Aging

Physical activity linked to greater mental flexibility in older adults

  • A correlation has been found between physical activity in healthy older adults and more variable resting-state brain activity.
  • More variable resting-state activity in older adults has previously been linked to better cognition.
  • No such correlation was found between cardiorespiratory fitness and resting-state brain activity.
  • The finding supports previous evidence linking higher levels of physical activity in old age with better cognition and brain health.

A study involving 100 healthy older adults (aged 60-80) has found that those with higher levels of physical activity showed more variable spontaneous brain activity in certain brain regions (including the precuneus, hippocampus, medial and lateral prefrontal, and temporal cortices). Moreover, this relationship was positively associated with better white-matter structure.

Higher rates of activity when the brain is “at rest” have previously been shown to be associated with better cognitive performance in older adults, especially in IQ and memory.

The brain regions showing this relationship all play an important role in major resting-state networks, including the default mode network, the motor network, and networks associated with executive control and salience detection. They are all highly connected.

Participants' physical activity over a week was measured using accelerometers. Cardiorespiratory fitness was also assessed. Participants were generally not very active and not very fit.

The findings add to evidence linking higher fitness and physical activity with greater brain integrity and higher cognitive performance. They are also consistent with previous studies showing an increase in such brain signal fluctuations among older adults participating in physical exercise programs.

Interestingly, level of brain activity fluctuations was only correlated with physical activity, not with cardiorespiratory fitness. This indicates that CRF and physical exercise cannot be considered as functional equivalents — there must be some aspects of physical activity not captured by a measure of cardiorespiratory fitness.

It's also worth noting that there wasn't a significant correlation between sedentary time and resting-state brain activity fluctuations, although this may be because the participants all showed not-very-dissimilar levels of sedentary time.

http://www.eurekalert.org/pub_releases/2015-08/uoia-slp082415.php

Reference: 

Burzynska AZ, Wong CN, Voss MW, Cooke GE, Gothe NP, Fanning J, et al. (2015) Physical Activity Is Linked to Greater Moment-To-Moment Variability in Spontaneous Brain Activity in Older Adults. PLoS ONE 10(8): e0134819. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134819

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No benefit in omega-3 supplements for cognitive decline

  • A large study of older adults with age-related macular degeneration found no cognitive benefit from taking omega-3 supplements, or supplements of lutein and zeaxanthin.

A large, five-year study challenges the idea that omega-3 fatty acids can slow age-related cognitive decline. The study, involving 4,000 older adults, was part of the Age-Related Eye Disease Study (AREDS), which established that daily high doses of certain antioxidants and minerals can help slow the progression of age-related macular degeneration. However, a follow-up study found the addition of omega-3 fatty acids to the AREDS formula made no difference.

Omega-3 fatty acids are believed to be responsible for the health benefits associated with regularly eating fish, which is associated with lower rates of AMD, cardiovascular disease, and possibly dementia.

In this study, participants from the AREDS study, all of whom had early or intermediate AMD, were randomly assigned to either omega-3, or lutein and zeaxanthin (nutrients found in large amounts in green leafy vegetables), or both, or a placebo. As they all had AMD, participants also took the AREDS formula, which includes vitamins C, E, beta carotene, and zinc. Cognitive testing took place at the beginning, at 2 years, and at 4 years.

There was no benefit to these supplements: all groups showed a similar rate of cognitive decline over the study period.

The researchers speculate that the failure to find a benefit may lie in the age of the participants — it may be that supplements, to be of benefit, need to be started earlier. The other possibility (and the one I myself give greater weight to, although both factors may well be influential) is that these nutrients need to be taken in food to be effective.

It should be noted that the omega-3 fatty acids taken were those found in fish, not those found in plant foods such as flaxseed, walnuts, soy products, and canola and soybean oils.

http://www.eurekalert.org/pub_releases/2015-08/nei-nss082115.php

http://www.eurekalert.org/pub_releases/2015-08/tjnj-eop082115.php

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Limited benefit of physical activity for preventing cognitive decline

  • A large study of older adults (70+) found no cognitive benefit from a regular exercise program, compared to another social & mental intervention.
  • However, a subset of participants (those over 80, and those with poor physical function at the beginning of the study) did show improvement in executive function.
  • Participants in both programs showed no cognitive decline over the two-year period, suggesting both interventions were helpful.

