Placebo Effect Research Articles

Peripheral blood transcriptomic profiling of molecular mechanisms commonly regulated by binge drinking and placebo effects

Molecular responses to alcohol consumption are dynamic, context-dependent, and arise from a complex interplay of biological and external factors. While many have studied genetic risk associated with drinking patterns, comprehensive studies identifying dynamic responses to pharmacologic and psychological/placebo effects underlying binge drinking are lacking. We investigated transcriptome-wide response to binge, medium, and placebo alcohol consumption by 17 healthy heavy social drinkers enrolled in a controlled, in-house, longitudinal study of up to 12 days. Using RNA-seq, we identified 251 and 13 differentially expressed genes (DEGs) in response to binge drinking and placebo, respectively. Eleven protein-coding DEGs had very large effect sizes in response to binge drinking (Cohen’s d > 1). Furthermore, binge dose significantly impacted the Cytokine-cytokine receptor interaction pathway (KEGG: hsa04060) across all experimental sequences. Placebo also impacted hsa04060, but only when administered following regular alcohol drinking sessions. Similarly, medium-dose and placebo commonly impacted KEGG pathways of Systemic lupus erythematosus, Neutrophil extracellular trap formation, and Alcoholism based on the sequence of drinking sessions. These findings together indicate the “dose-extending effects” of placebo at a molecular level. Furthermore, besides supporting alcohol dose-specific molecular changes, results suggest that the placebo effects may induce molecular responses within the same pathways regulated by alcohol.

Nocebo expectations rather than placebo expectations affect topical pain relief: A randomized clinical trial

Patients' expectations and beliefs regarding the potential benefits and harms of medical interventions may induce placebo and nocebo effects, and affect the response to pain therapies. In a randomized clinical trial, we examined the effect of placebo and nocebo expectations on pain relief and adverse events (AEs) in association with a topical treatment among 65 cancer survivors experiencing chronic musculoskeletal pain. Participants received either a 1% camphor-based topical pain patch or a placebo treatment for 14 days. We measured pain severity with the worst pain item of the Brief Pain Inventory (BPI) at baseline and 14 days and treatment expectations at baseline with validated expectation questionnaires. We found that high vs. low nocebo expectations decreased pain severity improvements by 2.5 points (95% confidence interval [CI] −3.8 to −1.2; p<0.001) on a 0–10 numeric rating scale of the BPI and pain response rate by 42.7% (95% CI 0.2–0.6; p<0.001) at day 14, irrespective of placebo expectation status or treatment arms. Patients with high vs. low nocebo expectations in the true arm reported 22.4% more unwanted AEs. High nocebo expectations were associated with increased AEs by 39.5% (odds ratio: 12.0, 95% CI 1.2, 145.5; p=0.029) and decreased pain response in the true arm vs. placebo. Our study demonstrated that nocebo expectations, rather than placebo expectations, elevate the risk of AEs and compromise the effect of topical pain interventions. The findings raise the possibility that nocebo expectations may worsen somatic symptoms through heightening central pain amplification and should be further investigated.

Comments on energy conservation treatments for MS-related fatigue and a new proposal

Psychological treatments of MS-related fatigue mostly depend on energy conservation programs. We argue that the evidence for energy conservation training is weak – in contrast to some reviews on this topic. The reasons for our concerns are the use of informed passive control groups allowing negative placebo effects, the lack of predefined primary outcome parameter, statistically rather than clinically significant effects, and the use of insensitive fatigue questionnaires. We propose to base psychological interventions not on a view of fatigue as a constant loss of mental energy but as a subjective representation (“feeling”) of an inflammatory state, which draws away attentional capacity. This conceptualization allows to develop a three-step treatment approach: Getting short-term control on fatigue, extinction to reduce fatigue-related avoidance behavior, and a systematic increase of activities by pacing. Our proposal depends on the techniques, that can interrupt ongoing feelings of fatigue and can serve as a basis for extinction. We propose that Progressive Muscle Relaxation might be such a technique. The advantage of our model is that it shares similarities with well-established treatments for phobias and chronic pain and we discuss the shared set of assumptions. Hopefully, this will help to improve the treatment of fatigue in future.

