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Aging and Cognition

Aging and Cognition. Raja Parasuraman George Mason University Fairfax, VA, USA. Presentation to the Aging and Personal Wellness Course, May 1, 2009. Overview. Demographics of aging and Alzheimer’s disease Cognitive aging: Facts and myths Cognitive and brain changes in early Alzheimer’s

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Aging and Cognition

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  1. Aging and Cognition Raja Parasuraman George Mason University Fairfax, VA, USA Presentation to the Aging and Personal Wellness Course, May 1, 2009 1

  2. Overview • Demographics of aging and Alzheimer’s disease • Cognitive aging: Facts and myths • Cognitive and brain changes in early Alzheimer’s • The good news about cognitive aging • Cognitive training • Mental activity • Physical exercise • Dietary factors • Conclusions: Aging well 2

  3. Demographics of aging and Alzheimer’s disease 3

  4. Age Distribution of US Population 1980 1990 2002 85+ 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 4 Data source: The Bureau of the Census

  5. GLOBAL AGING TRENDS: 2000 - 2050 5 Source: UN Work Force on Aging (2004).

  6. Risk of Alzheimer’s by Age and Sex 6

  7. Alzheimer’s Statistics (US) Present • 5.3 Million people have Alzheimer’s (2008) • Annual cost of care: $148 billion • 6th leading cost of death Future • 7.7 million Alzheimer’s cases by 2030 • 11 - 16 million Alzheimer’s cases by 2050 • Over 60% of cases in 2050 will be 85 or older 7

  8. Cognitive aging: Facts and myths 8

  9. Cognitive Aging: Facts On average, aging is accompanied by • Vision and hearing loss • Decline in short-term memory • Poorer long-term memory • Decrease in speed of processing 9

  10. Life-Span Cognitive Changes Park et al. (2002) 10

  11. 80 60 40 20 0 20 30 40 50 60 70 Growth in Verbal Knowledge (Roberts & Parasuraman, 2003) Normalized Petersen Scale (1-100) Age 11

  12. Cognitive Aging: Myths “Everything declines, it’s all downhill.” NO! Some cognitive functions decline (episodic memory) Others remain stable (crystallized intelligence) Others improve (vocabulary, knowledge, wisdom) While others show minimal decline (selective attention, “implicit” memory) 12

  13. Cognitive Aging: Caveats “It’s all downhill for everybody.” NO! Large differences between individuals Some people show little or no decline Others show greater decline The reasons for these differences — nature (genes) or nurture (environment) are not well known Life style factors—exercise, diet, mental stimulation, social engagement—can alter individual trajectories of cognitive aging 13

  14. Trajectories of Cognitive Aging Cognition Functional Threshold Age 14

  15. Cognitive and brain changes in early Alzheimer’s 15

  16. Alzheimer’s Disease Patient Auguste D Alois Alzheimer 16

  17. Criteria for Clinical Diagnosis ofAlzheimer’s Disease (NINCDS-ADRDA) Dementia established by clinical exam and documented by Mini-Mental State or similar test Deficits in two or more areas of cognition Progressive worsening of memory Absence of systemic disorders or other brain diseases Other exclusions….. 17

  18. Brain Changes in Alzheimer’s Disease 18

  19. Brain Changes in Alzheimer’s Disease Plaques (Beta amyloid) Neurofibrillary tangles 19

  20. Neurofibrillary Tangles (Braak & Braak, 1991) No Clinical Symptoms 20 Disease Progression

  21. Pre-Clinical Detection of AD 21

  22. The Apolipoprotein E (APOE) Gene Important in cholesterol transport and for building myelin in neurons Inherited as one of three alleles or variants: e2, e3, and e4 6 Genotypes: e2/e2, e2/e3, e2/e4, e3/e3, e3/e4,e4/e4 The e4 Allele of the APOE Gene: major risk factor for AD Most common Least common 22

  23. The APOE Gene 23

  24. Testing Attention and Memory Spatial attention: Moving attention to different parts of the visual field Visual search: Finding a target among distractors Working memory: Keeping an item in mind for a brief period of time 24

  25. Spatial Attention and Visual Search: Where’s Waldo? 25

  26. The “Spotlight” of Spatial Attention 26

  27. 27

  28. 28

  29. Visual Search Time in Alzheimer’s Disease 2.0 Young seconds Healthy Old 1.0 Mild AD 0 Cued Target Uncued Target 29

  30. PET Scan During Visual Search 30 Corbetta (1998). Proceedings of the National Academy of Sciences.

  31. 800 600 400 200 0 0-10% 11-20% 21-30% 31-40% 41-50% Visual Search Deficit and Cortical Metabolism Slowing of Visual Search (milliseconds) Degree of Metabolic Reduction in Right Parietal Cortex (from PET Scan) 31

