New Scientist – June 10 2017

NEWS & TECHNOLOGY
Drug boosts
self-confidence
Helen Thomson
LIFE is full of decisions, and it can
be hard to know if you’re making
the right one. But a drug that
blocks the rush of noradrenaline
through your body could boost
your confidence, and lead to
new treatments for obsessive
compulsive disorder.
How much we trust our
decisions is governed by
the process we use to assess
our own behaviour, called
metacognition. “We see many
symptoms associated with poor
metacognitive judgement in
schizophrenia and OCD,” says
Tobias Hauser at University
College London. “In OCD, for
instance, people may constantly
go and check whether they’ve
closed a door. They are poor at
judging whether they have done
something correctly or not.”
Little is known about the neural
underpinnings of metacognition,
but it is likely to involve brain
areas modulated by the chemicals
dopamine and noradrenaline. So
Hauser’s team asked 40 people to
take a drug that blocks dopamine
or noradrenaline either before or
after a placebo. Another 20 people
received two doses of the placebo.
Eighty minutes after receiving
their second treatment, the
volunteers performed a task in
which they had to decide whether
the overall motion of a burst
of randomly moving dots was
directed to the left or right. They
also indicated how confident
they were in each judgement.
Comparing self-assessed
confidence against actual
performance revealed that
reducing noradrenaline boosts
people’s metacognitive insight.
The drug that does this, called
propranolol, made volunteers
more likely to accurately say
whether their answer had been
correct or wrong, without
affecting the accuracy of their
decisions (eLife, doi.org/f955nn).
“This study is the first to
show that metacognition can be
selectively enhanced by drugs in
the absence of differences in task
performance,” says Steve Fleming
at University College London,
who wasn’t involved in the study.
Hauser says noradrenaline is
released when we unexpectedly
encounter uncertainty, such
as when we make an incorrect
decision. “We think this burst of
SUEDHANG/PLAINPICTURE
noradrenaline when you make
an error erases the information
about a task that you recently
stored in your memory.”
This could mean that someone
who has struggled to reach a
decision may have their system
reset, rendering them unable to
draw on as much information to
evaluate this decision. “You are no
longer able to properly judge how
well you did in the task because
you’re judging your decision
using less evidence,” says Hauser.
–Sure you’re choosing the right one?–
Blocking noradrenaline seems
to reduce this. Propranolol is
used to treat high blood pressure,
but it may also prove useful for
some of the symptoms of OCD
and schizophrenia.
People without conditions
like these may also benefit. “It is
likely to have an effect in real-life
decision-making. Whether you
trust what you’re writing, whether
you’re confident in what you’re
saying – all our actions involve
metacognition,” says Hauser. ■
Huge methane
blowout as the
ice age ended
CALL it the largest fart in Earth’s
history. As the ice age came to a close
12,000 years ago, retreating glaciers
in the Barents Sea north of Norway
triggered unprecedented blowouts of
methane gas from massive dome-like
features – pingos – on the seabed.
Karin Andreassen at the Centre for
Arctic Gas Hydrate, Environment and
Climate at the Arctic University of
Norway, and her colleagues, pieced
together the story using detailed
seismic and geologic data of the
Barents seabed captured through
high-resolution echo sounding
from ships. They also looked at the
composition of methane-containing
gases still spewing up from the
remains of 100 pingos.
Analysis of the gas profiles
revealed that the methane originated
30,000 years ago from hydrocarboncontaining
rock about a kilometre
below the seabed. Thick layers of ice
over the seabed kept any methane
that percolated upwards trapped in
the uppermost layer of sediment.
Inside the sediment, the gas was
converted into a solid ice-like mixture
called a gas hydrate.
Then, 17,000 to 15,000 years ago,
the ice sheet began to retreat rapidly.
The hydrates began to decompose,
forming the kilometre-wide methane
blisters, or pingos, on the seafloor,
beneath a thin crust of remaining
gas hydrate.
“When the ice sheets
melted the pingos burst,
belching methane into
the atmosphere”
By 12,000 years ago, the ice
sheets had melted and the pingos
were exposed to warm water that
weakened the remaining gas hydrates
so much they burst, belching methane
into the atmosphere (Science, DOI:
10.1126/science.aal4500).
The risks of something similar
happening today are hard to predict.
“Unless a glacier happens to cap
a deep thermogenic [hydrocarbon]
source, the lack of any carbon would
preclude the formation of massive
shallow hydrates,” says Patrick Crill at
Stockholm University in Sweden. “So
I’m not too worried.” Andy Coghlan ■
12|NewScientist|10June2017