scholarly journals Placebo response and psychosis: a putative shared mechanism

2021 ◽  
Author(s):  
Emily Hird

Computational cognitive theory proposes that our experiences represent an optimisation between new information and prior beliefs, which are updated to best reflect reality. However, experiences can be biased. One example is the placebo response (PR), where a persistent belief in the effectiveness of a treatment relieves symptoms, even though the ‘treatment’ is an inert sugar pill. Another example is psychosis, which is characterised by unusual percepts and beliefs in the form of hallucinations and delusions. Antipsychotic medication, the primary treatment for psychosis, is often ineffective and accompanied by severe side-effects, but we have not identified an effective alternative. This is likely because the large and heterogenous placebo response in psychosis is likely to create noise in trials and so disrupts attempts to identify new treatments. This well-recognised issue could be solved if we can predict how an individual is likely to respond to placebo treatment and account for placebo responses. Importantly, biomarkers predicting the placebo response have been identified chiefly in pain and depression, but not in psychosis. Quantifying individual belief-updating, and tendency to rely on prior beliefs versus new information, would provide a sensitive method to predict the PR in psychosis.

2021 ◽  
Author(s):  
Tobias Kube ◽  
Lukas Kirchner ◽  
Gunnar Lemmer ◽  
Julia Glombiewski

Aberrant belief updating has been linked to psychopathology, e.g., depressive symptoms. While previous research used to treat belief-confirming vs. -disconfirming information as binary concepts, the present research varied the extent to which new information deviates from prior beliefs and examined its influence on belief updating. In a false feedback task (Study 1; N = 379) and a social interaction task (Study 2; N = 292), participants received slightly positive, moderately positive or extremely positive information in relation to their prior beliefs. In both studies, new information was deemed most reliable if it was moderately positive. Yet, differences in the positivity of new information had only small effects on belief updating. In Study 1, depressive symptoms were related to difficulties in generalizing positive new learning experiences. The findings suggest that, contrary to traditional learning models, the larger the differences between prior beliefs and new information, the more beliefs are not updated.


2022 ◽  
Author(s):  
Tobias Kube

When updating beliefs in light of new information, people preferentially integrate information that is consistent with their prior beliefs and helps them construe a coherent view of the world. Such a selective integration of new information likely contributes to belief polarisation and compromises public discourse. Therefore, it is crucial to understand the factors that underlie biased belief updating. To this end, I conducted three pre-registered experiments covering different controversial political issues (i.e., Experiment 1: climate change, Experiment 2: speed limit on highways, Experiment 3: immigration in relation to violent crime). The main hypothesis was that negative reappraisal of new information (referred to as “cognitive immunisation”) hinders belief updating. Support for this hypothesis was found only in Experiment 2. In all experiments, the magnitude of the prediction error (i.e., the discrepancy between prior beliefs and new information) was strongly related to belief updating. Across experiments, participants’ general attitudes regarding the respective issue influenced the strength of beliefs, but not their update. The present findings provide some indication that the engagement in cognitive immunisation can lead to the maintenance of beliefs despite disconfirming information. However, by far the largest association with belief updating was with the magnitude of the prediction error.


2020 ◽  
Author(s):  
Tobias Kube ◽  
Julia Glombiewski

People update their beliefs selectively in response to good news and disregard bad news, referred to as the optimism bias. Yet, the precise cognitive mechanisms underlying this asymmetry in belief updating are largely unknown. In three experiments, we tested the hypothesis that cognitive immunisation against new information contributes to optimistic belief updating (e.g. through questioning the reliability of new information). In each study, participants received new information in relation to their prior beliefs, and we examined the influence of cognitive immunisation on belief updating by using a three-group modulation protocol: In one group, cognitive immunisation against new information was promoted; in another group, cognitive immunisation was inhibited; and a control group received no manipulation. This modulation protocol was applied to beliefs about the self, i.e. performance expectations (Experiment 1&2; N=99 and N=93), and beliefs about climate change (Experiment 3; N=227) as an example of factual beliefs. The results of Experiments 1&2 showed that the cognitive immunisation manipulation had no influence on the update of performance-related expectations. In Experiment 3, we did find significant group differences in belief updating, and this effect interacted with participants’ general attitudes towards climate change: people who were sceptical about man-made climate change lowered their estimates of the projected temperature rise particularly if they perceived scientific information on climate change as being fraught with uncertainty. These findings suggest that the importance of cognitive immunisation in belief updating may depend on the content of beliefs (i.e. self-related vs. factual) and participants’ attitudes to the subject in question.


