O presente trabalho busca revisar fatores metodológicos e relativos aos pacientes associados com a resposta ao placebo em ensaios clínicos randomizados de antidepressivos em crianças e adolescentes através de uma atualização da revisão sistemática Placebo Response in Randomized Controlled Trials of Antidepressants for Pediatric Major Depressive Disorder de Bridge et al., publicada em 2009 com dados referentes ao período de 1997 a 2006. Este estudo analisou preditores relacionados ao indivíduo, como gênero, proporção de caucasianos, primeiro episódio depressivo, idade, tempo de doença e gravidade de sintomas depressivos. Quanto a possíveis preditores metodológicos, foram analisados ano de publicação, número de locais de estudo, número de pacientes randomizados, tempo de estudo, local (nos Estados Unidos ou não), se houve placebo run in period, o uso de placebo para todos os participantes anteriormente à randomização e a média de participantes randomizados por local de estudo. Esta revisão identificou como preditor mais importante para resposta ao placebo a variável número de locais de estudo, mesmo com controle para gravidade de doença. Publicado em 2009, este estudo foi o único ao investigar efeito placebo primariamente a analisar dados referentes apenas aos transtornos depressivos na infância e na adolescência e exclusivamente antidepressivos de segunda geração, não incluindo antidepressivos tricíclicos. Tendo em vista que mais de uma década se passou desde a publicação do estudo mais recente incluído, nesta dissertação buscou-se atualizar esses resultados, utilizando os mesmos critérios de busca de estudos e de inclusão e de exclusão, também fazendo uso das mesmas variáveis e análises estatísticas. A análise compreendeu o período de 2006 a 2015, com a inclusão de 4 novos estudos publicados e não publicados, que preencheram os mesmos critérios descritos em 2009. A amostra de pacientes aumentou cerca de 26%, com o número de pacientes randomizados aumentando de 2.862 para 3.608. As características de estudo que tiveram associação estatisticamente significativa com a resposta ao placebo foram número de pacientes randomizados e número de locais de estudo. Após análise por regressão múltipla, o único preditor de resposta ao placebo foi o número de locais de estudo. Diferentemente do estudo anterior não houve associação entre a proporção de respondedores ao placebo e o ano de publicação. Utilizando a estratégia de investigação mais semelhante possível e com a inclusão dos últimos dez anos em estudos, o principal achado do estudo original pôde ser replicado, e o conhecimento sobre o tema atualizado. / This study aims to review methodological and patient characteristics associated with placebo response in randomized clinical trials of antidepressants in children and adolescents with major depressive disorder. We aim to update the study Placebo Response in Randomized Controlled Trials of Antidepressants for Pediatric Major Depressive disorder. Bridge et al. published this study in 2009 with data comprehending 1997 to 2006. The authors examined patient characteristics such as gender, proportion of Caucasian, recurrent depression, age, duration of illness and severity of depressive symptoms. Also possible clinical trial predictors were publication year, number of study sites, number of randomized patients, study duration, location (USA and non-USA), placebo run-in period, and mean number of participants per study site. The strongest predictor of placebo response found was number of study sites, even controlling for severity of illness. Furthermore placebo response has increased over the years in the studies analyzed. This review was the only study to investigate primarily placebo response in depressive disorder in childhood and adolescence and second-generation antidepressants, not including tricyclic antidepressants. The article presented here sought to update these results using the same search syntax, as well as inclusion and exclusion criteria, performing analysis with the same variables and statistical strategy. The update included research from 2006 to December 2015, with the inclusion of 4 published and unpublished studies that met the same criteria described in 2009. The sample increased around 26%: the number of patients randomized was 2,862 in the 2009 review, reaching to 3,608 in 2016. Number of patients randomized and number of study sites were the only variables that were significantly correlated with placebo response. Severity of depressive symptoms was not associated with placebo response in this update. After multiple regression analyses, the only predictor of placebo response was number of study sites. Unlike the previous study, there was no correlation between response to placebo and year of publication. Using the most similar research strategy with a larger sample the main finding of the original study could be replicated.

The phenomenon of not relying solely up on one's own judgment and of distorting one's perception toward a perceived social norm has been observed to take place with a rather large percentage of subjects participating in a number of research projects. Both Asch and Sherif have done extensive work showing this distortion of perception when an individual is placed in a group setting and finds himself in a contradictory position between his own perception and that of the other group members. The question arises as to whether or not acceptance of suggestion is a personality trait characteristic of the individual. To what extent, if any, will the trait of suggestibility manifest in one situation transfer to a second setting when suggestion is applied? Specifically, in this research project, individuals will be chosen according to their reactions to a placebo pill experiment. Placebo reactors will be those individuals who have manifest the internalization of suggestion in the experiment. Non-reactors will be chosen for their lack of placebo pill reaction which will be considered as rejection of the applied suggestion. Both the placebo reactors and non-reactors will be placed in an unstable experimental situation that has the possibilities of being structured according to the individual's perception or perceived social norm. Since the autokinetic illusion is almost universal, this phenomenon will be employed in the experimental procedure. Suggestion as to the amount of movement present in the autokinetic effect will then be given. The amount of movement will be recorded and tested for significance for the reactor and non-reactor groups.