A large, two-year study challenges the evidence that regular exercise helps prevent age-related cognitive decline.

The study involved 1,635 older adults (70-89) who were enrolled in the Lifestyle Interventions and Independence for Elders (LIFE) study. They were sedentary adults who were at risk for mobility disability but able to walk about a quarter mile. Participants had no significant cognitive impairment (as measured by the MMSE) at the beginning of the study. Around 90% (1476) made it to the end of the study, and were included in the analysis.

Half the participants were randomly assigned to a structured, moderate-intensity physical activity program that included walking, resistance training, and flexibility exercises, and the other half to a health education program of educational workshops and upper-extremity stretching.

In the physical activity condition, participants were expected to attend 2 center-based visits per week and perform home-based activity 3 to 4 times per week. The sessions progressed toward a goal of 30 minutes of walking at moderate intensity, 10 minutes of primarily lower-extremity strength training with ankle weights, and 10 minutes of balance training and large muscle group flexibility exercises.

The health education group attended weekly health education workshops during the first 26 weeks of the intervention and at least monthly sessions thereafter. Sessions lasted 60 to 90 minutes and consisted of interactive and didactic presentations, facilitator demonstrations, guest speakers, or field trips. Sessions included approximately 10 minutes of group discussion and interaction and 5 to 10 minutes of upper-extremity stretching and flexibility exercises.

Cognitive assessments were made at the beginning of the study and at 24 months, as well as a computerized assessment at either 18 or 30 months.

At the end of the study, there was no significant difference in cognitive score, or incidence of MCI or dementia, between the two groups. However, those in the exercise group who were 80 years or older ( 307) and those with poorer baseline physical performance ( 328) did show significantly better performance in executive function.

Executive function is not only a critical function in retaining the ability to live independently, research has also shown that it is the most sensitive cognitive domain to physical exercise.

Note also that there was no absolute control group — that is, people who received no intervention. Both groups showed remarkably stable cognitive scores over the two years, suggesting that both interventions were in fact effective in “holding the line”.

While this finding is disappointing and a little surprising, it is not entirely inconsistent with the research. Studies into the benefits of physical exercise for fighting age-related cognitive decline and dementia have produced mixed results. It does seem clear that the relationship is not a simple one, and what's needed is a better understanding of the complexities of the relationship. For example, elements of exercise that are critical, and the types of people (genes; health; previous social, physical, and cognitive attributes) that may benefit.

http://www.eurekalert.org/pub_releases/2015-08/tjnj-eop082115.php

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A diet to delay age-related cognitive decline

More evidence for the benefits of the Mediterranean diet for fighting age-related cognitive decline comes from a large 5-year study. The study involved 960 older adults, whose cognitive change was assessed over 4.7 years. Those who followed the MIND diet more rigorously showed an equivalent of being 7.5 years younger cognitively than those who followed the diet least.

The Mediterranean-DASH Diet Intervention for Neurodegenerative Delay is a hybrid of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets. It requires at least:

  • three servings of whole grains every day
  • a green leafy vegetable and one other vegetable every day
  • a glass of wine
  • snack most days on nuts
  • beans every other day or so
  • poultry at least twice a week
  • fish at least once a week
  • berries at least twice a week (blueberries are particularly recommended)
  • very limited intake of designated unhealthy foods, especially:
    • butter
    • sweets and pastries
    • whole fat cheese
    • fried or fast food

http://www.eurekalert.org/pub_releases/2015-08/rumc-eaa080415.php

http://www.theguardian.com/society/2015/aug/05/diet-high-in-leafy-green-vegetables-may-slow-cognitive-decline-in-elderly-study

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Aerobic exercise improves cognition in healthy older adults

A six-month pilot study involving 101 healthy older adults (65+), who were randomly put into one of three exercise interventions or a no-change control, has found that the exercise groups all showed significant improvement in visual-spatial processing and attention, with more improvement in visual-spatial processing occurring in those with higher levels of exercise.

