Placebo response in anxiety disorders

Low doses of fluoxetine for the treatment of emotional premenstrual syndrome: a randomized double-blind, placebo-controlled, pilot study

INTRODUCTION

The neuroactive metabolite of progesterone, allopregnanolone (ALLO), has been implicated in premenstrual syndrome (PMS) physiopathology and preclinical studies suggested that low doses of fluoxetine increase the ALLO brain concentration.

OBJECTIVES

To assess which low dose of fluoxetine (2 mg/d, 5 mg/d or 10 mg/d), administered exclusively during the luteal phase of menstrual cycle, has a potential effect for preventing or mitigating emotional PMS symptoms.

METHODS

In this randomized, double-blind, placebo-controlled pilot study, we followed 40 women (mean age = 29.7 +/- 7.4 years) with emotional PMS, during two menstrual cycles: cycle 1, without pharmacological intervention; and cycle 2, with pharmacological intervention. Participants took capsules, on average, seven days preceding the likely date of menses. We assessed the severity of PMS symptoms in both cycles using the Daily Record of Severity of Problems scale (DRSP).

RESULTS

There was an increase in the DRSP scores during the late luteal phase of cycle 1, confirming the diagnosis of emotional PMS. Low doses of fluoxetine (5 mg/d: 33.5%; 10 mg/d: 48.4%) reduced DRSP total score in the day before menses (day-1) at cycle 2 compared with day-1 at cycle 1. Fluoxetine 10 mg/d had the most consistent decline in emotional PMS symptoms; 70% of the participants reported a reduction greater than 40% in the DRSP score.

CONCLUSIONS

Low doses of fluoxetine, which may have no or few effect on the serotonergic system, but may interfere in the progesterone metabolization, seem to have some potential to mitigate emotional PMS symptoms. While the 10 mg/d of fluoxetine had the best performance on reducing emotional PMS symptoms, the 5 mg/d dose also seems to have some effect on emotional PMS symptoms. Further larger studies will help establish the lowest effective dose of flouxetine for PMS treatment.

Placebo effects in functional dyspepsia: Causes and implications for clinical trials

Placebo responses to an apparently inactive intervention are of interest from a scientific perspective as they suggest possible mechanism(s) at work beyond the intervention itself. They are also of interest from a clinical trials perspective since high rates of placebo response limit the potential to demonstrate worthwhile efficacy of a new intervention. This mini-review was motivated by the work of Bosman and colleagues(Neurogastroenterol Motil, 2022, and e14474) that is published in this issue of the journal in which they report on a systematic review and meta-analysis of placebo response in functional dyspepsia clinical trials. The review sets the scene for their work by putting it in the context of other disorders of brain-gut interaction and extra-gastrointestinal disorders. The review canvasses potential mechanisms of placebo response.

Central monitoring of depression and anxiety symptoms reduces placebo responses in depression clinical trials: A post hoc exploratory analysis of data from the phase III CCT-004 trial of vortioxetine

AIM

Clinical trials of antidepressants often fail to demonstrate their efficacy versus placebo, suggesting that patient selection based on physician ratings of depression may contribute to a high placebo response.

METHODS

In the CCT-004 trial of vortioxetine, central monitoring was employed to compare physician and patient ratings of depression and anxiety at baseline and over time to identify factors contributing to a large placebo response, as well as to explore the potential of a unique patient-rated clinical measure combining QIDS-J and Himorogi Self-rating Anxiety Scale (HSAS), to contribute to optimal patient selection at baseline and patient monitoring over time.

RESULTS

The CCT-004 trial showed similar trends between the QIDS-J and MADRS (Montgomery-Åsberg Depression Rating Scale) ratings. It was suggested that central monitoring of the QIDS-J and MADRS ratings of depression and anxiety symptoms helped reduce the baseline score inflation by calling the study sites' attention to discrepancies between these ratings at baseline; it also allowed these ratings to be assessed for their concordance over time. Of note, MDD patients with baseline QIDS-J scores ≥11/HSAS ≤19 were associated with the smallest placebo response, with the effect size being larger than that for those with QIDS-J scores ≤10/HSAS ≥20.

CONCLUSION

The use of both physician and patient ratings of depression and anxiety symptoms at baseline and over time, as well as their central monitoring, helped minimize the baseline score inflation and optimize patient monitoring over time, and allowed the antidepressant to be evaluated for its full therapeutic potential.

