seniors

Higher coffee consumption linked to lower dementia risk in women

  • A large study adds to evidence that caffeine helps older women fight cognitive impairment and dementia.
  • This is supported by two animal studies showing precisely how caffeine is valuable for keeping the brain healthy.

Data from the Women's Health Initiative Memory Study, involving 6,467 postmenopausal women (65+) who reported some level of caffeine consumption, has found that those who consumed above average amounts of coffee had a lower risk of developing dementia.

Caffeine intake was estimated from a questionnaire. The median intake was 172 mg per day (an 8-ounce cup of brewed coffee contains 95mg of caffeine, 8-ounces of brewed black tea contains 47mg, so slightly less than 2 cups of coffee or less than 4 cups of tea). The women were cognitively assessed annually.

Over ten years, 388 were diagnosed with probable dementia (209) or MCI (179). Those who consumed above the median amount of caffeine had a 36% reduction in risk. The average intake in this group was 261 mg (3 cups of coffee), while the average intake for those below the median was 64 mg per day (less than one cup).

Risk factors such as hormone therapy, age, race, education, body mass index, sleep quality, depression, hypertension, prior cardiovascular disease, diabetes, smoking, and alcohol consumption, were taken into account.

The findings are consistent with other research finding a benefit for older women. It should not be assumed that the findings apply to men. It also appears that there may be a difference depending on education level. This sample had a high proportion of college-educated women.

It should also be noted that there was no clear dose-response effect — we could put more weight on the results if there was a clear relationship between amount of caffeine and benefit. Part of the problem here, however, is that it’s difficult to accurately assess the amount of caffeine, given that it’s based on self-report intake of coffee and tea, and the amount of caffeine in different beverages varies significantly.

Moreover, we do have a couple of mechanisms for caffeine to help fight age-related cognitive decline.

A recent study using rats modified to have impaired receptors for the adenosine A2A produced rats showing typical characteristics of an aging brain. In humans, too, age-related cognitive decline has been associated with over-activation of these receptors and dysfunction in glucocorticoid receptors.

The rat study shows that over-activation of the adenosine A2A receptors reduces the levels of glucocorticoid receptors in the hippocampus, which in turn impairs synaptic plasticity and cognition. In other words, it is the over-activation of the adenosine receptors that triggers a process that ends with cognitive impairment.

The point of all this is that caffeine inhibits the adenosine A2A receptors, and when the rats were given a caffeine analogue, their memory deficits returned to normal.

Another more recent study has found that caffeine increases the production of an enzyme that helps prevent tau tangles.

Building on previous research finding that an enzyme called NMNAT2 not only protects neurons from stress, but also helps prevent misfolded tau proteins (linked to Alzheimer’s, and other neurodegenerative disorders), the study identified 24 compounds (out of 1,280 tested) as having potential to increase the production of NMNAT2. One of the most effective of these was caffeine.

When caffeine was given to mice modified to produce lower levels of NMNAT2, the mice began to produce the same levels of the enzyme as normal mice.

https://www.eurekalert.org/pub_releases/2016-10/oupu-fwc100316.php

https://www.eurekalert.org/pub_releases/2016-08/ind-cai083016.php

https://www.eurekalert.org/pub_releases/2017-03/iu-cbe030717.php

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Age-related drop in body temperature worsens Alzheimer's disease

  • A mouse study suggests that some Alzheimer’s symptoms are made worse by falling body temperature — and are helped by improving body temperature.

Our bodies’ ability to regulate its temperature gets worse with age, along with a slowing metabolism. We also become more vulnerable to Alzheimer's as we age. A study compared mice genetically engineered to manifest Alzheimer's symptoms as they age with normal mice. They found that these transgenic mice were worse at maintaining their body temperature as they aged, with the difference reaching almost 1° Celsius by the age of 12 months.

Moreover, there was an increase in Alzheimer’s symptoms (such as a greater increase in abnormal tau proteins and loss of synaptic proteins) in transgenic mice when they were exposed to low temperatures.

But — and this is the exciting bit — when the mice were given one week in a 28°C environment, and their body temperature increased by 1°C, beta-amyloid production dropped substantially, and memory test results were comparable to those of normal mice.

While obviously these results need to be replicated in humans, the findings do suggest that improving body temperature might be helpful for those in early stages of Alzheimer’s. Body temperature can be increased through physical activity, diet, drugs, or simply by turning the heat up.

http://www.eurekalert.org/pub_releases/2016-04/ul-dib040716.php

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Why people with Alzheimer's stop recognizing their loved ones

  • A finding that Alzheimer's sufferers' failure to recognize familiar faces is rooted in an impairment in holistic perception rather than memory loss, suggests new strategies to help patients recognize their loved ones for longer.

