The aim of this evaluator-blinded randomized clinical trial was to determine if manual therapy added to a therapeutic exercise program produced greater improvements than a sham manual therapy added to the same exercise program in patients with non-specific shoulder pain.
Forty-five subjects were randomly allocated into one of three groups:
- manual therapy (glenohumeral mobilization technique and rib-cage technique);
- thoracic sham manual therapy (glenohumeral mobilization technique and rib-cage sham technique);
- sham manual therapy (sham glenohumeral mobilization technique and rib-cage sham technique).
All groups also received a therapeutic exercise program. Pain intensity, disability, and pain-free active shoulder range of motion were measured post-treatment and at 4-week and 12-week follow-ups. Mixed-model analyses of variance and post hoc pairwise comparisons with Bonferroni corrections were constructed for the analysis of the outcome measures.
All groups reported improved pain intensity, disability, and pain-free active shoulder range of motion. However, there were no between-group differences in these outcome measures.
The authors concluded that the addition of the manual therapy techniques applied in the present study to a therapeutic exercise protocol did not seem to add benefits to the management of subjects with non-specific shoulder pain.
What does that mean?
I think it means that the improvements observed in this study were due to 1) exercise and 2) a range of non-specific effects, and that they were not due to the manual techniques tested.
I cannot say that I find this enormously surprising. But I would also find it unsurprising if fans of these methods would claim that the results show that the physios applied the techniques not correctly.
In any case, I feel this is an interesting study, not least because of its use of sham therapy. But I somehow doubt that the patients were unable to distinguish sham from verum. If so, the study was not patient-blind which obviously is difficult to achieve with manual treatments.
The aim of this study was to evaluate the effectiveness of craniosacral therapy on different features in migraine patients.
Fifty individuals with migraine were randomly divided into two groups (n = 25 per group):
- craniosacral therapy group (CTG),
- sham control group (SCG).
The interventions were carried out with the patient in the supine position. The CTG received a manual therapy treatment focused on the craniosacral region including five techniques, and the SCG received a hands-on placebo intervention. After the intervention, individuals remained supine with a neutral neck and head position for 10 min, to relax and diminish tension after treatment. The techniques were executed by the same experienced physiotherapist in both groups.
The analyzed variables were pain, migraine severity, and frequency of episodes, functional, emotional, and overall disability, medication intake, and self-reported perceived changes, at baseline, after a 4-week intervention, and at an 8-week follow-up.
After the intervention, the CTG significantly reduced pain (p = 0.01), frequency of episodes (p = 0.001), functional (p = 0.001) and overall disability (p = 0.02), and medication intake (p = 0.01), as well as led to a significantly higher self-reported perception of change (p = 0.01), when compared to SCG. The results were maintained at follow-up evaluation in all variables.
The authors concluded that a protocol based on craniosacral therapy is effective in improving pain, frequency of episodes, functional and overall disability, and medication intake in migraineurs. This protocol may be considered as a therapeutic approach in migraine patients.
Sorry, but I disagree!
And I have several reasons for it:
- The study was far too small for such strong conclusions.
- For considering any treatment as a therapeutic approach in migraine patients, we would need at least one independent replication.
- There is no plausible rationale for craniosacral therapy to work for migraine.
- The blinding of patients was not checked, and it is likely that some patients knew what group they belonged to.
- There could have been a considerable influence of the non-blinded therapists on the outcomes.
- There was a near-total absence of a placebo response in the control group.
Altogether, the findings seem far too good to be true.
This study aimed to evaluate the number of craniosacral therapy sessions that can be helpful to obtain a resolution of the symptoms of infantile colic and to observe if there are any differences in the evolution obtained by the groups that received a different number of Craniosacral Therapy sessions at 24 days of treatment, compared with the control group which did not received any treatment.
Fifty-eight infants with colic were randomized into two groups:
- 29 babies in the control group received no treatment;
- babies in the experimental group received 1-3 sessions of craniosacral therapy (CST) until symptoms were resolved.
Evaluations were performed until day 24 of the study. Crying hours served as the primary outcome measure. The secondary outcome measures were the hours of sleep and the severity, measured by an Infantile Colic Severity Questionnaire (ICSQ).
