Cognitive Shields Protecting Against Dementia

This post is based largely on “Cognitive Shields” by Andrew Merluzzi in the .  Psychological Science Observer (February 2015, 21-28).   There have been many previous Healthymemory blog posts about autopsies of people who have exhibited no symptoms of Alzheimer’s while alive, but who nevertheless have the so-called amyloid plaques and neurofibrillary tangles which provide the definitive basis for diagnosing the disease.  Now I have a percentage to place on this statement.  About a third of post-mortem brains with the telltale features of dementia—protein tangles or miniature strokes-came from people who never exhibited symptoms during life.

The explanation that has been offered for this is that certain individuals might build buffers over their lifetimes called cognitive reserve.  This post provides information on research on the cognitive shields that build this cognitive reserve.  Actively engaging the brain can boost older adult’s recall power.  One experiment randomly more than 200 adults (ages 60-90) to engage in a particular type of activity for 15 hours a week over the course of three months.  Some activities required significant cognitive investment such as digital photography or quilting.  The other participants engaged in more leisurely activities such as listening to classical music or completing word puzzles.  At the end of the experiment participants who engaged in digital photography or quilting showed a significant improvement in memory compared to the leisurely activity participants.

Another experiment  recruited 16 older adults to play a video game called “Neuroracer.”   Participants attempted to drive a car down a virtual road, keeping constant speed and lane position.  As they were doing this they also had to pay attention to sporadically appearing shapes, pressing a button whenever they observed a green circle.  The game became more difficult as performance improved.  The comparison group played an easier version of the game where they had to drive or pay attention to shapes, but not simultaneously.  The group who played the more difficult version of the game scored better on unrelated cognitive tests. Brain imaging with an EEG revealed noticeable differences at the neural level.  Participants who played the difficult version of the game  showed more coherent activation patterns in cognitive control networks including the prefrontal cortex.  These cognitive gains were still apparent six months later.

Physical exercise is also important as it increases the flow of oxygen to the brain.  See the healthy memory blog post “To Improve Your Memory, Build Your Hippocampus” (use the healthy memory blog search box).

Another study investigated whether exercise can induce neuroprotective effects for people who have a genetic risk for Alzheimer’s.  One hundred older adults many who carried the APOE gene which increases the risk of Alzheimer’s were studied.  The participants explained their normal exercise habits and had their brains scanned twice over a period of 18 months.  It was found that exercise was critically important for the at risk group with the APOE gene.  People with this gene who didn’t exercise exhibited a 3% decrease in hippocampal volume over time.  Those carrying the gene who did incorporate exercise into their lives—more than 15 minutes of moderate exercise at least three days a week—didn’t show any decreases in hippocampal volume.  The conjectures for this result are that staying active might reduce inflammation in the brain and promote neural growth in the hippocampus building  up cognitive and brain reserve.

Research has also found that bilingual older adults have more robust white matter then monolingual adults.  This suggests that the myelin on axons in these her bundles is more intact, which would help  to buffer against age-related changes in the size and structure of the brain.  Sone also argue that it might never be too late to learn another language.  But this does take commitment.

There are many more healthy memory blog posts on the cognitive reserve and the benefits of both cognitive and physical exercise.  It is important that this information be disseminated.  People should know that they need not be passive victims of dementia, nor should they wait for a medical treatment or vaccine to treat or prevent Alzheimer’s.  To a large exert we control our own fates and should take action.


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