Placebo Effect of Caffeine on Physiological Parameters and Physical Performance

This study aimed to analyse the placebo effect associated with a high dose of caffeine (9 mg/kg) on heart rate and its variability and on strength tests. Methods: 18 participants experienced in strength training (19.7 ± 2.3 years; 72.2 ± 15.0 kg; 169.6 ± 9.0 cm) performed two days of trials (caffeine-informed/placebo-ingested (placebo) and non-ingested (control)). Firstly, heart rate and its variability were measured while participants lay down for 15 min. After that, bench press and squat tests were performed at 3 different loads (50%, 75% and 90% of 1RM). Perception of performance, effort and side effects were also evaluated. Results: no differences were found in the vast majority of strength variables analysed. Resting heart rate decreased in the placebo trial (60.39 ± 10.18 bpm control vs. 57.56 ± 9.50 bpm placebo, p = 0.040), and mean RR increased (1020.1 ± 172.9 ms control vs. 1071.5 ± 185.7 ms placebo, p = 0.032). Heart rate variability and perception of performance and effort were similar between conditions (p &gt; 0.05 in all cases). Side effects such as activeness and nervousness were reported while consuming the placebo. Conclusions: the placebo effect did not modify performance in the majority of the strength test variables, HRV and perception of performance and effort. However, resting heart rate was reduced, mean RR increased, and some side effects appeared in the placebo trial.

Transcriptomic Profiles Associated with Experimental Placebo Effects in Chronic Pain.

Gene expression networks associated with placebo effects are understudied; in this study, we identified transcriptomic profiles associated with placebo responsivity. Participants suffering from chronic pain underwent a verbal suggestion and conditioning paradigm with individually tailored thermal painful stimulations to elicit conditioned placebo effects. Participants reported pain intensity on a visual analog scale (VAS) anchored from zero = no pain to 100 = maximum imaginable pain. RNA was extracted from venous blood and RNA sequencing and validation tests were performed to identify differentially expressed genes (DEGs) associated with placebo effects, controlling for sex and level of pain. Unbiased enrichment analyses were performed to identify biological processes associated with placebo effects. Of the 10,700 protein-coding genes that passed quality control filters, 667 were found to be associated with placebo effects (FDR <0.05). Most genes (97%) upregulated were associated with larger placebo effects. The 17 top transcriptome-wide significant genes were further validated via RT-qPCR in an independent cohort of chronic pain participants. Six of them (CCDC85B, FBXL15, HAGH, PI3, SELENOM, and TNFRSF4) showed positive and significant (P < 0.05) correlation with placebo effects in the cohort. The overall DEGs were highly enriched in regulation of expression of SLITs and ROBOs (R-HSA-9010553, FDR = 1.26e-33), metabolism of RNA (R-HSA-8953854, FDR = 1.34e-30), Huntington's disease (hsa05016, FDR = 9.84e-31), and ribosome biogenesis (GO:0042254, FDR = 2.67e-15); alternations in these pathways might jeopardize the proneness to elicit placebo effects. Future studies are needed to replicate this finding and better understand the unique molecular dynamics of people who are more or less affected by pain and placebo.

Replace: a randomized controlled trial on the effect of hydrocortisone or placebo in patients with reported symptoms of glucocorticoid-induced adrenal insufficiency after terminating prednisolone for polymyalgia rheumatic/giant cell arteritis

Replace: a randomized controlled trial on the effect of hydrocortisone or placebo in patients with reported symptoms of glucocorticoid-induced adrenal insufficiency after terminating prednisolone for polymyalgia rheumatic/giant cell arteritis

Is there a spinal tap responder in progressive supranuclear palsy? The first prospective study.

Progressive supranuclear palsy (PSP) is a progressive neurodegenerative disease, and sometimes shows idiopathic normal pressure hydrocephalus (iNPH)-like presentations. We aimed to evaluate spinal tap responsiveness in patients with PSP, including the effect of sham spinal tap. Eleven patients with PSP, ten with probable/definite iNPH, and eight control patients were prospectively enrolled. All participants underwent sham spinal tap and spinal tap procedures. Gait was evaluated using wearable inertial sensors. We defined "tap responders" as individuals with a 10% or more improvement from baseline in any of the gait parameters (timed up-and-go test total time, stride length, and velocity during straight walking under single-task and cognitive dual-task conditions). We compared the ratio of responders in patients with PSP to patients with iNPH and controls. The ratio of tap responders and the ratio of sham tap responders in patients with PSP were significantly higher than those in control patients, and not different from those in patients with iNPH. PSP patients with iNPH-like MRI features tended to respond to the spinal tap compared to those without such imaging features. Notably, one patient with PSP, who responded to the spinal tap beyond the effect of sham spinal tap, was treated by the shunt operation. This is the first prospective study to demonstrate tap and shunt responsiveness in patients with PSP while highlighting the placebo effects of the spinal tap in patients with PSP or iNPH. Our findings suggest that some PSP patients have impaired cerebrospinal fluid circulation, contributing to a distinct component of the clinical spectrum.