The perception of pain can be modulated by a variety of factors such as biological/pharmacological treatments as well as potent cognitive and emotional manipulations. Placebo and nocebo effects are among the most prominent examples for such manipulations. Placebo and nocebo manipulations cause reliable psychological and physiological changes, although the administered agent or treatment is inert. The present dissertation aimed at investigating the role of cognitive and emotional influences in the generation of placebo and nocebo effects on pain perception. In addition, the feasibility of solely psychological placebo manipulations to alter the perception of pain was tested. Two commonly discussed preconditions for the generation of placebo and nocebo effects are prior experiences (i.e., past encounter of drug effects) and expectations (i.e., positive or negative attitudes towards an intervention). So far, research on placebo and nocebo effects relied on the administration of sham interventions, which resembled medical treatments like inert pills, creams or injections. However, such experimental procedures deal with confounds due to earlier experiences and expectations resulting from the individual’s history with medical interventions. Accordingly, the implementation of a placebo manipulation that is completely new to an individual, seems necessary to disentangle the contribution of experience and expectation for the induction of placebo and nocebo effects. To this end, in Experiment 1 the level of experience and expectation regarding a placebo-nocebo treatment was stepwise manipulated across three different experimental groups. To avoid any resemblances to earlier experiences and individual expectations, a mere psychological placebo-nocebo treatment was chosen that was new to all participants. They were instructed that visual black and white stripe patterns had been found to reliably alter the perception of pain. One group of participants received only the placebo-nocebo instruction (expectation), a second group experienced a placebo-nocebo treatment within a conditioning phase (experience) but no instruction, and a third group received the combination of both that is a placebo-nocebo instruction and a placebo-nocebo conditioning (experience + expectation). It was shown that only the experience + expectation group revealed significantly higher pain ratings and physiological responses during nocebo, compared to placebo trials of the succeeding test phase. These findings demonstrate that the induction of a mere psychological placebo-nocebo effect on pain is in principle possible. Most important, results indicate that such effects most likely rely on both, a positive treatment experience, due to the encounter of an effective intervention (placebo conditioning), and a positive expectation about the intervention (placebo instruction).Besides experience and expectation, the current mood state has been shown to modulate pain and to impact the induction of placebo and nocebo effects. In this vein it has been demonstrated that placebo effects come along with positive affect, while nocebo effects often occur together with elevated feelings of anxiety. To clarify the interaction of emotions and placebo-nocebo manipulations on pain perception, in Experiment 2 the paradigm of Experiment 1 was modified. Instead of black and white stripe patterns, positive and negative emotional pictures were presented, which either cued pain increase (nocebo) or pain decrease (placebo). Two experimental groups were compared, which differed with regard to the instructed contingency of positive pictures serving as placebo and negative pictures serving as nocebo cues or vice versa (congruent vs. incongruent). Results indicate that the differentiation of placebo and nocebo trials (behaviorally and physiologically) was more pronounced for the congruent compared to the incongruent group. However, in the incongruent group, affective pain ratings were also significantly higher for nocebo (positive pictures) than placebo (negative pictures) trials, similar to the congruent group. These findings demonstrate that a placebo-nocebo manipulation is capable to dampen and even reverse the originally pain augmenting effect of negative emotions. The results of Experiment 2 were further corroborated in Experiment 3, when the design was adapted to the fMRI scanner, and again a congruent and an incongruent