For the human
brain, there is no such thing as over the hill. Psychologists researching the
normal changes of ageing have found that although some aspects of memory and
processing change as people get older, simple behaviour changes can help people
stay sharp for as long as possible.
Although
researchers are still piecing together what happens in a healthy ageing brain,
they can explain some typical changes. Noted cognitive psychologists such as
Fergus Craik, PhD, and Timothy Salthouse, PhD, have been investigating what
happens and compiling the results, as well as trying to improve the methodology
of this growing field of research.
To understand what
happens on the outside, it is important to know what happens on the inside. The
brain's volume peaks in the early 20s and gradually declines for the rest of
life. In the 40s, when many people start to notice subtle changes in their
ability to remember new names or do more than one thing at a time, the cortex
starts to shrink. Other key areas also show modest changes. Neurons (nerve
cells) can shrink or atrophy and there is a large reduction in the
extensiveness of connections among neurons (dendritic loss). The normally
ageing brain has lower blood flow and gets less efficient at recruiting
different areas into operations.
As the brain
changes, so does behaviour. And so, given that blood flow drops the most in the
frontal cortex, people most commonly experience declines in verbal fluency or
the ability to find the words they want. They also have to work harder at "executive
function" planning and organizing their activities. The areas most
affected after that include the parietal cortex which affects construction and
visuomotor performance (practice that golf swing!), and the medial temporal
area which affects the ability to make new long-term memories and think
flexibly.
Using neuroimaging
and increasingly sensitive psychological tests, researchers have refuted the
model that people, as they get older, go into a general mental decline.
Instead, psychologists are developing a model of specific deficits that show
very different rates of decline and also vary widely among individuals. They
also suspect that middle-aged sensitivities about memory loss may be
exacerbated by comparisons with one's youthful performance. It may be more
realistic to compare one's performance to healthy age-matched peers instead.
Psychologists are
building evidence for a consistent pattern of change. Episodic (what did I have
for breakfast?), source (where did I learn about that new car?), and flashbulb
(where were you on April 1, 2022?) memory decline the most. Semantic (words,
facts and concepts) and procedural ("it is like riding a bicycle - you
never forget") memory decline the least. Storage capacity is not the
issue; the brain is not an overloaded hard drive. Rather, the changes appear to
come in how people encode and retrieve information. Interference, such as
distraction, blocks encoding more and slower processing may hurt retrieval,
such as being able to remember names and dates. Still, even with these subtle
changes, most older adults still seem to efficiently acquire new information
and park it in long-term memory. And implicit learning - learning without
conscious effort - seems to more or less be spared into old age.
Can anything be done
for older adults who start showing signs of memory problems? New evidence on
what can be done to keep older minds fit is demonstrated in psychologist
Michael Marsiske's research. Challenging oneself by learning a new language or
playing a new musical instrument may be a solution to preventing memory
problems or the development of dementia or Alzheimer's. From a study called
Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE), which
Marsiske co-directed with other psychologists (Karlene Ball, George Rebok,
Sherry Willis) and non-psychologists and with funding from the National
Institute on Ageing and the National Institute of Nursing Research, Marsiske
and colleagues found that short mental workouts improved performance and was
sustained even five years later. In the study, approximately 2,800 volunteers
were assigned to one of three training conditions (trained participants
received instruction in one of three different kinds of thinking skills:
memorizing lists, reasoning [looking for patterns in strings of numbers or
letters] and visual concentration.) and a condition where no training occurred.
All trained participants received a baseline of ten hours of instruction. Half of the trained participants received an extra eight hours of "booster" training. Five years later, compared to untrained controls, the participants in each training group still showed a significant performance advantage on learned thinking skills. Furthermore, participants receiving booster training showed even more significant benefit in the areas of reasoning and visual concentration. In addition, there was evidence that training "transferred" to real world skills. Participants in all three groups reported fewer limitations in performing tasks of daily living than the participants in the no training group. The participants in the reasoning-trained group showed the most improvement. And, in the area of visual concentration, participants who received eighteen hours of training (booster training group) were compared with those who received the basic ten hours of training, blind observers found that booster participants were significantly quicker at everyday activities, including accurately reading instructions on medicine bottles, finding items in a pantry or reacting to road signs on a computer.
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