DEAR DOCTOR K:
What kind of memory changes am I likely to experience as I get older? Why do these changes happen?
Many people begin to notice changes in their powers of recall around the age of 50. You may have to rack your brain to remember a name or word that is familiar to you. You may find it increasingly difficult to divide your attention among more than one activity or source of information. And you may get more easily distracted than when you were younger.
You’ll notice that different kinds of memory decline with age. These include episodic memory (which stock you sold last year from your retirement account), semantic memory (facts, such as the year World War I started) and spatial memory (such as the directions to a new location). Changes in the brain may be to blame.
Storing memories is a three-step process. In the first step, your brain acquires an experience. It does this by encoding the memory of that experience. That short-term memory is temporarily stored. Then it is consolidated into a more lasting memory. The last step in the memory process is retrieval. To recall a memory, your brain must reactivate the right pattern of neurons.
I think of it in terms of what happens with your computer. You type information into the microprocessor or central processing unit — the “thinking” part of the computer, or “consciousness.” That typed information is the “experience.” The thinking part of the computer then sends the information to a temporary storage area, random-access memory (RAM). Then it is sent to long-term memory — the “C drive.” When that information needs to be retrieved, the microprocessor goes and finds it on the C drive and pulls it back into consciousness.
(I hope any brain scientists that may be reading this column will forgive me this oversimplification.)
Changes take place in the brain as we age. These changes can undermine the encoding, consolidation and retrieval of new information. For example, as we age, we lose neurons in the hippocampus, a brain area involved with memory processing. In another change, structures on the surface of neurons that allow them to communicate with one another may stop functioning normally.
These changes make it harder to concentrate. As you age, you learn information more slowly and may not absorb as much detail. You may have more trouble recalling information because you didn’t fully learn it in the first place. (The memories that last are those that you paid the closest attention to when you formed them.)
In addition, executive function, which involves the overall regulation of thinking and behavior, declines with age. These higher-order processes are what enable us to plan, sequence, initiate and work toward some goal.
These changes may sound disturbing, but they don’t impair your ability to function effectively. Your ability to make sense of what you know and to form reasonable arguments and judgments is well-preserved. Moreover, the wisdom that you’ve gained from experience over the years remains unscathed.