Lecture 4: Language, Visuospatial Functions, Normal Brain Ageing

Question 1

Normal ageing effect on language

• Age effect language functions varies:

Answer 1

Age effect language functions varies:

• Vocabulary maintained with ageing, or even improvement
• Word production, retrieval of word sounds, declines
• Syntactic processing declines

Question 2

Normal ageing effect on language

• Knowledge word meaning, vocabulary

Answer 2

Knowledge word meaning, vocabulary

• Older adults larger vocabulary than younger adults
• more words represented in the lexicon
• superior performance on NART, providing definitions or using larger variety of words in discourse.
• Vocabulary starts to decline only in 80s or 90s
• not just cohort effect. Longitudinal studies: improved vocabulary until very old age.

Question 3

Normal ageing effect on language

• 2 subscales Vocabulary (40 items) and Abstract Thinking (20 items)
• from: Verhaeghen (2003)
• WAIS-R Vocabulary

Answer 3

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• Vocabulary unaffected by age

Question 4

Vocabulary unaffected by age

• knowledge
• Knowledge: WAIS Vocabulary and Spot-a-Word test (e.g. flonty – xylophone)

Answer 4

• Longitudinal study: Berlin Aging Study. No deterioration until age 90 (thick line)
  
  • from: Singer et al. (2001)

Question 5

Normal ageing effect on language

• Language production

Answer 5

Language production

• More difficulties in language production, in particular retrieving the correct word
• Problem not in the semantic system (words not lost)
• Problem in retrieving the correct phonology

Question 6

(part of) language production system:

• knowledge about words stored in semantic system, transferred into sounds in phonological system to produce words
• Problem in retrieving the correct phonology

Answer 6

Problem in retrieving the correct phonology

• tip of the tongue state (TOT)
• temporarily unable to produce well-known word
• most common with proper names
• More naturally occurring TOTs in older adults -diary study (Burke et al., 1991)
  • however, 97% resolved: information not lost
  • Also more TOTs induced in laboratory in older adults

Question 7

Language production

• Explanation TOT: result insufficient transmission of activation to correct phonological codes

Answer 7

Explanation TOT: result insufficient transmission of activation to correct phonological codes

• Aging would reduce transmission of activation more TOTs.
• Proper names more vulnerable
  
  • lack meaning, few semantic connections
  • single link between representation of person and their name
  • Baker vs baker

Question 8

¨Normal ageing effect on language

• Syntax
• understanding and production complex syntax deteriorates with ageing
  • linked to impairments in working memory
• Syntax comprehension:

Answer 8

Syntax comprehension

• Older adults perform less well answering questions about sentences with complex syntax
• Older adults less accurate judging plausibility complex sentences (Waters & Caplan, 2005)
• Accuracy associated with WM capacity (e.g. reading span)
  
  • Older adults had poorer WM scores than young adults
  • Participants with higher WM capacity were less affected by syntactic complexity.

Question 9

Normal ageing effect on language

• Syntax production

Answer 9

Syntax production

• In speech older adults produce shorter utterances with simpler syntactic structure than younger adults.
• Vocabulary larger in older adults, but WM poorer
  
  • WM may contribute to age effect in sentence production

Question 10

Language effects in normal ageing

• in sum:

Answer 10

• Overall, age effect language smaller than memory or EF
• Clear age effect word production (retrieving word from lexicon)
• Syntax comprehension and production declines with age
• Vocabulary improves with age

Question 11

Visual search tasks:

• Verhaeghen (2017): conjunction search task
• Potter et al (2012): search for target pasta among different types pasta

Answer 11

• Verhaeghen (2017): healthy older adults slower than younger adults in visual search tasks, in particular conjunction search

Question 12

Visuoconstructional tasks

• Block design (Robins-Wahlin et al., 1993)
  
  • 219 healthy older adults (75-96 yrs)
  • Block Design with and without time limit