experimental group were compared. Behavioral, physiological and neurophysiological markers of pain processing revealed a differentiation between nocebo and placebo conditions that was present irrespective of the experimental group. In addition, the fMRI analysis revealed an increased engagement of prefrontal areas for the incongruent group only, supposedly reflecting the reinterpretation or appraisal process when positive pictures were cueing negative outcomes. Taken together, the results of the present studies showed (a) that it is possible to induce a placebo-nocebo effect on pain solely by a psychological manipulation, (b) that both, prior experiences and positive expectation, are necessary preconditions for this placebo-nocebo effect, (c) that the impact of negative emotion on pain can be dampened and even reversed by placebo-nocebo manipulations, and (d) that most likely a cognitive top-down process is crucial for the induction of (psychological) placebo-nocebo effects. These results significantly enhance our understanding of psychological mechanisms involved in the induction of placebo-nocebo effects. Further, a fruitful foundation for future studies is provided, which will need to determine the contributions of primarily nocebo or placebo responses mediating the effects as demonstrated in the present studies. In a long-term perspective, the present findings may also help to exploit placebo effects and prevent from nocebo effect in clinical contexts by further elucidating crucial psychological factors that contribute to the placebo and nocebo response. / Die Wahrnehmung von Schmerz kann durch eine Vielzahl von Faktoren beeinflusst werden, darunter biologische und pharmakologische Interventionen sowie potente kognitive und emotionale Manipulationen. Placebo- und Nocebo-effekte gehören mit zu den eindrucksvollsten Beispielen für die Wirksamkeit derartiger Manipulationen. Placebo- und Nocebo-Behandlungen können zu manifesten psychologischen und physiologischen Veränderungen führen, obwohl die verabreichten Substanzen frei von Wirkstoffen bzw. den angewandten Scheinbehandlungen keine Wirkung zugeschrieben wird. In der vorliegenden Dissertation wurden kognitive und emotionale Einflussfaktoren auf die Induktion von Placebo- und Nocebo-Effekten bei der Wahrnehmung von Schmerz untersucht. Darüber hinaus sollte die Möglichkeit zur Verwendung rein psychologischer Placebo-Nocebo Manipulationen für die Modulation von Schmerz getestet werden. Zwei zentrale Voraussetzungen für die Erzeugung von Placebo und Nocebo-Effekten sind vorherige Erfahrung (z.B. auf Grund früherer Erfahrungen mit einem Medikament) und Erwartung (z.B. eine positive oder negative persönliche Einstellung gegenüber einer Therapie). Bisher basierte die Forschung zu Placebo- und Nocebo-Effekten vornehmlich auf Ergebnissen von Untersuchungen die Schein-Behandlungen oder Leerpräparate einsetzten wie z.B. Tabletten, Cremes oder Injektionen, die herkömmlichen medizinischen Interventionen sehr ähnlich sind. Jedoch ergibt sich bei einem derartigen experimentellen Vorgehen stets das Problem einer Konfundierung der Ergebnisse durch den Einfluss früherer Erfahrungen oder der individuellen Erwartungshaltung an die Behandlung, die aus einer Vorgeschichte medizinischer Therapieerlebnissen herrührt. Daraus leitet sich die Notwendigkeit von anderweitigen, dem Probanden völlig unbekannten Placebo-Interventionen ab, um die jeweilige Beteiligung von Erwartungs- und Erfahrungsprozessen für die Induktion von Placebo- und Nocebo-Effekten bestimmen zu können. Zu diesem Zweck wurden in Experiment 1 Erwartung und Erfahrung in drei Experimentalgruppen stufenweise und unabhängig voneinander manipuliert. Um einer Ähnlichkeit zu früheren Behandlungs-Erfahrungen und dadurch abgeleiteten Erwartungen vorzubeugen, wurde ein rein psychologisches Placebo-Nocebo Verfahren herangezogen, das mit Sicherheit allen Teilnehmern unbekannt war. Sie wurden darüber informiert, dass die Betrachtung von schwarz-weißen Streifenmustern eine wissenschaftlich bestätigte Wirkung auf die Schmerzwahrnehmung hätte. Eine Gruppe der Teilnehmer erhielt lediglich eine Placebo-Nocebo Instruktion (Erwartung), eine zweite Gruppe erlebte tatsächlich die Kopplung von zwei verschiedenen Streifenmustern mit unterschiedlich starken Schmerzreizen während einer Konditionierungs-Phase (Erfahrung) bekam aber keine Instruktion und eine dritte Gruppe erhielt