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Biomedical subjects

Irving Kirsch

Publications and source records attributed to Irving Kirsch.

15 recordsLinked to original sources
PubMed2006

Clinical trials and the response rate illusion.

Clinical trial outcome data can be presented and analyzed as mean change scores or as response rates. These two methods of presenting the data can lead to divergent conclusions. This article explores the reasons for the apparently divergent outcomes produced by these methods and considers their implications for the analysis and reportage of clinical trial data. It is shown that relatively small differences in improvement scores can produce relatively large differences in expected response rates. This is because differences in response rates do not indicate differences in the number of people who have improved; they indicate differences in the number of people whose degree of improvement has pushed them over a specified criterion. Therefore, patients classified as non-responders may have shown substantial and clinically significant improvement, and these are the patients who are most likely to become responders when given medication. Response rates based on continuous data do not add information, and they can create an illusion of clinical effectiveness.

Antidepressive Agents↗
PubMed2006

Sham device v inert pill: randomised controlled trial of two placebo treatments.

OBJECTIVE: To investigate whether a sham device (a validated sham acupuncture needle) has a greater placebo effect than an inert pill in patients with persistent arm pain. DESIGN: A single blind randomised controlled trial created from the two week placebo run-in periods for two nested trials that compared acupuncture and amitriptyline with their respective placebo controls. Comparison of participants who remained on placebo continued beyond the run-in period to the end of the study. SETTING: Academic medical centre. PARTICIPANTS: 270 adults with arm pain due to repetitive use that had lasted at least three months despite treatment and who scored > or =3 on a 10 point pain scale. INTERVENTIONS: Acupuncture with sham device twice a week for six weeks or placebo pill once a day for eight weeks. MAIN OUTCOME MEASURES: Arm pain measured on a 10 point pain scale. Secondary outcomes were symptoms measured by the Levine symptom severity scale, function measured by Pransky's upper extremity function scale, and grip strength. RESULTS: Pain decreased during the two week placebo run-in period in both the sham device and placebo pill groups, but changes were not different between the groups (-0.14, 95% confidence interval -0.52 to 0.25, P = 0.49). Changes in severity scores for arm symptoms and grip strength were similar between groups, but arm function improved more in the placebo pill group (2.0, 0.06 to 3.92, P = 0.04). Longitudinal regression analyses that followed participants throughout the treatment period showed significantly greater downward slopes per week on the 10 point arm pain scale in the sham device group than in the placebo pill group (-0.33 (-0.40 to -0.26) v -0.15 (-0.21 to -0.09), P = 0.0001) and on the symptom severity scale (-0.07 (-0.09 to -0.05) v -0.05 (-0.06 to -0.03), P = 0.02). Differences were not significant, however, on the function scale or for grip strength. Reported adverse effects were different in the two groups. CONCLUSIONS: The sham device had greater effects than the placebo pill on self reported pain and severity of symptoms over the entire course of treatment but not during the two week placebo run in. Placebo effects seem to be malleable and depend on the behaviours embedded in medical rituals.

Acupuncture Analgesia↗
PubMed2006

Investigating placebo effects in irritable bowel syndrome: a novel research design.

Little is known about placebo effects with scientific precision. Poor methodology has confounded our understanding of the magnitude and even the existence of the placebo effect. Investigating placebo effects presents special research challenges including: the design of appropriate controls for studying placebo effects including separating such effects from natural history and regression to the mean, the need for large sample sizes to capture expected small effects, and the need to understand such potential effects from a patient's perspective. This article summarizes the methodology of an ongoing NIH-funded randomized controlled trial aimed at investigating whether the placebo effect in irritable bowel syndrome (IBS) exists and whether the magnitude of such an effect can be manipulated to vary in a manner analogous to "dose dependence." The trial also uses an innovative combination of quantitative and qualitative methods.

Acupuncture Therapy↗
PubMed2006

Brain activity associated with expectancy-enhanced placebo analgesia as measured by functional magnetic resonance imaging.

