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PubMed2004

Placebo-controlled trials in major depression are necessary and ethically justifiable: how to improve the communication between researchers and ethical committees.

Despite numerous placebo-controlled clinical trials with antidepressants were conducted in humans and a large amount of data was already published in the last two decades, the members of the 4th European Expert Forum on Ethical Evaluation of Placebo-Controlled Studies in Depression were agreed that placebo-controlled trials with antidepressants also in the future are essential. Placebo-controlled studies measure the effect size in a reliable way and establish sensitivity and internal validity. They are scientifically sound and interpretable in terms of efficacy and are, therefore, clinically more relevant than non-placebo-controlled clinical trials. The "Note of Clarification" of the Declaration of Helsinki opens up where such trials are acceptable. This statement of the members of the 4th European Expert Forum is directed to academia, members of Ethic Committees, regulators, and industry to facilitate their decisions towards clinical studies with antidepressants. "Checklists" for the contents of patients information are given as well as for the investigator.Placebo-controlled clinical trials are scientifically necessary, ethical and feasible. The administration of the placebo is in itself a non-specific treatment and experts agree that there appears to be no increased suicidal risk in the placebo-group of carefully selected and monitored study patients.

Antidepressive Agents↗
PubMed2006

Placebo analgesia.

The placebo effect is the effect that follows the administration of an inert treatment (the placebo), be it pharmacological or not. It is important to understand that a placebo procedure simulates a therapy through the surrounding psychosocial context. Therefore, the study of the placebo effect is the study of the psychosocial context around the patient and its effects on the patient's brain. The real placebo response is a psychobiological phenomenon that can be due to different mechanisms, for example expectation and conditioning. Thus, there is not a single placebo effect but many, so that we have to look for different mechanisms in different conditions and in different systems and apparatuses. Today we are beginning to understand some of the neurobiological mechanisms of the placebo response, and this knowledge may help better understand the top-down control of the incoming sensory input, like pain, and the intricate interaction between mind and body.

Analgesia↗
PubMed2004

Placebo mechanisms and reward circuitry: clues from Parkinson's disease.

Recent evidence indicates that the placebo effect in Parkinson's disease is mediated by the release of dopamine in the dorsal striatum. Interestingly, there is also placebo-induced dopamine release in the ventral striatum, which establishes a connection between the placebo effect and reward mechanisms. Specifically, we propose that placebo responses are related to the activation of the reward circuitry. Here, the clinical benefit induced by placebos represents the reward. The magnitude of the placebo effect likely depends on the a priori probability of clinical benefit. This notion has profound implications in the design of clinical trials and placebo investigations.

Animals↗
PubMed2001

Evaluation of the placebo effect and reproducibility of blood pressure measurement in hypertension.

Pharmacologic studies in hypertension often describe blood pressure (BP) reductions in placebo control groups. This placebo effect is currently debated, as it seems to be related to BP measurement methods and as a regression to the mean phenomenon may lead to misinterpretation. Furthermore, data on pulse pressure are lacking. This study was designed to evaluate the placebo effect on BP and to differentiate it from regression to the mean. According to a crossover design, 26 mild-to-moderate hypertensive patients who were treated with placebo or given no treatment were followed-up for 1 month. Clinic and ambulatory BP was assessed at baseline and at the end of each 1-month period. Placebo administration resulted in significant reductions in clinic systolic, diastolic, and mean BP (P < .01), ambulatory 24-h SBP (P < .05), and daytime systolic, diastolic, and mean BP (P < .01, P < .05, P < .01, respectively). No significant differences were noted for pulse pressure and heart rate or between BP values measured at baseline and after 1 month without treatment. Despite a significant correlation between changes in clinic and ambulatory BP, the scatter of individual data suggests that the placebo response observed with one method cannot be systematically extrapolated to the other method. This study conclusively shows the effect of placebo in mild-to-moderate hypertension on both clinic and ambulatory systolic, diastolic, and mean BP, in which it has been shown to differ from the regression to the mean phenomenon. This effect was not observed for pulse pressure or heart rate.