Psycho-Neuro-Endocrine-Immunological Basis of the Placebo Effect: Potential Applications beyond Pain Therapy

The placebo effect can be defined as the improvement of symptoms in a patient after the administration of an innocuous substance in a context that induces expectations regarding its effects. During recent years, it has been discovered that the placebo response not only has neurobiological functions on analgesia, but that it is also capable of generating effects on the immune and endocrine systems. The possible integration of changes in different systems of the organism could favor the well-being of the individuals and go hand in hand with conventional treatment for multiple diseases. In this sense, classic conditioning and setting expectations stand out as psychological mechanisms implicated in the placebo effect. Recent advances in neuroimaging studies suggest a relationship between the placebo response and the opioid, cannabinoid, and monoaminergic systems. Likewise, a possible immune response conditioned by the placebo effect has been reported. There is evidence of immune suppression conditioned through the insular cortex and the amygdala, with noradrenalin as the responsible neurotransmitter. Finally, a conditioned response in the secretion of different hormones has been determined in different studies; however, the molecular mechanisms involved are not entirely known. Beyond studies about its mechanism of action, the placebo effect has proved to be useful in the clinical setting with promising results in the management of neurological, psychiatric, and immunologic disorders. However, more research is needed to better characterize its potential use. This review integrates current knowledge about the psycho-neuro-endocrine-immune basis of the placebo effect and its possible clinical applications.

Focusing in on the Future of Focused Ultrasound as a Translational Tool

This article summarizes the field of focused ultrasound for use in neuromodulation and discusses different ways of targeting, delivering, and validating focused ultrasound. A discussion is focused on parameter space and different ongoing theories of ultrasonic neuromodulation. Current and future applications of the technique are discussed.

Pain, the uknown: epistemological issues and related clinical implications

Despite the huge development of pain management in the past decades, pain remains elusive and many patients still remain in the middle of the ford struggling between low drug efficacy and their overuse. A reason for pain elusiveness is its nature of subjective phenomenon, escaping the meshes of the objectivist, mechanist-reductionist net prevailing in medicine. Actually, pain is not only a symptom but an essential aspect of life, consciousness and contact with the world and its noetic and autonoetic components play a key role in the development of the concepts of pleasure-unpleasure and good-evil. The intensity and tolerability of pain and suffering also depends on what the pain means to the patient. The outstanding effects of placebo and nocebo, behavioral and non-pharmacological techniques warrant the need for a shift from the traditional positivist idea of patient as passive carrier of disease to the patient as active player of recovery and move toward a patient's centered approach exploiting individual resources for recovery. Among the mentioned techniques, hypnosis has proved to increase pain threshold up to the level of surgical analgesia, improve acute and chronic pain as well as coping and resilience, helping to decrease both drug overuse and the costs of pharmacological therapy. The wealth of available data suggest the need for a holistic approach, aiming to take care of the individual as an inseparable mind-body unit in its interplay with the environment, where patient's inner world, his/her experience and cognition are taken into due account as powerful resources for recovery through a phenomenological-existential approach.

A Feasibility Study of Lavender Aromatherapy in an Awake Craniotomy Environment

PURPOSE

Integrative medicine interventions are needed for awake craniotomies, as many patients experience anxiety. Lavender aromatherapy significantly reduces anxiety or pain in a variety of surgical procedures. This feasibility study used lavender aromatherapy during awake craniotomies to determine the number of patients who would consent and complete the study, the technicality of lavender aromatherapy use, and acceptance by operating room (OR) staff.

METHODS

We approached 40 consecutive patients (≥18 years old). Exclusion criteria were pulmonary issues or sensitivity to lavender. Outcome measures in consented patients were enrollment and completion rates, anxiety and pain as measured by the Visual Analog Scale for Anxiety (VAS-A) and Visual Analog Scale for Pain (VAS-P), and satisfaction with pain control using the Patient Opinion of Pain Management (POPM) survey.

RESULTS

Of the 40 patients approached, 4 declined participation or had their surgery cancelled. Of the remaining 36, 4 required increased sedation during surgery and 1 was unable to detect lavender. Thus, 31 patients (77.5%) completed the study. VAS-A and VAS-P scores trended lower after lavender inhalation, but the difference did not reach statistical significance. There was a slight increase in VAS-P score at the OR1 time point. Expectancy for reduction in both anxiety and pain were not significantly different. Improvement in anxiety also was not different, while improvement in pain trended lower (P=0.025). POPM results indicated the majority of patients were either "satisfied" or "very satisfied" with pain management.

