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Neuropsychology of Ageing > Lecture 3: Executive Functions and Speed > Flashcards

Lecture 3: Executive Functions and Speed Flashcards

1
Q

¨What are executive functions (EF)?

  • general agreement
  • Multiple processes for control and regulation
A
  • No single definition EF or standard tests for EF
  • General agreement: EF refers to the control of thought and regulation of behaviour
    • “EF are multifaceted control processes that regulate thought and behaviour” (Reuter-Lorenz et al., 2016, p. 246)
  • Multiple processes for control and regulation
    • Resistance to interference, inhibitory control or inhibition
    • Cognitive flexibility, task switching or task shifting
    • Monitoring, updating or memory updating
  • variety of tests attempt to assess EF processes
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2
Q

What are executive functions (EF)?

  • Important for everyday activities:
A
  • Important for everyday activities:
    • e.g. instrumental activities of daily living (IADL)
  • EF would be particularly susceptible to effect ageing
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3
Q

Age effect inhibition

  • Stroop:
  • Uttl & Graf (1997).
A

Stroop:

  • Increase incongruent color-word RTs with ageing: less efficient inhibition
  • Relatively little effect age on word and color conditions
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4
Q

Age effect inhibition

  • Haylings sentence completion (McAlister &Schmitter-Edgecombe, 2016)
A
  • The captain decided to stay with the sinking ……?
  • Young adults (M 21) > young old (M 68) = old (M 79)
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5
Q

Executive functions and speed

  • Age effect task switching
    • TMT - Trials B (McAlister &Schmitter-Edgecombe, 2016)
    • Young adults = Young old = Old old

Number – letter task

A
  • Young adults > young old = Old old
    • meaning young aadults are better than young olds, young olds perform similar to old olds
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6
Q

Executive functions and speed

  • CANTAB spatial working memory task (Robbins et al. 1998)
    • Open box by touching screen
    • Collect blue tokens hidden in boxes
    • Token never hidden in same box twice (keep spatial positions in WM)
A
  • Age effect working memory (Robbins et al. 1998)
  • More errors (open box where token had already been found) with increasing age.
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7
Q

Age effect working memory

  • Reading span (McAlister &Schmitter-Edgecombe, 2016)
    • Remember last word of 6 sentences read aloud
A

Reading span

  • Young adult > young old > old old (the younger the better)
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8
Q
  • Meta-analysis executive function and ageing studies (Verhaeghen, 2011)
A
  • Poorer performance older adults on wide range EF tasks
    • Larger difference young-old on EF conditions than on control conditions
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9
Q

Longitudinal studies:

  • Follow-up EF Baltimore Longitudinal Study of Aging (Goh, An & Resnick, 2012)
    • 148 participants, 56-86 years at first assessment, follow-up for up to 14 years
A
  • Inhibition: perseverations on fluency task.
  • Switching: TMT
  • Decline EF with age, but inter-individual variation
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10
Q

Executive functions (EF)

  • Important for everyday activities:
A
  • Important for everyday activities:
    • e.g. instrumental activities of daily living (IADL)
    • Trails B predicted informant-rated IADL
    • Neuropsychological EF tasks explained 19-23% measures daily functioning (McAlister &Schmitter-Edgecombe, 2016)
  • EF would be particularly susceptible to effect ageing
  • EF impairment may underlie impairments other cognitive tasks
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11
Q

Executive functions and speed

  • Stern & White (2003)
  • concept
A
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12
Q

EF theories of ageing

  • Role of EF in cognitive ageing:
  • Handbook of Psychology of Aging, Ch. 13
A

Role of EF in cognitive ageing:

  • Inhibitory deficits theory
  • Goal maintenance deficit
  • Production deficit hypothesis
  • Frontal lobe hypothesis of cognitive ageing
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13
Q

EF theories of ageing

  • Inhibitory deficits theory
A

Inhibitory deficits theory:

  • core deficit ageing: difficulties to inhibit irrelevant information or to control interference
  • Inhibition deficit affects other functions, in particular working memory
    • irrelevant material enters WM
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14
Q

