14957Good News About Gettin Old
- Jun 28, 2006Older but Mellower: Aging brain shifts gears to
Given all the bad news that science has delivered about
brain cells withering and memory waning as the years mount,
older people have a right to be cranky. But, instead, the
over-50 crowd handles life's rotten realities and finds
life's bright side more effectively than whippersnappers
do. In no small part, that's because the aging brain makes
critical emotional adjustments, a new study indicates.
Advancing age heralds a growth in emotional stability
accompanied by a neural transition to increased control
over negative emotions and greater accessibility of
positive emotions, according to a team led by neuroscientist
Leanne M. Williams of Westmead (Australia) Hospital. A brain
area needed for conscious thought, the medial prefrontal
cortex, primarily influences these emotional reactions in
older adults, Williams and her colleagues say.
In contrast, people under age 50 experience negative
emotions more easily than they do positive ones. These
younger adults' emotion-related activity centers on the
amygdala, a brain structure previously implicated in
automatic fear responses.
This gradual reorganization of the brain's emotion system
may result from older folk responding to accumulating
personal experiences by increasingly looking for meaning
in life, the researchers propose in the June 14 Journal of
Evidence that emotional functions improve in older brains
"indicates that our ability to register the significance of
information is preserved, and even enhanced, as we age,"
Williams says. Older people may benefit from associating
information they need to remember with personally
significant matters, such as a favorite tune, he adds.
Ironically, older individuals' reliance on the medial
prefrontal cortex to regulate emotions comes as aging kills
cells in this area. The surviving neurons somehow pick up
the slack, the investigators note.
The researchers studied 122 males and 120 females, ages 12
to 79, who had no current or past mental illnesses and good
Scores on a questionnaire that assesses emotional stability
rose steadily from adolescence into the senior years.
Brain testing occurred as volunteers viewed images of various
facial expressions. They had been told to identify the
emotion in each expression and to rank its intensity.
Researchers measured neural response using functional
magnetic resonance imaging, which tracked blood-flow changes,
and an electrode-studded cap that monitored brain cells'
In older adults, mushrooming medial prefrontal cortex
activity triggered by negative facial expressions occurred
in conjunction with neural responses that have been linked
to conscious thought. This pattern appeared even in older
adults who displayed especially low numbers of prefrontal
In contrast, young people showed far more medial prefrontal
activity, and thus conscious thought, in response to positive
facial expressions than older people did.
The new results provide a neural framework for growing
evidence that, unlike young people, older adults focus on
positive information and downplay negative events, remarks
psychologist Mara Mather of the University of California,
Santa Cruz. The amygdala showed little volume decline with
age in the new study, so it's unlikely that age-related
shrinkage of that structure causes the psychological shift,
"Older adults apparently use cognitive-control processes
supported by prefrontal brain regions to help them avoid
experiencing negative information and focus instead on
positive information," Mather says.