sowohl die Placebo-Nocebo Instruktion als auch die Placebo-Nocebo Konditionierung (Erfahrung + Erwartung). Es konnte gezeigt werden, dass während der anschließenden Testphase lediglich die kombinierte Erfahrung + Erwartung Gruppe signifikant unterschiedliche Schmerzratings und physiologische Reaktionen auf die Schmerzreize während der Placebo- im Vergleich zu den Nocebo-Durchgängen aufwies. Diese Ergebnisse belegen, dass die Induktion eines rein psychologischen Placebo-Nocebo Effektes auf die Schmerzwahrnehmung prinzipiell möglich ist. Besonders hervorzuheben ist dabei die Notwendigkeit beider Prozesse, nämlich einer tatsächlichen Erfahrung der Wirksamkeit der Therapie (Placebo-Nocebo Konditionierung) und einer positiven Erwartung hinsichtlich der Intervention (Placebo-Nocebo Instruktion). Neben Erfahrung und Erwartung, hat die momentane Stimmung entscheidenden Einfluss auf die die Induktion von Placebo- und Nocebo-Effekten einerseits, sowie generell auf die Wahrnehmung von Schmerz andererseits. In diesem Zusammenhang konnte gezeigt werden, dass Placebo-Effekte mit einer Verbesserung der Stimmung einhergehen, Nocebo-Effekte hingegen häufig von gesteigerter Angst begleitet sind. Um die Interaktion von Emotionen und Placebo-Nocebo Manipulationen zu eruieren, wurde das in Experiment 1 etablierte Paradigma angewendet und modifiziert. Anstelle von Streifenmustern, wurden positive und negative emotionale Bilder präsentiert, die entweder eine Schmerz-Verstärkung (Nocebo) oder eine Schmerz-Linderung (Placebo) anzeigten. Zwei Experimentalgruppen wurden miteinander verglichen, die sich hinsichtlich der Kontingenz von positiven Bildern als Placebo- und negativen Bildern als Nocebo-Indikator, bzw. umgekehrt, positiven Bildern als Nocebo- und negativen Bildern als Placebo-Indikator, unterschieden (kongruent vs. inkongruent). Es zeigte, dass die Unterscheidung (Schmerzratings und physiologische Reaktionen auf den Schmerzreiz) zwischen Placebo- und Nocebo-Durchgängen in der kongruenten Gruppe stärker ausgeprägt war als in der inkongruenten Gruppe. Allerdings waren die affektiven Schmerzratings der inkongruenten Gruppe ebenfalls in Nocebo-Durchgängen (positive Bilder) signifikant höher als in Placebo-Durchgängen (negative Bilder), ähnlich zur kongruenten Gruppe. Die Daten zeigen damit, dass eine Placebo-Nocebo Manipulation in der Lage ist, die genuin Schmerz verstärkende Wirkung negativer Emotionen abzuschwächen und sogar umzukehren. Die Befunde aus Experiment 2 konnten zusätzlich in Experiment 3 gestützt werden, welches das zuvor getestete Design ins fMRT überführte und gleichermaßen eine kongruente und eine inkongruente Experimentalgruppe miteinander verglich. Verhaltensmaße sowie physiologische und neurophysiologische Korrelate der Schmerzwahrnehmung ergaben eine eindeutige Differenzierung zwischen Placebo- und Nocebo-Durchgängen, unabhängig von der Experimentalgruppe. Darüber hinaus zeigte sich in der inkongruenten Bedingung eine verstärkte präfrontale Aktivierung für den Vergleich von Nocebo- und Placebo-Durchgängen, was potenziell auf einen zusätzlichen Re- Interpretations- oder Appraisal-Prozess zurückzuführen ist, der sich einstellt, wenn ein positives Bild eine negative Konsequenz vorhersagt. Zusammengefasst zeigen die vorliegenden Studien, dass es (a) möglich ist einen Placebo-Nocebo Effekt mit einer rein psychologischen Manipulation hervorzurufen, dass (b) im Fall rein psychologischer Placebo-Nocebo Manipulationen sowohl Erfahrung als auch positive Erwartung notwendig sind, dass (c) der Einfluss negativer Emotionen auf Schmerz mittels einer Placebo-Nocebo Manipulation reduziert und sogar umgekehrt werden kann und (d) höchstwahrscheinlich ein kognitiver (Neu-) Bewertungsprozess für die Induktion (psychologischer) Placebo-Nocebo Effekte essentiell ist. Die Ergebnisse tragen zum Verständnis der beteiligten psychologischen Prozesse bei der Induktion von Placebo-Nocebo Effekten erheblich bei. Darüber hinaus stellen die verwendeten Paradigmen eine vielseitige Ausgangsposition für zukünftige Studien dar, die klären müssen, ob für die gefunden Ergebnisse vornehmlich Placebo- oder Nocebo-Effekte verantwortlich sind. Perspektivisch könnten die vorliegenden Befunden helfen, die psychologischen Grundlagen der Placebo-Nocebo Antwort näher zu beleuchten und damit sogar im klinischen Kontext zum Ausschöpfen von Placebo- sowie zur Vorbeugung von Nocebo-Effekten beizutragen.

