Search results

Purpose – A placebo effect is a (positive) change in health outcomes that is due to a (positive) change in beliefs about the value of a treatment. Placebo effects might be “behavioral,” in the sense that revised beliefs lead to behavioral changes or new actions that in turn yield changes in health outcomes. Placebo effects might also include a “physiological” component, which refers broadly to non-behavioral, brain-modulated mechanisms by which new beliefs cause changes in health outcomes. Nearly all formal economic models of human behavior are consistent with behavioral placebo effects, but strongly inconsistent with their physiological counterparts. The reason is that the latter effects can imply that expectations enter, rather than multiply, state-contingent preferences. It is therefore unfortunate that little evidence exists on physiological placebo effects. We report data from novel clinical experiments with caffeine that seek to provide such evidence.

Methods – Subjects visit the clinic on multiple occasions. On each visit they ingest either a placebo or caffeine pill. Subjects only know the probability with which the pill includes caffeine. We obtain physiological measurements prior to ingestion and at 30, 60, and 90min after ingestion. Importantly, we constrain subjects to remain seated and read pre-selected magazines during the interval between treatment and outcome measurement.

Findings – Our design provides particularly clean inference because it (i) eliminates the possibility of behavioral confounds; (ii) provides for measurements at the individual level; (iii) manipulates beliefs without deception; and (iv) uses salient rewards. We find evidence for the existence of physiological placebo effects mediated by expectations.

Implications – Our results are consistent with the possibility that the prefrontal cortex provides external, top-down control that modulates physiological outcomes, and make a case for the importance of research geared toward developing appropriate and tractable frameworks that accommodate non-linear relationships between expectations and preferences.

Marketers of beauty products capitalize on consumers’ perception of beauty to enact a price placebo effect through setting high prices to insinuate a superior performing product. Yet, in the context of growing alternative beauty movements emphasizing inner beauty and self-acceptance, little is known on how the effect of price on a product’s perceived effectiveness and satisfaction is bounded by different modes of beauty conceptualization (BC). Hence, this study aims to investigate how distinct perceptions of beauty impact the effectiveness-based and satisfaction-based price placebo effects in Muslim-majority markets such as Turkey compared to markets largely driven by Western values such as New Zealand.

This research is based on a quasi-experimental factorial design based on the manipulation of the level of price for a beauty product and the observation of the extent of BC. The sample included 144 participants from Turkey and 147 participants from New Zealand.

This research finds that the manipulation of the price (low vs high) equally activates the effectiveness-centered price placebo effect in both countries. When expectations are taken into account, the (satisfaction-based) price placebo effect is non-existent in New Zealand, while in Turkey the higher price leads to an opposite effect: a significant decrease in satisfaction. It is also found that the effect of price on effectiveness is moderated by BC. In both countries, the price placebo effect is activated only when consumers narrowly conceptualize beauty, while this effect does not hold for broad conceptualizers. The effect of BC on the price placebo appears to be stronger in New Zealand in comparison to Turkey.

Marketing managers’ awareness of different perceptions of beauty and how these may influence the price placebo effect in different cultures would allow them to decide what strategies are most appropriate for different groups of customers. For example, by pursuing the movement toward inner beauty and its broad conceptualization, high-end brands are likely to compromise opportunities to capitalize on the price placebo effect. On the other hand, this alternative perspective may cultivate profound satisfaction in the long-term.

The price placebo effect disappears when people conceptualize beauty from a broad (inner) perspective. This suggests that public policymakers, to counteract the negative effects of misleading marketing and to create fair exchanges, must promote broad BC in society.

This study contributes to the body of the existing research on price placebo by offering unique insights into the boundary conditions of the price placebo effect underscored by BC in two distinct cultural-religious settings. Also, it proposes two different variations of price placebo, namely, effectiveness-centered vs satisfaction-centered. From a methodological point of view, it is the first project in the Islamic marketing discipline that applies the Islamic perspective on causality.

Accumulating evidence highlights the importance of microbiota-directed intervention in neuropsychiatric disorders. This study aims to investigate the effects of probiotic supplements as an adjunct therapy in combination with Ritalin in children with attention-deficit hyperactivity disorder (ADHD).

Children with ADHD, aged 6–12 years, who had an intelligent quotient of ≥70 were enrolled in the study. Participants were randomly assigned to either the group that received probiotics or the group that received the placebo in addition to the weight-adjusted dose of Ritalin. Parents were asked to complete the revised Conners Parent Rating Scale–short version (CPRS–RS), and the psychiatrist completed the seven-point Clinical Global Impression–Severity (CGI–S) scale. Two study groups were compared in three time points, including T1 (before intervention), T2 (at the end of fourth week) and T3 (at the end of the eighth week).