Written Imaginal Exposure for Hoarding Disorder: A Preliminary Pilot Study.

Hoarding disorder (HD) is marked by difficulty discarding possessions. Many refuse treatment or drop out, which may be due to treatment's incorporation of in-home decluttering, which is feared and avoided. Thus, strategies to prepare patients for decluttering/discarding are needed. Imaginal exposure (IE), or imagining one's worst fears about discarding, could be one such strategy. This pilot preliminarily tested a short-duration IE intervention compared with a control intervention. Over 3 days, adults diagnosed with HD (n = 32) were randomly assigned to either write about and imagine their worst fears about discarding (IE condition) or a neutral topic (control writing [CW] condition). The IE condition showed significant improvements in HD symptoms from preintervention to 1-week follow-up, with medium to large effects; however, the CW condition did as well. Comparing change scores between conditions, the IE condition's improvements were not significantly different than the CW condition's. Overall, IE was helpful in improving HD symptoms, but this pilot did not indicate that it was more helpful than CW. This raises important questions about possible demand characteristics, placebo effects, or regression to the mean, and it has implications for the design and methodology of other studies assessing IE's utility.

An Overview of the Neurobiological Mechanisms of Expectations and Placebo Effects in Pain and Health Care

An Overview of the Neurobiological Mechanisms of Expectations and Placebo Effects in Pain and Health Care

Comparative Effectiveness of Panchamrut Parpati and Placebo in Management of Grahani W.S.R. to Irritable Bowel Syndrome - Study Protocol for a Single Blind, Randomized Controlled Trial

Abstract: Background: Ayurveda has described several treatment modalities regarding the treatment of Grahani Roga including the usage of herbs and formulations, yoga and lifestyle modifications. On the other hand, systematic data regarding their efficacy relative to placebo are not currently available. The purpose of this study is to compare the efficacy of the Ayurvedic formulation Panchamrut Parpati with a placebo, which contains an inert component called starch, in the treatment of Grahani Roga patients. Methods and design: In a prospective, single- centered, randomized controlled trial,60 patients, between 19 and 60 years, diagnosed with Grahani Roga, presenting with cardinal features of Grahani Roga as presented in Ayurvedic texts, two groups will be randomly assigned. In Group one, the patients will receive Panchamrut Parpati and in Group two, patients will receive Placebo filled with starch. Guidelines regarding Pathya-apathya will be given to both the groups. The course of treatment will last for 28 days for both groups. Outcomes will be evaluated on 14th&amp;28th (During treatment) &amp; 56th day (post-treatment). Result:The primary result will be assessed by checking the grading of the cardinal symptoms of Grahani Roga mentioned in Ayurvedic texts. Secondary outcome will check for improvement in laboratory investigations and quality of life of the patient. Conclusion: This trial compares the efficacy of Panchamrut Parpati with Placebo in the patients of Grahani roga. Panchamrut Parpati is envisioned to improve the symptoms of Grahani Roga, thus proving to be effective in management of patients of Grahani Roga. Trial registration: CTRI/2023/07/055048

The Efficacy of Multivitamin, Vitamin A, Vitamin B, Vitamin C, and Vitamin D Supplements in the Prevention and Management of COVID-19 and Long-COVID: An Updated Systematic Review and Meta-Analysis of Randomized Clinical Trials.

