Download Alzheimer`s Disease

Memory Impairments: Alzheimer's Disease
______________________________________
1) Discuss some basic issues regarding Alzheimer's
Disease (AD) including incidence, symptoms,
diagnoses and causes.
2) Examine the particular memory deficits found in
 Episodic memory
 Autobiographical memory
 Semantic Memory
 Implicit Memory
 Procedural Memory
3) Discuss attempts to ameliorate the memory
differences observed in AD.
Alzheimer's Disease – The basics
______________________________________
Incidence:
15% of people over 65; 45% of people over 85
And the country is getting older
Time course:
 Early Stage
o Minor memory problems
EX: Word-finding problems (Lindy)
o Mild disorientation / confusion
 Middle Stage
o Slowly develop more pronounced, very
broad memory difficulties
o Disorientation / confusion
o Day-to-day variability
o Depression
EX: Driving Sydney
 End stage
Alzheimer's Disease – Diagnoses / Causes
______________________________________
Diagonsis:
Via autopsy
 neuritic plaques

 neurofibrillary tangles

 Located throughout brain

 Reduced brain weight

Reduced metabolic activity
Causes:
Unknown
 genes, smoking, education, head injuries
Difficulties:
Distinguishing dementia from amnesia:
1) IQ
2) Orientation
3) Confabulation
4) Semantic memory
Measurement - MMSE
Deficits in AD – Episodic Memory
______________________________________
Declarative memory
Deficits across the board
EX:
SP effects remain intact
Delay is the key:
Q: What brain structure does this implicate?
Recognition deficits are less than recall deficits
Q: What does that imply about the cause?
Encoding? Storage? Retrieval?
Autobiographical memory
 Same distribution as healthy adults, but
 Temporal gradient
EX: Sydney's recollection of my family
No consensus in the literature.
Encoding? Storage? Retrieval?
Fromholt & Larsen (1991)
___________________________________________
# of Memories
# of memories
30
25
20
Healthy
15
AD
10
5
0
0
20
40
60
80
Age at Event
% of memories
% of meomries
30
25
20
Healthy
15
AD
10
5
0
0
20
40
Age at Event
60
80
Deficits in AD – Semantic Memory
______________________________________
Huge deficits
 Used to stage the disease
EX:
 Better with pictures than definitions
 No LOP effect
________________________________________
Encoding? Storage? Retrieval?
Consistency – if a subject fails to identify a picture of
a common object, s/he will be unlikely to respond
correctly when given the definition.
EX:
Problems with consistency:
 Retrieval failures can produce 'consistent'
behavior
EX:
Identifying the Cause of Semantic Memory
Deficits in AD: Rohrer, et al. (1999)
______________________________________
Theoretical Question: Do semantic memory deficits
in AD result from the loss of stored information,
or from impaired retrieval?
Empirical Question: Will AD patients' produce
relatively fast RTs on a verbal fluency task?
Previous work suggesting storage problems:
 Subcategory cues do not aid category fluency
 Fewer specific examples
 Category fluency worse than letter fluency
o Different patterns from HD
Previous work suggesting retrieval problems:
 Normal semantic priming
 Sentence completion RT correlated with
difficulty
 Some show no differences in deficits on
category vs. letter fluency
Key piece of data: RT is directly related to the size of
the category: more members====>slower RTs.
EX: College / grad school admission
Rohrer, et al. (1999)
______________________________________
Results:
Both patient groups produced fewer items
AD
than age-matched controls
HD
than age-matched controls
Interpretation:
 AD patients
 Therefore, dementia patients suffer
Points to ponder:
Do these data unambiguously prove that Rohrer
et al.'s interpretation is correct?
 Age differences b/t patient populations
and corresponding control groups
 late papers
Rohrer et al.’s (1999) data
______________________________________
Deficits in AD – Procedural Memory
______________________________________
AD patients can still do many everyday tasks:
EX: folding laundry (highly idiosyncratic)
Also learn standard laboratory tasks at roughly the
same rate (when difficulty is controlled)
 pursuit tasks
 implicit sequence learning
Motor-encoding enhances explicit memory
Pick up the cup
Subsequent memory is better for performed
actions relative to imagined actions or read
statements.
Deficits in AD – Memory Interventions
______________________________________
Things that seem to help
 Imagery
EX:
 Self-reference / generation
EX:
 Personal items
EX:
 Errorless learning
EX:
 Music
EX: Schulkind and Cespedes (2002)
Fischer, Sananbenesi, Wang, Dobbin, & Tsai (2007)
___________________________________________
Question: Neuron death is a problem: can we reverse
neuron death and in so doing, restore previously
learned information?
Multiple experiments:
1. Establish that drugs cause neurodegeneration
a. How did they do that?
2. Establish that neurodegeneration interferes with
memory
a. How did they do that?
3. What was the cause of the memory loss?
a. Storage (loss of neurons)
b. Retrieval (loss of synaptic connections)
4. How did they examine this question
a. Introduced EE
5. Why was EE effective?
a. Restored synapses in ACC
b. How?
i. Modifies genes to promote plasticity
ii. But can’t rule out additional neurons
Killam, Cautin, & Santucci (2005)
___________________________________________
Experimental question: Are college athletes with a
history of concussions impaired relative athletes with
no history and/or non-athletes?
“Tissue deforming collisions with the internal wall
of the skull”
Multiple injuries associated with:
 Significant mental impairment
 Depression
 Stress management
Precautions
 Self-diagnosis
 Objective diagnosis
 Objective diagnosis under stress
 However, participation may be enough
Method:
 DIII athletes in contact (??) sports
 Matched for: gender, ethnicity, year, GPA,
 Concussion index scores (# x severity)
 RBANS, post-concussion checklist, Stroop
Killam, et al. (2005): Results and Discussion
___________________________________________
Results:
 Group Differences (Fisher’s LSD):
o Athletes – concussed or not were – were
o No differences on
o No differences in
 Correlations – concussive symptoms were:
o Predicted attention and delayed memory
o Recovery in non-recent concussed group
o Processing speed on Stroop
Discussion
 Immediate memory is
 Non-concussed athletes < controls
o GPAs were equivalent (??)
o Sub-clinical damage (??)
 Self-assessment
 More rest