The benefits of increasing exercise for visual-spatial processing, however, were fully accounted for by improvements in cardiorespiratory fitness, suggesting that exercise intensity may be more important than exercise duration.

The researchers suggest that individualized exercise programs designed to maximize cardiorespiratory fitness will be of greatest benefit.

The three exercise levels were: 150 minutes per week (the recommended level); 75 minutes per week; 225 minutes per week. Exercise was supervised, and mainly consisted of treadmill walking of moderate intensity. Participants exercised 3-5 days a week. Performance in five cognitive domains were tested: Verbal Memory, Visuospatial Processing, Simple Attention, Set Maintenance and Shifting, and Reasoning.

Note that only 77 individuals made it through the trial, and also adhered to at least 80% of the alloted amount of exercise. Unsurprisingly, the 225-minute group had the most trouble meeting the allotment: 70% of the group managed it, compared to 82% of the 75-minute group, and 85% of the 150-minute group. It's worth noting that, of those who met the 80% requirement, almost all (>95%) fully adhered to the prescription, and this was true across all exercise prescriptions.

http://www.eurekalert.org/pub_releases/2015-07/uokm-eci071515.php

Reference: 

Vidoni ED, Johnson DK, Morris JK, Van Sciver A, Greer CS, Billinger SA, et al. (2015) Dose-Response of Aerobic Exercise on Cognition: A Community-Based, Pilot Randomized Controlled Trial. PLoS ONE 10(7): e0131647. doi:10.1371/journal.pone.0131647

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Why older adults lose working memory capacity

The root of age-related cognitive decline may lie in a reduced ability to ignore distractors. A new study indicates that older adults put more effort into focusing during encoding, in order to compensate for a reduced ability to hold information in working memory. The finding suggests a multi-pronged approach to improving cognitive ability in older adults.

I've reported before on the idea that the drop in working memory capacity commonly seen in old age is related to the equally typical increase in distractability. Studies of brain activity have also indicated that lower WMC is correlated with greater storage of distractor information. So those with higher WMC, it's thought, are better at filtering out distraction and focusing only on the pertinent information. Older adults may show a reduced WMC, therefore, because their ability to ignore distraction and irrelevancies has declined.

Why does that happen?

A new, large-scale study using a smartphone game suggests that the root cause is a change in the way we hold items in working memory.

The study involved 29,631 people aged 18—69, who played a smartphone game in which they had to remember the positions of an increasing number of red circles. Yellow circles, which had to be ignored, could also appear — either at the same time as the red circles, or after them. Data from this game revealed both WMC (how many red circle locations the individual could remember), and distractability (how many red circle locations they could remember in the face of irrelevant yellow circles).

Now this game isn't simply a way of measuring WMC. It enables us to make an interesting distinction based on the timing of the distraction. If the yellow circles appeared at the same time as the red ones, they are providing distraction when you are trying to encode the information. If they appear afterward, the distraction occurs when you are trying to maintain the information in working memory.

Now it would seem commonsensical that distraction at the time of encoding must be the main problem, but the fascinating finding of this study is that it was distraction during the delay (while the information is being maintained in working memory) that was the greater problem. And it was this distraction that became more and more marked with increasing age.

The study is a follow-up to a smaller 2014 study that included two experiments: a lab experiment involving 21 young adults, and data from the same smartphone game involving only the younger cohort (18-29 years; 3247 participants).

This study demonstrated that distraction during encoding and distraction during delay were independent contributory factors to WMC, suggesting that separate mechanisms are involved in filtering out distraction at encoding and maintenance.

Interestingly, analysis of the data from the smartphone game did indicate some correlation between the two in that context. One reason may be that participants in the smartphone game were exposed to higher load trials (the lab study kept WM load constant); another might be that they were in more distracting environments.

While in general researchers have till now assumed that the two processes are not distinct, it has been theorized that distractor filtering at encoding may involve a 'selective gating mechanism', while filtering during WM maintenance may involve a shutting down of perception. The former has been linked to a gating mechanism in the striatum in the basal ganglia, while the latter has been linked to an increase in alpha waves in the frontal cortex, specifically, the left middle frontal gyrus. The dorsolateral prefrontal cortex may also be involved in distractor filtering at encoding.