In this study, a well established expectancy manipulation model was combined with a novel placebo intervention, a validated sham acupuncture needle, to investigate the brain network involved in placebo analgesia. Sixteen subjects completed the experiment. We found that after placebo acupuncture treatment, subjective pain rating reduction (pre minus post) on the placebo-treated side was significantly greater than on the control side. When we calculated the contrast that subtracts the functional magnetic resonance imaging (fMRI) signal difference between post-treatment and pretreatment during pain application on placebo side from the same difference on control side [e.g., placebo (post - pre) - control (post - pre)], significant differences were observed in the bilateral rostral anterior cingulate cortex (rACC), lateral prefrontal cortex, right anterior insula, supramarginal gyrus, and left inferior parietal lobule. The simple regression (correlation) analysis between each subject's fMRI signal difference of post-treatment and pretreatment difference on placebo and control side and the corresponding subjective pain rating difference showed that significant negative correlation was observed in the bilateral lateral/orbital prefrontal cortex, rACC, cerebellum, right fusiform, parahippocampus, and pons. These results are different from a previous study that found decreased activity in pain-sensitive regions such as the thalamus, insula, and ACC when comparing the response to noxious stimuli applied to control and placebo cream-treated areas of the skin. Our results suggest that placebo analgesia may be configured through multiple brain pathways and mechanisms.

Acupuncture Analgesia↗
PubMed2006

Effects of misleading questions and hypnotic memory suggestion on memory reports: a signal-detection analysis.

In 2002, the first author and colleagues reported data indicating that both hypnosis and misleading questions decreased the accuracy of memory reports and decreased "don't know" response rates, that the effects of misleading questions were significantly greater than those of hypnosis, and that the two effects were additive. Using a sample of 194 undergraduate students, the present study replicated the findings that misleading questions reduce accuracy and "don't know" responding but failed to replicate the negative effect of hypnosis on memory reports. Signal detection analysis indicated that misleading questioning produced decreased sensitivity accompanied by higher response bias, though affecting sensitivity more than producing a criterion shift.

Adolescent↗
PubMed2006

Suggestion reduces the stroop effect.

We examined the effects of suggestion on Stroop interference in highly suggestible individuals. Participants completed the Stroop task with and without a suggestion to perceive Stroop words as meaningless symbols. Half the participants were given this suggestion in hypnosis, and half were given the suggestion without the induction of hypnosis. Suggestion produced a significant reduction in Stroop inhibition, accounting for about 45% of the variance in Stroop responding, regardless of whether hypnosis had been induced. These findings indicate that suggestion can at least partially overcome the automaticity associated with the Stroop effect.

Adult↗
PubMed2005

Placebo psychotherapy: synonym or oxymoron?

Contrary to some recent claims, the placebo effect is real and in some cases very substantial. Placebo effects can be produced or enhanced by classical conditioning, but consistent with virtually all contemporary conditioning theories, these effects are generally mediated by expectancy. Expectancy can also produce placebo effects that are inconsistent with conditioning history. Although expectancy also plays an important role in psychotherapy outcome, the logic of placebo-controlled trials does not map well onto psychotherapy research. The idea of evaluating the efficacy of psychotherapy by controlling for nonspecific or placebo factors is based on a flawed analogy and should be abandoned.

Conditioning, Psychological↗
PubMed2005

The effects of hypnotic and nonhypnotic imaginative suggestion on pain.

BACKGROUND: Few studies have compared placebo and suggested pain reduction. PURPOSE: Hypnotic and nonhypnotic imaginative analgesia suggestions were compared against a placebo in reducing experimental pain. The mediator role of response expectancies and the moderator role of hypnotic and nonhypnotic imaginative suggestibility were evaluated. METHODS: Sixty participants previously assessed for hypnotic and nonhypnotic imaginative suggestibility were assigned to one of two experimental conditions or a no-treatment control condition. In the "placebo first" condition, participants received placebo, followed by imaginative and then hypnotic analgesia suggestions. In the "placebo last" condition, participants received imaginative and then hypnotic suggestions, followed by placebo. RESULTS: Imaginative and hypnotic suggestions did not differ significantly and were more effective than no treatment in reducing pain. The placebo was no different from the analgesia suggestions and was more effective than no treatment, but only when administered after the suggestions. Pain reduction was mediated by expectancy but was not significantly related to suggestibility or hypnotizability, the latter operationalized as hypnotic suggestibility with imaginative suggestibility statistically controlled. CONCLUSIONS: In the general population, nonhypnotic imaginative suggestions may be as effective as hypnotic suggestions in reducing pain. Response expectancies would seem to be an important mechanism of placebo and suggested pain reduction.

