Vârstele creierului IV
- From: Confutius <proroku@xxxxxxxxxxx>
- Date: Sun, 5 Apr 2009 05:51:16 -0700 (PDT)
The five ages of the brain: Adulthood
05 April 2009 by Graham Lawton
New Scientist
The slippery slope
So you're in your early 20s and your brain has finally reached
adulthood. Enjoy it while it lasts. The peak of your brain's powers
comes at around age 22 and lasts for just half a decade. From there
it's downhill all the way.
The peak of your brain's powers comes at age 22 and lasts for just
half a decade
This long, slow decline begins at about 27 and runs throughout
adulthood, although different abilities decline at different rates.
Curiously, the ones that start to go first - those involved with
executive control, such as planning and task coordination - are the
ones that took the longest to appear during your teens. These
abilities are associated with the prefrontal and temporal cortices,
which are still maturing well into your early 20s.
Episodic memory, which is involved in recalling events, also declines
rapidly, while the brain's processing speed slows down and working
memory is able to store less information.
So just how fast is the decline? According to research by Art Kramer,
a psychologist at the University of Illinois in Urbana-Champaign, and
others, from our mid-20s we lose up to 1 point per decade on a test
called the mini mental state examination (see graph). This is a 30-
point test of arithmetic, language and basic motor skills that is
typically used to assess how fast people with dementia are declining.
A 3 to 4 point drop is considered clinically significant. In other
words, the decline people typically experience between 25 and 65 has
real-world consequences.
That all sounds rather depressing, but there is an upside. The
abilities that decline in adulthood rely on "fluid intelligence" - the
underlying processing speed of your brain. But so-called "crystallised
intelligence", which is roughly equivalent to wisdom, heads in the
other direction. So even as your fluid intelligence sags, along with
your face and your bottom, your crystallised intelligence keeps
growing along with your waistline. The two appear to cancel each other
out, at least until we reach our 60s and 70s (see "The five ages of
the brain: 5 Old age").
There's another reason to be cheerful. Staying mentally and physically
active, eating a decent diet and avoiding cigarettes, booze and mind-
altering drugs seem to slow down the inevitable decline. And if it is
too late to live the clean life, don't panic. You still have one more
chance to turn it around.
.
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