  32. Visual Search Time in Healthy Adults with the APOE e4 Gene 2.0 Non-e4 seconds 1 e4 Allele 1.0 2 e4 Alleles 0 Cued Target Uncued Target 32

  33. APOE, Cognition, and AD Healthy adults in their 60s with the APOE-e4 gene have cognitive deficits qualitatively similar (though less marked) to those with diagnosed AD show 3-year longitudinal changes in cognition that are characteristic of AD patients Problems: APOE-e4 is only a risk factor for AD Not all with APOE-e4 will develop AD Some AD patients do not have APOE-e4 Hence, APOE-e4 may interact with other genes and other (lifestyle?) factors to produce AD 33

  34. Longitudinal Study of APOE, Cognition, and Brain Structure 5-year study sponsored by National Institute on Aging Early detection of AD essential for preventative treatments AD onset may precede clinical diagnosis by 20-30 years Healthy adults aged 40 to 65 years Genotyped for APOE and other neurotransmission genes Measures Cognition General health MRI measures of brain structure 34

  35. The good news about cognitive aging 35

  36. Life Style Factors Influencing Cognitive Aging • Cognitive training • Mental stimulation • Physical exercise • Dietary factors • Social engagement 36

  37. Cognitive training 37

  38. Effects of Practice on Memory Search Time (Hertzog et al., 1996) Old Young 38

  39. Effects of Practice on Sustained Attention (Parasuraman & Giambra, 1991) Young Each session lasted 30 minutes Task requires maintaining attention and detecting a critical target presented infrequently (~ 1 every 2 minutes) Old Old Young 39

  40. Questions on Cognitive Training Effects in Older Adults • Do they transfer to other (unpracticed) tasks? • Ball et al. (2002) found little transfer from one cognitive domain (e.g., visual search) to another (e.g., reasoning) • Can the benefits be maintained? • Willis et al. (2006)—the ACTIVE Study—found gains over a 5-year period • Do the gains transfer to everyday cognitive activities? • Willis et al. (2006) found some benefit for self-reported Instrumental Activities of Daily Living (IADLs) 40

  41. Some Better News on Cognitive Training • Training for more complex cognitive abilities— “executive” functions carried out by the prefrontal cortex of the brain • Benefits transfer to other complex cognitive tasks (Kramer et al., 2006) • Benefits are associated with changes in prefrontal cortex activation in older adults 41

  42. Mental activity 42

  43. Mental Activity • Often difficult to quantify • Self, peer, or expert raters • Example activities • Reading • Attending a play • Playing chess, scrabble, and other challenging games • But not watching television! • Composite score of level of mental activity 43

  44. Longitudinal Study on Mental Activity(Wilson et al., 2003) • Large sample study: 4,000 older adults in a biracial community in Chicago area • Rated on 7 mentally stimulating activities • Followed at 3-year intervals for 6 years • In-home interviews and tests of cognitive function • Cognitive decline over 6 years 19% less for those with higher ratings of mental activity • Effect remained after controlling for depression, health, and other factors 44

  45. Mental Activity and Alzheimer’s Disease (Wilson et al., 2007) • 775 older adults without AD followed for 5 years • Rated on 9 mentally stimulating activities • 90 people developed AD • Those with low mental activity 2.5 times more likely to develop AD Low Activity Cumulative Hazard of AD High Activity 45 Study Year

  46. Physical exercise 46

  47. Why Should Physical Exercise Influence Cognition in Older Adults? • Because of the well known connection between exercise and disease • Heart disease • Type 2 diabetes • Breast and colon cancer • Hence exercise may maintain cognition through reduced risk of diseases associated with cognitive decline • Because respiratory and pulmonary function affects cognition “It is exercise alone that supports the spirits and keeps the mind in vigor” — Cicero 47

  48. Benefits of Aerobic Exercise for Cognition (Kramer et al., 1999) • 124 sedentary but healthy older adults • Aerobic exercise group — walking • Control group — stretching and toning • Both groups trained for 1 hour a day, 3 days a week for 6 months • Aerobic group showed better performance in • Processing task-relevant information • Switching rapidly between tasks • Inhibiting a pre-programmed response • All “executive” attention tasks 48

  49. Meta-Analysis of Exercise Studies (Colcombe & Kramer, 2003) 49

  50. Dietary factors 50

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