2019 ◽  
Author(s):  
Ben M Tappin ◽  
Gordon Pennycook ◽  
David Gertler Rand

A surprising finding from U.S. opinion surveys is that political disagreements tend to be greatest among the most cognitively sophisticated opposing partisans. Recent experiments suggest a hypothesis that could explain this pattern: cognitive sophistication magnifies politically biased processing of new information. However, the designs of these experiments tend to contain several limitations that complicate their support for this hypothesis. In particular, they tend to (i) focus on people’s worldviews and political identities, at the expense of their other, more specific prior beliefs, (ii) lack direct comparison with a politically unbiased benchmark, and (iii) focus on people’s judgments of new information, rather than on their posterior beliefs following exposure to the information. We report two studies designed to address these limitations. In our design, U.S. subjects received noisy but informative signals about the truth or falsity of partisan political questions, and we measured their prior and posterior beliefs, and cognitive sophistication, operationalized as analytic thinking inferred via performance on the Cognitive Reflection Test. We compared subjects’ posterior beliefs to an unbiased Bayesian benchmark. We found little evidence that analytic thinking magnified politically biased deviations from the benchmark. In contrast, we found consistent evidence that greater analytic thinking was associated with posterior beliefs closer to the benchmark. Together, these results are inconsistent with the hypothesis that cognitive sophistication magnifies politically biased processing. We discuss differences between our design and prior work that can inform future tests of this hypothesis.


Author(s):  
Ziqing Yao ◽  
Xuanyi Lin ◽  
Xiaoqing Hu

Abstract When people are confronted with feedback that counters their prior beliefs, they preferentially rely on desirable rather than undesirable feedback in belief updating, i.e. an optimism bias. In two pre-registered EEG studies employing an adverse life event probability estimation task, we investigated the neurocognitive processes that support the formation and the change of optimism biases in immediate and 24 h delayed tests. We found that optimistic belief updating biases not only emerged immediately but also became significantly larger after 24 h, suggesting an active role of valence-dependent offline consolidation processes in the change of optimism biases. Participants also showed optimistic memory biases: they were less accurate in remembering undesirable than desirable feedback probabilities, with inferior memories of undesirable feedback associated with lower belief updating in the delayed test. Examining event-related brain potentials (ERPs) revealed that desirability of feedback biased initial encoding: desirable feedback elicited larger P300s than undesirable feedback, with larger P300 amplitudes predicting both higher belief updating and memory accuracies. These results suggest that desirability of feedback could bias both online and offline memory-related processes such as encoding and consolidation, with both processes contributing to the formation and change of optimism biases.


1998 ◽  
Vol 13 (5) ◽  
pp. 254-263 ◽  
Author(s):  
G Emilien ◽  
JM Maloteaux ◽  
A Seghers ◽  
G Charles

SummaryThe use of a placebo control group in the evaluation of a new product is today considered by most as a necessary condition of experimental drug research. Placebo response is an essential consideration in all clinical trials. If not properly controlled, incorrect and dangerous conclusion may be inferred for a product efficacy and safety profile. However, the inclusion of a placebo group in clinical trials in neuropsychiatric research raises several ethical and scientific questions. Whereas in certain indications, such as suicidal patients and severe and psychotic depression, the use of a placebo is generally not accepted, it is difficult to assess drug efficacy. This article discusses the concept of placebo in clinical trials, the occurrence of adverse events after placebo treatment and the high response rate of placebo in neuropsychiatric clinical research. The experimental methodology to adequately control all the factors involved is also analysed and discussed.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ra Ham Lee ◽  
Jae-Don Oh ◽  
Jae Sam Hwang ◽  
Hak-Kyo Lee ◽  
Donghyun Shin