Background and aim: Many patients with cancer experience emesis (nausea and vomiting) during radiotherapy. The overall aim of this thesis was to improve the situation for patients with risk for emesis during radiotherapy, by evaluating emesis in patients receiving verum (genuine) acupuncture, sham (simulated) acupuncture or standard care during radiotherapy. Methods: In study I, a cross-sectional sample (n=368) treated with radiotherapy over various fields answered a study-specific questionnaire. In study II, 80 healthy volunteers were randomized to receive needling with verum acupuncture or non-penetrating telescopic sham needles by one of four physiotherapists. In study III, 215 patients were randomly allocated to verum (n=109) or non-penetrating telescopic sham (n=106) acupuncture during their entire radiotherapy period over abdominal or pelvic fields. The same 215 patients were also included in study IV. They were compared to 62 patients irradiated over abdominal or pelvic fields, selected from study I. Results: In study I, the weekly prevalence of nausea was 39 % in all radiotherapy-treated patients and 63 % in abdominal or pelvic irradiated patients. Age younger than 40 years and previous experience of nausea in other situations were characteristics associated with an increased risk for nausea. Of the 145 nauseous patients, 34 % considered their antiemetic treatment as insufficient. Patients with nausea reported lower level of quality of life compared to patients free from nausea. In study II, most individuals needled with verum (68 %) or sham (68 %) acupuncture could not identify needling type, and that blinding result varied from 55 to 80 % between the four therapists. In study III, nausea was experienced by 70 % (mean number of days=10.1) and 25 % vomited during the radiotherapy period. In the sham group 62 % experienced nausea (mean number of days=8.7) and 28 % vomited. Ninety five percent in the verum and 96 % in the sham group believed that the treatment had been effective for nausea. In both groups, 67 % experienced other positive effects, on relaxation, mood, sleep or pain-reduction, and 89 % were interested in receiving the treatment again. In study IV, the weekly prevalence of nausea and vomiting was 38 and 8 % in the verum group, 37 and 7 % in the sham group and 63 and 15 % in the standard care group. The nausea difference between the acupuncture and the standard care cohort was statistically significant, also after overall adjustments for potential confounding factors. The nausea intensity in the acupuncture cohort was lower compared to the standard care cohort (p=0.002). Patients who expected nausea had increased risk for nausea compared to patients who expected low risk for nausea (Relative risk 1.6). Conclusions and implications: Nausea was common during abdominal or pelvic field irradiation in patients receiving standard care. Verum acupuncture did not reduce emesis compared to sham acupuncture, while reduced emesis was seen in both patients treated with verum or sham acupuncture. Health-care professionals may consider identifying and treating patients with increased risk for nausea in advance. The telescopic sham needle was credible. Researchers may thus use and standardize the sham procedure in acupuncture control groups. The choice of performing acupuncture during radiotherapy cannot be based on arguments that the specific characters of verum acupuncture have effects on nausea. It is important to further study what components in the acupuncture procedures that produce the dramatic positive but yet not fully understood antiemetic effect, making it possible to use those components to further increase quality of care during radiotherapy.

The placebo effect represents a fascinating example of how cognition can influence the physiology of the brain and body. The expectation of therapeutic benefit elicited by a placebo given in the guise of active medication has been proposed to be a form of reward expectation, and is associated with activation of brain reward circuitry. Prominent placebo effects occur in Parkinson’s disease (PD), where the expectation of symptom improvement stimulates dopamine release in the striatum. In the work described in this dissertation, positron emission tomography with [¹¹C] raclopride was used to investigate the relationship between the strength of expectation of benefit and the degree of dopamine release in PD, and how this relationship corresponds to current models of dopamine function in reward. Chapter 3 describes a pilot study conducted in patients who had undergone subthalamic nucleus deep-brain stimulation (STN-DBS) in which we examined how awareness of stimulator status (ON or OFF) affected synaptic dopamine levels compared to when subjects were blind. No difference was detected between conditions; however, it proved to be difficult to maintain blinding due to the profound effects of STN-DBS. Chapter 4 describes the development of the methodology for the analysis of high-resolution PET data, in which we utilized the combined efforts of neuroscience and imaging physics to optimize the analysis of [¹¹C] raclopride PET data. In Chapter 5, I describe the use of verbal instructions to manipulate patients’ expectations in order to investigate how the likelihood of receiving levodopa influenced dopamine release when the patients were in fact given placebo. Placebo-induced dopamine release was differentially modulated by expectation in the dorsal and ventral striatum: dopamine release in the putamen was related monotonically to expected reward value, whereas dopamine released in the ventral striatum reflected the uncertainty of benefit or the salience of the expectation. The placebo effect in PD therefore involves at least two related but separate mechanisms: the expectation of benefit itself, which is scaled to reflect the value of the drug to the patient and is mediated by nigrostriatal dopamine, and the uncertainty or salience of benefit that is mediated by mesolimbic dopamine.

No description available.