CONCLUSIONS

This study demonstrated 77.5% completion and the ability to integrate lavender aromatherapy into the OR. Thus, we plan to conduct a randomized clinical trial to assess efficacy of lavender aromatherapy.

Feelings of Clinician-Patient Similarity and Trust Influence Pain: Evidence From Simulated Clinical Interactions

Pain is influenced by many factors other than external sources of tissue damage. Among these, the clinician-patient relationship is particularly important for pain diagnosis and treatment. However, the effects of the clinician-patient relationship on pain remain underexamined. We tested the hypothesis that patients who believe they share core beliefs and values with their clinician will report less pain than patients who do not. We also measured feelings of perceived clinician-patient similarity and trust to see if these interpersonal factors influenced pain. We did so by experimentally manipulating perceptions of similarity between participants playing the role of clinicians and participants playing the role of patients in simulated clinical interactions. Participants were placed in 2 groups on the basis of their responses to a questionnaire about their personal beliefs and values, and painful thermal stimulation was used as an analog of a painful medical procedure. We found that patients reported feeling more similarity and trust toward their clinician when they were paired with clinicians from their own group. In turn, patients' positive feelings of similarity and trust toward their clinicians-but not clinicians' feelings toward patients or whether the clinician and patient were from the same group-predicted lower pain ratings. Finally, the most anxious patients exhibited the strongest relationship between their feelings about their clinicians and their pain report. These findings increase our understanding of context-driven pain modulation and suggest that interventions aimed at increasing patients' feelings of similarity to and trust in health care providers may help reduce the pain experienced during medical care.

PERSPECTIVE

We present novel evidence that the clinician-patient relationship can affect the pain experienced during medical care. We found that "patients" in simulated clinical interactions who reported feeling more similarity and trust toward their "clinicians" reported less pain, suggesting that increasing feelings of clinician-patient similarity and trust may reduce pain disparities.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

The placebo effect has often been considered a nuisance in basic and particularly clinical research. This view has gradually changed in recent years due to deeper insight into the neuro-bio-behavioral mechanisms steering both the placebo and nocebo responses, the evil twin of placebo. For the neuroscientist, placebo and nocebo responses have evolved as indispensable tools to understand brain mechanisms that link cognitive and emotional factors with symptom perception as well as peripheral physiologic systems and end organ functioning. For the clinical investigator, better understanding of the mechanisms driving placebo and nocebo responses allow the control of these responses and thereby help to more precisely define the efficacy of a specific pharmacological intervention. Finally, in the clinical context, the systematic exploitation of these mechanisms will help to maximize placebo responses and minimize nocebo responses for the patient's benefit. In this review, we summarize and critically examine the neuro-bio-behavioral mechanisms underlying placebo and nocebo responses that are currently known in terms of different diseases and physiologic systems. We subsequently elaborate on the consequences of this knowledge for pharmacological treatments of patients and the implications for pharmacological research, the training of healthcare professionals, and for the health care system and future research strategies on placebo and nocebo responses.

INFLUENCE OF STUDY DESIGN ON TREATMENT RESPONSE IN ANXIETY DISORDER CLINICAL TRIALS

OBJECTIVE

The influence of study design variables and publication year on response to medication and placebo was investigated in clinical trials for social anxiety disorder (SAD), generalized anxiety disorder (GAD), and panic disorder (PD).

METHOD

Hierarchical linear modeling determined whether publication year, treatment assignment (medication vs. placebo), study type (placebo-controlled or active comparator), study duration, and the number of study visits affected the mean change associated with medication and placebo.

RESULTS

In the 66 trials examined, the change associated with both medication and placebo increased over time (t = 4.23, df = 39, P < .001), but average drug-placebo differences decreased over time (t = -2.04, df = 46, P = .047). More severe baseline illness was associated with greater drug-placebo differences for serotonin norepinephrine reuptake inhibitors (SNRIs, t = 3.46, df = 106, P = .001) and selective serotonin reuptake inhibitors (SSRI, t = 10.37, df = 106, P < .001). Improvement with medication was significantly greater in active-comparator studies compared to placebo-controlled trials (t = 3.41, df = 39, P = .002). A greater number of study visits was associated with greater symptom improvement in PD trials relative to SAD (t = 2.83, df = 39, P = .008) and GAD (t = 2.16, df = 39, P = .037).