This review aims to evaluate the efficacy of any vitamin administration(s) in preventing and managing COVID-19 and/or long-COVID. Databases were searched up to May 2023 to identify randomized clinical trials comparing data on the effects of vitamin supplementation(s) versus placebo or standard of care on the two conditions of interest. Inverse-variance random-effects meta-analyses were conducted to estimate pooled risk ratios (RRs) and 95% confidence intervals (CIs) for all-cause mortality between supplemented and non-supplemented individuals. Overall, 37 articles were included: two regarded COVID-19 and long-COVID prevention and 35 records the COVID-19 management. The effects of vitamin D in preventing COVID-19 and long-COVID were contrasting. Similarly, no conclusion could be drawn on the efficacy of multivitamins, vitamin A, and vitamin B in COVID-19 management. A few positive findings were reported in some vitamin C trials but results were inconsistent in most outcomes, excluding all-cause mortality (RR = 0.84; 95% CI: 0.72-0.97). Vitamin D results were mixed in most aspects, including mortality, in which benefits were observed in regular administrations only (RR = 0.67; 95% CI: 0.49-0.91). Despite some benefits, results were mostly contradictory. Variety in recruitment and treatment protocols might explain this heterogeneity. Better-designed studies are needed to clarify these vitamins' potential effects against SARS-CoV-2.

Pharmacological efficacy and potential of the use of nitazoxanide, a thiazolide drug with a wide spectrum of action

The article is devoted to the possibility and prospects of using nitazoxanide in a wide range of diseases. Based on literature data, the authors evaluate the pharmacological effectiveness and substantiate the potential of using nitazoxanide in bacterial, helminthic, protean, viral and oncological diseases. This information is of interest and can be used to decide on the need to conduct clinical trials of nitazoxanide in Russia. A systematic search for current information was conducted in four databases until December 1, 2023: PubMed, EMBASE, Web of Science and Cochrane Library. The work included preclinical studies in vitro and in vivo, as well as randomized clinical trials comparing the pharmacological effectiveness of nitazoxanide and placebo. The broad-spectrum thiazolide drug nitazoxanide has antibacterial, antiprotozoal, anthelmintic, antiviral and antitumor activity. This is achieved through its pharmacological properties, namely: regulation of the cell cycle, apoptosis, cell proliferation and migration; activation of innate immunity; influence on the synthesis and activation of cell proteins, some of which are links in cellular signaling pathways; binding to proteins of viruses, bacteria, protozoa and helminths with disruption of their vital functions; immunomodulating effect by regulating the activity of pro- and anti-inflammatory cytokines. The article systematizes and summarizes current information on the pharmacodynamics of nitazoxanide, as well as the results of preclinical and clinical studies of the drug, and discusses further prospects.

Placebo response in patients with Dravet syndrome: Post-hoc analysis of two clinical trials

ObjectiveDravet syndrome is a rare, early childhood-onset epileptic and developmental encephalopathy. Responses to placebo in clinical trials for epilepsy therapies range widely, but factors influencing placebo response remain poorly understood. This study explored placebo response and its effects on safety, efficacy, and quality of life outcomes in patients with Dravet syndrome. MethodsWe performed exploratory post-hoc analyses of pooled data from placebo-treated patients from the GWPCARE 1B and GWPCARE 2 randomized controlled phase III trials, comparing cannabidiol and matched placebo in 2–18 year old Dravet syndrome patients. All patients had ≥4 convulsive seizures during a baseline period of 4 weeks. Results124 Dravet syndrome-treated patients were included in the analysis (2–5 years: n = 35; 6–12 years: n = 52; 13–18 years: n = 37). Convulsive seizures were experienced by all placebo group patients at all timepoints, with decreased median convulsive seizure frequency during the treatment period versus baseline; the number of convulsive seizure-free days was similar to baseline. Convulsive seizure frequency had a nominally significant positive correlation with age and a nominally significant negative correlation with body mass index. Most placebo-treated patients experienced a treatment-emergent adverse event; however, most resolved quickly, and serious adverse events were infrequent. Placebo treatment had very little effect on reported Caregiver Global Impression of Change outcomes versus baseline. InterpretationPlacebo had little impact on convulsive seizure-free days and Caregiver Global Impression of Change versus baseline, suggesting that these metrics may help differentiate placebo and active treatment effects in future studies. However, future research should further assess placebo responses to confirm these results.

