Summary: A new study provides contrary evidence to popular belief and states people with congenital intellectual disabilities are sensitive to placebo-like effects.
Source: Karolinska Institute.
Contrary to earlier beliefs, people with severe congenital intellectual disability are sensitive to placebo-like effects, new research from Karolinska Institutet shows, published in the scientific journal Neurology. The results suggest that the influence of implicit social signals on expectancy effects has been underestimated.
The placebo effect is an example of how the power of the mind may influence the functions of the body, such as when a simple sugar pill alleviates pain when the taker believes it to be a real analgesic.
But placebo-like effects also occur when expectations influence the efficacy of real drugs. Until now, placebo researchers have presumed that this type of expectancy effect requires higher-order intellectual functions, such as reasoning, abstract thinking and predicting the future. But it now turns out to be more complex than that.
“Our results challenge the existing ideas of how treatment expectations are formed and we can now propose other more intuitive processes as a possible basis of the placebo effect, such as the ability to internalise the expectations of the people around you,” says Karin Jensen, assistant professor at Karolinska Institutet’s Department of Clinical Neuroscience.
Analysis of 24 medical studies
She and her colleagues at Karolinska Institutet and Harvard Medical School analysed 24 published medical studies involving people with congenital intellectual disability (an IQ below 70), including diagnoses such as Down’s, fragile x or Prader-Willi syndrome. Half of the studies were so-called open-label, in which all participants received active drugs. The other type were placebo-controlled, in which the participants did not know whether they were being given a placebo or active drug.
“We only compared the results from those who received real drugs, and found significant differences in treatment outcomes between the two groups – despite the fact that the patients had received exactly the same drugs,” says Dr Jensen. “The only difference between the groups was the likelihood of getting an active drug.”
Subtle social cues could be important
The conclusion is that implicit expectations conveyed by the people who administer the drugs, or who are otherwise involved in the treatment, are likely to influence the patients’ neurobiology and, ultimately, their response to treatment. In that sense, expectancy effects are not only the result of facts and suggestions but also the subtle social cues the patients pick up from the people around them.
“This aspect of the placebo effect has been underestimated,” says Dr Jensen. “This means that the models we’ve created of how the placebo effect works should be revised so that the focus isn’t just on advanced cognitive functions, such as the patient’s ability to create abstract future scenarios.”
About this neuroscience research article
Funding: The study was financed in part by the National Institutes of Health, USA. The researchers involved have no commercial stake in the results.
Source:Karolinska Institute Image Source: NeuroscienceNews.com image is in the public domain. Original Research:Abstract for “Certainty of genuine treatment increases drug responses among intellectually disabled patients” by Karin B. Jensen, Irving Kirsch, Moa Pontén, Annelie Rosén, Kathy Yang, Randy L. Gollub, Vincent des Portes, Ted J. Kaptchuk, Aurore Curie in Neurology. Published online May 16 2017 doi:10.1212/WNL.0000000000003934
Cite This NeuroscienceNews.com Article
[cbtabs][cbtab title=”MLA”]Karolinska Institute “Placebo Effect Despite Intellectual Disability.” NeuroscienceNews. NeuroscienceNews, 17 May 2017. <https://neurosciencenews.com/placebo-intellectual-disability-6702/>.[/cbtab][cbtab title=”APA”]Karolinska Institute (2017, May 17). Placebo Effect Despite Intellectual Disability. NeuroscienceNew. Retrieved May 17, 2017 from https://neurosciencenews.com/placebo-intellectual-disability-6702/[/cbtab][cbtab title=”Chicago”]Karolinska Institute “Placebo Effect Despite Intellectual Disability.” https://neurosciencenews.com/placebo-intellectual-disability-6702/ (accessed May 17, 2017).[/cbtab][/cbtabs]
Certainty of genuine treatment increases drug responses among intellectually disabled patients
Objective: To determine the placebo component of treatment responses in patients with intellectual disability (ID).
Methods: A statistical meta-analysis comparing bias-corrected effect sizes (Hedges g) of drug responses in open-label vs placebo-controlled clinical trials was performed, as these trial types represent different certainty of receiving genuine treatment (100% vs 50%). Studies in fragile X, Down, Prader-Willi, and Williams syndrome published before June 2015 were considered.
Results: Seventeen open-label trials (n = 261, 65% male; mean age 23.6 years; mean trial duration 38 weeks) and 22 placebo-controlled trials (n = 721, 62% male; mean age 17.1 years; mean trial duration 35 weeks) were included. The overall effect size from pre to post treatment in open-label studies was g = 0.602 (p = 0.001). The effect of trial type was statistically significant (p = 0.001), and revealed higher effect sizes in studies with 100% likelihood of getting active drug, compared to both the drug and placebo arm of placebo-controlled trials. We thus provide evidence for genuine placebo effects, not explainable by natural history or regression toward the mean, among patients with ID.
Conclusions: Our data suggest that clinical trials in patients with severe cognitive deficits are influenced by the certainty of receiving genuine medication, and open-label design should thus not be used to evaluate the effect of pharmacologic treatments in ID, as the results will be biased by an enhanced placebo component.
“Certainty of genuine treatment increases drug responses among intellectually disabled patients” by Karin B. Jensen, Irving Kirsch, Moa Pontén, Annelie Rosén, Kathy Yang, Randy L. Gollub, Vincent des Portes, Ted J. Kaptchuk, Aurore Curie in Neurology. Published online May 16 2017 doi:10.1212/WNL.0000000000003934