CONCLUSIONS

Placebo response is substantial in SAD, GAD, and PD trials, and its rise over time has been associated with diminished drug-placebo differences. Study design features that influence treatment response in anxiety disorder trials include patient expectancy, frequency of follow-up visits, and baseline illness severity.

Selective serotonin-reuptake inhibitors in the treatment of panic disorder: a systematic review of placebo-controlled studies

The selective serotonin-reuptake inhibitors are widely used in clinical practice in the treatment of panic disorder (PD). This article undertakes an up-to-date, systematic review of the published double-blind, placebo-controlled, randomized, short-term studies with currently available selective serotonin-reuptake inhibitors in the treatment of PD. Sertraline, paroxetine, citalopram, escitalopram, fluoxetine and fluvoxamine have all been proven to be superior to pill-placebo, although the placebo effect has been shown to be extremely important in patients with PD. The authors also explore the anxiolytic mechanism of action of this antidepressant drug class and the preclinical studies that are being developed to clarify the etiopathogenic mechanisms of PD and, more precisely, the role of the serotoninergic system in this pathogenesis. These steps are considered fundamental for the improvement of pharmacological treatment of PD.

A meta-analytic review of the effects of psychotherapy control conditions for anxiety disorders

BACKGROUND

Little is known about the magnitude of improvement associated with psychotherapy control conditions for adult anxiety disorders. This information is important for the design of psychosocial treatment efficacy studies.

METHOD

We performed a computerized search of treatment outcome studies of anxiety disorders conducted between the first available year and 1 March 2007. In addition, we examined the reference lists from identified articles and asked international experts to identify eligible studies. We included studies that randomly assigned adult patients suffering from anxiety disorders to either cognitive-behavioral treatment or psychotherapy control condition. For each study, the two authors independently selected psychometrically sound measures of anxiety disorder severity. In addition, we collected data on attrition and treatment response.

RESULTS

Of the 1165 studies that were initially identified, 19 studies (454 patients) met inclusion criteria and were included in the analyses. The random effects analysis yielded a pre- to post-treatment Hedges' g effect size of 0.45 (95% confidence interval 0.35-0.46, z=8.50, p<0.001). The mean weighted response and attrition rates were 25.0% and 14.2%, respectively. There was no evidence for publication bias, nor was there a significant relationship between the effect size and diagnostic group, study year or number of treatment sessions.

CONCLUSIONS

Psychotherapy control conditions are associated with significant improvements when administered to adults suffering from anxiety disorders. In addition, they are associated with a relatively low attrition rate. These findings can inform the design of future psychotherapy outcome studies.

Effect of personality type on pharmacodynamics through changing pharmacokinetics

A few studies have showed that there is an association between the genetic polymorphisms of drug-metabolizing enzyme, CYP2D6, to persons with different personality type. More and more evidences suggested that personality type is kind of behavioral or psychological factor which might influence the pharmacodynamics as well as patient's gender, age, disease, and genetic background. We hypothesized that personality affect the pharmacodynamics through changing pharmacokinetic mediated by different polymorphism of drug-metabolizing enzymes. Since many major diseases, from cancer to infectious disease, are involved with risky Type A personality, we appeal for attention to the clinical pharmacologist and psychiatrists further to study personality pharmacokinetics for individualized medicine.

Generalised anxiety disorder

Generalised anxiety disorder is a persistent and common disorder, in which the patient has unfocused worry and anxiety that is not connected to recent stressful events, although it can be aggravated by certain situations. This disorder is twice as common in women than it is in men. Generalised anxiety disorder is characterised by feelings of threat, restlessness, irritability, sleep disturbance, and tension, and symptoms such as palpitations, dry mouth, and sweating. These symptoms are recognised as part of the anxiety syndrome rather than independent complaints. The symptoms overlap greatly with those of other common mental disorders and we could regard the disorder as part of a spectrum of mood and related disorders rather than an independent disorder. Generalised anxiety disorder has a relapsing course, and intervention rarely results in complete resolution of symptoms, but in the short term and medium term, effective treatments include psychological therapies, such as cognitive behavioural therapy; self-help approaches based on cognitive behavioural therapy principles; and pharmacological treatments, mainly selective serotonin reuptake inhibitors.