Humans↗
PubMed2004

The role of cognition in classical and operant conditioning.

For the past 35 years, learning theorists have been providing models that depend on mental representations, even in their most simple, deterministic, and mechanistic approaches. Hence, cognitive involvement (typically thought of as expectancy) is assumed for most instances of classical and operant conditioning, with current theoretical differences concerning the level of cognition that is involved (e.g., simple association vs. rule learning), rather than its presence. Nevertheless, many psychologists not in the mainstream of learning theory continue to think of cognitive and conditioning theories as rival families of hypotheses. In this article, the data pertaining to the role of higher-order cognition in conditioning is reviewed, and a theoretical synthesis is proposed that provides a role for both automatic and cognitively mediated processes.

Cognition↗
PubMed2004

Conditioning, expectancy, and the placebo effect: comment on Stewart-Williams and Podd (2004).

Classical conditioning is included as a component in the response expectancy model of placebo responding. Though introspectable when attention is drawn to them, expectancies need not be in awareness while guiding behavior. Most placebo effects are linked to expectancies, and classical conditioning is one factor (but not the only factor) by which these expectancies can be produced and altered. Conditioned placebo effects without expectancies exist but are relatively rare in humans. The adaptive advantage of cognition is increased response flexibility. For it to convey that benefit, however, it must be capable of overriding the influence of simpler automatic processes. Thus, the higher up the phylogenetic scale, the smaller the role of nonconscious conditioning processes and the larger the role of cognition.

Cognition↗
PubMed2002

National Depressive and Manic-Depressive Association consensus statement on the use of placebo in clinical trials of mood disorders.

A consensus conference on the use of placebo in mood disorder studies consisted of expert presentations on bioethics, biostatistics, unipolar depression, and bipolar disorder. Work groups considered evidence and presented statements to the group. Although it was not possible to write a document for which there was complete agreement on all issues, the final document incorporated input from all authors. There was consensus that placebo has a definite role in mood disorder studies. Findings of equivalence between a new drug and standard treatment in active control studies is not evidence of efficacy unless the new drug is also significantly more effective than placebo. Add-on studies in which patients are randomized to standard therapy plus the investigational drug or standard therapy plus placebo are especially indicated for high-risk patients. Mood disorders in elderly and pediatric patients are understudied, and properly designed trials are urgently needed. Research is needed on the ethical conduct of studies to limit risks of medication-free intervals and facilitate poststudy treatment. Patients must fully understand the risks and lack of individualized treatment involved in research.

Bipolar Disorder↗
PubMed2002

Virtual reality exposure therapy for the treatment of fear of flying: a controlled investigation.

Forty-five participants who refused to fly during a screening test and who also met Diagnostic and Statistical Manual of Mental Disorders criteria for specific phobia, agoraphobia, or panic disorder with agoraphobia were randomly assigned to 5 sessions of either virtual reality exposure (VRE) or attention-placebo group treatment (GT). At posttreatment, 65% of VRE participants and 57% of GT participants flew during a test flight. Both groups showed significant improvement following treatment on standardized self-report measures of flight anxiety, with a better outcome for the VRE group on 4 of 5 of these measures. At 6-month follow-up, however, most group differences had disappeared; VRE resulted in a better outcome on only 1 of 5 standardized flight anxiety measures.

Adult↗
PubMed2002

Immediate and persisting effects of misleading questions and hypnosis on memory reports.

Immediate and persisting effects of misleading questions and hypnosis on memory reports were assessed. After listening to a story, 52 highly suggestible students and 59 low and medium suggestible students were asked misleading or neutral questions in or out of hypnosis. All participants were then asked neutral questions without hypnosis. Both hypnosis and misleading questions significantly increased memory errors, and misleading questions produced significantly more errors than did hypnosis. The 2 effects were additive, so that misleading questions in hypnosis produced the greatest number of errors. There were no significant interactions with level of hypnotic suggestibility. Implications of these findings for the per se exclusion of posthypnotic testimony are discussed.

Adolescent↗