventemotion-laden flashbacksstrong affective response
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DRT: Further AssumptionsVAM blocks SAM:
controls & contextualizes SAM-based responses
WM-systems & the creation SAMs & VAMS:Verbal WM required for VAMsVisuo-spatial WM required for SAMs
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DRT: ImplicationsCreation of PTSD-evoking representations:
Dissociative reactions to traumatic event knocks-out WM capacity necessary for VAM creation
SAM encoded regardless VAM-less SAMs PTSD symptoms
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Testing DRT w/ Dual Task DesignGeneral Paradigm:
Watch horrific film while engaged in either:(a) spatial task (b) verbal task
General Predictions:spatial task knock out SAM reduce PTSD symptomsverbal task knock out VAM increase PTSD symptoms.
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The Experiment(s)Participants:
Healthy, young adults 20/group
Materials:12.5 min film – actual traffic accidents
Instructions:Watch film for later memory test
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The Experiment(s)Concurrent Tasks (between-subjects):
Control – no concurrent taskVisual-spatial inference – tap out a preseficed pattern on buttonsVerbal-interference – count backwards by 3s
Main DV:# of intrusive memories recalled in 7-day diary
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The Experiment(s)Expectation:
Counting interferes w/ VAM creationTapping interferes w/ SAM creation
Prediction:# intrusive memories:counting > control > interference
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Results: # of Intrusions
Control Tapping
# of
Intru
sion
s
0
1
2
3
4
5
6
7
8
9
10 Exp. 2As predicated:• tapping <
control
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Results: # of Intrusions
Control Tapping
# of
Intru
sion
s
0
1
2
3
4
5
6
7
8
9
10
Control Counting
Exp. 2 Exp. 3As predicated:• tapping <
control• counting >
control
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DRT: DiscussionDRT correctly predictions intrusion patterns.But:• Are these data PTSD-relevant?• If so,
– How do VAM-less SAMs create PTSD?– How do VAMs inhibit SAM-trigged responses?– PTSD in non-humans?
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The Mnemonic “Model”
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A Memory-based Model of Post-traumatic Stress Disorder: Evaluating Basic Assumptions Underlying PTSD Diagnosis
A telling and misleading title.
Rubin, Berntsen, & Klindt-Johansen. (2009) Psychological Review
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The “Models”
DSM ModelProximal Event: A1 event & A2 reaction
Response: Symptoms
Mnemonic Model
Proximal Event: A1 event & A2 reaction
Response: Symptoms
Memory for A1& A2
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“most direct evidence for ... memory ...as a causal agent is that observation that eliminating or enhancing memory in various ways changes PTSD symptom severity”
Support for Mnemonic Position
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Amnesia reduces or eliminates PTSD • Organic amnesia – traumatic brain injury • Pharmacologically-induced amnesia
– Propranolol treatment reduced PTSD symptoms in emergency room patients (Pitman et al, 2002)
• Childhood Amnesia– Before 3: No PTSD– 3-to-7: PTSD symptoms increase w/ age– After 7: PTSD unrelated to age
Memory & PTSD
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PTSD symptoms , as availability of traumatic memory
• Method: correlate Centrality of Event Scale (CES; B&R, 2006, 2007) w/ PTSD symptom.– CES measures importance of traumatic event:
• To personal identity• As a turning point • As a reference point
• Results: r’s ranging from .35 to .51
Memory & PTSD
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• Is the DSM “model” a strawman?• What is required to make the mnemonic
“model” a model?• Does anyone ever consider the material
consequences of traumatic events and their relation to PTSD?
Questions