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Impairments in Dementia

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Title: Impairments in Dementia


1
Impairments in Dementia
  • Lorna Bourke

2
Definition
  • 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.

3
Detection 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

4
Limitations 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.

5
Self-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

6
Informant-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

7
Characteristics 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

8
What 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

9
Cortical 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

10
Alzheimers 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)

11
Alzheimers 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?

12
Alzheimers 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
13
Alzheimers 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).

14
Phonological 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

15
Working 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)

16
Working 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

17
Inhibition, 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)

18
Conclusions
  • 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
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