I dagsläget finns det en hel del kosttillskott som lovar bättre prestation, men många av substraten har inte tillräckligt med forskning bakom dem som bevisar att de verkligen fungerar. Tre av de kosttillskotten där det finns mycket forskning på och har visat sig förbättra prestationen är kreatin, koffein och natriumbikarbonat. Nyare forskning har studerat supplementering av beta-alanin som tros kan fördröja muskeltröttheten under fysisk aktivitet. Det är inte mycket av denna forskning gjord på överkroppen hos elitidrottare, därför ska detta undersökas i denna studie. Många teorier om muskeltrötthet involverar att vätejoner (H+) som härrör från bl.a. laktat, ändrar pH-värdet i muskeln, vilket kan vara en av anledningarna till varför prestationen minskar. Beta-alaninsupplementering ökar karnosin nivåerna i muskeln vilket fungerar som en H+ buffert och kan motverka sänkningen av pH-värdet i muskeln och kanske därför kan fördröja muskeltröttheten. Syftet med denna studie var att se om fyra veckors beta-alaninsupplementering kan förbättra prestationen hos högintensividrottare. Testpersonerna delades upp i två grupper, en grupp som fick beta-alanin (n=6) och en placebogrupp (n=4) som fick maltodextrin 2,5 g 2 gånger om dagen. Testet som utfördes var ett modifierat wingatetest för överkroppen, det utfördes för- och eftertester. Även blodlaktat testades direkt efter utfört test samt 2 minuter efteråt. Testet resulterade inte i några statistiska signifikanta skillnader i average power och peak power varken hos gruppen med beta-alanin eller placebo (p≥0,13). Eftertesterna visade ett högre värde av blodlaktatet 2 min efter avslutat test i jämförelse med förtesterna i beta-alaningruppen (p=0,05). Slutsatsen av denna studie var att vi inte kunde visa att 4 veckors beta-alaninsupplementering leder till bättre prestation i överkroppen hos tränade individer i den utförda interventionen, större studier bör utföras.

The placebo effect represents a fascinating example of how cognition can influence the physiology of the brain and body. The expectation of therapeutic benefit elicited by a placebo given in the guise of active medication has been proposed to be a form of reward expectation, and is associated with activation of brain reward circuitry. Prominent placebo effects occur in Parkinson’s disease (PD), where the expectation of symptom improvement stimulates dopamine release in the striatum. In the work described in this dissertation, positron emission tomography with [¹¹C] raclopride was used to investigate the relationship between the strength of expectation of benefit and the degree of dopamine release in PD, and how this relationship corresponds to current models of dopamine function in reward. Chapter 3 describes a pilot study conducted in patients who had undergone subthalamic nucleus deep-brain stimulation (STN-DBS) in which we examined how awareness of stimulator status (ON or OFF) affected synaptic dopamine levels compared to when subjects were blind. No difference was detected between conditions; however, it proved to be difficult to maintain blinding due to the profound effects of STN-DBS. Chapter 4 describes the development of the methodology for the analysis of high-resolution PET data, in which we utilized the combined efforts of neuroscience and imaging physics to optimize the analysis of [¹¹C] raclopride PET data. In Chapter 5, I describe the use of verbal instructions to manipulate patients’ expectations in order to investigate how the likelihood of receiving levodopa influenced dopamine release when the patients were in fact given placebo. Placebo-induced dopamine release was differentially modulated by expectation in the dorsal and ventral striatum: dopamine release in the putamen was related monotonically to expected reward value, whereas dopamine released in the ventral striatum reflected the uncertainty of benefit or the salience of the expectation. The placebo effect in PD therefore involves at least two related but separate mechanisms: the expectation of benefit itself, which is scaled to reflect the value of the drug to the patient and is mediated by nigrostriatal dopamine, and the uncertainty or salience of benefit that is mediated by mesolimbic dopamine.