Answer 12

• Lower scores with higher age
• More accurate without than with time limit
• Difference with and without time limit increased with age

Question 13

Visuoconstructional tasks

• Clock Setting & Clock Reading (Robins-Wahlin et al., 1993)
  
  • Clock Setting: draw time in empty clock face
  • Clock Reading: tell time from position hands
  • Clock Drawing Test: empty circle
    
    • Add hours
    • Set hands at 11:10

Answer 13

• Clock setting: youngest 2 groups scored better than oldest 2 (p<.05)
• Clock reading: 3 youngest groups scored better than oldest group (p<.05)
• ¨Clock drawing in normal ageing (Von Gunter et al., 2008)
  
  • 51% participants had some difficulty placing numbers correctly in clock
  • 33% participants had some difficulty placing hands correctly in clock
  • Effect of age – participants over 80, more errors than younger groups, but only when level of education was low

Question 14

Visuoconstructional tasks

• Clock drawing in normal ageing

Answer 14

• errors CDT represent normal variation
• errors CDT do not need to indicate cognitive impairment
• CDT as screening for dementia: risk of false positives

Question 15

Normal ageing effect on visuospatial abilities

• Mental rotation
• Review Verhaeghen (2017):

Answer 15

• Review Verhaeghen (2017): mental rotation slowing in older adults
• Old adults slower to mentally rotate shapes and more errors (Dror & Kosslyn, 1994)

Question 16

Normal ageing effect on visuospatial abilities

• In sum

Answer 16

• Age effects more pronounced on more demanding visuospatial tasks
  
  • e.g. conjunction search, mental rotation (larger angles)
• Healthy older adults make errors on clock tests

Question 17

Brain changes in normal ageing

• Structural changes
  
  • Volume loss between ages 30 and 90:
  • Jernigan et al (2001): cross-sectional, compare structural brain changes 78 healthy adults between 30 and 90 years old

Answer 17

• Volume loss between ages 30 and 90:
  
  • 14% in cerebral cortex
  • 35% hippocampus
  • 26% cerebral white matter
• Jernigan et al. (2001):
  • 1) loss in hippocampus volume accelerated with ageing relative to gray matter losses elsewhere in brain.
  • 2) frontal lobes disproportionately affected by cortical volume loss relative to other cerebral lobes
  • 3) loss of white matter occurred later than loss of gray matter, but was ultimately greater

Question 18

Structural changes

• Raz et al. (2005): longitudinal, 5 year follow-up 72 healthy adults (age range at baseline 20 – 77)
• location of volume losses:

Answer 18

• Largest volume loss in prefrontal cortex and hippocampus
• Little volume loss in primary visual cortex

Question 19

Structural changes

• Fjell et al., (2013). Longitudinal study older adults (55-91):
• Volume changes over 1-year interval

volume reductions:

Answer 19

• Largest volume reductions in frontal and temporal areas
• Least changes around central sulcus and calcarine sulcus
• Within temporal and frontal areas, most decline in:
  
  • medial and lateral parts temporal lobe
  • medial and lateral orbitofrontal lobes

Question 20

Brain changes in normal ageing

• Functional change
• Cerebral blood flow (CBF)

Answer 20

Cerebral blood flow (CBF)

• Reduced resting state cerebral blood flow with ageing
  
  • Highest resting state CBF in visual and motor areas and in superior frontal cortex. Higher CBF in young and middle-aged adults (YA, MA) than in older adults (OA)
• Reduced CBF across whole cortex, average decrease ± 0.45% per year
  
  • specific areas of reduced CBF, include medial temporal lobes, hippocampus, frontal cortex

Question 21

Functional change

• Cerebral blood flow (CBF)
• during cognitive peformance

Answer 21

Cerebral blood flow (CBF)

• Increase in CBF during performance of cognitive tasks
• Old adults showed greater increase in CBF than younger adults
  
  • or activation in additional areas
• Increase activation would reflect compensation for reduced efficiency in older adults (Grady et al., 1994)
  • Increase rCBF in frontal areas in older adults, which is absent in younger adults