EF theories of ageing

  • Goal maintenance deficit
A

Goal maintenance deficit

  • Ability to maintain task-relevant goals deteriorates with ageing
  • Affects top-down processing and regulation of behaviour
    • Proactive control: prepare attention and action systems
    • Effect memory, including prospective memory
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15
Q

EF theories of ageing

  • Production deficit hypothesis
A

Production deficit hypothesis

  • Self-initiated, effortful processing declines with ageing
  • Deficit linked to impairments in frontal lobe functions
    • affects learning and memory
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16
Q

EF theories of ageing

  • Frontal lobe hypothesis of cognitive ageing
A

Frontal lobe hypothesis of cognitive ageing

  • Reductions in frontal lobe function can explain many age-related changes in cognition
  • EF deficits, which rely on intact frontal lobes, are first signs of cognitive ageing
  • EF affected disproportionally severely by ageing
17
Q

EF theories of ageing

Executive functions first cognitive abilities to decline.

  • Longitudinal evidence:
  • ¨Baltimore Longitudinal Study of Aging (Goh, An & Resnick, 2012)
A
  • Functions that deteriorated early included:
    • Switching (TMT), inhibition (perseverations on fluency), WM, long-term memory (delayed free recall)
18
Q

Age effects EF more severe than other functions

  • Cross-sectional evidence
A

Meta-analysis executive function and ageing studies (Verhaeghen, 2011)

  • EF impaired in older adults, but not disproportionally impaired
  • age effect in EF condition did not go beyond age effect in the control condition
    • Suggests no specific EF deficit
19
Q

Age effects EF more severe than other functions

  • Conclusion based on Brinley plots:
A
20
Q

Executive functions and speed

  • Stroop task: Brinley plot
A
  • RTs old adults in color-word condition not disproportionately higher than RTs in color condition (both conditions fall on single regression line)
21
Q

Executive functions and speed

  • Trail making Task: Brinley Plot
A
  • TMT : RTs old adults in Trials B not disproportionately higher than RTs in Trial A (points from both conditions fall on a single regression line)
  • Performance older adults poorer than performance young adults with constant factor.
22
Q

EF theories of ageing:

  • EF first cognitive abilities to decline
  • impairments EF more severe than other functions
  • summary of findings:
A
  • EF impaired in older adults
  • Impairments EF do not emerge earlier than in all other cognitive functions (i.e. memory)
  • Impairments are not disproportional: effects of age on EF not more severe than effect on other functions
23
Q

EF theories of ageing

  • executive functions impairments underlie deficits in other cognitive functions in older adults
  • What is the evidence?
  • Verhaeghen (2011): best fitting model to explore effect EF on other cognitive functions (based on 119 studies). All paths are significant.
A
  • Performance EF tasks not associated with other cognitive functions (over and above the effects of speed of responding)
    • Unlikely that EF impairments underlie age-related deficits in other cognitive functions
  • WM may be exception
24
Q

EF theories of ageing

  • EF relies on intact frontal lobes
  • Frontal lobes first brain areas to deteriorate with ageing
A
  • Positive correlations: larger PFC associated with better EF performance. (Yuan & Raz (2014))
  • Pfefferbaum et al. (2013): changes in brain volume with ageing
    • Healthy adults, 20 - 85 years, followed up 1 – 8 years
  • More rapid decline volume in lateral and medial frontal cortex, than in other parts of cortex
    • In line with frontal hypothesis
25
Q

EF theories of ageing

  • In sum:
A
  • Brain changes with ageing more in line with EF/frontal lobe hypotheses than cognitive changes
  • No evidence EF deficits can account for deficits in other cognitive functions
    • WM possible exception
26
Q

Executive functions and speed

  • Speed of processing
A
  • Slower processing speed key cognitive change in ageing
  • Older adults slower to process information than young adults
    • Reflected in longer reaction time (RT)
    • Each adult year increase in RT by ±1.5 millisecond
  • Response speed becomes faster over childhood and slows down in adulthood (Bedard et al. (2002). Inhibitory control across the life span. -> Picture)
27
Q