A total of 38 participants completed the study. After eight weeks of intervention, the probiotic group had a significant improvement regarding CPRS–RS scores in T2 (9.4 unit, p = 0.014) and T3 (18.6 unit, p < 0.001), compared to placebo. In addition, children in the probiotic group had 0.7 unit lower CGI in T3 (p = 0.018) than the placebo group. A significant reduction of CGI scores was observed in each interval (T2 vs T1, T3 vs T2 and T3 vs T1; p < 0.05). This significant change in CGI score between intervals was also detected in the placebo group in T2 vs T1 (p = 0.002) and T3 vs T1 (p < 0.001). Mean CPRS scores of the groups were different in T2 and T3 (p = 0.011 and p < 0.001, respectively) and mean CGI scores of the two study groups were different in T3 (p = 0.018).

Eight weeks of supplementation with probiotics had a favorable effect on symptoms and severity of ADHD. Therefore, probiotics as an adjuvant treatment might have a promising efficacy regarding the management of ADHD.

Drawing on signaling theory, this paper aims to argue in favor of a “placebo outsourcing effect” (POE) consisting of a positive relationship between provider’s bluffing and customer satisfaction.

The authors applied prediction-oriented segmentation SEM on a dyadic sample of 171 outsourcing relationships.

The authors highlighted two segments that display a form of POE, representing about three-quarters of the customer-provider dyads. The first segment exhibits a positive relationship between the provider’s bluffing and customer satisfaction that is further strengthened by the provider’s reputation and customer’s operational capabilities, while for the other segment, the provider’s bluffing has positive interactions with both operational capabilities and outsourcing experience. These findings show that service providers have reached the bluffing proficiency that enables them to bluff customer firms with varying levels of operational capabilities and outsourcing experience by using the most appealing signals for every type of customer.

Based on the findings, the authors provided to customer firms extensive guidelines to avoid the POE by frustrating service provider’s bluffing proficiency.

This study’s originality resides in the amendment of the disconfirmation paradigm of satisfaction in the outsourcing context by introducing and testing the POE.

Adipose tissue accumulation by trapping vitamin D and reducing its level may cause serious side effects. The purpose of this study is to determine the effects of vitamin D supplementation on dehydroepiandrosterone (DHEA), paraoxonase 1 (PON 1), insulin, free fatty acid (FFA), apolipoprotein-AI (Apo-AI) and apolipoprotein B (Apo-B) concentration in obese and overweight participants under low-calorie diet (LCD) program.

Healthy overweight and obese individuals (n = 70) with vitamin D deficiency were randomly assigned into 2 groups to receive either vitamin D supplements (an oral 2,000 IU vitamin D supplement) or placebo for 8 weeks.

All the participants were given an LCD program during the intervention. Vitamin D supplementation led to a significant increase in the levels of 25(OH)D (vitamin D vs placebo groups: 36.6 ± 9.8 vs 19.9 ± 3.5 ng/mL, p < 0.001), PON 1 levels (vitamin D vs placebo groups: 80 ± 25 vs 58 ± 23.2 ng/mL, p = 0.001), DHEA concentration (vitamin D vs placebo groups: 2.3 ± 0.7 vs 1.5 ± 0.6 ng/mL, p < 0.001) and Apo-AI levels (vitamin D vs placebo groups 3.7 ± 0.5 vs 3 ± 0.5 mg/dL, p < 0.001). Besides, intake of vitamin D supplements led to a significant decrease in FFA (vitamin D vs placebo groups: 3.1 ± 0.75 vs 3.5 ± 0.5 ng/mL, p = 0.001). After adjusting the analyses based on baseline levels, age and baseline body mass index measures, significant changes were observed in the insulin levels (0.03 ± 0.06 vs −1.7 ± 0.6 µIU/ml, p = 0.04). But the authors did not find any significant difference in the concentration of Apo-B between groups (vitamin D vs placebo groups: 71.5 ± 35.5 vs 66.6 ± 28.5 mg/dL, p = 0.05).

Overall vitamin D supplementation for eight weeks among vitamin D-deficient obese and overweight participants had beneficial effects on serum DHEA PON 1 FFA insulin and Apo- AI while it did not affect the Apo-B concentration.

Dietary fiber is not traditionally considered to have anti-inflammatory actions in skeletal muscle. This study aims to test the hypothesis that oat β-glucans fiber intake can inhibit exercise-induced inflammation.

Young adult males (age 18-30 years) consumed either oat bran β-glucans (2 × 1.5 g fiber/day) or placebo for 4 weeks (Trial 1: N = 11 for placebo, N = 9 for glucan; Trial 2: N = 7 for placebo, N = 8 for glucan). Muscle inflammatory stress was induced at baseline and post-intervention using a leg extension regimen.

Ingestion of β-glucans, but not placebo, protected against inflammation based on subjective soreness scores (two trials), as well as on plasma myeloperoxidase readings (one trial). Scores were subject ratings from 0 (no soreness) to 10 (injury that impairs movement). Mean soreness score was lower at 48 h after exercise stress: post-glucan treatment vs pre-treatment: Trial 1: 1.9 + 2.4 vs 3.3 + 2.2 (p = 0.05); Trial 2: 1.2 + 0.7 vs 3.9 + 2.7 (p < 0.05). Myeloperoxidase just after exercise stress increased for both groups pre-treatment, but only for the placebo group post-treatment: 62 + 12 vs 81 + 15 (p < 0.05).

