Amnestic disorders

Psychological Medicine - undergraduate lecture 2010

1. AMNESTIC DISORDERS
Dr Zahiruddin Othman
2010

2. ICD-10: Organic Mental Disorder
F00 Dementia in Alzheimer disease
F01 Vascular dementia
F02 Dementia in other diseases classified elsewhere
F03 Unspecified dementia
F04 Organic amnesic syndrome, not induced by
alcohol and other psychoactive substances
F05 Delirium, not induced by alcohol and other
psychoactive substances
F06 Other mental disorders due to brain damage and
dysfunction and physical disease
F07 Personality and behavioral disorders due to brain
disease, damage and dysfunction
F08 Unspecified organic or symptomatic disorder

3. DSM-IV: Cognitive Disorders
DELIRIUM
Delirium due to a GMC
DEMENTIA
AMNESTIC DISORDER
294.0 Amnestic disorder due to a GMC
294.8 Amnestic disorder NOS
OTHER COGNITIVE DISORDERS

4. Cognitive change
Impaired
Consciousness
or
Attention
Acute onset
Fluctuating course
Organic cause
Language
Orientation
Perception
Aphasia
Agnosia
Apraxia
Executive def.
AMNESTIC DISORDER DEMENTIA DELIRIUM
Cognitive deficits
Amnesia Amnesia Amnesia
Organic cause Organic cause

5. Memory Disturbances
CLINICAL
Time / onset
DISORDER
cause
AMNESIA
loss of memory
AMNESTIC (organic)
DISSOCIATIVE (psychogenic)
anterograde
retrograde
PARAMNESIA
error of memory
CONFABULATION
Unconscious filling
up gaps in memory
DEJA VU
“already seen” in
French

6. Organic Amnesic Syndrome

7. HM’s lesion:
bilateral medial
temporal lobe
removal

8. Nondeclarative
(implicit)
Declarative
(explicit)
Long-term memory
Simple
classical
conditioning Fact Event
Procedural
(skill & habit) priming
emotional Skeletal
musculature
Nonassociative
learning
Reflex
pathways Striatum
Medial temporal lobe
Diencephalon
Neocortex Cerebellum Amygdala
Squire’s Memory Taxonomy

9. What is affected? What is impaired?
Anterograde amnesia, episodic memory:
dramatic inability to learn something new
after the onset of amnesia due to inability to
build up new episodes.
Retrograde amnesia, an inability to
retrieve information that was learned
prior to the onset of amnesia if it was
not purely semantic or implicit memory
Impaired temporal localization of
past experience, as in Korsakoff,
which leads to confabulation
Autobiographic memory also intact,
but amnesic for recent events before
onset of amnesia

10. Confabulation
•‘‘False statements that are not made to
deceive, are typically more coherent than
thoughts produced during delirium”
•It ranges from small distortions on
laboratory tasks to striking bizarre stories
that patients tell in describing their
personal histories
•Typically occurs in the context of executive
deficits such as perseveration, poor self-
monitoring, and difficulty with self-initiated
processes

11. DSM-IV Amnestic Disorders

12. Transiet Global Amnesia [TGA]
•Characterized by a dense,
transitory inability to learn new
information and a variable inability
to recall events
•Assoc. with cerebrovascular
disease and pathology in
vetebrobasilar system

13. BLACKOUTS
Blackouts are periods of amnesia for
events that occur during heavy
drinking.
Typically, a person awakens the
morning after consumption and does
not remember what happened the
night before.
Blackouts are more a measure of the
amount of alcohol consumed at any
one time.

14. Chronic Amnestic Disorders
Causes - Pathological Process
Damage to specific diencephalic and
mediotemporal lobe structures (e.g.,
mamillary bodies, hippocampus, fornix)
–head trauma
–surgical intervention
–infarction of the distribution of PCA
–hypoxia
–herpes simplex encephalitis

15. •“Persisting” means the memory
disturbances persists long after the
effects of substance intoxication or
withdrawal have ended
•CNS depressants
–Alcohol, sedatives, hypnotics, anxiolytics,
anticonvulsants
•Toxin: lead, mercury, intratheceal
methotrexate, organophosphate
insecticides, and industrial solvents
Substance-Induced Persisting
Amnestic Disorder

16. WERNICKE-KORSAKOFF
SYNDROME [WKS]
Acute WKS: Mammillary body Acute WKS: Mammillary body
hemorrhageshemorrhages
Old WKS: mammillary body Old WKS: mammillary body
atrophyatrophy
Seen in
Alcoholics
Gastric cancer
Hyperemesis gravidarum

17. Treatment
•The primary goal in the amnestic disorders
is to discover and treat the underlying
cause.
•Some of these causes of amnestic disorder
are associated with dangerous self-
damaging behavior
–e.g., suicide attempts by hanging, carbon
monoxide poisoning, deliberate motor vehicle
accidents, self-inflicted gunshot wounds to the
head and chronic alcohol abuse