Adult↗
PubMed1996

Prediction of positive placebo response among chronic schizophrenic outpatients.

We undertook this study to determine whether predictors of positive placebo response in chronic schizophrenic outpatients could be identified. Twelve placebo responders and 33 placebo nonresponders who participated in a parallel-group, double-blind, 12-week clinical drug trial were compared. No significant differences between the groups were found with regard to 16 anamnestic and symptom variables. To investigate further which variables at baseline predicted positive placebo response, a stepwise linear regression model was created. Of the seven variables entered into the model, only high scores in the positive domain of the Positive and Negative Syndrome Scale (delusions, unusual thought content, grandiosity, and suspiciousness/persecution) at baseline predicted significantly positive placebo response (p = .0047). Because the onset of placebo response was gradual, the authors hypothesize that placebo response in chronic schizophrenia consists mainly of two ingredients: nonspecific psychotherapeutic effect caused by the several assessments carried out during the study, and regression toward the mean.

Age of Onset↗
PubMedDate not supplied

The antitussive effect of placebo treatment on cough associated with acute upper respiratory infection.

OBJECTIVE: The objective of this study was to determine the effects of a placebo treatment on cough in patients with cough associated with acute upper respiratory tract infection (URTI). METHODS: Patients with dry or slightly productive cough associated with a history of URTI were recruited. Cough frequency (CF) over 15 minutes was recorded by means of a microphone connected to a pen recorder. Cough suppression time (CST) was recorded when patients were instructed by means of a red light to try not to cough. Patients received either a single dose of vitamin E (placebo treatment) or no treatment. CF and CST were recorded before and 15 minutes after treatment. RESULTS: Twenty-seven patients were randomized to placebo treatment and 27 to the no-treatment group (mean age 22.6 years). The median difference between post- and pretreatment CF was -3 in the no-treatment group and -18 in the placebo group (p = .0003). There was a significant increase in CST in the placebo group compared with no treatment (p = .027). CONCLUSIONS: The results demonstrate that placebo treatment has significant antitussive activity. This placebo effect may be related to generation of central neurotransmitters such as endogenous opioids.

Acute Disease↗
PubMed2006

Predictors of the placebo response in functional dyspepsia.

BACKGROUND: Trials in functional dyspepsia report placebo response rates of 30% to 40%. AIM: We aimed to identify predictors of the placebo response. METHODS: Patients from primary, secondary and tertiary practices with functional dyspepsia defined by Rome II criteria were enrolled into one of four clinical trials; 220 patients were randomized to receive placebo. Scintigraphic assessment of gastric emptying at baseline was repeated at the end of the treatment in those with delayed emptying. After a 2 week run-in period, patients were followed for 8 weeks on placebo. Response was assessed on a weekly basis and a responder was defined as satisfactory relief of meal-related symptoms on at least 50% of weeks. RESULTS: The mean age was 44 years (range 18-82) and 74% were female; 76 (35%) were placebo responders. The predominant symptom was an unstable measure over the trial. Independent predictors of a lower placebo response were lower body mass index and a more consistent predominant symptom pattern (both P < 0.05). No association was seen with age, gender, centre type, baseline symptom score, baseline or change in gastric emptying, or baseline quality of life. CONCLUSION: In functional dyspepsia, a consistent predominant symptom pattern and lower body mass index may be associated with a lower placebo response rate.

Adolescent↗
PubMed1992

The role of personality factors and suggestion in placebo effect during mental stress test.

The aims of this study were first of all to document a placebo effect on systolic blood pressure and heart rate during mental arithmetic induced stress and secondly to assess the role of suggestion in producing this effect. Two types of placebo were used, a simple placebo and a placebo with an implied therapeutic action. Both were compared with alprazolam. A placebo response was seen in just over half of the volunteers when the cardiovascular changes to mental arithmetic induced stress in healthy volunteers were measured. This response appeared to be unaffected by the suggested therapeutic effect. Dominant, independent subjects, identified using the Cattell 16 PF personality test were less likely to respond to placebo. Alprazolam (0.5 mg) did not prevent, to a significantly greater degree than placebo, the systolic blood pressure or heart rate increases provoked by the mental stress.

