Early onset of selective serotonin reuptake inhibitor antidepressant action: systematic review and meta-analysis

Accelerating response to antidepressant treatment in depression: a review and clinical suggestions

OBJECTIVE

The primary objective of this article is to review the literature regarding the speed of response to antidepressant drugs and potential strategies to accelerate the antidepressant response in new antidepressant-free patients with depression. Based on these data, we try to propose both an effective and safe antidepressant treatment strategy to alleviate depressive symptoms at the earliest opportunity.

DATA SOURCES

Data were identified by searches of Medline (1966 to September 2009) and references from relevant articles and books. Search terms included depression, antidepressant, predictor, response, onset, acceleration, and augmentation. As our focus was on the acute phase treatment of depression, articles relevant to treatment-resistant depression were excluded. Only articles written in English or Japanese were consulted.

DATA SELECTION

Studies, reviews, and books pertaining to the treatment of depression with a special regard to accelerating therapeutic effects were selected.

DATA SYNTHESIS

Most of the available treatment guidelines for major depressive disorders recommend the continuous use of antidepressants for 4 to 8 weeks based on the idea of a delayed onset of response to these drugs. Contrary to this conventional belief, the recent data indicate that antidepressants start to exert their effects within 2 weeks and early non-response could predict a subsequent unfavorable outcome.

CONCLUSIONS

These findings suggest the need of revisiting the timing of an antidepressant switch for early non-responders, whereby switching could be commenced in as early as 2 weeks.

Fluvoxamine versus other anti-depressive agents for depression

BACKGROUND

Fluvoxamine, one of the oldest selective serotonin reuptake inhibitors (SSRIs), is prescribed to patients with major depression in many countries. Several studies have previously reviewed the efficacy and tolerability of fluvoxamine for the treatment of major depression. However, these reviews are now outdated.

OBJECTIVES

Our objective is to evaluate the effectiveness, tolerability and side effect profile of fluvoxamine for major depression in comparison with other anti-depressive agents, including tricyclics (TCAs), heterocyclics, other SSRIs, SNRIs, other newer agents and other conventional psychotropic drugs.

SEARCH STRATEGY

We searched the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register. Trial databases and ongoing trial registers in North America, Europe, Japan and Australia, were handsearched for randomised controlled trials. We checked reference lists of the articles included in the review, previous systematic reviews and major textbooks of affective disorder for published reports and citations of unpublished research. The date of last search was 31 August 2008.

SELECTION CRITERIA

We included all randomised controlled trials, published in any language, that compared fluvoxamine with any other active antidepressants in the acute phase treatment of major depression.

DATA COLLECTION AND ANALYSIS

Two independent review authors inspected citations and abstracts, obtained papers, extracted data and assessed the risk of bias of included studies. We analysed dichotomous data using odds ratios (ORs) and continuous data using the standardised mean difference (SMD). A random effects model was used to combine studies.

MAIN RESULTS

A total of 54 randomised controlled trials (n = 5122) were included. No strong evidence was found to indicate that fluvoxamine was either superior or inferior to other antidepressants regarding response, remission and tolerability. However, differing side effect profiles were evident, especially with regard to gastrointestinal side effects of fluvoxamine when compared to other antidepressants. For example, fluvoxamine was generally associated with a higher incidence of vomiting/nausea (versus imipramine, OR 2.23, CI 1.59 to 3.14; versus clomipramine, OR 2.13, CI 1.06 to 4.27; versus amitriptyline, OR 2.86, CI 1.31 to 2.63).

AUTHORS' CONCLUSIONS

We found no strong evidence that fluvoxamine was either superior or inferior to any other antidepressants in terms of efficacy and tolerability in the acute phase treatment of depression. However, differing side effect profiles were evident. Based on these findings, we conclude that clinicians should focus on practical or clinically relevant considerations, including these differences in side effect profiles.