This pilot study found that at least one type of dietary fiber can exert anti-inflammatory effects in skeletal muscle.

This paper aims to study the impact of combination Lactobacillus Rhamnosus Heriz I and Beta glucan on quality of life (QOL) in breast cancer (BC) patients receiving chemotherapy.

In all, 30 women with BC were enrolled in this randomized double-blind placebo-controlled clinical trial. Intervention group received either daily one capsule of L. rhamnosus strain Heriz I (2 × 10⁷ CFU) and two 10-mg capsules of soluble1–3,1–6,D-beta glucan and the placebo group receiving placebo, interval between two courses of chemotherapy. Health-related QOL was evaluated at baseline and end of the trial using the EORTC QOL Questionnaire version.3.0 (EORTC QLQ-C30).

The results showed that combination of L. rhamnosus Heriz I and Beta glucan supplementation in BC patients during chemotherapy improved functional scales score from 37.3 ± 12.1 to 39.8 ± 6.8 and this increase in comparison with placebo was significant after adjusting baseline value (p = 0.015). Changes in symptoms scores were not significant after intervention (p = 0.05) but the decreased score (66.1 ± 12.9 to 60.6 ± 9.4) was considerable clinically. As well as, changes in global health status/QOL score in intervention group in comparison with the placebo group was not significant (p = 0.93).

The findings suggest that combination of L. rhamnosus Heriz I and Beta glucan may be associated for improving functional scales and symptoms in patients with BC who underwent chemotherapy. To prove positive effect of supplements on other aspects of QOL, further studies are needed.

The purpose of this paper is to present and demonstrate how the use of a multifactor model in the analysis of market timing skill can be misleading because the use of a multifactor model does not suit all investment styles equally well. If the factors of the analysis model do not span the portfolio holdings of a fund with less conventional investment strategy, the use of a multifactor model may even deteriorate the overall inference in measuring the market timing skill of a large sample of funds.

This study investigates the limitations of multifactor models in the analysis of market timing skill by applying the traditional Treynor-Mazuy and Henriksson-Merton analysis models of market timing skill using a set of “placebo” funds which are “natural” passive market timers.

The results of the study show that the incorporation of the Carhart four-factor model into the analysis of market timing skill considerably reduces the percentage of significant market timing results. But, as expected, the reduction of bias is not equal for different investment styles, and it works best when the factors of the analysis model are related to the investment style of the placebo portfolio.

This style-related limitation of multifactor models in the analysis of market timing skill may result in detecting funds with less conventional investment strategies as market timers since the factors used in the analysis are not likely to span their investment styles.

This study shows that the use of a multifactor model may lead to inferring passive market timers with less conventional investment styles as market timers. In addition, the findings of the study leave option replication approaches as more preferable bias corrections than multifactor extensions.

This study aims to test the effects of Celliant armbands on grip strength in subjects with chronic wrist and elbow pain. Celliant® is a functional textile fabric containing minerals that emit infrared radiation (IR) in response to body heat. IR-emitting fabrics have biological effects including the reduction of pain and inflammation and the stimulation of muscle function.

A randomized placebo-controlled trial recruited 80 subjects (40 per group) with a six-month history of chronic wrist or elbow pain (carpal tunnel syndrome, epicondylitis or arthritis) to wear an armband (real Celliant or placebo fabric) on the affected wrist or elbow for two weeks. Grip strength was measured by a dynamometer before and after the two-week study.

For the placebo group, the mean grip strength increased from 47.95 ± 25.14 (baseline) to 51.69 ± 27.35 (final), whereas for the Celliant group, it increased from 46.3 ± 22.02 to 54.1 ± 25.97. The mean per cent increase over the two weeks was +7.8% for placebo and +16.8% for Celliant (p = 0.0372). No adverse effects was observed.

Limitations include the wide variation in grip strength in the participants at baseline measurement, which meant that only the percentage increase between baseline and final measurements showed a significant difference. Moreover, no subjective measurements of pain or objective neurophysiology testes was done.

Celliant armbands are easy to wear and have not been shown to produce any adverse effects. Therefore, there appears to be no barrier to prevent widespread uptake.

IR-emitting textiles have been studied for their beneficial effects, both in patients diagnosed with various disorders and also in healthy volunteers for health and wellness purposes. Although there are many types of textile technology that might be used to produce IR-emitting fabrics, including coating of the fabric with a printed layer of ceramic material, incorporating discs of mineral into the garment, the authors feel that incorporating ceramic particles into the polymer fibers from which the fabric is woven is likely to be the most efficient way of achieving the goal.

Celliant armbands appear to be effective in painful upper limb inflammatory disorders, and further studies are warranted. The mechanism of action is not completely understood, but the hypothesis that the emitted IR radiation is absorbed by nanostructured intracellular water provides some theoretical justification.