To return to the more recent study:

  • there was a significant decrease in WMC with increasing age in all conditions (no distraction; encoding distraction; delay distraction)
  • for older adults, the decrease in WMC was greatest in the delay distraction condition
  • when 'distraction cost' was calculated (((ND score − (ED or DD score))/ND score) × 100), there was a significant correlation between delay distraction cost and age, but not between encoding distraction cost and age
  • for older adults, performance in the encoding distraction condition was better predicted by performance in the no distraction condition than it was among the younger groups
  • this correlation was significantly different between the 30-39 age group and the 40-49 age group, between the 40s and the 50s, and between the 50s and the 60s — showing that this is a progressive change
  • older adults with a higher delay distraction cost (ie, those more affected by distractors during delay) also showed a significantly greater correlation between their no-distraction performance and encoding-distraction performance.

All of this suggests that older adults are focusing more attention during attention even when there is no distraction, and they are doing so to compensate for their reduced ability to maintain information in working memory.

This suggests several approaches to improving older adults' ability to cope:

  • use perceptual discrimination training to help improve WMC
  • make working memory training more about learning to ignore certain types of distraction
  • reduce distraction — modify daily tasks to make them more "older adult friendly"
  • (my own speculation) use meditation training to improve frontal alpha rhythms.

You can participate in the game yourself, at http://thegreatbrainexperiment.com/

http://medicalxpress.com/news/2015-05-smartphone-reveals-older.html

Reference: 

[3921] McNab, F., Zeidman P., Rutledge R. B., Smittenaar P., Brown H. R., Adams R. A., et al.
(2015).  Age-related changes in working memory and the ability to ignore distraction.
Proceedings of the National Academy of Sciences. 112(20), 6515 - 6518.

McNab, F., & Dolan, R. J. (2014). Dissociating distractor-filtering at encoding and during maintenance. Journal of Experimental Psychology. Human Perception and Performance, 40(3), 960–7. doi:10.1037/a0036013

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Evidence for the benefits of meditation in fighting age-related cognitive decline

A review of meditation research reported in January last year concluded that there were insufficient good studies to allow us to say that meditation clearly improves attention and cognition. Studies from 2014 suggest three factors that might be part of the reason for inconsistent research findings:

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Mnemonics for Seniors

  • Mnemonics can be effective strategies for older adults, but they require more training than younger adults
  • Mnemonic strategies with less memory load, like the keyword and the face-name association methods, are better strategies for older adults than strategies with a high memory load, such as the pegword and loci methods
  • The durability and effectiveness of mental images are enhanced if you spend some time attending to the quality of the image (e.g., how pleasant it is)
  • Because older adults have more trouble changing their habits, they are much less likely to continue to use a new method without explicit instructions to do so
  • Mnemonics that involve words rather than images may be more useful for most older adults
  • Mnemonics are not particularly useful for remembering information heard in the course of conversation, remembering an action performed, remembering to do something. Teaching yourself to repeat information is probably a more useful skill.

Aids to memory such as acronyms, rhymes, linking information by creating visual images or making up a story, are called mnemonics. Most popular memory courses teach mnemonic strategies. It is however only one type of memory strategy.

Mnemonics are however particularly appropriate for remembering names and dates. In a survey of over 100 elderly adults, learning and remembering people's names, and learning and remembering dates, were the two memory skills they most wanted to improve (Leirer Morrow Sheikh & Pariante 1990).

However, although mnemonics can be very effective, they do require a great deal of effort to master. In this page I report on research into the usefulness of various mnemonic strategies for older adults.

Pegword method

The pegword mnemonic is a strategy for learning lists. You memorize a list that converts numbers into visual images (one is a bun, two is a shoe, etc), and then use those images as pegs for the items you wish to remember. Thus, to remember a shopping list you imagine each item in turn with these images: an apple in a bun; a shoe full of beans; etc.

While the pegword strategy is effective, it does require a lot of training to be used successfully, and doesn't appear to be a good strategy for older adults.