Effects of sodium-glucose cotransporter 2 inhibitors on bone metabolism in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

BackgroundSodium glucose cotransporter 2 (SGLT2) inhibitors are widely used in type 2 diabetes mellitus (T2DM) therapy. The impact of SGLT2 inhibitors on bone metabolism has been widely taken into consideration. But there are controversial results in the study on the effect of SGLT2 inhibitors on bone metabolism in patients with T2DM. Therefore, we aimed to examine whether and to what extent SGLT2 inhibitors affect bone metabolism in patients with T2DM.MethodsA literature search of randomized controlled trials (RCTs) was conducted through PubMed, Web of Science, Embase, Cochrane databases, and Scopus from inception until 15 April 2023. Eligible RCTs compared the effects of SGLT2 inhibitors versus placebo on bone mineral density and bone metabolism in patients with T2DM. To evaluate the differences between groups, a meta-analysis was conducted using the random effects inverse-variance model by utilizing standardized mean differences (SMD).ResultsThrough screening, 25 articles were finally included, covering 22,828 patients. The results showed that, compared with placebo, SGLT2 inhibitors significantly increased parathyroid hormone (PTH, SMD = 0.13; 95%CI: 0.06, 0.20), and cross-linked C-terminal telopeptides of type I collagen (CTX, SMD = 0.11; 95%CI: 0.01, 0.21) in patients with T2DM, decreased serum alkaline phosphatase levels (ALP, SMD = -0.06; 95%CI: -0.10, -0.03), and had no significant effect on bone mineral density (BMD), procollagen type 1 N-terminal propeptide (P1NP), 25-hydroxy vitamin D, tartrate resistant acid phosphatase-5b (TRACP-5b) and osteocalcin.ConclusionsSGLT2 inhibitors may negatively affect bone metabolism by increasing serum PTH, CTX, and decreasing serum ALP. This conclusion needs to be verified by more studies due to the limited number and quality of included studies.Systematic review registrationPROSPERO, identifier CRD42023410701

Evidence and sources of placebo effects in transcranial direct current stimulation during a single session of visuospatial working memory practice

Transcranial direct current stimulation (tDCS) can be used to non-invasively augment cognitive training. However, the benefits of tDCS may be due in part to placebo effects, which have not been well-characterized. The purpose of this study was to determine whether tDCS can have a measurable placebo effect on cognitive training and to identify potential sources of this effect. Eighty-three right-handed adults were randomly assigned to one of three groups: control (no exposure to tDCS), sham tDCS, or active tDCS. The sham and active tDCS groups were double-blinded. Each group performed 20 min of an adapted Corsi Block Tapping Task (CBTT), a visuospatial working memory task. Anodal or sham tDCS was applied during CBTT training in a right parietal-left supraorbital montage. After training, active and sham tDCS groups were surveyed on expectations about tDCS efficacy. Linear mixed effects models showed that the tDCS groups (active and sham combined) improved more on the CBTT with training than the control group, suggesting a placebo effect of tDCS. Participants’ tDCS expectations were significantly related to the placebo effect, as was the belief of receiving active stimulation. This placebo effect shows that the benefits of tDCS on cognitive training can occur even in absence of active stimulation. Future tDCS studies should consider how treatment expectations may be a source of the placebo effect in tDCS research, and identify ways to potentially leverage them to maximize treatment benefit.

Modeling an evaluation of the efficacy of the novel neuroanalgesic drug mirogabalin for diabetic peripheral neuropathic pain and postherpetic neuralgia therapy

Diabetic peripheral neuropathic pain (DPNP) and postherpetic neuralgia (PHN) are challenging and often intractable complex medical conditions, with a substantial impact on the quality of life. Mirogabalin, a novel voltage-gated Ca2+ channel α2δ ligand, was approved for the indication of DPNP and PHN. However, the time course of effects has not yet been clarified.We aimed to establish pharmacodynamic and placebo effect models of mirogabalin and pregabalin in DPNP and PHN, and to quantitatively compare the efficacy characteristics (maximum efficacy, onset time, and other pharmacodynamic parameters) and safety of mirogabalin and pregabalin. Public databases were comprehensively searched for randomized placebo-controlled clinical trials. A model-based meta-analysis (MBMA) was developed to describe the time course of drug efficacy and placebo effects. Adverse events were compared using a fixed-effects meta-analysis. Sixteen studies including 5,147 participants were eligible for this study. The placebo effect was relatively high and gradually increased with time, and it required at least eight weeks to reach a plateau. The pharmacodynamic model revealed that the maximum pure efficacy for mirogabalin and pregabalin was approximately -7.85 % and -8.86 %, respectively; the efficacy of mirogabalin to relieve DPNP and PHN was not superior to that of pregabalin, and both drugs had similar safety. While the rate constant of the onset rate of pregabalin was approximately thrice as high as that of mirogabalin. In addition, the baseline level of pain was an important factor affecting pregabalin efficacy. These findings are helpful in evaluating the clinical extension value of mirogabalin. They suggest that the high placebo effect and the baseline level of pain should be considered when grouping patients in future research and development of voltage-gated Ca2+ channel neuroanalgesic.