AbstractMalignant melanoma is highly resistant to conventional treatments and is one of the most aggressive types of skin cancers. Conventional cancer treatments are limited due to drug resistance, tumor selectivity, and solubility. Therefore, new treatments with fewer side effects and excellent effects should be developed. In previous studies, we have analyzed antimicrobial peptides (AMPs), which showed antibacterial and anti-inflammatory effects in insects, and some AMPs also exhibited anticancer efficacy. Anticancer peptides (ACPs) are known to have fewer side effects and high anticancer efficacy. In this study, the insect-derived peptide poecilocorisin-1 (PCC-1) did not induce toxicity in the human epithelial cell line HaCaT, but its potential as an anticancer agent was confirmed through specific effects of antiproliferation, apoptosis, and cell cycle arrest in two melanoma cell lines, SK-MEL-28 and G361. Additionally, we discovered a novel anticancer mechanism of insect-derived peptides in melanoma through the regulation of transcription factor Sp1 protein, which is overexpressed in cancer, apoptosis, and cell cycle-related proteins. Taken together, this study aims to clarify the anticancer efficacy and safety of insect-derived peptides and to present their potential as future therapeutic agents.


Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Steven Warach ◽  
Yasir Al-Rawi ◽  
Anthony J Furlan ◽  
Jochen B Fiebach ◽  
Max Wintermark ◽  
...  

The DIAS-2 study was the only large, randomized intravenous thrombolytic trial that selected patients based on the presence of ischemic penumbra. However, DIAS-2 did not confirm the positive findings of the smaller DEDAS and DIAS trials, which also used penumbral selection. Therefore a reevaluation of the penumbra selection strategy is warranted. In post-hoc analyses we assessed the relationships of MRI-measured lesion volumes to clinical measures in DIAS-2, and the relationships of the presence and size of the diffusion-perfusion mismatch to the clinical effect of desmoteplase in DIAS-2 (MRI-selected patients) and in pooled data from MRI-selected 90- and 125-μg/kg dose groups in DIAS, DEDAS, and DIAS-2. In DIAS-2, lesion volumes correlated with NIHSS at both baseline and final time points (P<0·0001), and lesion growth was inversely related to good clinical outcome (P=0.004). In the pooled analysis, treatment was associated with 47% clinical response rate in desmoteplase (n=143) versus 34% in placebo (n=73; P=0.08). For both the pooled sample and for DIAS-2, increasing the minimum baseline mismatch volume (MMV) for inclusion increased the desmoteplase effect size, preferentially decreasing the placebo-response rate. There was a trend of statistically significant differences in effect size in ≤60 mL versus >60 mL baseline mismatch subgroups (P=0.083). The odds ratio for good clinical response between desmoteplase and placebo treatment was 2.83 (95% CI, 1.16-6.94, P=0.023) for a MMV >60 mL. Increasing the minimum NIHSS for inclusion did not affect treatment effect size. Pooled across all desmoteplase trials, penumbral selection by MRI diffusion-perfusion mismatch favored desmoteplase clinical benefit, especially for larger MMV. Based on these results, a three-fold reduction in future trial sample size requirements would be achieved using a criterion of baseline MMV >60 mL over any visible mismatch. These results support a modified diffusion-perfusion mismatch hypothesis for patient selection in later-time-window thrombolytic trials.


