Dementia scares people. Rates are rising.  New evidence shows decreased vision and hearing make dementia more likely.  One study out of Stanford found people who had vision loss and did not seek treatment showed five times the cognitive decline rate, and over nine times the Alzheimer’s rate as those without problems, through a period of eight and  a half years.

What gives? When the brain has trouble learning, it regenerates less – and less effectively. And when seeing and hearing decline even a bit, it’s not just harder to do simple tasks.  It’s harder to integrate everything else.

Seeing is Believing

We trust our vision.  Magicians trust that trust to fool us.

For most of our senses are tricks.   We normally “see” upside down and backwards.  Tens of thousands of image “pieces” are sent deep into our brains.  There they are picked up, connected, reorganized and rerouted.  Next pieced together inside other memories of what we have seen.  That’s what we call vision.

And all the while all that information is percolating through many different organs, affecting our speech, our thoughts, our movements, and pretty much all we do.

For much of what we “see” is cached memory.  We only focus on certain things, one at a time.  Magicians know this.  They let us think we’ve seen “everything” while moving about  through areas we do not well visualize, or just actively ignore.

Usually it is harder to trick hearing.  Hearing never turns off.  It is always checking the environment. And helping us learn from it.

For everything we do trains us.  That’s the nature of biological intelligence. The environment changes, we change.

So even small shifts in vision and hearing change the information flow across multiple body systems.  Particularly ones  we don’t think about.

How It Works

What happens when less information comes in than before?  It gets mashed up.   Garbled.

Consider cell phones. Move a few feet here or there.  Often you start missing words.  Sometimes service disintegrates completely.

So just think what happens when vision and hearing subtly decline.  Information quality is less.  All the way down the line.

Some of this loss is  cognitive.  If your vision is impaired it’s harder to read.  If you hear less well, it’s harder to differentiate words and sentences.

Yet other systems are affected, too.  Your muscles.  Your joints.  Figuring out where you are in three dimensional space.  All require good hearing and vision.

There are also knock on effects on stuff we normally are not conscious of. Like blood pressure and heart rate.  If the quality of information about the environment is subtly less, it’s harder to make corrections.

Even systems like immunity may be affected.  Moving more through the environment makes for greater learning.  People who walk in the morning experience less colds.

But if you can’t see well?  You’re less prone to go out and walk.  You’ll fear falling more, adding stress.  If you move around less, you’ll probably socialize less, leading to fewer of the many advantages of social contact, a large factor in preventing heart disease.

The same can be said for hearing loss.  People who can’t hear well often complain that restaurants and large social gatherings are a particular trial.  So they don’t go out as much.

And the body’s overall learning diminishes.

For all our information systems  are interconnected.  That includes ones like immunity, and the autonomic nervous system, we usually don’t think about very much.  Diminish the quality of biological information, and more work needs to be done with less resources.

What To Do

Some may think that aging itself means all these systems will decline together.  But that’s not necessarily true.

There’s plenty to do.

As Jane Brody points out, the medical care system can be helpful. Treat the glaucoma, get a functioning hearing aid that doesn’t bankrupt you, and information quality and flow are improved.

Many other factors worsen the risk of dementia.  They include depression, diabetes, heart disease and hypertension, and major sleep loss.  Improve each of these and information flow gets better.

Plus there are simple things that work.  Walking can improve depression and decrease the risk of hypertension, heart disease and stroke.  Socializing works very differently but has positive results for the same outcomes.  Having a well set biological clock system makes everything work together better.

Dementia is a failure of biological intelligence.  Multiple factors corrode the ability of the brain to reset and rebuild itself.

Yet we can aid that reset through our actions.   Everything we do is a teaching moment for the body.  Moving, conversing, visiting different environments, all help the body learn more and become more effective at adapting.

Intelligence is more than innate. It’s learned.  And the simplest modes  of activity and rest can teach it every day of your life.