|
|
|
|
Why some cope with stress better
than others
3 November, 2007
Scientists have identified a
difference in brain chemistry that
could explain why some people cope
better with stress than others.
Researchers from the University of
Texas Southwestern Medical Centre, the
United States, found that a key
pathway in mice differs in those who
cope well with stress and those who do
not.
The findings, published in the October
19, 2007, issue of the journal Cell,
could lead to new treatments for
conditions such as post-traumatic
stress disorder (PTSD). There is
increasing evidence that responses to
stress were linked to chemical
mechanisms in the brain.
People differ widely in their
responses to stressful situations –
while some people are highly resilient
to stress, some others struggle to
cope with stress.
The study found that, for example,
around a third of people might suffer
post-traumatic stress disorder after
an exceptionally traumatic event, such
as a terrorist attack or a natural
disaster.
The researchers examined differences
in mice facing a stressful situation
in the form of a larger more
aggressive mouse. Some of the mice
coped with the stress well and others
became timid and withdrew from social
interaction.
In the mice that did not cope well
with stress, nerve cells fired signals
at a faster rate in two areas of the
brain associated with pleasure and
reward, releasing a substance called
BDNF, which has previously been linked
to poor coping.
The resilient mice had no increase in
BDNF, probably because the neurons
were firing less rapidly. Blocking
BDNF in the timid mice caused them to
become more resistant to stress.
In mice, which coped better with
stress, there was also greater
regulation of genes in the key brain
regions, suggesting that resilience to
such conditions is an active process
rather than a lack of a response.
Analysis of brain samples from
depressed and non-depressed humans
showed that depressed people have a
40% increased level of BDNF.
The researchers concluded that
preventing BDNF release in certain
brain regions might be a way to
increasing the ability to cope with
stress or depression.
Dr Eric Nestler, professor of
psychiatry and leader of the study,
said chronic stress, depression,
post-traumatic stress disorder and
similar disorders might be treated by
promoting the mechanisms that underlie
resilience. However, he added, simply
blocking BDNF might also affect other
systems, so researchers would have to
find a way to target the specific
pathway involved in stress.
According to Dr Jonathan Bisson,
senior lecturer in psychiatry at the
University of Cardiff, the United
Kingdom, one of the theories of why
some people developed PTSD and others
did not was that certain areas of the
brain failed to tamp down the fearful
response to a traumatic situation.
Dr Martin Deahl, consultant
psychiatrist in Shropshire, the United
Kingdom, stressed that certainly
chemicals in the brain were very
important. However, “it does not mean
that you are born with it; life
experiences affects the makeup of
chemicals in the brain and why some
people are vulnerable is not known
exactly.”
|
|
|
|
|
|
