The snow globe of perception?
How
psychedelics exert such effects, especially after a single dose,
remains unclear. LSD and its chemical cousins share structural
similarities with the neurotransmitter serotonin, which is linked to
many aspects of mood, memory and pleasure. These psychedelics also bind
the same receptor sites in the brain as serotonin, but there the
similarity may end — studies have shown that the hallucinogens elicit
chemical cascades different from other compounds that bind at the same
receptor
2. To complicate matters further, LSD also acts at other receptors
3.
For
the moment, studying human behavioural responses rather than brain
chemistry may be more helpful in understanding how the drugs work. Robin
Carhart-Harris, a psychopharmacologist at Imperial College London who
has researched how psilocybin could treat depression, says that
psychedelics must work at both biological and psychological levels.
“Psychedelics probably work in addiction by making the brain function
more chaotically for a period — a bit like shaking up a snow globe —
weakening reinforced brain connections and dynamics,” he says.
Roland
Griffiths, a behavioural biologist at the Johns Hopkins University
School of Medicine in Baltimore, Maryland, is investigating the
influence of psilocybin on smoking cessation, and says that psychedelics
sometimes give rise to distinctive, insightful experiences that can
produce enduring positive changes in attitude, mood and behaviour.
“This
is impressive and important work,” says Matthew Johnson, a psychiatrist
also at Johns Hopkins University who is now running a small trial
looking at the effectiveness of psilocybin to treat nicotine addiction.
“Although this meta-analysis does not replace the need to test the
approach in new, well-designed and rigorous clinical trials, it puts
some more muscle behind the interpretation that the older literature
shows hints that psychedelic therapy might really help addiction.”
However,
Ken Checinski, a consultant addiction psychiatrist and independent
researcher based in London, says that although the results are exciting,
no pharmacological treatment should be seen as a magic bullet and that
modern therapeutic techniques have improved. “The included LSD trials
pre-date the use of psychological techniques such as motivational
interviewing and cognitive behaviour therapy,” he says.