People with Alzheimer's disease develop problems in recognizing familiar faces. It has been thought that this is just part of their general impairment, but a new study indicates that a specific, face-related impairment develops early in the disease. This impairment has to do with the recognition of a face as a whole.

Face recognition has two aspects to it: holistic (seeing the face as a whole) and featural (processing individual features of the face). While both are useful in object recognition, expert recognition (and face recognition is usually something humans are expert in) is built on a shift from featural to holistic processing.

The study compared the ability of people with mild Alzheimer's and healthy age- and education-matched seniors to recognize faces and cars in photos that were either upright or upside down. It found that those with Alzheimer's performed comparably to the control group in processing the upside-down faces and cars. This type of processing requires an analysis of the various features. Those with Alzheimer’s also performed normally in recognizing upright cars (car experts are likely to use holistic processing, but those with less expertise will depend more on featural processing). However, they were much slower and less accurate in recognizing faces.

Realizing that impaired facial recognition is based on a holistic perception problem, rather than being simply another failure of memory, suggests that strategies such as focusing on particular facial features or on voice recognition may help patients recognize their loved ones for longer.

http://www.eurekalert.org/pub_releases/2016-04/uom-wdp040816.php

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Different kinds of physical activity improve brain volume & cut Alzheimer's risk

  • A large long-running study adds to growing evidence that higher levels of physical activity reduce brain atrophy and Alzheimer's risk, and shows that many types of aerobic activity are beneficial.

Data from 876 patients (average age 78) in the 30-year Cardiovascular Health Study show that virtually any type of aerobic physical activity can improve brain volume and reduce Alzheimer's risk.

A higher level of physical activity was associated with larger brain volumes in the frontal, temporal, and parietal lobes including the hippocampus, thalamus and basal ganglia. Among those with MCI or Alzheimer's (25% of the participants), higher levels of physical activity were also associated with less brain atrophy. An increase in physical activity was also associated with larger grey matter volumes in the left inferior orbitofrontal cortex and the left precuneus.

Further analysis of 326 of the participants found that those with the highest energy expenditure were half as likely to have developed Alzheimer's disease five years later.

Physical activity was assessed using the Minnesota Leisure-Time Activities questionnaire, which calculates kilocalories/week using frequency and duration of time spent in 15 different leisure-time activities: swimming, hiking, aerobics, jogging, tennis, racquetball, walking, gardening, mowing, raking, golfing, bicycling, dancing, calisthenics, and riding an exercise cycle.

The study does not look at whether some types of physical activity are better than others, unfortunately, but its message that overall physical activity, regardless of type, helps in the fight against cognitive impairment is encouraging.

http://www.eurekalert.org/pub_releases/2016-03/ip-dko030916.php

http://www.eurekalert.org/pub_releases/2016-03/uops-bmc031016.php

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Hearing aid use linked to better cognition in hearing-impaired elderly

  • A study of older adults with impaired hearing supports the use of hearing aids to help fight the development of cognitive decline and dementia.

A study involving 100 older adults (aged 80-99) with hearing loss has found that those who used a hearing aid performed significantly better on a cognitive test (MMSE) than those who didn't use a hearing aid, despite having poorer hearing. Among non-users, participants with more hearing loss had lower MMSE scores than those with better hearing.

In the MMSE, participants give vocal responses to verbal commands. Executive function was also assessed with the Trail Making Test, Part B, which doesn't have a verbal or auditory component. On this test, although hearing aid users performed better than non-users, the difference was not statistically significant. Nor were scores correlated with hearing level.

The finding suggests that hearing loss is associated with sensory-specific cognitive decline rather than global cognitive impairment.

Of the 100 participants, 34 regularly used a hearing aid.

Previous studies have found hearing loss is associated with greater cognitive decline in older adults. A physician recently told the annual meeting of the American Association for the Advancement of Science (AAAS) that as much as 36% of dementia risk might be attributable to hearing impairment, and urged that doctors treat age-related hearing impairment more seriously.

The finding supports the view that use of hearing aids for the hearing impaired may help keep them more socially engaged, thus preventing or slowing the progression of cognitive decline and the development of dementia.

More than half of adults over age 75 have hearing loss, yet less than 15% of the hearing impaired use a hearing aid.

http://www.eurekalert.org/pub_releases/2016-04/cumc-hau042216.php

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