Normal Aging and Cognition Linas A' Bieliauskas, Ph'D'

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Normal Aging and CognitionLinas A. Bieliauskas,
Ph.D.

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Psychology Service VA Ann Arbor Healthcare
System
Department of Psychiatry Medical
School Department of Psychology School of
Literature, Science and the Arts The University
of Michigan
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Util, ANC, 2006, 141-172

• Prospective Memory Proper (required for episodic,
  one-time tasks such as buying groceries when
  going home
• Declines with age and related to declines in
  visual acuity and hearing level, working memory,
  intelligence.

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• Each neuron in the brain becomes exposed to the
  cumulative effects of biological wear and tear
  over the life span
• Studies of normal aging may be contaminated by
  pre-clinical dementing individuals
• The aging human brain may have a considerable
  potential for plasticity
• Breakdown in plasticity may be key to
  pathogenesis of Alzheimer disease

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Changes in the Brain

• Decreasing volume of cerebral hemispheres (0.55
  per year)
• Increasing volume of ventricles (3 per year)
• Increasing odds of cortical atrophy and
  ventricular enlargement (9 per year
• 90 year olds have almost 10 fewer neurons than
  20 year olds

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Specific Areas

• Prefrontal cortex with increased perseveration
• Visual processing areas with decreased
  performance on nonverbal working memory tasks
• Limbic structures with decline in explicit
  memory.
• Brain weight also decreases

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Memory and Aging

• More difficulty in rapidly forming associations
• Recall is more affected than registration

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Implicit vs. Explicit Learning

• Implicit refers to learning without knowing its
  basis (eg. Amnestic patients perform task better
  over time, though dont remember performing it).
• Implicit memory better preserved than explicit
  with aging.

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RecallltRecognition

• Thus, age-related decline in retrieval.
• Recall requires greater processing capacity, with
  age leading to limitations in processing
  capacity.
• Recall also provides no context i.e., difference
  between essay and multiple-choice exams.
• Recall also may be poorer due to decreased
  ability to screen out irrelevant information.

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More Recent Evidence

• Free recall, yes-no recognition, and
  forced-choice recognition all sensitive to age
  effects, but free-recall is most sensitive.
• Parker et al., JCEN, 2004, 428-440.
• Fastenau, P. S., Denburg, N. L., Abeles, N.
  (2003). In J. A. Knight E. F. Kaplan (Eds.),
  Handbook of Rey-Osterrieth Complex Figure Usage
  Clinical and Research Applications (pp. 335
  347). Odessa, FL Psychological Assessment
  Resources.

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Kemps Newson, JCEN, 2006, 28, 341-356.

• Reported norms for parallel forms of verbal and
  visuospatial stimuli for recall and recognition
• Recall declines more than recognition
• Recall shows a steeper decline after the age of 85

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Rate of Forgetting Does not Increase with Aging

• Fjell et al., 2005, JINS.
• Recognition/recall immediately, 20-30 min. later,
  and 75 days later, not at a greater rate in older
  vs. younger adults.
• Acquisition lower, however, due to false alarms
  and other memory measures were related to age.

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Fan Effect

• Subject required to distinguish between pairs of
  stimuli presented before, and foils with
  irrelevant pairs of these stimuli.
• E.G. The policeman drove home the butcher bought
  groceries
• Foil The policeman bought groceries.
• Deterioration in accuracy of memories, the more
  facts that are included.
• Separating targets fro distractions becomes more
  difficult with age.
  

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Memory Processing

• Automatic Processing encoding of information
  that requires little effort
• Effortful Processing requires designation of
  attentional capacity for encoding.
• Effortful processing may be more affected by
  aging.

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Memory Type

• Source memory is particularly vulnerable to
  effects of aging (Spencer Raz, 1955, Psych.
  Aging, 527-539)
• Memory for contexts or attributes
• Hippocampus implicated as well as frontal lobes

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But..

• Flashbulb memories (e.g., 911, assasinations,
  etc.) do not seem to be affected by age.
• Davidson et al., ANC, 2006, 196-206.