Statistically significant differences were observed in favor of the experimental group compared to the control group on day 24 in all outcome measures:
- crying hours (mean difference = 2.94, at 95 %CI = 2.30-3.58; p < 0.001);
- hours of sleep (mean difference = 2.80; at 95 %CI = – 3.85 to – 1.73; p < 0.001);
- colic severity (mean difference = 17.24; at 95 %CI = 14.42-20.05; p < 0.001).
Also, the differences between the groups ≤ 2 CST sessions (n = 19), 3 CST sessions (n = 10), and control (n = 25) were statistically significant on day 24 of the treatment for crying, sleep and colic severity outcomes (p < 0.001).
The authors concluded that babies with infantile colic may obtain a complete resolution of symptoms on day 24 by receiving 2 or 3 CST sessions compared to the control group, which did not receive any treatment.
Why do SCAM researchers so often have no problem leaving the control group of patients in clinical trials without any treatment at all, while shying away from administering a placebo? Is it because they enjoy being the laughingstock of the science community? Probably not.
I suspect the reason might be that often they know that their treatments are placebos and that their trials would otherwise generate negative findings. Whatever the reasons, this new study demonstrates three things many of us already knew:
- Colic in babies always resolves on its own but can be helped by a placebo response (e.g. via the non-blinded parents), by holding the infant, and by paying attention to the child.
- Flawed trials lend themselves to drawing the wrong conclusions.
- Craniosacral therapy is not biologically plausible and most likely not effective beyond placebo.
One of the numerous conditions chiropractors, osteopaths, and other manual therapists claim to treat effectively is tension-type headache (TTH). For this purpose, they (in particular, chiropractors) often use high-velocity, low-amplitude manipulations of the neck. They do so despite the fact that the evidence for these techniques is less than convincing.
This systematic review evaluated the evidence about the effectiveness of manual therapy (MT) on pain intensity, frequency, and impact of pain in individuals with tension-type headache (TTH).
Medline, Embase, Scopus, Web of Science, CENTRAL, and PEDro were searched in June 2020. Randomized clinical trials that applied MT not associated with other interventions for TTH were selected. The level of evidence was synthesized using GRADE, and Standardized Mean Differences (SMD) were calculated for meta-analysis.
Fifteen studies were included with a total sample of 1131 individuals. The analyses show that high-velocity, low-amplitude techniques were not superior to no treatment in reducing pain intensity (SMD = 0.01, low evidence) and frequency (SMD = -0.27, moderate evidence). Soft tissue interventions were superior to no treatment in reducing pain intensity (SMD = -0.86, low evidence) and frequency of pain (SMD = -1.45, low evidence). Dry needling was superior to no treatment in reducing pain intensity (SMD = -5.16, moderate evidence) and frequency (SMD = -2.14, moderate evidence). Soft tissue interventions were not superior to no treatment and other treatments on the impact of headache.
The authors concluded that manual therapy may have positive effects on pain intensity and frequency, but more studies are necessary to strengthen the evidence of the effects of manual therapy on subjects with tension-type headache. Implications for rehabilitation soft tissue interventions and dry needling can be used to improve pain intensity and frequency in patients with tension type headache. High velocity and low amplitude thrust manipulations were not effective for improving pain intensity and frequency in patients with tension type headache. Manual therapy was not effective for improving the impact of headache in patients with tension type headache.
So, this review shows that:
- soft tissue interventions are better than no treatment,
- dry needling is better than no treatment.
These two results fail to impress me. Due to a placebo effect, almost any treatment should be better than no therapy at all.
ALMOST, because high-velocity, low-amplitude techniques were not superior to no treatment in reducing the intensity and frequency of pain. This, I feel, is an important finding that needs an explanation.
As it is only logical that high-velocity, low-amplitude techniques must also produce a positive placebo effect, the finding can only mean that these manipulations also generate a negative effect that is strong enough to cancel the positive response to placebo. (In addition, they can also cause severe complications via arterial dissections, as discussed often on this blog.)
Perhaps; let me, therefore, put it simply and use the blunt words of a neurologist who once was quoted saying this:
DON’T LET THE BUGGARS TOUCH YOUR NECK!