O presente trabalho busca revisar fatores metodológicos e relativos aos pacientes associados com a resposta ao placebo em ensaios clínicos randomizados de antidepressivos em crianças e adolescentes através de uma atualização da revisão sistemática Placebo Response in Randomized Controlled Trials of Antidepressants for Pediatric Major Depressive Disorder de Bridge et al., publicada em 2009 com dados referentes ao período de 1997 a 2006. Este estudo analisou preditores relacionados ao indivíduo, como gênero, proporção de caucasianos, primeiro episódio depressivo, idade, tempo de doença e gravidade de sintomas depressivos. Quanto a possíveis preditores metodológicos, foram analisados ano de publicação, número de locais de estudo, número de pacientes randomizados, tempo de estudo, local (nos Estados Unidos ou não), se houve placebo run in period, o uso de placebo para todos os participantes anteriormente à randomização e a média de participantes randomizados por local de estudo. Esta revisão identificou como preditor mais importante para resposta ao placebo a variável número de locais de estudo, mesmo com controle para gravidade de doença. Publicado em 2009, este estudo foi o único ao investigar efeito placebo primariamente a analisar dados referentes apenas aos transtornos depressivos na infância e na adolescência e exclusivamente antidepressivos de segunda geração, não incluindo antidepressivos tricíclicos. Tendo em vista que mais de uma década se passou desde a publicação do estudo mais recente incluído, nesta dissertação buscou-se atualizar esses resultados, utilizando os mesmos critérios de busca de estudos e de inclusão e de exclusão, também fazendo uso das mesmas variáveis e análises estatísticas. A análise compreendeu o período de 2006 a 2015, com a inclusão de 4 novos estudos publicados e não publicados, que preencheram os mesmos critérios descritos em 2009. A amostra de pacientes aumentou cerca de 26%, com o número de pacientes randomizados aumentando de 2.862 para 3.608. As características de estudo que tiveram associação estatisticamente significativa com a resposta ao placebo foram número de pacientes randomizados e número de locais de estudo. Após análise por regressão múltipla, o único preditor de resposta ao placebo foi o número de locais de estudo. Diferentemente do estudo anterior não houve associação entre a proporção de respondedores ao placebo e o ano de publicação. Utilizando a estratégia de investigação mais semelhante possível e com a inclusão dos últimos dez anos em estudos, o principal achado do estudo original pôde ser replicado, e o conhecimento sobre o tema atualizado. / This study aims to review methodological and patient characteristics associated with placebo response in randomized clinical trials of antidepressants in children and adolescents with major depressive disorder. We aim to update the study Placebo Response in Randomized Controlled Trials of Antidepressants for Pediatric Major Depressive disorder. Bridge et al. published this study in 2009 with data comprehending 1997 to 2006. The authors examined patient characteristics such as gender, proportion of Caucasian, recurrent depression, age, duration of illness and severity of depressive symptoms. Also possible clinical trial predictors were publication year, number of study sites, number of randomized patients, study duration, location (USA and non-USA), placebo run-in period, and mean number of participants per study site. The strongest predictor of placebo response found was number of study sites, even controlling for severity of illness. Furthermore placebo response has increased over the years in the studies analyzed. This review was the only study to investigate primarily placebo response in depressive disorder in childhood and adolescence and second-generation antidepressants, not including tricyclic antidepressants. The article presented here sought to update these results using the same search syntax, as well as inclusion and exclusion criteria, performing analysis with the same variables and statistical strategy. The update included research from 2006 to December 2015, with the inclusion of 4 published and unpublished studies that met the same criteria described in 2009. The sample increased around 26%: the number of patients randomized was 2,862 in the 2009 review, reaching to 3,608 in 2016. Number of patients randomized and number of study sites were the only variables that were significantly correlated with placebo response. Severity of depressive symptoms was not associated with placebo response in this update. After multiple regression analyses, the only predictor of placebo response was number of study sites. Unlike the previous study, there was no correlation between response to placebo and year of publication. Using the most similar research strategy with a larger sample the main finding of the original study could be replicated.

VIEIRA, Alessandra Helen Magacho. Avaliação da eficiência de agentes anti-hiperestésicos no tratamento da hiperestesia dentinária. 2007. 