Knowing how the normal brain ages - and
how those changes affect your memory - can make the occasional senior moment
less worrisome. Here’s a timetable of normal brain aging by decade, starting in
your twenties.
We tend to think of our brain as
different from our other organs. But the brain undergoes predictable changes
over time, just like the heart. As with heart disease, good genes and a healthy
lifestyle can moderate these age-related changes, but it can't entirely stop
them.
Contrary to popular belief, brain
neurons (nerve cells) do not undergo a massive die-off with age. Evidence now
suggests that some neurons are indeed lost, but the brain continues to grow new
ones, albeit at a slower pace. What does happen is that nerve cells in the
brain begin to shrink. As a result, the connections between neurons (synapses)
begin to deteriorate over time, and chemical messengers (neurotransmitters)
become less available to carry information.
With advancing years, these
age-related changes alter the transmission of nerve impulses through the brain,
leading to slower cognitive processing and delays in recalling stored
information. But in the absence of a brain-destroying condition like a stroke
or Alzheimer's disease, these changes are mostly a nuisance and don't interfere
with a person's ability to function successfully. A general time frame for
normal brain aging is described below.
Normal brain aging – Your
Twenties
People in their 20s are at the top
of their mental game in terms of forming long-term memories and being able to
engage in complex reasoning. Creativity, too, may be at its highest during
these years, although twenty-somethings don't have a lock on creative
endeavors. Many writers, artists, and musicians are their most productive
during this time. Slight physical changes in the brain, such as neuron
shrinkage, start in a person's 20s.
Normal brain aging – Your
Forties
Most people will sense some slowing
of their mental processing during their 40s, especially in the area of working
(short-term) memory. Tasks like remembering phone numbers, doing mental
calculations, or playing challenging card games may require more effort than
they did in earlier years. The slow loss of brain volume continues and may
begin to accelerate.
Normal brain aging – Your
Fifties
The 50s are a threshold, the
beginning of accelerated loss of brain volume and more noticeable changes in
memory and other areas of cognition. Cognitive changes include:
- Processing speed slows further. It takes more time to recall names and words.
- Learning something new takes longer. Once learned, however, the information is usually retained.
- Multi-tasking (doing several things at once) becomes more difficult.
- Attention to detail wanes. You probably will remember fewer details of a novel, movie, or painting than a younger person would.
- Placing an event in time and place becomes more difficult. You may remember the event but not exactly when or where it occurred.
- Visuospatial processing is more difficult. This might translate into more trouble in copying three-dimensional designs or in reassembling an appliance.
Normal brain aging – Your Sixties
Loss of brain volume continues. The
hippocampus and amygdala - brain structures that are critical to memory and
other cognitive abilities - are particularly vulnerable. These structures may
have shrunk by as much as 25% from their size in young adulthood. The cognitive
changes that began in the 50s become more noticeable in one's 60s. Cognitive
processing speed may slow further, making it more difficult to learn new
information or master complex mental tasks. It also becomes harder to
concentrate and to "tune out" distractions. The brain is less adept
at forming new memories and establishing the associations that enable us to
recall stored memories. Tip-of-the-tongue experiences are more common because
the brain has to work harder to retrieve names, dates, and words.
Normal brain aging – Your Seventies and beyond
People in their 70s and 80s vary
widely in their cognitive abilities. Many not only remain quite sharp
throughout these years but also gain in wisdom. For others, the wear-and-tear
of high blood pressure, diabetes, heavy alcohol use, and other health problems
will have taken a toll on memory and general cognitive ability. People who
develop dementia typically begin to show signs of the disorder in their mid-to
late-70s.
(Source: John Hopkins Health Alert,
posted in Memory on 29 March 2010)
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