Adult↗
PubMed2003

The placebo effect on mood and behavior: possible role of opioid and dopamine modulation of the hypothalamic-pituitary-adrenal system.

There has been an increasing interest in the placebo effect over the past several decades. The relationship between the placebo effect and the underlying mechanisms of the body that control and maintain health is still not well understood. Significant evidence suggests that endogenous opioids and dopamine are involved in the mechanisms of the placebo effect. The endogenous opioid and dopaminergic systems have been demonstrated to exert effects on the functional activity of the hypothalamic-pituitary-adrenal (HPA) axis. The HPA system contributes to regulation of mood and behavior. The author suggests that opioid and dopamine modulation of the HPA system is one of the neurobiological mechanisms of the placebo effect on mood and behavior. To elucidate the underlying biological mechanisms of placebo effects and to study the use of placebo in clinical practice to improve health are two important and interrelated tasks. Future studies of the neurobiology of the placebo response may yield interesting and important results.

Affect↗
PubMed1999

Characteristics of placebo responses in medical treatment of premenstrual syndrome.

OBJECTIVE: This study characterizes the responses to placebo medication of patients with premenstrual syndrome (PMS) who were randomly assigned in controlled treatment trials. Possible predictors of placebo response were also examined. METHOD: Subjects from two randomized controlled trials were pooled. The 101 subjects met defined criteria for severe PMS, remained eligible after 1 month of single-blind placebo lead-in treatment, and were randomly assigned to 3 months of double-blind placebo treatment. Improvement in the current study was defined as a decrease of at least 50% in premenstrual symptom score from the pretreatment baseline. RESULTS: At endpoint, 20 (20%) of the placebo-treated subjects showed sustained improvement, 18 of these in at least 3 of the 4 months of placebo medication. Another 42% of subjects partially improved, and 39% were clearly unimproved throughout the study period. CONCLUSIONS: Some patients with severe PMS experience significant and sustained improvement with placebo medication, but the majority report only partial or no improvement. Patients who sustain improvement for at least 2 consecutive months are likely to remain improved, indicating the importance of nondrug factors in clinical care.

Adolescent↗
PubMed2004

The placebo response: its putative role as a functional salutogenic mechanism of the central nervous system.

The concept of placebo has evolved over time. Generally believed to be the basis of the premodern pharmacopoeia, the placebo has been adopted in practice as a harmless but unscientific approach towards alleviating symptoms. Currently, many medical scientists view placebos pejoratively as confounding elements in the analysis of randomized control trials.This article examines the changing attitudes towards placebos and the persistent controversies that surround their administration. The possible role of the placebo response as a functional salutogenic brain mechanism is considered, and elements of Edelman's neurobiological model of self and attractor theory are combined to explain how a unitary response by the central nervous system might yield diverse placebo effects. It is concluded that placebo responses are rooted in the complexity of mind/body interactions and that their underlying physiological mechanisms may be elucidated via methods that directly examine brain activity as the basis of subjective experience.

Central Nervous System↗
PubMed1999

Placebos in medicine.

Although placebo may be defined as a treatment that does not have a specific effect on the illness for which it is being used, or as an intervention for which there is no scientific theory explaining its mechanism of action, placebo can be an effective therapeutic intervention. Placebo can be administered as a drug or as a procedural intervention. Multiple factors affect the ultimate intensity of the placebo response. One of these factors is the approach taken by the health care provider in administering an intervention. The medical literature is replete with clinical studies showing beneficial results of placebo administration. Physicians should attempt to better understand placebo to harness its beneficial effects, avoid nocebo or negative effects, and maximize the placebo response.

Adult↗
PubMed1998

A randomized, placebo-controlled comparison of oral valacyclovir and acyclovir in immunocompetent patients with recurrent genital herpes infections. The Valaciclovir International Study Group.