A new paradigm for the prediction of antidepressant treatment response

Current treatment of Major Depressive Disorder utilizes a trial-and-error sequential treatment strategy that results in delays in achieving response and remission for a majority of patients. Protracted ineffective treatment prolongs patient suffering and increases health care costs. In addition, long and unsuccessful antidepressant trials may diminish patient expectations, reinforce negative cognitions, and condition patients not to respond during subsequent antidepressant trials, thus contributing to further treatment resistance. For these reasons, it is critical to identify reliable predictors of antidepressant treatment response that can be used to shorten or eliminate lengthy and ineffective trials. Research on possible endophenotypic as well as genomic predictors has not yet yielded reliable predictors. The most reliable predictors identified thus far are symptomatic and physiologic characteristics of patients that emerge early in the course of treatment. We propose here the term “response endophenotypes” (REs) to describe this class of predictors, defined as latent measurable symptomatic or neurobiologie responses of individual patients that emerge early in the course of treatment, and which carry strong predictive power for individual patient outcomes. Use of REs constitutes a new paradigm in which medication treatment trials that are likely to be ineffective could be stopped within 1 to 2 weeks and other medication more likely to be effective could be started. Data presented here suggest that early changes in symptoms, quantitative electroencephalography, and gene expression could be used to construct effective REs. We posit that this new paradigm could lead to earlier recovery from depressive illness and ultimately produce profound health and economic benefits.

An algorithm for the pharmacological treatment of depression

OBJECTIVE

Non-response to treatment with antidepressants (AD) is a clinical problem.

METHOD

The algorithm for pharmacological treatment of the Dutch multidisciplinary guideline for depression is compared with four other algorithms.

RESULTS

The Dutch algorithm consists of five subsequent steps. Treatment is started with one out of many optional ADs (step 1); in case of non-response after 4-10 weeks, best evidence is for switching to another AD (step 2); next step is augmentation with lithium as the best option (step 3); the next step is a monoamine oxidase inhibitor (MAOI) (step 4); and finally electroconvulsive therapy (step 5). There are major differences with other algorithms regarding timing of augmentation step, best agents for augmentation and role of MAOI.

CONCLUSION

Algorithms for AD treatment vary according to national and local preferences. Although the evidence for most of the treatment strategies is rather meagre, an AD algorithm appears to be an useful instrument in clinical practice.

Diminished neural processing of aversive and rewarding stimuli during selective serotonin reuptake inhibitor treatment

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) are popular medications for anxiety and depression, but their effectiveness, particularly in patients with prominent symptoms of loss of motivation and pleasure, has been questioned. There are few studies of the effect of SSRIs on neural reward mechanisms in humans.

METHODS

We studied 45 healthy participants who were randomly allocated to receive the SSRI citalopram, the noradrenaline reuptake inhibitor reboxetine, or placebo for 7 days in a double-blind, parallel group design. We used functional magnetic resonance imaging to measure the neural response to rewarding (sight and/or flavor of chocolate) and aversive stimuli (sight of moldy strawberries and/or an unpleasant strawberry taste) on the final day of drug treatment.

RESULTS

Citalopram reduced activation to the chocolate stimuli in the ventral striatum and the ventral medial/orbitofrontal cortex. In contrast, reboxetine did not suppress ventral striatal activity and in fact increased neural responses within medial orbitofrontal cortex to reward. Citalopram also decreased neural responses to the aversive stimuli conditions in key "punishment" areas such as the lateral orbitofrontal cortex. Reboxetine produced a similar, although weaker effect.

CONCLUSIONS

Our findings are the first to show that treatment with SSRIs can diminish the neural processing of both rewarding and aversive stimuli. The ability of SSRIs to decrease neural responses to reward might underlie the questioned efficacy of SSRIs in depressive conditions characterized by decreased motivation and anhedonia and could also account for the experience of emotional blunting described by some patients during SSRI treatment.

Rationale and design of the randomised clinical trial comparing early medication change (EMC) strategy with treatment as usual (TAU) in patients with major depressive disorder--the EMC trial

Background

In Major Depressive Disorder (MDD), the traditional belief of a delayed onset of antidepressants' effects has lead to the concept of current guidelines that treatment durations should be between 3-8 weeks before medication change in case of insufficient outcome. Post hoc analyses of clinical trials, however, have shown that improvement usually occurs within the first 10-14 days of treatment and that such early improvement (Hamilton Depression Rating Scale [HAMD] decrease ≥20%) has a substantial predictive value for final treatment outcome. Even more important, non-improvement (HAMD decrease <20%) after 14 days of treatment was found to be highly predictive for a poor final treatment outcome.