Efgartigimod and Ravulizumab for Treating Acetylcholine Receptor Auto-antibody-Positive (AChR-Ab+) Generalized Myasthenia Gravis: Indirect Treatment Comparison.

Efgartigimod and ravulizumab, both approved for treating acetylcholine receptor auto-antibody-positive (AChR-Ab+) generalized myasthenia gravis (gMG), have not been directly compared. This paper assessed comparative effects of efgartigimod vs. ravulizumab for treating adults with AChR-Ab+gMG using indirect treatment comparison methods. The matching-adjusted indirect comparison used data from two randomized trials of adult men and women. The ADAPT (efgartigimod vs. placebo; individual patient data available) population was reweighted to match the CHAMPION (ravulizumab vs. placebo; index study; aggregate data available) population. The relative effect of efgartigimod versus placebo was estimated in this reweighted population and compared with the observed ravulizumab versus placebo effect to estimate the efgartigimod versus ravulizumab effect. The outcomes were Myasthenia Gravis Activities of Daily Living (MG-ADL), QuantitativeMyasthenia Gravis (QMG), and Myasthenia Gravis Quality of Life 15-item-revised scale (MG-QoL15r) assessed as cumulative effect (area under the curve; AUC) over 26 weeks (primary) and change from baseline at 4 weeks and time of best response (week 4 for efgartigimod; week 26 for ravulizumab). For MG-QoL15r, efgartigimod had a statistically significant improvement compared with ravulizumab over 26 weeks [mean difference (95% confidence interval): -52.6 (-103.0, -2.3)], at week 4 [-4.0 (-6.6, -1.4)], and at time of best response [-3.9 (-6.5, -1.3)]. Efgartigimod had a statistically significant improvement over ravulizumab in MG-ADL at week 4 [-1.9 (-3.3, -0.5)] and at time of best response [-1.4 (-2.8, 0.0)] and in QMG at week 4 [-3.2 (-5.2, -1.2)] and at time of best response [-3.0 (-5.0, -1.0)]. For AUC over 26 weeks, improvements were not significantly different between efgartigimod and ravulizumab for MG-ADL [-8.7 (-36.1, 18.8)] and QMG [-13.7 (-50.3, 22.9)]. Efgartigimod may provide a faster and greater improvement over 26 weeks in quality of life than ravulizumab in adults with AChR-Ab+gMG. Efgartigimod showed faster improvements in MG-ADL and QMG than ravulizumab.

Placebo Control and Blinding in Randomized Trials of Procedural Interventions

Unlike medications, procedural interventions are rarely trialed against placebo prior to becoming accepted in clinical practice. When placebo-controlled trials are eventually conducted, procedural interventions may be less effective than previously believed. To investigate the importance of including a placebo arm in trials of surgical and interventional procedures by comparing effect sizes from trials of the same procedure that do and do not include a placebo arm. Searches of MEDLINE and Embase identified all placebo-controlled trials for procedural interventions in any specialty of medicine and surgery from inception to March 31, 2019. A secondary search identified randomized clinical trials assessing the same intervention, condition, and end point but without a placebo arm for paired comparison. Placebo-controlled trials of anatomically site-specific procedures requiring skin incision or endoscopic techniques were eligible for inclusion; these were then matched to trials without placebo control that fell within prespecified limits of heterogeneity. Random-effects meta-regression, with placebo and blinding as a fixed effect and intervention and end point grouping as random effects, was used to calculate the impact of placebo control for each end point. Data were analyzed from March 2019 to March 2020. End points were examined in prespecified subgroups: patient-reported or health care professional-assessed outcomes, quality of life, pain, blood pressure, exercise-related outcomes, recurrent bleeding, and all-cause mortality. Ninety-seven end points were matched from 72 blinded, placebo-controlled trials (hereafter, blinded) and 55 unblinded trials without placebo control (hereafter, unblinded), including 111 500 individual patient end points. Unblinded trials had larger standardized effect sizes than blinded trials for exercise-related outcomes (standardized mean difference [SMD], 0.59; 95% CI, 0.29 to 0.89; P < .001) and quality-of-life (SMD, 0.32; 95% CI, 0.11 to 0.53; P = .003) and health care professional-assessed end points (SMD, 0.40; 95% CI, 0.18 to 0.61; P < .001). The placebo effect accounted for 88.1%, 55.2%, and 61.3% of the observed unblinded effect size for these end points, respectively. There was no significant difference between unblinded and blinded trials for patient-reported end points (SMD, 0.31; 95% CI, -0.02 to 0.64; P = .07), blood pressure (SMD, 0.26; 95% CI, -0.10 to 0.62; P = .15), all-cause mortality (odds ratio [OR], 0.23; 95% CI, -0.26 to 0.72; P = .36), pain (SMD, 0.03; 95% CI, -0.52 to 0.57; P = .91), or recurrent bleeding events (OR, -0.12; 95% CI, -1.11 to 0.88; P = .88). The magnitude of the placebo effect found in this systematic review and meta-regression was dependent on the end point. Placebo control in trials of procedural interventions had the greatest impact on exercise-related, quality-of-life, and health care professional-assessed end points. Randomized clinical trials of procedural interventions may consider placebo control accordingly.