OBJECTIVE: To compare valacyclovir hydrochloride with acyclovir in the treatment of recurrent genital herpes infection. DESIGN: A multicenter, double-blind, placebo-controlled, randomized, parallel-design study. SETTING: University clinics (dermatology, gynecology, and infectious diseases) and private practices. PATIENTS: One thousand two hundred patients with recurrent genital herpes simplex infections. INTERVENTIONS: Patients self-initiated oral therapy with 1000 mg of valacyclovir hydrochloride twice daily, 200 mg of acyclovir 5 times daily, or placebo for 5 days. MAIN OUTCOME MEASURES: Resolution of all signs and symptoms of recurrent genital herpes infection. RESULTS: Both drugs were significantly more effective than placebo in speeding resolution of herpetic episodes (median duration, 4.8, 4.8, and 5.9 days, respectively); the hazards ratios for valacyclovir and acyclovir vs placebo were 1.66 (95% confidence interval [CI], 1.38-2.01) and 1.71 (95% CI, 1.41-2.06) (both P < .001). Similarly, valacyclovir and acyclovir significantly hastened lesion healing (hazards ratios vs placebo were 1.88 [95% CI, 1.53-2.32] and 1.90 [95% CI, 1.55-2.34], respectively; P < .001). Pain duration was shorter in valacyclovir- and acyclovir-treated patients (median, 2 vs 3 days). Viral shedding stopped 2.55 times faster in patients treated with valacyclovir and 2.24 times faster in patients treated with acyclovir than in patients treated with placebo. Aborted episodes, in which lesions did not progress beyond the macule or papule stage, tended to occur in more patients treated with valacyclovir (25.9%) or acyclovir (24.8%) than in patients treated with placebo (19.8%). Valacyclovir and acyclovir did not differ significantly with regard to their respective effects on any of the above efficacy parameters. The nature, severity, and frequency of adverse events did not differ among the 3 treatment groups. CONCLUSIONS: Twice-daily valacyclovir was as effective and well tolerated in the treatment of recurrent genital herpes simplex virus infection as 5-times-daily acyclovir. Therefore, valacyclovir could prove a useful alternative to acyclovir when convenience of dosing or compliance issues are the prime considerations in treatment.

Acyclovir↗
PubMed1993

Alprazolam in the treatment of premenstrual syndrome. A double-blind, placebo-controlled trial.

OBJECTIVE: To evaluate the efficacy of alprazolam in the treatment of premenstrual syndrome. DESIGN: A randomized, double-blind, placebo-controlled, crossover trial of alprazolam during eight menstrual cycles. SETTING: Outpatient clinic at the National Institute of Mental Health, Bethesda, Md. PARTICIPANTS: Twenty-two women with prospectively confirmed premenstrual syndrome entered this study. All subjects were either self-referred or were referred by their physicians. All reported having regular menstrual cycle lengths, were taking no medication, and were free of current or recent medical or psychiatric illness. Two subjects did not complete the trial. INTERVENTION: Participants were assigned to receive alprazolam or placebo as follows: cycle 1, 0.25 mg of alprazolam or placebo three times daily beginning on menstrual cycle day 16; cycle 2, 0.50 mg of alprazolam or placebo three times daily according to the regimen during the first cycle; cycles 3 and 4, 0.75 mg of alprazolam or placebo three times daily from menstrual cycle day 16 and continued throughout the fourth menstrual cycle to evaluate the efficacy of relatively long-term (approximately 6 weeks) treatment with alprazolam. MAIN OUTCOME MEASURES: Daily self-report symptoms ratings were completed during the entire study period. RESULTS: We observed no significant differences in the severity of premenstrual symptom ratings during alprazolam administration compared with placebo on any scale except the Beck Depression Inventory Scale. The Beck Depression Inventory ratings demonstrated a statistically (F1,19 = 7.1, P < .05), but not clinically, significant improvement in depressive symptoms during alprazolam administration compared with placebo. CONCLUSION: Our findings do not support alprazolam as a uniformly effective treatment for the symptoms of premenstrual syndrome.

Adult↗
PubMed2000

Olanzapine treatment of psychotic and behavioral symptoms in patients with Alzheimer disease in nursing care facilities: a double-blind, randomized, placebo-controlled trial. The HGEU Study Group.