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Attention

• Divided Attention declines in the elderly
• Supports the Fan Effect
• Selective attention, i.e., the ability to
  disregard irrelevant stimuli, is more susceptible
  to disruption in adults.
• Older adults are more likely to believe false
  information (Chen, 2002, ANC), though only when
  messages have low personal relevance (Hess et
  al., 2005, ANC).

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Attitude Ratings

• Older adults are more likely than younger adults
  to provide attitude ratings consistent with the
  likablness of the source.
• Selectivity of engagement of cognitive resources
  proportional to relevance to the individual less
  relevance greater age effects.
• Hess et al., 2005, ANC, 149-174.

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Dual Task Findings

• Holtzer, Stern, Rakitin (NP, 2005, 18-27)
• NP tests yielded 2 factors
• Attention/Executive and Memory (age-related)
• Motor Speed and Cognitive Status
• Memory and Motor Speed strongest predictors of
  single-task performance (Delayed Visual
  Recognition task)
• Attention/Executive factor best predictor of
  dual-task performance
• Compromised Central Executive may underlie
  age-related decline in dual task performance

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Working Memory Decline

• Hartman et al., 2004, JCEN
• Older adults had global reductions in ability to
  identify concepts on a sorting task in all
  modalities.
• Related not to selective attention or
  interference, but to reduced working memory
  contributions from aging.
• Also increased perseverative responses

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Attentional Switching

• Declines in the very old, and in Alzheimer
  disease
• Specifically, there is a decline in the ability
  to disengage.
• Interacts with visual difficulties to
  particularly affect tasks such as driving.

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Effortful vs. Automatic Processing

• Familiar, commonly used skills need little
  attentional capacity
• Tasks requiring one to deal with more complex or
  usual stimuli are more taxing and require greater
  attentional capacity
• Effortful tasks are more affected in the elderly

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Differential with dementia

• However, when dual tasks are processed, (finger
  tapping speech) patients with DAT perform worse
  than normal elderly controls if the tasks are
  effortful, but perform equally when the tasks are
  automatized.
• Crossley, Hiscock, Foreman, JCEN, 2004, 332-346.

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Visuospatial Attention

• Eye movements (saccades) 200 ms to move ones
  eyes clearly impaired in DAT
• Shifts of Attention (visual search) patients
  with DAT get stuck
• Spatial scale of Attention (7-8 degrees of visual
  angle around fixation point patients with DAT
  show reduced effects of cue size on targets,
  i.e., scaling of spatial attention is impaired.

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Summary of Cognitive and Neural Changes with Aging

• Cerebral aging integration of brain
• and behavioral models of cognitive function
• Denise C. Park, PhDThad A. Polk, PhD Joseph A.
  Mikels, MS
• Stephan F.Taylor, MD Christy Marshuetz, PhD
• Dialogues in Clinical Neuroscience - Vol 3 . No.
  3 . 2001

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Freedom House Study Royall et al., JINS, 2005,
899-909.

• 547 70 and 80 year olds studied over 3 years
• Most measures showed significant rates of change
  over time
• Executive Interview and Trailmaking Test closely
  related to decline in IADLs
• Nonverbal measures best suidted to prediction of
  age-related functional decline

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The Frontal Aging Hypothesis

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Nitin Gogtay et al.

• Proceedings of the National Academy of Sciences
  of the USA, 101(21)8174-8179, May 25 2004
• http//www.loni.ucla.edu/thompson/DEVEL/dynamic.h
  tml

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Frontal Functions

• Reasoning, as measured by analogies, declines
  with age
• Tests related to frontal lobe functioning decline
  with age
• Retrieval declines more than recognition

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• Suggestion that prefrontal cortex leads most in
  the aging process
• Though aging effects can be more widely
  distributed in the brain, tasks loaded on
  executive function appear to be more affected.
• Left lateral prefrontal cortex activated in
  younger adults on conflictual tasks may mediate.
  Older adults show more conflictual response than
  younger, but do not activate.

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Humor

• Uekermann, Channon, Daum JINS, 2006, 12,
  184-191.
• Older group selects fewer correct punchlines and
  poorer at mentalistic questions
• Older group not poorer at nonmentalistic questions

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3. What did Martin think when the visitor said
Yeah, Ive come to connect up your telephone?
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Mental Flexibility

• Wecker et al., NP, 2005, 345-352.
• Verbal and nonverbal cognitive switching between
  response sets (Delis tasks)
• Significant age effects when gender, ed., IQ,
  component skills are partialed out.
• Executive functions/cognitive switching are
  affected by age independently from age-related
  changes in component skills.

