smokers' behaviour is more important than the potency of their pot or how
much of the psychoactive ingredient THC they take in for predicting who will
become dependent, according to a small new study.
Researchers have debated whether smokers of high-potency cannabis varieties are
at greater risk of addiction because they get more THC, or if they compensate
for the pot's strength by using or inhaling less of it.
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That doesn't really matter, say the authors of the new report. Smokers of
potent pot do get more THC than smokers of traditional varieties, they found.
But it's their style of pot smoking that predicted who was most likely to
"No drug use is without risk," said lead author
Peggy van der Pol, a doctoral candidate at the Trimbos Institute of the
Netherlands Institute of Mental Health and Addiction. "When using stronger
cannabis you will likely take in more THC than when using less potent
cannabis," she told Reuters Health in an email.
Most previous research into cannabis dependence has looked mainly
at how frequently a person uses cannabis, Van der Pol and her team note in the
journal Addiction. But the assumption that
heavier THC exposure leads to greater addiction risk ignores the possibility
that THC dose is not the main determinant of who becomes dependent, they write.
Van der Pol and her team analysed data on 98 young adults taking part in an
ongoing long-term study of frequent marijuana users in the Netherlands. The
participants were recruited from coffee houses where the sale and use of
cannabis is permitted and via referrals. Each person reported smoking marijuana
on at least three days a week for more than a year.
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At the start of the study, three quarters of the participants were men and 23
years old, on average. One in three met the criteria for marijuana dependence
at that point. A year and a half after recruitment, and then a year and a half
after that, the participants were interviewed about their cannabis use and
asked to smoke a joint in a comfortable setting while researchers documented
details of their behaviour.
Exposed to more THC
To simulate real-world conditions, smokers were asked to
bring their own cannabis and to roll their own joints. Contrary to the authors'
original predictions, the smokers of the more potent pot varieties did not roll
weaker joints. They used more cannabis in each joint than their peers who
smoked lower-strength cannabis. Smokers of potent varieties did inhale less
smoke and they smoked at a slower pace than their peers, the study team found.
"Users seem to partly adjust, or 'titrate' their THC
intake, but not sufficiently so to fully compensate for the THC-strength,"
van der Pol told Reuters Health. "So users of more potent cannabis are
generally exposed to more THC." These adjustments in smoking behaviour may
not be intentional, she added.
"On average, users seem not to fully compensate for cannabis strength by
inhaling less smoke. Yet, as the smoking behaviour may be an unconscious
process, users are likely unaware whether or not they (partly) compensate their
intake." Taking smaller and less frequent puffs on their marijuana joints
did not appear to alter their risk of dependence either, the results indicate.
The decreased volume of marijuana puffs – determined by a device that measured
puff volume, duration, and related factors – and the total number of puffs was
associated with more severe marijuana dependence, both at the start of the
study and at follow up, the researchers note. Total monthly exposure to THC did
predict the severity of dependence at the three-year mark, but not independent
of a person's dependence status at the beginning of the study.
levels of THC
Only smoking behaviours – like how much of a joint people
smoked, or how frequently they puffed – predicted dependence at the three-year
mark regardless of THC exposure or dependence status at the start, the
Dr Wilson Compton, Deputy Director of the National Institute on Drug Abuse
(NIDA) told Reuters Health via email, "This is an important study that
helps to understand that increasing potency of marijuana may be related to
of THC, despite some reductions in how much people smoke when the
marijuana is stronger."
Compton, who was not involved in the study, added, "This is an important
area of research, and we do need a better understanding of it, but we remain
concerned particularly for new and young users who may not titrate in the same
way as experienced users, and thus may be exposing their brains to higher
levels of THC from the outset."
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