Blinding, Placebo Effect, and GRADE Methodology—What Is Relevant?

Blinding, Placebo Effect, and GRADE Methodology—What Is Relevant?

Wild Blueberry Extract Intervention in Healthy Older Adults: A Multi-Study, Randomised, Controlled Investigation of Acute Cognitive and Cardiovascular Effects.

Circadian and homeostatic declines in cognitive performance are observed during the day, most commonly at 14:00. Additionally, postprandial reductions in cognitive ability have been widely demonstrated 1 h after lunch consumption, affecting domains of executive functioning (EF), episodic memory (EM), and attention. Existing evidence shows that anthocyanin-rich foods such as berries may improve or attenuate the decline in EF and EM in ageing adults. Further research is required to assess whether extracts such as wild blueberry extract (WBE) may be beneficial for cognitive function across an acute timeframe, including known periods of reduced functioning. (1) Study 1: ROAB: To investigate the efficacy of WBE in maintaining EF and EM throughout the day alongside measures of cardiovascular outcomes in healthy older adults. A range of WBE doses were utilised to identify the optimal dose at which cognitive and cardiovascular effects occur. (2) Study 2: BEAT: To replicate alleviation of cognitive decline during a predicted post-lunch dip whilst also improving cardiovascular outcomes following acute WBE 222 mg supplementation. Both studies employed a randomised, double-blind, cross-over, placebo-controlled design to explore the effects of WBE intervention versus placebo on several outcomes, including EM, EF, blood pressure, and heart rate in a healthy older adult population (aged 68-75). In ROAB, 28 participants received a single dose of WBE 111 mg, 222 mg, 444 mg, or 888 mg or placebo over a 5-week period, each separated by a 1-week washout. Outcomes were measured at 0 h, 2 h, 4 h, and 6 h post intervention, with intervention occurring immediately after baseline (0 h). In BEAT, 45 participants received WBE 222 mg and placebo (1-week washout). Outcomes were measured at 0 h and 6 h (14:00) when a post-lunch dip was anticipated. This was further enhanced by consumption of lunch 1 h prior to cognitive testing. The WBE 222 mg intervention aligned with known peaks in plasma blueberry polyphenol metabolites at 2 h post dosing, which would coincide with a predicted drop in post-lunch performance. ROAB: A significant dip in executive function was apparent at the 4 h timepoint for placebo only, indicating attenuation for WBE doses. Strikingly, WBE 222 mg produced acute reductions in both systolic and diastolic blood pressure compared with placebo. BEAT: EF reaction time was found to be significantly faster for WBE 222 compared to placebo at the predicted post-lunch dip (14:00), with no other notable benefits on a range of cognitive and cardiovascular outcomes. These two studies indicate that WBE may have cardiovascular benefits and attenuate the natural cognitive decline observed over the course of the day, particularly when a decline is associated with a circadian rhythm-driven postprandial dip. However, it is important to acknowledge that effects were subtle, and benefits were only observed on a small number of outcomes. Further research is required to explore the utility of WBE in populations already experiencing mild cognitive impairments.