73 f. Dissertação (Mestrado em Odontologia) - Universidade Federal do Ceará, Fortaleza, 2007. / Submitted by denise santos (denise.santos@ufc.br) on 2011-11-11T12:19:27Z No. of bitstreams: 1 2007_dis_ahmvieira.pdf: 439759 bytes, checksum: 5e74e60196092de44987ea3520080f39 (MD5) / Approved for entry into archive by Eliene Nascimento(elienegvn@hotmail.com) on 2011-12-05T12:26:16Z (GMT) No. of bitstreams: 1 2007_dis_ahmvieira.pdf: 439759 bytes, checksum: 5e74e60196092de44987ea3520080f39 (MD5) / Made available in DSpace on 2011-12-05T12:26:16Z (GMT). No. of bitstreams: 1 2007_dis_ahmvieira.pdf: 439759 bytes, checksum: 5e74e60196092de44987ea3520080f39 (MD5) Previous issue date: 2007 / Dentinal hypersensitivity is a complex sensorial condition which can cause considerable concern in the dental office. Despite the large number of different proposed kinds of treatment, there is no product or therapy reported in literature that could be considered ideal to eliminate this uncomfortable situation. The aim of this study, comprised by two manuscripts, was: (1) to critically review the literature related to the main evidences about the etiology and the management of dentinal hypersensitivity; (2) to evaluate the clinical performance of different dentine desensitizers in the treatment of dentinal hypersensitivity. In study 1, the scientific literature related to the issue was analyzed through the results of laboratory and clinical investigations searched using medline and manual tracing of references cited scientific papers. In study 2, a total of 164 teeth, from 30 patients with clinical diagnosis of moderate or severe dentinal hypersensitivity, were randomly divided into three groups and clinically evaluated according to the desensitizing treatment under study: gallium-aluminun-arsenide (GaAlAs) laser therapy, 3% potassium oxalate application and placebo gel application. Treatment sessions were performed at seven-day intervals for four consecutive weeks and the degree of sensitivity in response to tactile (probe) and evaporative (air blast) stimuli was assessed according to a visual analogue scale at baseline, immediately after and three months after the last treatment session. Data scores were submitted to Kruskal-Wallis statistical analysis (p=0.05) and were analyzed by dentinal hypersensitivity reduction for each observational moment in relation to baseline. The critical review presented in study 1 showed that the reviewed literature points out several treatment modalities ranging from simple procedures, which can be performed by the patient him/herself, to complex procedures that involve the combination of therapies. The results of study 2 demonstrated that the treatment of dentinal hypersensitivity performed with both active and control groups produced statistically significant reduction of pain in response to evaporative and tactile stimulation immediately after and three months after treatment (p<0.05). No significant differences among the three groups could be detected in both immediate and mediate evaluations irrespective of the applied stimulus (p>0.05). In conclusion, the results of these studies suggest that knowledge about the available desensitizing products and the factors involved in the mechanism of the dentinal hypersensitivity is indispensable in order to perform an effective treatment. Besides, it could be concluded that the three treatments performed in the clinical study were effective for treating dentinal hypersensitivity and that the placebo effect plays an important role in sensitivity reduction. / A hiperestesia dentinária é um fenômeno sensorial complexo e de difícil solução na clínica odontológica. Apesar da grande diversidade de tratamentos propostos, ainda não existe uma terapia considerada ideal para eliminar essa situação desconfortável. Esta dissertação, constituída por dois artigos científicos, teve por objetivos: (1) revisar criticamente a literatura disponível sobre os principais aspectos relacionados à etiologia e ao tratamento da hiperestesia dentinária; (2) avaliar clinicamente a eficiência de agentes anti-hiperestésicos no tratamento da hiperestesia dentinária. No estudo 1, a literatura científica pertinente ao assunto foi analisada através dos resultados de investigações clínicas e laboratoriais pesquisadas usando a base de dados medline e busca manual de referências citadas em artigos científicos. No estudo 2, um total de 164 dentes, provenientes de 30 pacientes com diagnóstico de hiperestesia dentinária moderada ou severa, foi dividido aleatoriamente em três grupos e avaliado clinicamente de acordo com o tratamento administrado: aplicação de laser de arseniato de gálio-alumínio (AsGaAl), aplicação de gel de oxalato de potássio a 3% e aplicação de gel placebo. As aplicações dos tratamentos foram realizadas em intervalos semanais, durante o período de quatro semanas consecutivas e o grau de sensibilidade foi mensurado para cada dente através de uma escala visual analógica em resposta aos estímulos tátil (sonda exploradora) e evaporativo (jato de ar) antes da primeira aplicação (baseline), imediatamente após e três meses após a última aplicação dos tratamentos. Os dados foram submetidos à análise estatística pelo teste de Kruskal-Wallis (p=0,05) e o grau de redução da hiperestesia dentinária foi avaliado para cada um dos períodos observacionais em relação ao baseline. A análise crítica apresentada no artigo 1 mostrou que a literatura apresenta diversos tipos de tratamento para a hiperestesia dentinária, que variam desde procedimentos simples, que podem ser executados pelo próprio paciente, até procedimentos complexos, que envolvem a combinação de diferentes terapias. Os resultados do artigo 2 demonstraram que a aplicação dos tratamentos propostos, inclusive o placebo, proporcionou redução estatisticamente significante, imediata e mediata, da sensibilidade em resposta aos estímulos tátil e evaporativo (p<0,05). No entanto, não houve diferença estatisticamente significante entre os três grupos estudados, independentemente do estímulo aplicado, tanto na avaliação imediata quanto na mediata (p>0,05). Em conclusão, os resultados desses estudos indicam que o conhecimento acerca do mecanismo de ocorrência da hiperestesia dentinária e dos agentes anti-hiperestésicos disponíveis é indispensável para a elaboração de um tratamento eficiente. Além disso, concluiu-se que os três tratamentos utilizados no estudo clínico são eficientes para a redução da hiperestesia dentinária e que existe grande influência do efeito placebo na redução da sensibilidade dolorosa.