age memory loss alzheimers

Age-related memory loss is annoying and sometimes alarming (“Am I losing my mind”?), but you should relax. It’s perfectly normal. There is a difference between age-related memory loss and memory loss due to the more serious condition, Alzheimer’s disease.

Why does it happen? The answer to such a simple question is only now becoming understood. Scientists’ forays into the brain have yielded a rich understanding of how it works, and studies on memory, in particular, are shedding light on the dark corners of cognition.

 

Two types of memory

There are two types of memory: long-term memory and short-term memory, which is also called working memory. Long-term memory is etched into our brain through neuronal circuits that are formed by protein bridges. Formation of these bridges requires repetition. For example, if you crammed for a test the night before and never reviewed it again, you may remember the stuff until the test, but the information will be consigned to oblivion. This is the nature of short-term memory.

But repeating the information again and again will result in the formation of thicker and thicker protein bridges. Remember how painful it was to memorize the multiplication tables for the first time? I trust you don’t have a problem with it anymore because you repeated it thousands of times by now.

Indeed, aging adults don’t have much problem with long-term memory. The problem we have is remembering where we left the car keys. I have probably spent a month’s worth of my life looking for my glasses, the car keys, and most embarrassingly, my car in the parking garage. If you think that’s no big deal, just ask Republican presidential primary candidate, Rick Perry who lost 2011 race because of a nationally-televised “senior moment”—now better known as his “Oops Moment.”

Working memory is somewhat different. It is the temporary retention of information that was just experienced, but no longer exists in the external environment (“what’s the phone number Siri gave me 10 minutes ago?”). Or it could be something that was just retrieved from long-term memory (“I left my car yesterday on the second level, which I don’t normally use”). Working memory is what enables us to keep several pieces of information active while we try to do something with them.

Until relatively recently, the dogma was that we can store 7 (plus or minus 2) items, such as a string of numbers or words, in short term memory. But memory whizzes have proved academics wrong. They devised the technique of chunking, in which you string together chunks of items. For example, you could probably retain the string 1,4,9,2,1,0,1,2 if you try to remember them as individual items. But if you chunk 1492 and 10/12 (Columbus lands in the Bahamas in 1492, on October 12), you could remember a lot more. In fact, if you can make up a story out of each chunk, you can remember a huge number of items.

Experiments have shown that the number of chunks that can be stored in short-term memory tends to fall around 4. Although tricks like this can be quite useful for impressing your friends at a cocktail party, working memory is, in fact, quite purposeful. We hold all these pieces of information together in order to solve a problem or carry out a task. And when we are done with the task, we allow the memory to fade because there is no point in burdening the brain with unnecessary information.

 

Pay attention!

If you read Joshua Foer’s wonderful book Moonwalking with Einstein, you will realize that remembering 4 chunks of data is a gross underestimation. This is because that is the number of chunks you can remember if you are only allowed to view the data for a short time—say 1 second because you are competing in a memory contest. But if you are given enough time to pay attention, then the number of chunks you can remember is theoretically unlimited. It’s a function of how imaginative you are in making up a story that strings them together in a way that is meaningful to you.

Attention and short-term memory are closely associated in the brain. In fact, there are a lot of neurobiological evidence that suggests the anatomical location of attention and short-term memory overlap in the brain and may well be identical. Studies using fMRI show that the same areas ‘light up’ when attention and memory are tested.

 

A bit of anatomy and physiology

Neurophysiological studies (EEG) and imaging studies (fMRI) all point to the posterior parietal lobe, at the junction with the temporal lobe (temporoparietal junction) as central to working (short-term) memory. But that’s not the only region involved in short-term memory. The visual cortex, located in the occipital lobe, just posterior to the parietal lobe, is activated when the memory has a visual component. And the auditory cortex is activated when sound (such as musical, or phonological, components are involved). The “traffic cop” that filters and organizes all these stimuli resides in the dorsolateral (upper and to the side) of the prefrontal cortex (PFC).

The prefrontal cortex is in the front of the frontal lobe

The neurons that store memories don’t just sit there passively, rather they excite each other to keep information “in mind”, that is, generating persistent electrical activity. Recent data show that an intracellular molecule, cyclic adenosine monophosphate (cAMP), weakens the connectivity between the neurons whereas inhibiting cAMP signaling strengthens connectivity and cognitive ability.

 

How can we use this information?

Several facts stand out. First and foremost, pay attention! Don’t just drop your keys wherever. Make a mental note: Keys are in the bowl that is on the kitchen table. Another example is the recollection of drivers compared to passengers. If you drive the car to a new friend’s house, you would most likely be able to find it again the next day (provided you weren’t just following the instructions on your GPS app). But if you were just a passenger in the car, you would have a much harder time finding your way. This is because as a driver, you have to pay attention to your environment, and consciously or unconsciously, you fix signposts and cues in your mind. As a passive passenger, you don’t have to.

Another practical lesson is repetition. You create thicker, more lasting connections between the neurons that store the memory. As we get older, we find it more difficult to learn a foreign language. But it is not impossible. Just repeat the word or phrase again and again. You will eventually master it—guaranteed.

As any chess player will tell you: The masters have an amazingly quick reaction to any position on the board. What would take me many minutes to analyze, they do in a second or two. What’s their secret? Are they super intelligent (or am I stupid)? The answer is neither—it is practice, or in other words, repetition. Those whizzes have under their belts thousands and thousands of games. They have seen them all, several times over. So when they are faced with a certain pattern, they recognize it immediately.

Malcolm Gladwell popularized the idea that 10,000 hours of practice will turn you an “outlier” (namely, exceptional) in your chosen skill. Hogwash! If you practice even 100,000 hours, but your mind is miles away, you’d accomplish close to nothing. You can become an expert in your skill, but you need to pay attention, be mindful, and focus. In other words, the quality of practice counts more than its quantity.

In general, you need to keep your body, and your brain, in good shape and exercise, and keep your mind engaged by reading, writing, and learning new skills, such as a musical instrument or a new language. These activities increase the blood flow to the brain and release brain-derived neurotrophic factor (BDNF), a peptide important in creating new neurons and maintaining the protein bridges between neurons that absolutely essential to maintaining memory.

And, while you are at it, don’t forget to eat your veggies and fruits and get plenty of exercise because, as they say, you are what you eat and what you do.


This post was first published on April 13, 2012. It was reviewed by the author and updated on 07/06/2017.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.

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