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Executive Decline Hypothesis

• Prefrontal Cortex Function Theory PFC is the
  area of the brain most sensitive to aging (West,
  Psyc. Bull., 1996, 272-292.
• Executive Function strongly linked to recall and
  recognition measures and and age (Ferrer-Caja,
  Crawford, Bryan ANC, 2002, 231-249.

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General Processing Resources

• Salthouse proposes that age-related differences
  on speed of processing, divided attention, and
  working memory capacity are relatively
  equivalent.
• Decreased speed of information processing may be
  the underlying change responsible for multiple
  changes.

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Reduced Processing Resources

• Statistical Argument used via structural
  equation modeling
• Processing speed viewed as fundamental component
  of the architecture of human cognition.
• Performance degraded when processing slows
  because relevant operations cannot be
  successfully executed and because products of
  earlier processing may not be available.

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But

• Statistical Argument Only
• Reaction time slows by about 20 between age 20
  and 60, or about 2 msec. per decade between age
  18 and 93 women more variable than men Deary
  Der, 2005, ANC).
• The same could be said for graying of the hair

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And.

• Inferences based on cross-sectional data up to
  71 shared variance inferred
• Longitudinal data shows far less shared variance
  between memory changes and changes in processing
  speed
• Hultsch et. al. Memory Changes in Aging, 1998
• Lemke Zimprich only 37 common variance (ANC,
  2005, 57-77)

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Slowing also related to degree of working memory
involvement

• Verhaeghen, Cerella, Basak 2006, ANC, 254-280.
• Measured processing efficiency of older vs.
  younger adults
• Age related slowing least for low-complexity
  verbal tasks, more for verbal multiplicative
  tasks and visuospatial low complexity, and
  greatest for high multiplicative visuo-spatial
  processing tasks.

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Greater Complexity to Visuospatial Tasks
Supported?

• Greater decline for visuospatial tasks in the
  elderly
• Slowing shows greater interaction with complex
  visuospatial tasks

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Some Overall Conclusions

• Sensory changes with time
• Memory affected, recall more than recognition
• Visuospatial processing declines
• Analogy-like reasoning and executive functioning
  decline
• Divided and selective attention decline

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Evidence from Neuroimaging

• The Harold Model Hemispheric Asymmetry
  Reduction in Older Adults
• Brain activity during cognitive performance is
  less lateralized in older vs. younger adults.
• Bilateral activity may reflect network as well as
  regional changes, and may reflect compensatory as
  well as dedifferentiated processes

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In General, Greater Areas of Activation in Older
Adults

• Even for a simple motor task (a visually paced
  button pressing task)
• Elderly subjects recruit additional cortical and
  subcortical areas (contralateral and ipsilateral
  sensorimotor cortex, lateral premotor area,
  supplementary motor area, ipsilateral and
  contralateral cerebellum, and putamen.
• Mattay et al., Neurology, 2002 630-635.

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• Large areas of frontal cortex are recruited for
  compensation on letter-matching tasks
  (Reuter-Lorenz et al., Psychol. Sci., 1999,
  494-500).
• Working memory tasks, lateralized in younger
  adults, are bilateral in older adults
• However, there is a decline in chemical
  correlation between brain regions with advancing
  age potential for decreased inhibition i.e.
  decreased efficiency in frontal lobes.

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Meaning

• Compensatory or adaptive?
• Strategy differences or functional differences?
• What do young adults do with these areas?

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Three Possible Interpretations

• Compensatory recruiting extra brain areas
  supported by Reuter-Lorenz
• Loss of inhibition
• Dedifferentiation -gt
  

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Frontal Cortex Has Different Circuits
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Anerior Cingulate Syndrome

• Apathy

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Orbitofrontal Syndrome

• Personality change, behavioral disinhibition,
  emotional lability
• Irritability and potential aggressive outbursts
• Inappropriate response to social cues and
  interkpersonally insensitive
• Lacking in empathy and judgment
• Bilateral -gtutilization behavior
• Normal Card Sorting