Four studies have found no lasting improvement in memory when middle-aged or elderly subjects have been instructed in the pegword technique (Smith 1975a, Mason & Smith 1977, Hellebusch 1976, Wood & Pratt 1987).

Method of loci

The method of loci (places) is the classic mnemonic, first invented by the ancient Greeks, and is considerably easier to learn than the pegword technique. Using a place you know very very well - perhaps a familiar route, your house, or a particular room in it - you mentally visualize the items you want to remember in particular places.

This technique has had somewhat more success in improving memory in older adults, although not to the extent seen in younger adults taught the strategy. This may be due to older adults' slower rate of processing information. Older adults who are already experienced in using imagery are likely to find the technique more useful.

Robertson-Tchabo, Hausman, & Arenberg (1976) found elderly subjects successfully used the method, but only when explicitly instructed to do so.

Anschutz, Camp, Markley & Kramer (1985; 1987) found elderly subjects could be trained to use the method to remember shopping list items, but tended not to use it when asked to learn new lists several weeks later, and many reported not using the strategy when interviewed several years later.

Rose & Yesavage (1983); Kliegl, Smith & Baltes (1989) found the improved memory performance seen in elderly subjects was less than that found for similarly trained young adults.

The reduced benefit of the method to older adults may be due to their slower rate of processing information. Lindenberger, Kliegl & Baltes (1992) found that elderly adults who were experienced in using imagery (graphic designers) performed better than other elderly adults, although still not to the level of young adults.

Keyword method

One of the most effective mnemonic strategies is the keyword method. This is particularly effective for learning new words. Gruneberg & Pascoe (1996) had success in teaching a group of older women Spanish words using the keyword method of foreign language learning.

Face-name associations

Perhaps the most widely used mnemonic is the face-name association method. This strategy involves choosing something distinctive about the face, finding a word or phrase (the "keyword") that is similar to the name, and creating a visual image that links the distinctive feature with the keyword.

Yesavage & Rose (1984a) found older adults significantly improved their memory of names using this method, although the improvement was limited (they still only remembered 24% of names - but this was double what they remembered prior to training).

General remarks about mnemonic training

Long-lasting memory improvement is hampered by the difficulty older adults have in changing their habits - that is, they rarely use a new method without explicit instructions to do so.

The effectiveness of the method of loci and keyword method can apparently be increased by having the participants make affectiveness judgments (such as judging the degree of pleasantness) of each image they generate. This appears not only to increase the degree of improvement, but also the durability of the images (how long they are remembered for) (Yesavage & Rose 1984b (method of loci); Yesavage, Rose & Bower 1983 (face-name assoc)).

While relaxation training may improve learning in elderly adults who are anxious, it appears to hinder learning if the participants have low anxiety levels! (Yesavage, Rose & Spiegel 1982)

It does appear that age affects mnemonic training, in that it becomes less effective the older you are, especially with the more complex method of loci vs the simpler keyword methods (Yesavage, Sheikh, Friedman & Tanke 1990). This is not to say older adults cannot learn these techniques, merely that that older adults need extensive and intensive training to really benefit (Neely & Backman 1993a,b; Stigsdotter & Backman 1989).

Older adults can learn effectively by teaching themselves, but such instruction needs to be supplemented by periodic group discussions (Flynn & Storandt 1990).

Verbal mnemonics may be more useful for older adults who find imagery effortful. Hill, Storandt & Simeone (1990) found that a take-home manual on the use of organization in aiding memory resulted in substantial improvement. The story method has also been found to be of benefit (Hill, Allen & McWhorter, 1991), although its effectiveness depends on the person's ability to construct a narrative (Drevenstedt & Belleza 1993).

The most problematic memory tasks for older adults however are probably those which involve information experienced only once, incidentally – something heard in the course of conversation, remembering an action performed, remembering to do something. Training in the benefits of repetition is probably of more benefit than mnemonic training, for these instances.

