Title: Impairments in Dementia
1Impairments in Dementia
2Definition
- Dementia Impairment in 2 or more cognitive
domains sufficient to interfere with activities
of daily living - Impairment Decline in cognitive function from
previously attained levels - Dementia diagnoses requires cognitive decline for
that individual principle of intra-individual
change.
3Detection of Dementia
- Intra-individual cognitive change
- Serial cognitive testing (prospective) or
- Informant (use patient as own control)
- Interference with daily activities
- Informant (use patient as own control)
- Inter-individual comparison
- Cognitive test-performance in comparison to
age-matched and education-matched norms - May not reflect either cognitive change or
functional impairment
4Limitations of cognitive tests
- Demography affects performance
- Poorer with
- Increasing age
- Less education
- Female sex
- Rural residency
- Lower occupational level
- Minority status
- Cultural, ethnic, and linguistic variables
- Cultural biases
- Measures developed and standardised on white
population - Non-demented elderly
- 22 of non-white and
- 11 of white sample met neuropsychological
criteria for impairment sufficient for dementia.
5Self-reported cognitive function
- Memory complaints are common (44 of normal
elderly) but are often unrelated to disease - Self-reported cognitive normality or impairment
is unreliable - Does not correlate with psycho-metric performance
- Does not predict future onset of dementia
- In contrast informant reports are reliable of
current cognitive status, and in non-demented
elderly predict development of dementia
6Informant-based assessment of dementia
- Advantages
- Face valid (relevant to everyday cognitive
function) - Longitudinal perspective (assess change)
- Cultural fairness (not confounded by demography)
- Absence of ceiling and floor effects
- Absence of practice effects
- Accurate, sensitive to even mild dementia
- Disadvantages
- Informant reliability
- Time
7Characteristics of informants
- Relationship to participant
- ARDC
- 47 Spouse
- 38 Adult child
- 15 Other relative, friend, health professional
- Community 225 randomly sampled older AA, 93 had
informants - 17 Spouse
- 24 Adult child
- 21 Other relative
- 37 Friend
- Frequency of contact
- Living with participant/see frequently most
accurate - With less exposure, informants underestimate
level of impairment
8What conditions result in dementia
- Alzheimers Disease (50 of all cases)
- Gradual change in the neurons or nerve cells in
the brain as well as neurotransmitters - Vascular Dementia (next most common form)
- Repeated damage to areas of the brain caused by
blockages in the blood cells (small strokes) (aka
hardening of the arteries) - Parkinsons Disease
- AIDS
- TB
- Huntingtons Disease
- MS
- Fungal infections
9Cortical and sub-cortical dementia
- Cortical dementia
- Problems with memory, thinking and language
- Alzheimers Disease
- aphasia, apraxia, amnesia, agnosia
- difficulty finding words
- difficulty comprehending written or spoken
material - speech is normal but language is impaired
- inability to learn new information
- lack of insight
- motor functioning normal at least in the early
stages - Sub-cortical dementia (affects parts of the brain
below the cortex) - Characterised by slowing, difficulty in
retrieving information from memory and altered
mood - Parkinsons Disease and MS
- language ability usually normal but speech is
impaired - difficulty with retrieving information that is
learned - insight usually present
- mood apathetic or depressed
- Medicine
- No medical cure for most dementias
10Alzheimers Disease
- Belleville, Peretz Malenfant (1996)
- Theoretical understanding of the nature of memory
impairment - Distinction from normal aging
- Diagnosis is usually only confirmed by post
mortem - Diagnosis whilst alive is complicated by the fact
that deficits coincide with normal aging (mostly
memory deficits) - Distinction normally based on severity (i.e.
extreme version of normal deterioration)
11Alzheimers Disease
- Memory decline
- Spatial memory
- Disorientation a few feet from home
- Semantic long-term memory
- Forgetting of familiar names of people and
objects - Working memory
- Phonological memory and executive functioning
- Difficulty in following the thread of a
conversation - Impaired sentence comprehension (Waters Caplan,
1994) - Loss of linguistic knowledge or compromised WM?
- Can they be independently damaged?
12Alzheimers Disease and Working Memory
Working Memory ModelBaddeley and Hitch (1974,
1983, 1986)
Central Executive
Episodic Buffer
Visuo-Spatial Sketchpad
Phonological Loop
Visual Episodic
Language Semantics
LTM
Baddeley (2000) reports the addition of an
additional component Episodic Buffer
13Alzheimers Disease and Working Memory
- Compared to aged matched controls
- Decrease in digit span (capacity to store verbal
information) (Spinnler, Della Sala, Bandera
Baddeley,1988) - Lower performance on Brown-Peterson procedure
(Sullivan, Corking Growden, 1986) - Attributed to poorer availability of attention
component of WM (CE) (Baddeley, Logie, Bressi,
Della Sala Spinnler, 1991).
14Phonological WM and Alzheimers Disease
- Morris (1984)
- Normal phonological similarity and word length
effects - Therefore, Phonological WM deficit may occur from
deficits in Central Executive functioning - Baddeley, Logie, Bressi, Della Sala Spinnler
(1986) - Decrement in performance on divided attention
task
15Working memory and Alzheimers Disease
- Belleville et al (1996)
- Hypotheses
- Qualitatively and quantitatively different
pattern of WM impairment from normal aged-matched
controls and young patients - Results
- AD poorer performance in Brown-Peterson task (CE)
- AD poorer performance in Phonological WM (digit
span) - Conclusions
- Differences in CE functioning supports previous
research - But multiple deficits in WM found
- Why discrepancy in results
- Other samples less severe (CE first to become
impaired) - Differences in dependent variables used
- Peterson-Brown technique is not a pure measure
of CE (has phonological storage element)
16Working memory, language comprehension and
Alzheimers Disease
- MacDonald, Almor, Henderson, Kempler Andersen
(2001) - Reading span task (Daneman Carpenter, 1980)
- Not sensitive enough to measure cognitive and
linguistic performance complex dual task
paradigm - Digit span task (Baddeley, 1986)
- Simple instructions
- Valuable predictor of performance on the
comprehension of grammatical, semantic and
discourse relations - Conclusions
- Phonological WM not the resource that enables
language processing (biological and experiential
factors) - Correlations between the two common task
demands - AD patients impaired in language comprehension
and digit span tasks - Consistent with the connectionist approach to
language processing
17Inhibition, working memory and Alzheimers Disease
- Borgo, Giovannini, Moro, Semenza, Arcicasa
Zaramella (2003) - So far,
- CE and Phonological Memory
- Disentangling CE from Phonological Memory
- Maintenance of active verbal information PL
- Inhibition of interfering information CE
- Frontal Lobe Patients (Owen, Morris, Shakian,
Polkey Robbins(1996) - Impairment in complex spatial memory tasks
- Generalised deficit in WM processing not apparent
- Memory and executive functioning play dissociable
roles - Compared Frontal Lobe Patients to AD Patients
- No clear dissociation found
- Uneven no of participants (parametric tests could
not be used)
18Conclusions
- Dementia
- Differential patterns of association between WM
and different types of dementia. - Inconsistency in measures and results between
studies - Importance of neuropsychological data
- Importance of research conducted by psychologists