19 October 2019 | New Scientist | 9FOR people who are addicted
to cannabis, one treatment
option may be, paradoxically,
to take pills that contain an
extract of the drug.
The first test of the idea
has found that people taking
capsules of this extract, known
as cannabidiol (CBD), nearly
halved the amount of cannabis
they smoked, according to
results presented at New
Scientist Live on 12 October.
Cannabis is often seen as a
soft drug, but according to one
estimate about one in 10 people
can become addicted, getting
withdrawal symptoms such as
anxiety when they try to stop
using it. The number of those
seeking treatment because they
can’t quit smoking cannabis has
been rising in the past decade,
linked with use of the more
potent form known as skunk,
said Val Curran of UniversityCollege London at the event.
There are two main
psychoactive substances
in cannabis, one of which is
CBD. The other compound is
tetrahydrocannabinol (THC),
which is responsible for the
drug’s high. While THC tends
to increase anxiety, CBD calms.
“CBD gets rid of the toxic
effects of THC,” said Curran.
Her team ran a trial, in
which people took CBD for four
weeks to alleviate withdrawal
symptoms to help them quit
smoking cannabis. It involved
82 people classed as severely
addicted to the drug, who
were given one of three different
doses of CBD in capsule form
or a placebo. All of them also
had psychological support.
The middle dose of
400 milligrams worked best,
said Curran. After six months,
it halved the amount of
cannabis people used compared
with placebo, as shown by tests
for THC in their urine. The
highest dose of 800 milligramswas slightly less effective than
the middle one. The lowest dose
didn’t work. The 400 milligram
dose also more than doubled
the number of days when
people had no THC in their
urine. “That’s really
remarkable,” said Curran.
A previous study has shown
that people can also be helped
to quit smoking cannabis
by treatment with Sativex,a cannabis extract with both CBD
and THC, deployed in a similar
way to nicotine replacement
therapy for tobacco users.
There could be advantages
to using CBD alone, says Iain
McGregor at the University of
Sydney, Australia, who helped
run the Sativex study. “CBD
has a variety of anti-addictive
properties.” McGregor’s team
is also investigating CBD as a
treatment for alcohol addiction.
“Two of the main features
during alcohol detoxification
are severe anxiety and risk of
seizures. We think CBD has
very strong anxiety-reducing
properties,” he says.
Curran’s team has also
found preliminary evidence
that CBD may help people to
give up smoking tobacco.
CBD supplements are
increasingly sold in pharmacies
and health food shops as
remedies for a range of illnesses,
but at much lower doses than
those used in Curran’s trial.
And most of the health claims
made for them aren’t based on
evidence. “If anyone can’t stop
smoking cannabis, I would
advise people to seek medical
assistance,” says McGregor. ❚FOSSIL skeletons found embedded
in rock at a site in South Africa may
be about to once more rewrite our
understanding of ancient humans.
“We have another major hominin
discovery,” revealed renowned
palaeoanthropologist Lee Berger
at New Scientist Live.
In the past decade, Berger,
who is at the University of the
Witwatersrand in South Africa,
and his team have discovered
two new species of human ancestor.
In 2010, Berger and his then
9-year-old son found the remains
of a new species of human in
the hills north of Johannesburg.
This was Australopithecus sediba,
which lived around 2 million years
ago and could be our closest
ape-like ancestor.
Then, in 2013, Berger hit the
jackpot again, with thousands of
fossil bones found deep inside the
Rising Star cave system, also near
Johannesburg. These turned out
to belong to a new species of
small-brained hominin called
Homo naledi, which lived very
recently, around 250,000 years
ago, and has a strange mix of
modern and archaic features.
Speaking on 12 October,
Berger said his third major
discovery involves hominin fossils
found near the Rising Star caves.
These bones haven’t yet been
excavated due to the challenging
nature of their location.
So could this be another new
species? “I don’t know. We haven’t
got them out of the rock yet,” Berger
told New Scientist. “All I have is a
glimpse of several individuals.” The
large jaw and teeth mean that the
skeletons don’t belong to H. naledi
or A. sebida, he said.
Early next year we can also
expect a study that reveals a
relationship between H. naledi
and another species, says Berger.
“That will be big news,” he says.
“These are exciting times.” ❚Cannabis plants
contain the chemical
cannabidiolHuman evolution DrugsAlison George Clare Wilson and Jason Arunn MurugesuSEASTOCK/GETTY IMAGESCBD capsules may treat
cannabis addiction
Another shake-up
for humanity’s
ancient family tree?
2019
“ Some cannabis users
become addicted, getting
withdrawal symptoms
when they try to stop”