Impairments in Dementia

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Impairments in Dementia

• Lorna Bourke

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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.

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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

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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.

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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

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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

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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

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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

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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

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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)

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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?

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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
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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).

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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

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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)

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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

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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)

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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