BACKGROUND: Patients with Alzheimer disease (AD) commonly exhibit psychosis and behavioral disturbances that impair patient functioning, create caregiver distress, and lead to institutionalization. This study was conducted to assess the efficacy and safety of olanzapine in treating psychosis and/or agitation/aggression in patients with AD. METHODS: A multicenter, double-blind, placebo-controlled, 6-week study was conducted in 206 elderly US nursing home residents with AD who exhibited psychotic and/or behavioral symptoms. Patients were randomly assigned to placebo or a fixed dose of 5, 10, or 15 mg/d of olanzapine. The primary efficacy measure was the sum of the Agitation/Aggression, Hallucinations, and Delusions items (Core Total) of the Neuropsychiatric Inventory-Nursing Home version. RESULTS: Low-dose olanzapine (5 and 10 mg/d) produced significant improvement compared with placebo on the Core Total (-7.6 vs -3.7 [P<.001] and -6.1 vs -3. 7 [P =.006], respectively). Core Total improvement with olanzapine, 15 mg/d, was not significantly greater than placebo. The Occupational Disruptiveness score, reflecting the impact of patients' psychosis and behavioral disturbances on the caregiver, was significantly reduced in the 5-mg/d olanzapine group compared with placebo (-2.7 vs -1.5; P =.008). Somnolence was significantly more common among patients receiving olanzapine (25.0%-35.8%), and gait disturbance occurred in those receiving 5 or 15 mg/d (19.6% and 17.0%, respectively). No significant cognitive impairment, increase in extrapyramidal symptoms, or central anticholinergic effects were found at any olanzapine dose relative to placebo. CONCLUSION: Low-dose olanzapine (5 and 10 mg/d) was significantly superior to placebo and well tolerated in treating agitation/aggression and psychosis in this population of patients with AD.

Aged↗
PubMed2004

A multicenter, randomized, double-blind, placebo-controlled trial of paroxetine in children and adolescents with social anxiety disorder.

BACKGROUND: Social anxiety disorder is a debilitating, highly prevalent disorder in children and adolescents. If left untreated, it can interfere with emotional, social, and school functioning. OBJECTIVE: To evaluate the efficacy and tolerability of paroxetine in children and adolescents with social anxiety disorder. DESIGN AND SETTING: Multicenter, 16-week, randomized, double-blind, placebo-controlled, flexible-dose, parallel-group, outpatient study. Patients A total of 322 children (8-11 years of age) and adolescents (12-17 years of age) with social anxiety disorder as their predominant psychiatric illness. Intervention Eligible patients were randomized (1:1) to receive paroxetine (10-50 mg/d) or placebo. RESULTS: Four hundred twenty-five patients were screened, and 322 were randomized to treatment. Of these, 319 were included in the intention-to-treat population (paroxetine, n = 163; placebo, n = 156). At the week 16 last observation carried forward end point, the odds of responding (Clinical Global Impression-Improvement score of 1 or 2) were statistically significantly greater for paroxetine (77.6% response [125/161]) than for placebo (38.3% response [59/154]) (adjusted odds ratio, 7.02; 95% confidence interval, 4.07 to 12.11; P<.001). The proportion of patients who were "very much" improved (Clinical Global Impression-Improvement score of 1) was 47.8% (77/161) for paroxetine compared with 14.9% (23/154) for placebo. Adverse events occurring at an incidence of 5% or greater for paroxetine and twice that for placebo were insomnia (14.1% vs 5.8%), decreased appetite (8.0% vs 3.2%), and vomiting (6.7% vs 1.9%). Withdrawals due to adverse events were infrequent (5.5% [9/163] for paroxetine and 1.3% [2/156] for placebo). CONCLUSION: Paroxetine is an effective, generally well-tolerated treatment for pediatric social anxiety disorder.

Adolescent↗
PubMed2004

Efficacy of disulfiram and cognitive behavior therapy in cocaine-dependent outpatients: a randomized placebo-controlled trial.

