22 February 2020 | New Scientist | 37We all inherit different variations of NPY
genes. Some protect against stress, while
others increase the risk of an impaired stress
response and the psychiatric conditions
related to this. So perhaps these special forces
soldiers hit the genetic jackpot. However, there
are tantalising hints that we aren’t stuck with
the NPY that our genes dictate. For instance,
after a surprise simulated ambush, the
NPY levels of marines who had previously
completed an eight-week course on
mindfulness returned to normal far quicker
than those of soldiers without such training.
Another common thread that links
chilled-out people is to do with their personality,
particularly their sense of humour. Research
shows that people who see the funny side of
life’s mishaps are likely to interpret and react
to stress more positively, buffering themselves
against some of the negative effects. For
instance, in a study of firefighters, Michael
Sliter at Indiana University–Purdue University
Indianapolis, found that, in general, the
number of symptoms of PTSD and burnout
they reported correlated with the number of
stressful situations they had been in over the
past month. But firefighters who used humour
more often as a coping mechanism were less
likely to experience these negative effects.
Laughing releases feel-good hormones
thought to make us less likely to ruminate on
or re-experience stressful events. It also helps
us build relationships, providing the social
support that is a key to resilience. But there is
good news for anyone who struggles to find
their funny bone. A pilot study in Austria
put 35 people who were experiencing stress,
exhaustion or depressive symptoms through
a seven-week “humour training” course,
including role play, finding humour in
everyday life, cultivating playfulness and
learning how to make others laugh. The
training seemed to decrease perceived stress
and increase cheerfulness, although it was
limited by not having a control group.
An additional factor influencing your
stress resilience is more surprising. Growing
evidence points to an intimate relationship
between gut bacteria and our mood and
behaviour. What’s more, several studies
have highlighted differences between the
gut bacteria in people with stress-related
conditions, such as depression and PTSD,
and in people without these. Stress can also
make your gut more leaky, allowing bacteria
to escape into your bloodstream, which
triggers inflammation that can lead to physical
and mental health problems. One study, for
example, found that couples experiencing“If they are able to find the same
ingredients – dependable, supportive,
close relationships – the ill effects of
childhood adversity can certainly be reduced.”
Moreover, an individual’s ability to cope
with stress isn’t purely down to early life
experiences. Genes also play a role, especially
those involved in the production of a chemical
called neuropeptide Y (NPY). Exactly how this
works is unknown, but animal experiments
suggest that NPY acts as a kind of on-off switch
for the stress response. Faced with a threat,
production soars, helping to instigate a rapid
response, but levels quickly return to normal
once the danger is over.
To assess NPY’s role in humans, studies often
focus on members of elite military forces who
perform well under extreme stress. For
example, researchers at the US National Center
for PTSD in Connecticut compared blood
samples from US special forces and regular
soldiers during a training exercise at Fort Bragg
in North Carolina, where they were deprived
of food and sleep, pursued by the “enemy”
and interrogated when caught. This revealed
that the special forces soldiers sustained
higher levels of NPY for longer during the
exercise. Their NPY also returned to its
original level more quickly afterwards,
showing that they were better able to recover
from the stress they had experienced. In
addition, the more NPY an individual released,
the less confusion and fewer mental health
issues they reported during the training.Whether facing
a delayed flight
(left) or a war
zone (below),
our natural
resilience to
stress varies,
but we can learn
to cope better“ Human studies
often focus on
members of elite
military forces
who perform well
under stress”
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