Advocates of so-called alternative medicine (SCAM) often sound like a broken record to me. They bring up the same ‘arguments’ over and over again, no matter whether they happen to be defending acupuncture, energy healing, homeopathy, or any other form of SCAM. Here are some of the most popular of these generic ‘arguments’:
1. It helped me
The supporters of SCAM regularly cite their own good experiences with their particular form of treatment and think that this is proof enough. However, they forget that any symptomatic improvement they may have felt can be the result of several factors that are unrelated to the SCAM in question. To mention just a few:
- Regression towards the mean
- Natural history of the disease
2. My SCAM is without risk
Since homeopathic remedies, for instance, are highly diluted, it makes sense to assume that they cannot cause side effects. Several other forms of SCAM are equally unlikely to cause adverse effects. So, the notion is seemingly correct. However, this ‘argument’ ignores the fact that it is not the therapy itself that can pose a risk, but the SCAM practitioner. For example, it is well documented – and, on this blog, we have discussed it often – that many of them advise against vaccination, which can undoubtedly cause serious harm.
3. SCAM has stood the test of time
It is true that many SCAMs have survived for hundreds or even thousands of years. It is also true that millions still use it even today. This, according to enthusiasts, is sufficient proof of SCAM’s efficacy. But they forget that many therapies have survived for centuries, only to be proved useless in the end. Just think of bloodletting or mercury preparations from past times.
4 The evidence is not nearly as negative as skeptics pretend
Yes, there are plenty of positive studies on some SCAMs This is not surprising. Firstly, from a purely statistical point of view, if we have, for instance, 1 000 studies of a particular SCAM, it is to be expected that, at the 5% level of statistical significance, about 50 of them will produce a significantly positive result. Secondly, this number becomes considerably larger if we factor in the fact that most of the studies are methodologically poor and were conducted by SCAM enthusiasts with a corresponding bias (see my ALTERNATIVE MEDICINE HALL OF FAME on this blog). However, if we base our judgment on the totality of the most robust studies, the bottom line is almost invariably that there is no overall convincingly positive result.
5. The pharmaceutical industry is suppressing SCAM
SCAM is said to be so amazingly effective that the pharmaceutical industry would simply go bust if this fact became common knowledge. Therefore Big Pharma is using its considerable resources to destroy SCAM. This argument is fallacious because:
- there is no evidence to support it,
- far from opposing SCAM, the pharmaceutical industry is heavily involved in SCAM (for example, by manufacturing homeopathic remedies, dietary supplements, etc.)
6 SCAM could save a lot of money
It is true that SCAMs are on average much cheaper than conventional medicines. However, one must also bear in mind that price alone can never be the decisive factor. We also need to consider other issues such as the risk/benefit balance. And a reduction in healthcare costs can never be achieved by ineffective therapies. Without effectiveness, there can be no cost-effectiveness.
7 Many conventional medicines are also not evidence-based
Sure, there are some treatments in conventional medicine that are not solidly supported by evidence. So why do we insist on solid evidence for SCAM? The answer is simple: in all areas of healthcare, intensive work is going on aimed at filling the gaps and improving the situation. As soon as a significant deficit is identified, studies are initiated to establish a reliable basis. Depending on the results, appropriate measures are eventually taken. In the case of negative findings, the appropriate measure is to exclude treatments from routine healthcare, regardless of whether the treatment in question is conventional or alternative. In other words, this is work in progress. SCAM enthusiasts should ask themselves how many treatments they have discarded so far. The answer, I think, is zero.
8 SCAM cannot be forced into the straitjacket of a clinical trial
This ‘argument’ surprisingly popular. It supposes that SCAM is so individualized, holistic, subtle, etc., that it defies science. The ‘argument’ is false, and SCAM advocates know it, not least because they regularly and enthusiastically cite those scientific papers that seemingly support their pet therapy.
9 SCAM is holistic
This may or may not be true, but the claim of holism is not a monopoly of SCAM. All good medicine is holistic, and in order to care for our patients holistically, we certainly do not need SCAM.
1o SCAM complements conventional medicine
This argument might be true: SCAM is often used as an adjunct to conventional treatments. Yet, there is no good reason why a complementary treatment should not be shown to be worth the effort and expense to add it to another therapy. If, for instance, you pay for an upgrade on a flight, you also want to make sure that it is worth the extra expenditure.
11 In Switzerland it works, too
That’s right, in Switzerland, a small range of SCAMs was included in basic health care by referendum. However, it has been reported that the consequences of this decision are far from positive. It brought no discernible benefit and only caused very considerable costs.
I am sure there are many more such ‘arguments’. Feel free to post your favorites!