CONTEXT: Disulfiram has emerged as a promising treatment for cocaine dependence, but it has not yet been evaluated in general populations of cocaine users. OBJECTIVES: To compare the effectiveness of disulfiram therapy with that of a placebo condition in reducing cocaine use and to compare the effectiveness of 2 active behavioral therapies-cognitive behavior therapy (CBT) and interpersonal psychotherapy (IPT)-in reducing cocaine use. DESIGN: Randomized, placebo-controlled, double-masked (for medication condition), factorial (2 x 2) trial with 4 treatment conditions: disulfiram plus CBT, disulfiram plus IPT, placebo plus CBT, and placebo plus IPT. SETTING: A community-based outpatient substance abuse treatment program. PATIENTS: A total of 121 individuals meeting the criteria for current cocaine dependence. INTERVENTIONS: Patients received either disulfiram (250 mg/d) or placebo in identical capsules. Medication compliance was monitored using a riboflavin marker procedure. Both behavioral therapies (CBT and IPT) were manual guided and were delivered in individual sessions for 12 weeks. MAIN OUTCOME MEASURES: Random regression analyses of self-reported frequency of cocaine use and results of urine toxicology screens. RESULTS: Participants assigned to disulfiram reduced their cocaine use significantly more than those assigned to placebo, and those assigned to CBT reduced their cocaine use significantly more than those assigned to IPT (P<.01 for both). Findings were consistent across all study samples (eg, intention to treat, treatment initiators, and treatment completers). Benefits of disulfiram use and CBT were most pronounced for participants who were not alcohol dependent at baseline or who fully abstained from drinking alcohol during treatment. Adverse effects experienced by participants who received disulfiram were mild and were not considerably different from those experienced by participants who received placebo. CONCLUSIONS: Disulfiram and CBT are effective therapies for general populations of cocaine-dependent individuals. Disulfiram seems to exert a direct effect on cocaine use rather than through reducing concurrent alcohol use.

Adult↗
PubMed2001

Antidepressants using active placebos.

BACKGROUND: Although there is a consensus that antidepressants are effective in depression, placebo effects are also thought to be substantial. Side effects of antidepressants may reveal the identity of medication to participants or investigators and thus may bias the results of conventional trials using inert placebos. Using an 'active' placebo which mimics some of the side effects of antidepressants may help to counteract this potential bias. OBJECTIVES: To investigate the efficacy of antidepressants when compared with 'active' placebos. SEARCH STRATEGY: The Cochrane Collaboration Depression, Anxiety and Neurosis review groups's search strategy was used to search MEDLINE (1966-2000), PsychLIT (1980-2000) and EMBASE (1974-2000) and this was last done in July 2000. Reference lists from relevant articles and textbooks were searched and 12 specialist journals were handsearched up to 1996. SELECTION CRITERIA: Randomised and quasi randomised controlled trials comparing antidepressants with active placebos in people with depression. DATA COLLECTION AND ANALYSIS: Since many different outcome measures were used a standard measure of effect was calculated for each trial. A subgroup analysis of inpatient and outpatient trials was conducted. Two reviewers independently assessed whether each trial met inclusion criteria. MAIN RESULTS: Nine studies involving 751 participants were included. Two of them produced effect sizes which showed a consistent and statistically significant difference in favour of the active drug. Combining all studies produced a pooled estimate of effect of 0.39 standard deviations (confidence interval, 0.24 to 0.54) in favour of the antidepressant measured by improvement in mood. There was high heterogeneity due to one strongly positive trial. Sensitivity analysis omitting this trial reduced the pooled effect to 0.17 (0.00 to 0.34). The pooled effect for inpatient and outpatient trials was highly sensitive to decisions about which combination of data was included but inpatient trials produced the lowest effects. REVIEWER'S CONCLUSIONS: The more conservative estimates from the present analysis found that differences between antidepressants and active placebos were small. This suggests that unblinding effects may inflate the efficacy of antidepressants in trials using inert placebos. Further research into unblinding is warranted.

Antidepressive Agents↗