Methods/Design

The EMC trial is a phase IV, multi-centre, multi-step, randomized, observer-blinded, actively controlled parallel-group clinical trial to investigate for the first time prospectively, whether non-improvers after 14 days of antidepressant treatment with an early medication change (EMC) are more likely to attain remission (HAMD-17 ≤7) on treatment day 56 compared to patients treated according to current guideline recommendation (treatment as usual; TAU). In level 1 of the EMC trial, non-improvers after 14 days of antidepressant treatment will be randomised to an EMC strategy or TAU. The EMC strategy for this study schedules a first medication change on day 15; in case of non-improvement between days 15-28, a second medication change will be performed. TAU schedules the first medication change after 28 days in case of non-response (HAMD-17 decrease <50%). Both interventions will last 42 days. In levels 2 and 3, EMC strategies will be compared with TAU strategies in improvers on day 14, who experience a stagnation of improvement during the course of treatment. The trial is supported by the German Federal Ministry of Education and Research (BMBF) and will be conducted in cooperation with the BMBF funded Interdisciplinary Centre Clinical Trials (IZKS) at the University Medical Centre Mainz and at six clinical trial sites in Germany.

Discussion

If the EMC strategies lead to significantly more remitters, changes of clinical practice, guidelines for the treatment of MDD as well as research settings can be expected.

Trial Registration

Clincaltrials.gov Identifier: NCT00974155; EudraCT: 2008-008280-96.

Vilazodone, a novel dual-acting serotonergic antidepressant for managing major depression

Major depressive disorder (MDD) affects <or= 15% of the general population and imparts a significant economic and psychosocial burden. Despite the availability of a wide range of drugs for treating MDD, the majority of patients fail to achieve complete and sustained remission of symptoms. Vilazodone is a novel dual-acting serotonergic antidepressant currently in clinical development for the treatment of MDD. Vilazodone combines the effects of a selective serotonin reuptake inhibitor with 5-HT(1A) receptor partial agonist activity. In a recent Phase III clinical trial, vilazodone showed significant antidepressant efficacy compared to placebo with a statistically significant onset of effect at 1 week. Overall dropout rates were low. Diarrhea, nausea and headache were the most common adverse events reported. In addition, there was no significant difference between placebo and vilazodone in terms of sexual dysfunction as measured by the Arizona Sexual Experiences Scale. A unique feature of the vilazodone clinical program is the concurrent development of biomarkers that may predict treatment response and common side effects. Vilazodone offers a dual mechanism of action, good general tolerability with the potential for less impairment of sexual function than selective serotonin reuptake inhibitors and the possibility of personalized treatment for MDD.

The Timing of Antidepressant Effects: A Comparison of Diverse Pharmacological and Somatic Treatments

Currently available antidepressants used to treat major depressive disorder (MDD) unfortunately often take weeks to months to achieve their full effects, commonly resulting in considerable morbidity and increased risk for suicidal behavior. Our lack of understanding of the precise cellular underpinnings of this illness and of the mechanism of action of existing effective pharmacological treatments is a large part of the reason that therapies with a more rapid onset of antidepressant action (ROAA) have not been developed. Other issues that need to be addressed include heterogeneous clinical concepts and statistical models to measure rapid antidepressant effects. This review describes the timing of onset of antidepressant effects for various therapies used to treat MDD. While several agents produce earlier improvement of depressive symptoms (defined as occurring within one week), the response rate associated with such agents can be quite variable. These agents include both currently available antidepressants as well as other pharmacological and non-pharmacological interventions. Considerably fewer treatments are associated with ROAA, defined as occurring within several hours or one day. Treatment strategies for MDD whose sustained antidepressant effects manifest within hours or even a few days would have an enormous impact on public health.

Rethinking depression and the actions of antidepressants: uncovering the links between the neural and behavioral elements