My point here is this:
the ‘arguments’ used in defense of SCAM are not truly arguments; they are fallacies, misunderstandings, and sometimes even outright lies.
It is not often that I publish a paper with a philosopher in a leading journal of philosophy. In fact, it is the first time, and I am rather proud of it – so much so that I must show my readers (the article is freely available via the link below and I encourage everyone to read the full text) the abstract of our article entitled WHY HOMOEOPATHY IS PSEUDOSCIENCE (Synthese (2022) 200:394):
Homoeopathy is commonly recognised as pseudoscience. However, there is, to date, no systematic discussion that seeks to establish this view. In this paper, we try to fill this gap. We explain the nature of homoeopathy, discuss the notion of pseudoscience, and provide illustrative examples from the literature indicating why homoeopathy fits the
bill. Our argument contains a conceptual and an empirical part.
In the conceptual part, we introduce the premise that a doctrine qualifies as a pseudoscience if, firstly, its proponents claim scientific standing for it and, secondly, if they produce bullshit to defend it, such that, unlike science, it cannot be viewed as the most reliable knowledge on its topic. In the empirical part, we provide evidence that homoeopathy fulfils both criteria. The first is quickly established since homoeopaths often explicitly claim scientificity.
To establish the second, we dive into the pseudo-academic literature on homoeopathy to provide evidence of bullshit in the arguments of homoeopaths. Specifically, we show that they make bizarre ontological claims incompatible with natural science, illegitimately shift the burden of proof to sceptics, and mischaracterise, cherry-pick, and misreport the evidence. Furthermore, we demonstrate that they reject essential parts of established scientific methodology and use epistemically unfair strategies to immunise their doctrine against recalcitrant evidence.
And here is our conclusion:
At the beginning of the paper, we noted that homoeopathy is commonly named one of the prototypical pseudosciences. However, there has been, to date, no comprehensive discussion as to what makes it a pseudoscience. Moreover, the problem is not trivial since the most well-known and influential demarcation criteria, such as Popper’s falsifiability criterion and Kuhn’s problem-solving criterion, cannot account for it, as we have shown. We have tried to fill this research gap using a novel bullshitology-based approach to the demarcation problem. Following this approach, we have argued that homoeopathy should be regarded as pseudoscience because its proponents claim scientific standing for it and produce argumentative bullshit to defend it, thus violating important epistemic standards central to science.
This study aimed to evaluate the efficacy of Persian barley water in controlling the clinical outcomes of hospitalized COVID-19 patients. It was designed as a single-blind, add-on therapy, randomized controlled clinical trial and conducted in Shiraz, Iran, from January to March 2021. One hundred hospitalized COVID-19 patients with moderate disease severity were randomly allocated to receive routine treatment (per local protocols) with or without 250 ml of Persian barley water (PBW) daily for two weeks. Clinical outcomes and blood tests were recorded before and after the study period. Multivariable modeling was applied using Stata software for data analysis.
The length of hospital stay (LHS) was 4.5 days shorter in the intervention group than the control group regardless of history of cigarette smoking (95% confidence interval: -7.22, -1.79 days). Also, body temperature, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and creatinine significantly dropped in the intervention group compared to the control group. No adverse events related to PBW occurred.
The authors from the Department of Traditional Medicine, Shiraz University of Medical Sciences, Shiraz, Iran, concluded that this clinical trial demonstrated the efficacy of PBW in minimizing the LHS, fever, and levels of ESR, CRP, and creatinine among hospitalized COVID-19 patients with moderate disease severity. More robust trials can help find safe and effective herbal formulations as treatments for COVID-19.
I must admit, I did not know about PBW. The authors explain that PBW is manufactured from Hordeum vulgare via a specific procedure. According to recent studies, barley is rich in constituents such as selenium, tocotrienols, phytic acid, catechin, lutein, vitamin E, and vitamin C; these compounds are responsible for their antioxidant and anti-inflammatory properties. Barley grains also have immune-stimulating effects, antioxidant properties, protective effects on the liver and digestive systems, anti-cancer effects, and act to reduce uric acid levels.
But even if these effects would constitute a plausible mechanism for explaining the observed effects (which I do not think they do), the study itself is more than flimsy.
I do not understand why researchers investigating an important issue do not make sure that their study is as rigorous as possible.
- Why not use an adequately large sample size?
- Why not employ a placebo?
- Why not double-blind?
- Why not report the most important outcome, i.e. mortality?