Differences in cognitive factors between "true drug" versus "placebo pattern" response to fluoxetine as defined by pattern analysis

OBJECTIVE

Pattern analysis has identified two types of response patterns to antidepressants: "true drug" response (TDR) and "placebo pattern" response (PPR). This study examines the relationship between cognitive factors and TDR and PPR to fluoxetine.

METHODS

We assessed 310 outpatients meeting DSM-III-R criteria for major depressive disorder (MDD) who were enrolled in an 8-week open trial of fluoxetine 20 mg/day. Response patterns were determined using the clinical global impressions-improvement (CGI-I). We administered the following self-rated scales to all patients at the baseline visit and at endpoint: perceived stress scale (PSS), cognitions questionnaire (CQ), Beck hopelessness scale (BHS) and dysfunctional attitudes scale (DAS).

RESULTS

One hundred and thirty-four patients had TDR, 66 patients had PPR, and 110 patients were non-responders (NR). Demographic variables and severity of depression at baseline (HAMD-17) were not significantly different between the two response pattern groups. We compared cognitive factors before and after treatment across patients with TDR and PPR, and there were no significant differences at baseline in CQ, PSS, BHS, and DAS scores. At endpoint, outpatients with PPR had significantly lower scores on the PSS (p < 0.001) compared to the patients with TDR, even after adjusting for multiple comparisons and severity of depression at endpoint.

CONCLUSIONS

Significant differences in cognitive/psychological factors, specifically lower post-treatment perceived stress, accompany "placebo" pattern of response to antidepressant treatment and differentiate it from "true drug" response pattern, as defined by pattern analysis.

An internet-based randomized, placebo-controlled trial of kava and valerian for anxiety and insomnia

The herbal extracts kava and valerian are the leading dietary supplements used in the self-management of anxiety and insomnia, respectively. There is limited evidence to support their effectiveness for these common symptoms. The Internet has been used to a limited extent for research, but it is not known whether randomized controlled trials can be conducted entirely using Internet technology. We performed a randomized, double-blind, placebo-controlled trial using a novel Internet-based design to determine if kava is effective for reducing anxiety and if valerian is effective for improving sleep quality. E-mail recruitment letters and banner advertisements on websites were used to recruit a large pool of interested participants (1551) from 45 states over an 8-week period. Participants were first asked to read study information, complete an online informed consent process, and undergo electronic identity verification. In order to be eligible for the study, participants were required to have 1) anxiety as documented by scores of at least 0.5 standard deviations above the mean on the State-Trait Anxiety Inventory State subtest (STAI-State) on 2 separate occasions, and 2) insomnia, defined as a "problem getting to sleep or staying asleep over the past 2 weeks." We randomly assigned 391 eligible participants to 1 of the following 3 groups, and mailed 28 days' supply: kava with valerian placebo (n = 121), valerian with kava placebo (n = 135), or double placebo (n = 135). The primary outcome measures were changes from baseline in anxiety (STAI-State questionnaire) and insomnia (Insomnia Severity Index [ISI]) compared with placebo. Participants receiving placebo had a 14.4 point decrease in anxiety symptoms on the STAI-State score and an 8.3 point decrease in insomnia symptoms on the ISI. Those receiving kava had similar reductions in STAI-State score (2.7 point greater reduction in placebo compared with kava; 95% confidence interval [CI], -0.8 to +6.2). Those receiving valerian and placebo had similar improvements in sleep (0.4 point greater reduction in the placebo than the valerian group; 95% CI, -1.3 to +2.1). Results were similar when limited to the 83% of participants who adhered to study compounds for all 4 weeks. Neither kava nor valerian relieved anxiety or insomnia more than placebo. This trial demonstrates the feasibility of conducting randomized, blinded trials entirely via the Internet.