Author(s):  
Philip Graham

Cognitive behaviour therapy (CBT) is derived from both behavioural and cognitive theories. Using concepts such as operant conditioning and reinforcement, behavioural theories treat behaviour as explicable without recourse to description of mental activity. In contrast, mental activity is central to all concepts derived from cognitive psychology. Both sets of theories have been of value in explaining psychological disorders and, in the design of interventions they have proved an effective combination. Central to that part of cognitive theory that is relevant to CBT is the concept of ‘schemas’, first described in detail by Jean Piaget. A schema is a mental ‘structure for screening, coding, and evaluating impinging stimuli’. The origin of mental schemas lies in the pre-verbal phase when material is encoded in non-verbal images that, as the child's language develops, gradually become verbally labelled. They form part of a dynamic system interacting with an individual child's physiology, emotional functioning, and behaviour with their operation depending on the social context in which the child is living. There are similarities but also differences between schemas and related concepts in psychoanalysis, such as Freudian ‘complexes’ and Kleinian ‘positions’. Schemas can be seen as organized around anything in the child's world, especially objects, beliefs, or emotions. They develop from past experience. The processing of new information in relation to such schemas can usefully be seen as involving the evaluation of discrepancies between information that is received and information that is expected. If there is a discrepancy, (the information not corresponding with that expected), then during the coding process information may be distorted so that it no longer creates discomfort, or, more adaptively, it may be incorporated into a modified schema.


Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3325-3325
Author(s):  
Carla M. Van Bennekom ◽  
Gregory A. Abel ◽  
Richard M. Stone ◽  
Kenneth C. Anderson ◽  
Noopur Raje ◽  
...  

Abstract Background: Exploration of multiple myeloma (MM) and myelodysplastic syndrome (MDS) patients’ attitudes toward participation in research, newly approved treatments, and potential treatment side effects can guide efforts to increase both participation in research and acceptance of treatments among diverse patient subgroups. Methods: The Patient Registries at Slone: Myeloma & MDS are national disease-based observational registries conducted by Boston University. All patients diagnosed with these diseases within 4 months of enrollment are eligible for inclusion. Subjects enroll by mail or over the Internet; information on treatment, clinical events, quality of life, and attitudes toward research participation, new treatments, and possible side effects is obtained by questionnaire at baseline and at six-month intervals. We reviewed answers to attitudinal questions obtained from baseline questionnaires completed by 104 MM and 126 MDS patients enrolled between June 2006 and June 2007 (residing in 40 states). We also calculated a composite “side effect concern” score based on the answers to 11 questions on specific side effects. Results: Most patients reported willingness to participate in clinical trials (81% MM; 86% MDS) and to consider a new treatment that had benefited some patients, but for which side effects were not yet known (81% MM; 87% MDS). Differences among subgroups categorized according to age, geographic region of residence, education, or race were small. Thirteen percent, 65%, and 22% reported they were very, somewhat, and not at all willing, respectively, to try a new, potentially beneficial treatment that could also rarely cause death. Approximately 75% of patients reported they would be very concerned about serious infection as a treatment side effect, and 36% and 29%, respectively, reported they would be very concerned about vomiting and fever. Most patients reported lower levels of concern about other possible side effects. Median side effect concern scores were 14 for both MM and MDS patients (range 1–24 for MM and 0–24 for MDS). The median score was 14 for both those willing and those not willing to participate in research. The median was 15.5 for those not at all willing to try a new treatment compared to 12.5 for those very willing to try such treatment (p=0.02). Scores did not vary appreciably by age, geographic region of residence, education, race, or history of any of 6 diseases. MDS patients who reported having undergone treatment for their disease had a median score of 13 compared to 16 for those who reported no treatment (p=0.03); among MM patients, the medians were similar for those with and without prior treatment. Conclusion: MM and MDS patients in a large national registry largely indicate a willingness to participate in research and consider newly-approved treatments. Most patients reported concerns about possible side effects of treatment; higher levels of concern were associated with less willingness to try a new treatment, but were not associated with willingness to participate in research.


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