As it stands, nobody will take this study seriously. Perhaps this is a good thing – but perhaps PBW does have positive effects (I know it’s a long shot) and, in this case, a poor-quality study would only prevent an effective therapy come to light.
Placebo effects are a fascinating subject. In so-called alternative medicine (SCAM), they are particularly important because much of SCAM seems to rely on little more than placebo effects. Therefore, I think this new paper is of some relevance to us.
The aim of this systematic review was to quantify the placebo effect of intraarticular injections for knee osteoarthritis in terms of pain, function, and objective outcomes. Factors influencing placebo effect were investigated.
Out of 2,363 records, 50 articles on 4,076 patients were included. The meta-analysis showed significant improvements up to the 6-month follow-up: Visual Analogue Scale (VAS)-pain −13.4 mean difference (MD) (95% confidence interval [CI]: −21.7/−5.1; P < 0.001), Western Ontario and McMaster Osteoarthritis Index (WOMAC)-pain −3.3 MD (95% CI: −3.9/−2.7; P < 0.001). Other significant improvements were WOMAC-stiffness −1.1 MD (95% CI: −1.6/−0.6; P < 0.001), WOMAC-function −10.1 MD (95% CI: −12.2/−8.0; P < 0.001), and Evaluator Global Assessment −21.4 MD (95% CI: −29.2/−13.6; P < 0.001). The responder rate was 52% (95% CI: 40% to 63%). Improvements were greater than the “minimal clinically important difference” for all outcomes (except 6-month VAS-pain). The level of evidence was moderate for almost all outcomes.
The authors concluded that the placebo effect of knee injections is significant, with functional improvements lasting even longer than those reported for pain perception. The high, long-lasting, and heterogeneous effects on the scales commonly used in clinical trials further highlight that the impact of placebo should not be overlooked in the research on and management of knee osteoarthritis.
The authors furthermore confirmed that “the main finding of this meta-analysis is that placebo is an important component of the effect of injective treatments for patients with KOA, with saline injections being able to provide relevant and long-lasting results not only in terms of pain relief but also with respect to stiffness resolution and function improvement. These results are both statistically and clinically significant and can be perceived by patients up to 6 months.”
I would dispute that!
To explain why it might help to read our 1995 BMJ paper on the subject:
We often and wrongly equate the response seen in the placebo arm of a clinical trial with the placebo effect. In order to obtain the true placebo effect, other non-specific effects can be identified by including an untreated control group in clinical trials. A review of the literature shows that most authors confuse the perceived placebo effect with the true placebo effect. The true placebo effect is highly variable, depending on several factors that are not fully understood. A distinction between the perceived and the true placebo effects would be helpful in understanding the complex phenomena involved in a placebo response.
In other words, what the authors picked up in their analysis (i.e. the changes that occurred in the placebo groups between the start of a trial and after placebo application) is not just the placebo response; it is, in fact, a combination of a placebo effect, concomitant interventions/care, regression towards the mean, natural history of the condition and possibly other factors.
Does it matter?
Yes, it does!
Placebo effects are not nearly as powerful and long-lasting as the authors conclude. And this means virtually all their implications for clinical practice are incorrect.
Third molar extraction is a painful treatment and thus is often used to investigate the effects of analgesics on pain. Hypnotherapy is said to help to reduce pain and to decrease the intake of postoperative systemic analgesics. Therefore, it seems reasonable to study the effects of hypnotherapy on the pain caused by third molar extraction.
In this study, the effectiveness of a brief hypnotic induction for patients undergoing third molar extractions was investigated. Data were collected from 33 patients with third molar extractions on the right and left sides. Patients received two different types of interventions in this monocentric randomized crossover trial. Third molar extraction was conducted on one side with reduced preoperative local anesthetics and an additional brief hypnotic induction (Dave Elman technique). The other side was conducted with regular preoperative local anesthetics without a brief hypnotic induction (standard care). Intake of postoperative systemic analgesics was allowed in both treatments.
Patients’ expectations about hypnosis were assessed at baseline. The primary outcome was the area under the curve with respect to ground of pain intensity after the treatment. Secondary outcomes were the amount of postoperative analgesics consumed and the preferred treatment.