References

  1. Anschutz, L., Camp, C.J., Markley R.P. & Kramer J.J. 1985. Maintenance and generalization of mnemonics for grocery shopping by older adults. Experimental Aging Research, 11, 157-60.
  2. — 1987: A three-year follow-up on the effects of mnemonics training in elderly adults. Experimental Aging Research, 13, 141-3.
  3. Drevenstedt, J. & Belleza, F.S. 1993. Memory for self-generated narration in the elderly. Psychology and Aging, 8, 187-96.
  4. Flynn, T.M. & Storandt, M. 1990. Supplemental group discussions in memory training for older adults. Psychology and Aging, 5, 178-81.
  5. Gruneberg,M.M. & Pascoe, K. 1996. The Effectiveness of the Keyword Method for Receptive and Productive Foreign Vocabulary Learning in the Elderly. Contemporary Educational Psychology, 21, 102-9.
  6. Hellebusch, S.J. 1976. On improving learning and memory in the aged: The effects of mnemonic strategy, transfer, and generalization. Dissertation Abstracta International, 1459-B (University Microfilms No. 76-19, 496).
  7. Hill, R.D., Allen, C. & McWhorter, P. 1991. Stories as a mnemonic aid for older learners. Psychology and Aging, 6, 484-6.
  8. Hill, R.D., Storandt, M. & Simeone, D. 1990. The effects of memory skills training and incentives on free recall in older learners. The Journals of Gerontology: Psychological Sciences, 45, P227-232.
  9. Kliegl, R., Smith, J. & Baltes, P.B. 1989. Testing-the-limits and the study of adult age differences in cognitive plasticity of a mnemonic skill. Developmental Psychology, 25, 247-56.
  10. Leirer, V.O., Morrow, D.G., Sheikh, J.I. & Pariante, G. 1990: Memory skills elders want to improve. Experimental Aging Research, 17, 155-8.
  11. Lindenberger, U., Kliegl, R. & Baltes, P.B. 1992. Professional expertise does not eliminate age differences in imagery-based memory performance during adulthood. Psychology and Aging, 7, 585-93.
  12. Mason, S.E. & Smith, A.D. 1977. Imagery in the aged. Experimental Aging Research, 3, 17-32.
  13. Neely, A.S. & Backman, L. 1993a. Maintenance of gains following multifactorial and unifactorial memory training in late adulthood. Educational Gerontology, 19, 105-17.
  14. — b. Long-term maintenance of gains from memory training in older adults: Two 3 ½ year follow-up studies. The Journal of Gerontology: Psychological Sciences, 48, P223-37.
  15. Robertson-Tchabo, E.A., Hausman, C.P. & Arenberg, D. 1976 . A classical mnemonic for older learners: A trip that works. Educational Gerontology, 1, 215-26.
  16. Rose, T.L. & Yesavage, J.A. 1983. Differential effects of a list-learning mnemonic in three age groups. Gerontology, 29, 293-8.
  17. Smith, A.D. 1975. Partial learning and recognition memory in the aged. International Journal of Aging and Human Development, 6, 359-65.
  18. Stigsdotter, A. & Backman, L. 1989. Multifactorial memory training with older adults: How to foster maintenance of improved performance. Gerontology, 35, 260-7.
  19. Wood, I.E. & Pratt, J.D. 1987. Pegword mnemonic as an aid to memory in the elderly: A comparison of four age groups. Educational Gerontology, 13, 325-339.
  20. Yesavage, J.A. & Rose, T.L. 1984a. The effects of a face-name mnemonic in young, middle-aged, and elderly adults. Experimental Aging Research, 10, 55-57.
  21. Yesavage, J.A. & Rose, T.L. 1984b. Semantic elaboration and the method of loci: A new trip for older learners. Experimental Aging Research, 10, 155-59.
  22. Yesavage, J.A., Rose, T.L. & Bower, G.H. 1983. Interactive imagery and affective judgments improve face-name learning in the elderly. Journal of Gerontology, 38, 197-203.
  23. Yesavage, J.A., Rose, T.L. & Spiegel, D. 1982. Relaxation training and memory improvement in elderly normals: Correlation of anxiety ratings and recall improvement. Experimental Aging Research, 8, 195-8.
  24. Yesavage, J.A., Sheikh, J.I., Friedman, L. & Tanke, E. 1990. Learning mnemonics: Roles of aging and subtle cognitive impairment. Psychology and Aging, 5, 133-7.

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