The role of endogenous opioids in the placebo effect in post-traumatic stress disorder

The concept of the placebo effect has received a considerable attention over the past several decades. The placebo effect has been observed in different psychiatric disorders, including post-traumatic stress disorder (PTSD), a chronic and severe disorder precipitated by exposure to a psychologically distressing event. The placebo response rates in patients with PTSD range from 19% to 62%. A considerable number of research publications suggest that endogenous opioids are involved in the mechanisms of the placebo effect. Endogenous opioid peptides play an important role in stress response and in the pathophysiology of PTSD. Therefore, endogenous opioids may be involved in the neurobiology of the placebo effect in PTSD. Possibly, the endogenous opioid system mediates the effect of placebo on all 3 PTSD symptom clusters (re-experiencing symptoms, avoidance and numbing, and physiologic arousal). The placebo effect-related activation of the endogenous opioid system may result in an improvement in intrusive symptomatology and symptoms of increased arousal because the administration of exogenous opioids improve these symptoms. The placebo effect-related activation of the endogenous opioid system may have a mood-enhancing effect, and, consequently, diminish avoidance and numbing. Multiple neurotransmitter and neuroendocrine pathways may be involved in the mechanisms of the placebo effect in PTSD. Further studies of the neurobiology of the placebo effect on patients with PTSD and other psychiatric disorders may produce interesting and important results.

A method for controlling for a high placebo response rate in a comparison of venlafaxine XR and diazepam in the short-term treatment of patients with generalised anxiety disorder

This randomised, double-blind, placebo-controlled study compared the efficacy of venlafaxine XR (75 or 150 mg/d) with diazepam (15 mg/d) over an 8-week treatment period in 540 non-depressed outpatients with generalised anxiety disorder (GAD). At week 8, significant improvements from baseline were observed in the venlafaxine XR, diazepam and placebo groups. Although these improvements were higher in the first two groups than in the placebo group for each of the primary efficacy variables (Hamilton Rating Scale for Anxiety (HAM-A) total, HAM-A psychic anxiety factor, Hospital Anxiety and Depression Scale (HAD) anxiety sub-scale and Clinical Global Impression (CGI) improvement), there were no statistically significant differences between groups. These non-positive results were thought to be due to the very high placebo response observed in some centres. To understand the variability of the study, a secondary preplanned analysis was performed. This involved sub-dividing the study centres according to their ability to detect a two-point mean difference between diazepam and placebo at week 8 on the HAM-A total score. Centres able to show such a difference were termed verum-sensitive. Improvements from baseline to week 8 in venlafaxine XR-treated patients from verum-sensitive centres were significantly greater than in placebo on each of the primary efficacy measures (P </= 0.05). This suggests that those centres able to detect an anxiolytic effect of diazepam were also able to detect an anxiolytic effect of venlafaxine XR. Significant differences in baseline demographics, rates of adverse event reporting and rates of patient discontinuations were noted between patients enrolled at verum-sensitive and verum-insensitive sites. These results reflect the importance of study centre selection in accurately determining efficacy in placebo-controlled trials.

Generalised anxiety disorder: treatment options

In recent years generalised anxiety disorder (GAD) has become a much better defined disorder, with specific criteria distinguishing it from the other anxiety disorders; however, it still lacks the same public and scientific interests as some of the other anxiety disorders such as panic and social phobia. Nevertheless, refinement in the treatment of GAD is becoming more evident through the conduct of clinical trials. Up until the mid-1980's, treatment consisted primarily of benzodiazepines. However, as a result of growing characterisation of their abuse potential, other therapeutic options were explored. Benzodiazepines became seen as an effective short-term therapy, and buspirone and some of the newer antidepressants have become the treatment of choice for patients with GAD requiring long-term treatment. Buspirone was the first available alternative to the benzodiazepines in the US; however, the initial excitement over this agent was somewhat dampened because of its mild efficacy combined with a slow onset of action. The antidepressants were seen as beneficial for the treatment of GAD because of the high comorbidity with depression, thus allowing a better outcome for these patients. The antidepressants that offer both a good adverse effect profile and efficacy are the selective serotonin reuptake inhibitors including paroxetine, and the serotonin-norepinephrine reuptake inhibitors such as venlafaxine. Clinicians should also consider the potential benefits of psychotherapy as an adjunct to medication. There are a number of potentially new pharmacotherapies being investigated, including newer serotonin 5-HT1A receptor agonists, cholecystokinin receptor antagonists, neurokinin receptor antagonists, gabapentin and its analogues, and gamma-aminobutyric acid (GABA)A receptor modulators. However, these compounds are all in the early stages of investigation, and there are no new therapies expected to be released in the near future. Nonetheless, in the search for the ideal anxiolytic, a more positive outlook is allowed by imminent future research for new treatment options in patients with GAD.

