There is a very common form of forgetfulness that is not really a failure of memory. When we get in our car to drive to place A and find ourselves instead on the road to the more familiar place B, this is not a failure of memory. When we clear the table and find ourselves putting the margarine in the dishwasher or the dirty plate in the fridge, this is not a failure of memory. When we go into a room intending to do one thing and do something else instead, this is not, really, a failure of memory.
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Prevalence of Parkinson's Disease
After Alzheimer's disease, the second most common neurodegenerative disorder is Parkinson’s disease. In the U.S., at least 500,000 are believed to have Parkinson’s, and about 50,000 new cases are diagnosed every year1 (I have seen other estimates of 1 million and 1.5 million — and researchers saying the numbers are consistently over-estimated while others that they are consistently under-estimated!). In the U.K., the numbers are 120,000 and 10,0002.
Most cognitive processes decline with age
It does appear that most component processes of cognition decline with advanced age if the difficulty level is sufficiently high. For example, the following processes have all shown age effects:
You may have heard of “g”. It’s the closest we’ve come to that elusive attribute known as “intelligence”, but it is in fact a psychometric construct, that is, we surmise its presence from the way in which scores on various cognitive tests positively correlate.
In other words, we don’t really know what it is (hence the fact it is called “g”, rather than something more intelligible), and in fact, it is wrong to think of it as a thing. What it is, is a manifestation of some property or properties of the brain — and we don’t know what these are.
I recently read an interesting article in the Smithsonian about procrastination and why it’s good for you. Frank Partnoy, author of a new book on the subject, pointed out that procrastination only began to be regarded as a bad thing by the Puritans — earlier (among the Greeks and Romans, for example), it was regarded more as a sign of wisdom.
Many people, particularly as they get older, have concerns about short-term memory problems: going to another room to do something and then forgetting why you’re there; deciding to do something, becoming distracted by another task, and then forgetting the original intention; uncertainty about whether you have just performed a routine task; forgetting things you’ve said or done seconds after having said or done them; thinking of something you want to say during a conversation, then forgetting what it was by the time it’s your turn to speak, and so on.
Brain autopsies have revealed that a significant number of people die with Alzheimer’s disease evident in their brain, although in life their cognition wasn’t obviously impaired. From this, the idea of a “cognitive reserve” has arisen — the idea that brains with a higher level of neuroplasticity can continue to work apparently normally in the presence of (sometimes quite extensive) brain damage.
"Consolidation" is a term that is bandied about a lot in recent memory research. Here's my take on what it means.
Becoming a memory
Initially, information is thought to be encoded as patterns of neural activity — cells "talking" to each other. Later, the information is coded in more persistent molecular or structural formats (e.g., the formation of new synapses). It has been assumed that once this occurs, the memory is "fixed" — a permanent, unchanging, representation.
The other day I was sitting in the sunshine in my living room going through some journal articles I'd photocopied. I realized I needed to staple the pages together and went down to my study to get the stapler. Approaching my desk, I decided to check my email while I was there. And then, I decided to check my library account online to see whether a book I had requested had turned up. When I'd done that, I went back upstairs to my papers. Where I realized, of course, that I'd forgotten the stapler.
We don’t deliberately practice our memories of events — not as a rule, anyway. But we don’t need to — because just living our life is sufficient to bring about the practice. We remember happy, or unpleasant, events to ourselves, and we recount our memories to other people. Some will become familiar stories that we re-tell again and again. But facts, the sort of information we learn in formal settings such as school and university, these are not something we tend to repeatedly recount to ourselves or others — not for pleasure anyway!