Question 22

Theories of normal brain ageing:

• Account for differences between brain areas in vulnerability to ageing
  
  • Frontal theory of ageing
  • Last in first out
  • Anterior-to-posterior gradient of vulnerability

Answer 22

Frontal theory of ageing – frontal lobes are particularly vulnerable to effect of ageing

• Parts frontal lobes vulnerable to effect of ageing

Last in, first out – late maturing brain areas are most vulnerable to effect of ageing

• Late maturing medial frontal areas, particularly vulnerable to effect of ageing

Anterior-to-posterior gradient of vulnerability

• Anterior areas (frontal) more vulnerable to effect ageing than posterior areas (e.g. occipital)

Evolutionary account

• Brain areas that developed later in evolution (e.g. prefrontal areas) are most vulnerable to ageing

Frontal/last in, first out/anterior-to-posterior/evolutionary

• Theories in line with early and pronounced decline of frontal areas
• Theories not in line with early and pronounced decline of medial temporal areas
• Maturation completed earlier than prefrontal areas
• Relatively “old” brain areas

Question 23

Association decline in cognitive function and brain changes with ageing?

• Persson et al. (2012): longitudinal study
  
  • Changes hippocampus associated with changes in memory performance?
  • 26 healthy older adults 55 – 79 years,
  • Baseline 2002-2003, follow-up 2008-2009
  • Tasks: 5 episodic memory tests, including delayed recall and recognition – single sumscore

Answer 23

Activation:

• Hippocampus: persons whose memory performance declined - reduction in activation
• Parahippocampal gyri: persons whose memory performance declined - increase in activation in these areas

Volume

• Hippocampus volume: persons whose memory performance declined over time - smaller hippocampus volume at follow-up

Question 24

Distinguish brain changes normal ageing from early pathological brain changes

• Overlap in areas affected
• Changes reflection of abnormal ageing in persons in very early stage of dementia (incipient dementia)?
• Possible solution:

Answer 24

• select participants who score same as young participants (“superagers”) or older adults at very low risk of dementia

Question 25

* “superagers” or older adults at very low risk of dementia. * volume reduction?

Answer 25

* Resnick et al. (2003): significant reduction brain volume in all cortical lobes in 24 very healthy older participants (no medical condition or cognitive impairment 4 years after the initial assessment) * Fjell et al. (2013): brain atrophy in participants classed at very low risk of dementia (based on performance cognitive tests, negative CSF amyloid and negative APOE 4) Healthy participants at low risk to develop dementia: 3 years and 4 years (cognitively) healthy after study entry. 55-91 years at study baseline * Reduction in volume across most of the cortex * Strongest reductions in temporal areas and prefrontal areas * medial and lateral temporal lobes * medial and lateral frontal lobes. * specific structures: hippocampus declined most in volume * only area around central sulcus no reduction in volume **Very unlikely all participants were in preclinical stage of dementia: cortical atrophy (most likely) not only driven by dementia/AD.**

Question 26

Distinct changes in normal ageing and dementia

Answer 26

* Brain atrophy in healthy older participants, participants with MCI and AD. * Areas with more (blue) or less (red) atrophy relative to overall atrophy of the whole brain. * Common pattern: high levels of atrophy in all 3 groups in lateral and medial temporal cortex. * Distinct pattern: relatively high level of atrophy in frontal cortex in healthy older adults * Low-risk healthy adults: changes likely to be part of normal ageing

Question 27

Neuropathology in cognitively healthy older adults * Postmortem examination brains of healthy older adults

Answer 27

Postmortem examination brains of healthy older adults * range of abnormalities associated with dementia observed * including amyloid plaques, neurofibrillary tangles, minor vascular infarcts, Lewy bodies. * More than 50% cognitively normal persons had dementia pathology * Why normal performance on cognitive tests despite brain abnormalities?