The placebo response in social phobia

The placebo response forms a growing problem in randomized, placebo-controlled clinical trials in psychiatry. Research into the placebo response is on the increase, but remains very limited in relation to social phobia. Together with the dropout rate, the placebo effect is an important factor limiting the discriminative properties of any study. In this study, we reviewed 15 placebo-controlled studies in social phobia, focussing on patients and study characteristics. In social phobia, the placebo effect has turned out to be moderately large and has shown no increase over the past decade. Placebo response was highest in large, multicentred trials and was independent of study duration. No validation for a placebo run-in was found. Taking into account both response to placebo and active drug, as well as dropout rate, the most discriminative results are probably to be expected in a sample of patients who are moderately to severely impaired. More research in the field of the placebo response is needed.

The psychobiology of anxiolytic drug. Part 2: Pharmacological treatments of anxiety

Benzodiazepines have been the mainstay of pharmacological treatment of anxiety over the last 4 decades. The problems associated with their use prompted the research for alternative agents that would be useful in anxiety conditions. Old classes of antidepressants, such as tricyclic antidepressants and monoamine oxidase inhibitors, showed effectiveness in some anxiety syndromes, even in areas where benzodiazepines were not very effective. Newer antidepressants, the selective serotonin-reuptake inhibitors, also appear very useful in some anxiety states, and their favourable side-effect profile has elevated them to first-line treatment tools in these conditions. However, the ideal anxiolytic does not exist. Research with other new compounds is very active, and some experimental drugs show promise for the future.

Side effects and time course of response in a placebo-controlled trial of fluoxetine for the treatment of geriatric depression

A high rate of improvement among patients who receive placebo in controlled trials of antidepressants can complicate the evaluation of true drug effect. Placebo response may be a reaction to the psychosocial factors of study participation or a function of changes in the natural course of depression. Drug side effects may also influence patients' expectations, and they should be distinguished from the somatic symptoms associated with major depression. The authors reanalyzed data from a large, multicenter, placebo-controlled clinical trial of fluoxetine treatment of geriatric depression to evaluate similarities and differences between responders and nonresponders in both treatment groups. Specifically, the authors examined weekly somatic complaints as possible predictors of response and of dropout, as well as the time course and onset of response. Fluoxetine was superior to placebo on all outcome measures. Among somatic complaints associated with fluoxetine response, headache before and after randomization was associated with a good response and anxiety after randomization was associated with a poor response. Somnolence before and after randomization was associated with a good placebo response. Early and persistent improvement occurred among similar proportions of responders in both groups. The difference between fluoxetine and placebo seemed to be a persistent response beginning during the 4th week. Pretreatment somnolence was associated with early, persistent improvement in both groups and may serve as a marker for placebo response.

A randomised, double-blind, placebo-controlled trial of dexamphetamine in adults with attention deficit hyperactivity disorder

OBJECTIVE

The aim of this paper is to determine the efficacy of dexamphetamine in adult attention deficit hyperactivity disorder (ADHD) in a naturalistic setting.

METHOD

A randomised, double-blind, placebo-controlled study of dexamphetamine was conducted by two psychiatrists in private practice who saw a total of 68 consecutive referrals of patients thought to have ADHD by their referring general practitioners. Patients were admitted to the study if their current level of ADHD symptoms satisfied DSM-IV criteria (modified for use in adults), and were not currently comorbid for major mood disturbance or substance abuse. Response to medication was assessed by repeated administration of these modified DSM-IV criteria, self- and relatives' rating, as well as clinician rating using the Clinical Global Impressions Scale. More general outcome measures included the Brief Symptom Inventory and a patient satisfaction questionnaire. Medication side effects were recorded, including monitoring blood pressure and weight change. Urinalysis monitored concurrent substance usage and compliance.

RESULTS

Dexamphetamine had a significant therapeutic response exceeding the placebo response (p = 0.045). The response was similar in both genders and across the age range. It was detected by patients, their relatives and the two clinicians. The only significant side effect was weight loss. One patient on dexamphetamine discontinued the trial because of an event possibly related to the medication.

CONCLUSIONS

In the short term, dexamphetamine appears to be efficacious in treating adult ADHD. As this is the first study in the literature, the result requires replication. Given that stimulant medication use in adult ADHD appears to be long-term, studies of long-term efficacy need to be carried out.