Speed of processing

  • Age-related slowing affects wide variety of tasks and cognitive functions
A

Age-related slowing affects wide variety of tasks and cognitive functions

  • Affects cognitive efficiency by restricting speed at which cognitive processes can be executed
    • see model Verhaeghen (2011)
  • Affects accuracy - decreased quantity of information processed necessary to complete a task
    • Products earlier processing may be lost by the time later processing occurs
28
Q

Speed of processing

  • Slowing general effect that affects all functions to the same extend?

or

  • Effect ageing on speed more substantial on some tasks that on others?
A

Slowing general effect that affects all functions to same extend

  • Cerella’s linear rate model (1985): RTs older adults linear function of RTs young adults
  • Myerson’s information loss model (1990): RTs older adults described by positively accelerated power function of RTs young adults

Effect ageing on speed more substantial on some tasks that on others?

  • Salthouse’s theory of processing speed (1985): common and task-specific effects of age-related slowing in cognitive tasks
29
Q

Slowing general effect?

  • Verhaeghen (2017): results 307 studies comparing response times in young and old adults
A
  • Single dimension of general slowing can explain most variance in older adults RTs
  • Different effects ageing in different domains
  • Larger age-effects on visuospatial tasks than on language tasks
    • Larger age-effects on more higher-level visuospatial tasks - mental rotation, conjunction visual search
  • Smaller age effects in tasks without decision component
30
Q

Slowing general effect?

  • Slowing does not affect all functions to the same extend
A
  • Slowing does not affect all functions to the same extend
    • largest age-effect in visuospatial tasks
    • smaller age-effects in simple detection task and lexical tasks
  • EF tasks – slowing in baseline/control version of the task can account for the slowing in the “executive” condition.
31
Q

Age-related slowing and task difficulty

  • RTs on range of tasks from 50 studies (Verhaeghen, 2017):
  • ¨X-axis – age
  • ¨Y-axis – slowing relative to RTs of 25-year olds
  • ¨Z-axis – RTs 25-year olds for this particular task (index of task difficulty)
A
  • Slowing progressively larger with advancing age
  • Slowing increases with task difficulty (Z)
  • Fastest response times in early adulthood
32
Q

Explanations of age-related slowing

  • increased caution in older adults – higher priority on accuracy than on speed
    • evidence?
  • Disuse – older adults lack practice
  • Loss of brain connectivity
A
  • Change instructions: emphasize speed (to detriment of accuracy): older adults still slower than younger adults
  • Disuse – older adults lack practice
    • implies larger practical effect in older adults, has not been found
  • ¨Loss of brain connectivity
    • In line with faster responses early adulthood – peak of connectivity
    • Deterioration white matter integrity with ageing affects connections
33
Q

Loss of brain connectivity related to processing speed?

  • Penke et al (2010):
A
  • Penke et al (2010):
    • white matter integrity (fractional anisotropy), within 8 white matter tracts, was associated with processing speed in healthy older adults​
    • white matter integrity not associated with other cognitive tasks: memory (WMS) or intelligence (WAIS
34
Q

Processing speed may reflect health of brain (white matter integrity) or body in general

  • Link between processing speed and mortality (Shipley et al. 2006)
A
  • Link between processing speed and mortality (Shipley et al. 2006)
    • Slower RTs, higher risk of dying, from any cause.
    • Significant association RTs and mortality in both older and young adults
35
Q

Consequences of slowing

  • Slower information processing affects wide-range of tasks
A
  • Slower RTs associated with poorer performance on cognitive tasks
  • 62-93% variance in more complex cognitive tasks explained by differences in response times (Verhaeghen, 2017)
36
Q

Consequences of slowing

  • Slowing does not need to be the cause of cognitive deficits
A
  • Slowing and deficits on other cognitive tasks may result from the same underlying process
    • Speed may be a sensitive indicator of brain function (e.g. RTs and mortality)
    • Impaired brain function would affect both speed and other cognitive functions
37
Q

Speed of processing

  • In sum:
A
  • Pronounced effect age on speed
  • Slowing does not affect all tasks equally
  • Slowing associated with other cognitive functions
    • Slowing may underlie age-related deficits in other cognitive functions

Neuropsychology of Ageing (12 decks)

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