There was no evidence that the area under the curve with respect to ground of pain differed between the two interventions (controlling for gender). There was, however, evidence to show that the patients’ expectations affected the effectiveness of the brief hypnotic induction. This means that patients with high expectations about hypnosis benefit more from treatment with reduced preoperative local anesthetics and additional brief hypnotic induction.
The authors concluded that, in this study, additional a brief hypnotic induction with reduced preoperative local anesthetic use did not generally reduce posttreatment pain after third molar extraction more than regular local anesthetics. The expectation of the patients about the effectiveness of hypnosis affected the effectiveness of the brief hypnotic induction so that patients with high expectations had a larger benefit from a brief hypnotic induction than patients with low expectations.
The most interesting findings here are, in my view, that:
- Hypnotherapy is not as effective as many enthusiasts claim.
- Expectation influences the outcome of hypnotherapy.
Expectation is, of course, a determinant of the size of the placebo response. Thus, this finding is interesting but far from unexpected. I would go as far as postulating that similar results would be obtained with most treatments regardless of whether they are alternative or conventional. The difference is that, in the case of alternative therapies, the expectation is a major (if not the only) determinant of the outcome, while it merely somewhat improves the outcome of an effective treatment. To put it differently, so-called alternative medicine (SCAM) relies entirely/mostly on expectation, while conventional medicine does not.
Crystal healing is the treatment of all types of illnesses via the ‘healing energy’ of gemstones. It is as implausible as so-called alternative medicine (SCAM) gets. In my recent analysis of 150 SCAMs, I concluded that “there are no rigorous trials testing the therapeutic value of crystal healing”. This assumption is further confirmed by published papers like this one:
Recently, crystal healing and gemstone therapy, also known as litho- or gemmotherapy, is extensively promoted in the media, newspapers and the internet. There is also a growing interest of cancer patients in this unconventional treatment, resulting in the need for oncologists to give informed advice to their patients and to prevent them from wasting hope, time and money in an ineffective treatment, and at worst to postpone the necessary treatment of this life threatening disease. In the context of the currently ever-growing New-Age wave, believing in crystal healing has spread widely in the population. It is a historical belief similar to that of charmstones, rather than one based on modern scientific practices and advances. Pleasant feelings or seeming successes of crystal healing can be attributed to the strong placebo effect, or the believers wanting it to be true and seeing only things that back that up: cognitive bias. A scientific proof of any positive effect beyond a placebo effect does not exist. Even though this treatment can be generally regarded as harmless and without toxicity, it should not be recommended to cancer patients. Thereby we will help prevent our patients from wasting hope, time and money in an ineffective treatment, and at worst to postpone the necessary treatment of this life threatening disease, resulting in a worsened prognosis.
Yet, it seems that we were not entirely correct. Recently, I came across an article that mentions such a study:
A study conducted in 2001 by British psychologist Christopher French challenged 80 volunteers to differentiate between real and fake crystals after holding them in their hands for five minutes and meditating. Six people felt nothing at all, and the rest reported feeling some energy, whether in the form of tingling in the body or an improved sense of wellbeing. Both groups, though—whether holding the fake crystals or the real ones—reported similar impressions, suggesting the placebo effect could be at play.
“When scientists conduct robust clinical trials, they want to strip the intervention of these placebo effects to figure out if it has a specific benefit,” Jarry explains. “Alternative medicine’s reputation benefits strongly from these non-specific placebo effects. Enough people will start to feel better after using crystals (because of regression to the mean, self-limiting illness, misremembering, etc.), and they will publicly testify to their improvement, giving the illusion that crystals work. What they don’t know is what would have happened had they not used the crystals.”
So, if you want to keep a hunk of amethyst at your desk to alleviate your grief, or a Tiger’s Eye stone to clear the mind, go ahead: they may not be manipulating a sacred energy field around your body to heal you, but they can certainly manipulate your mind.
Unfortunately, the link provided does not lead directly to the study but to the publication list of Chris French. This in turn leads us to the reference in question:
French, C. C., O’Donnell, H., & Williams, L. (2001). Hypnotic susceptibility, paranormal belief and reports of ‘crystal power’. British Psychological Society Centenary Annual Conference, Glasgow, 28-31 March 2001. (Abstract published in Proceedings of the British Psychological Society, 9(2), 186).
Sadly, I cannot find the paper online and I suspect it exists only as an abstract in a conference book (I have emailed Chris and asked him). In any case, his study did not test the therapeutic value; so, my above statement is not entirely false.