Sunday, December 25, 2011

Memory Protection

We are talking about memory.  In the last post, I mostly rambled on about some past memories, both first-hand memories as well as second-hand (an interesting thought: how many of your memories are based on vivid events someone else experienced and told to you?).  My original intent, however, was to do some exploring about the neurological aspect of memory.  So I'll continue here with more focus on cognition and memory.

I was watching a TV show the other night called "Into the Wormhole", which talks about the latest research in physics and related topics. This episode was about immortality and geriatric research (I suppose this is physics--immortality.....infinity?) and some promising progress toward extending the life span of yeast and mice.  The researchers confidently state that that it won't be long before human life spans will be increased to 800 years or more.  Really? Aside from the question of where we're going to put all those octocentinarians (didn't these researchers ever learn about "carrying capacity" in school?), there's the worry about caring for them.  Perhaps their bodies can live for 800 years, but what about their minds and memories? 

Most people suffer what is known as Age-Related Memory Impairment (AMi), and the deficits often involve short-term memory. As people age, their ability to refresh recently acquired information declines.  This decline is linked to faults in "episodic memory" processing, which relies on knowing the when and where the information was acquired.  That is, the information content is linked to the source of the information and associated physical or emotional factors, so that remembering is facilitated, for example, by simply imagining where you were when the information was acquired.  As a student, I could often recall my notes on a specific topic by visualizing the page in my textbook or notebook.  That linking apparently does not work as well as we age--with new information.  I think such links remain mostly intact for memories laid down when we were younger (for normal aging; people with diseases such as Alzheimer's apparently suffer more severe injuries to neural pathways). So, a sight or smell or activity (brushing your hair, feeding the dog) automatically stimulates a specific memory or recall of information learned in the distant past. 

As we age, those associations between the information and the surrounding factors are not made or are only poorly made.  That is my observation of my short-term memory changes.  I will perform some routine task such as taking a daily vitamin or brushing my teeth and an hour later I'm wondering if I did or if I'm remembering yesterday's routine. I cannot recall anything specific or different about the surroundings that would tell me, "Yes, you definitely took your vitamin because the phone rang right after or you noticed that a light bulb was burned out in the bathroom."  These lapses happen to everyone at all ages, but now seem to be more frequent. I now consciously note something about my surroundings or do something unusual (reverse my routine) if I want to ensure I recall doing something (and avoid repeating it). I now appreciate why those pill dispensers with compartments corresponding to the days of the week are so popular with the elderly.

In his later years, my father seemed to have suffered from an extreme case of short-term memory loss.  He could not remember what he had for lunch or that he had just taken his medication an hour before (although he could vividly remember events 70 years in the past).  His inability to make that linkage between the act of taking his medicine and the situation surrounding that act (who was present, what time of day it was, whether the TV was playing, etc.) meant that he could not distinguish that particular event from similar events of taking his medicine on previous days.  This memory impairment was incredibly stressful for him because he was aware of it.  If you asked him, he could not tell you whether or not he had taken his medicine that day. He remembered taking medicine in the past, but not specific instances. 

What can one do to protect memory as we age? There are all the usual suggestions: keeping mentally active, following a healthy diet, avoiding medications that impair memory, etc.  Those of us in science have no deficiency in terms of intellectual activities.  We write, do math, create graphics and other visual images, and speak in front of audiences.  We use "both sides" of our brains: the left hemisphere, which supposedly involves linear, logical, analytical thinking and the right, which involves nonlinear, holistic, intuitive thinking. Is this enough to protect us from AMi or more dreaded things such as dementia? I once thought so, but am not so sure anymore. 

I came across an interesting bit of research, which found that auditory training (music training) improved memory abilities as one ages.  In fact, the number of years of musical training was predictive of non-verbal memory performance and time span of cognitive ability.  The suggestion seems to be that there is something unique about the auditory experience.  Perhaps.  Or maybe it's just the fact that musicians have developed secondary linkages in their brains through a novel activity that is unlike daily activities involving, for example, reading or writing or walking.  In other words, your brain has developed backup pathways that can take over when the primary ones are blocked during aging or disease.

My guess is that other novel activities requiring mental concentration or memorization (and stimulate new neural linkages) would work similarly.  I've mentioned this idea before, but it's worth repeating.  In his book, "A Whole New Mind" Daniel Pink talks about how to expand your mind or to keep it sharp.  One activity he explored was drawing.  He signed up for drawing lessons and discovered that drawing is all about relationships or "perspective".  Drawing is all about seeing, in other words.  Learning to draw or paint will develop and strengthen aspects of your brain that you may not use often.

I think the novel aspect of the activity is what is relevant, not the specific activity.

I think the take-home message here is: have some hobbies that are mentally challenging and different from your primary work activities.  If drawing or playing a musical instrument do not appeal to you, I think physical activities requiring substantial skill or concentration will do the same thing: golf, skiing, surfing, Tai Chi, or learning a second language.  It's not clear if taking up these things later in life has the same effect as adopting them in one's twenties.  I imagine that forming redundant pathways and linkages early on when your brain is still developing is more effective than trying to do it with an older brain.  I played a musical instrument for many years and also developed drawing and painting skills.  In my thirties and early forties, I learned karate and became fairly skilled at it.  I no longer play an instrument or train in karate, but I think those brain pathways are still there; I remember how to read music, for example, or perform a karate move (although my body may no longer be able to carry out the physical action).  Now I wish I had done more activities like these.

But, it's never too late. 

There are programs involving brain games designed to improve cognitive function such as Lumosity and CogniFit.  You usually have to pay a subscription to get access to all the programs designed to get your brain in shape.  Some will do an assessment of your cognitive abilities for free and let you do some initial training.  I've tried these and they definitely teach you some things about your mental abilities and where you need improvement.  I was shocked to discover that my "working memory" was way, way above average, more than twice that of the world average (either I am that good or the people taking the assessment are really bad at this).  This score did not agree with my impression that my memory was on the decline.  My reaction time was also above average--again not my perception.  On the other hand, my divided attention and spatial perception abilities, which I always thought were very good, were below average.  In any case, wherever your weakness, the program designs training to improve those cognitive skills.

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