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ould hypnosis relieve pain? The
largest meta-analysis to date concludes that it could be a viable, safe,
cost-effective option.
Hypnosis might provide an innovative
way to treat pain.
Researchers
estimate that chronic pain affects more than 1.5 billion individuals globally.
Doctors
often prescribe opioid medications to treat this type of pain. However, these
drugs are expensive and, of course, highly addictive.
As
the opioid crisis unfolds, scientists are increasingly
focused on finding alternative ways to tackle pain.
Recently,
researchers from the University of Greenwich in London, United Kingdom,
assessed whether hypnosis might be useful against certain types of pain. To do
this, they collated and analyzed 85 existing studies.
Hypnosis
is side-effect free and, if individuals use pre-recorded audio to produce
hypnosis, it can be incredibly cost-effective.
The
researchers published their meta-analysis in the journal Neuroscience
and Biobehavioral Reviews.
Hypnosis and pain revisited
Over
the years, several studies and reviews have assessed hypnosis as an analgesic —
sometimes, researchers refer to this as hypnoanalgesia. For instance, a review published in 2016 looked at pain during
childbirth.
The
authors concluded that "Hypnosis may reduce the overall use of analgesia
during labor, but not epidural use." The authors also explain that
"[f]urther research is needed in the form of large, well‐designed randomized controlled trials."
Another review, published in 2000, looked at pain more generally. The
researchers combined data from 18 studies.
The authors concluded that there was a
"moderate to large hypnoanalgesic effect." Although intriguing,
according to the authors of the current review, these findings had
"several important limitations," not least a lack of studies to
include in their analysis.
Since
2000, interest in hypnoanalgesia has grown, and the number of new studies has
grown in line. In total, the latest analysis includes 85 studies.
All
of the studies used experimental pain models, such as extreme cold, shocks,
pressure, exercise, and lasers. Also, all of the studies compared the benefits
of hypnosis with no treatment (rather than testing them against a placebo or drug), and
they all recruited healthy adults.
The
researchers only collected studies that used a quantitive assessment of pain,
for instance, the use of a 10-point scale. Overall, the analysis included 3,632
participants.
Sensitivity to hypnosis
Because
not everyone succumbs to hypnosis to the same extent, the review also took into
account each participant's level of susceptibility.
There
are a number of ways that researchers can assess how susceptible someone is to
hypnosis. For instance, following a suggestion that the participant's arm is
heavy, they might lower their hand. If they drop it by 6 inches or more, the
practitioner might consider them to be more suggestible than someone whose arm
moved only 1 inch.
Once
the analysis was complete, the results came out in favor of hypnosis as a
potentially useful analgesic. Lead author Trevor Thompson, Ph.D., says:
"This is by far the largest review of its kind,
examining the effects of hypnosis in over 3,500 people, and presents very
compelling evidence. About 15% of the population are highly receptive to hypnosis,
and those people saw just over a 40% drop in pain."
It
was not just the people who were most susceptible to hypnosis who saw the
benefits. Most people are moderately suggestible, and they experienced a 29%
reduction in pain.
The
authors also note that evidence indicates that it is possible to increase
hypnotic suggestibility in a variety of ways, including training and
practice, non-invasive brain stimulation, and by pharmacological agents,
such as nitrous oxide.
"Based
on these findings, most people would experience around a 30% drop in pain or
more, which is generally considered to be clinically meaningful pain
relief."
Lead
author Trevor Thompson, Ph.D.
Interestingly,
the analysis also revealed that the effect size was similar whether the person
underwent hypnosis in person or via an audio recording.
If
hypnosis truly can reach these levels of analgesia, it could be a game-changer.
"In the United States, around 47,000 people died from opioid overdosing in
2017, and around a quarter of people prescribed the drugs for pain misuse
them," explains Thompson.
He continues, "Our findings suggest hypnosis
could be a safe and effective alternative. It can be administered quickly,
cheaply and easily at home with a 20-minute audio recording."
The
researchers plan to continue their dive into hypnoanalgesia, specifically
looking at chronic complaints, such as lower back pain. Currently,
however, there are not enough data available to reach definite conclusions.
Reservations and limitations
The
authors note certain limitations to the current analysis. First and foremost,
it is not possible to compare pain models with chronic pain, which can have
very different physical and psychological aspects.
Generally,
the pain inductions that researchers used in the studies produced a brief
experience of pain. This analysis could not ascertain how the efficacy of
hypnosis might change over longer lengths of time, as in chronic conditions.
Another
of the authors' concerns is that the average age of participants was relatively
young, at around 24. The authors wonder whether older populations might see the
same level of effect.
They conclude that "[a]lthough the role of
hypnotic intervention in clinical pain settings is well researched, limited
high-quality data with numerous design biases prohibit reliable conclusions
[...] and further well-controlled clinical studies are needed."
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