Despite major strides in the understanding of mechanisms of antidepressant drug action, few, if any, widely applicable drug treatments with new mechanisms have been developed since the selective serotonin reuptake inhibitors in the late 1970's. One factor that may contribute to this lack of advance is reliance on a set of flawed assumptions that have guided most new drug development over the past quarter century. These assumptions have been particularly deleterious to the development of treatments with mechanisms distinctly different from currently approved treatments. One such assumption is that antidepressant actions on clinical aspects are delayed for several weeks. We review the results of studies on time to improvement and describe two collaborative, multidisciplinary studies during this period which employed a behavioral component model for assessment of change, as an alternative to the conventional "diagnostic-specific" research model. These studies incorporated a novel neurobehavioral framework for describing depressive episodes. The studies indicated that (1) depressive states are comprised of relatively independent and somewhat opposed behavioral and emotional components of anxiety-agitation and depression-retardation, coexisting with a third dimension, hostility, all of which might indicate some degree of mixed state phenomenology, (2) drugs selectively targeted at serotonergic and noradrenergic systems have differing profiles of impact on the behavioral dimensions of depressive states and (3) the sequence of behavioral improvements initiated by pharmacodynamically different drugs also differ. In the aggregate these consistent observations provide the basis for a new paradigm on the nature of major depression. The proposition links drug-induced neural and behavioral changes of antidepressants with prediction of clinical outcome based on early response. We submit that the proposed approach may bring about a new paradigm for improving behavioral technology and design of studies capable of identifying drugs with novel properties and rapid onset of improvement, while avoiding some problematic constructs in past biological research on depression.

Frontal electroencephalogram changes in early phase antidepressant treatment predict clinical response in major depressive disorder

Evaluation of: Leuchter AF, Cook IA, Marangell LB et al.: Comparative effectiveness of biomarkers and clinical indicators for predicting outcomes of SSRI treatment in major depressive disorder: results of the BRITE-MD study. Psychiatry Res. 169, 124–131 (2009) and Leuchter AF, Cook IA, Marangell LB et al.: Effectiveness of a quantitative electroencephalographic biomarker for predicting differential response or remission with escitalopram and bupropion in major depressive disorder. Psychiatry Res. 169, 132–138 (2009). The investigators of the Biomarkers for Rapid Identification of Treatment Effectiveness in Major Depression (BRITE-MD) study calculated the Antidepressant Treatment Response (ATR) index, a biomarker of frontal quantitative electroencephalogram changes, after 1 week of escitalopram treatment and examined whether the ATR had utility as a predictor of outcome after a further 7 weeks of treatment. The ATR index predicted response and remission at week 7, whereas the symptom reduction in Hamilton Depression Rating Scale scores by week 1 only predicted response at week 7. Other markers, such as genetic polymorphisms (5-HTTLPR and 5HT2A), the clinician-rated global impression of improvement and serum drug concentrations, did not provide significant predictive utility. Notably, high ATR values predicted response to escitalopram, while low ATR values predicted response to bupropion. The findings provocatively suggest that the ATR index may be a useful predictor for short-term antidepressant outcome. These results may encourage the future work that will be necessary to evaluate the role of the ATR index and clinical measures as predictors of both short- and long-term antidepressant treatment outcomes.

Smoking induces long-lasting effects through a monoamine-oxidase epigenetic regulation

BACKGROUND

Postulating that serotonin (5-HT), released from smoking-activated platelets could be involved in smoking-induced vascular modifications, we studied its catabolism in a series of 115 men distributed as current smokers (S), never smokers (NS) and former smokers (FS) who had stopped smoking for a mean of 13 years.

METHODOLOGY/PRINCIPAL FINDINGS

5-HT, monoamine oxidase (MAO-B) activities and amounts were measured in platelets, and 5-hydroxyindolacetic acid (5-HIAA)--the 5-HT/MAO catabolite--in plasma samples. Both platelet 5-HT and plasma 5-HIAA levels were correlated with the 10-year cardiovascular Framingham relative risk (P<0.01), but these correlations became non-significant after adjustment for smoking status, underlining that the determining risk factor among those taken into account in the Framingham risk calculation was smoking. Surprisingly, the platelet 5-HT content was similar in S and NS but lower in FS with a parallel higher plasma level of 5-HIAA in FS. This was unforeseen since MAO-B activity was inhibited during smoking (P<0.00001). It was, however, consistent with a higher enzyme protein concentration found in S and FS than in NS (P<0.001). It thus appears that MAO inhibition during smoking was compensated by a higher synthesis. To investigate the persistent increase in MAO-B protein concentration, a study of the methylation of its gene promoter was undertaken in a small supplementary cohort of similar subjects. We found that the methylation frequency of the MAOB gene promoter was markedly lower (P<0.0001) for S and FS vs. NS due to cigarette smoke-induced increase of nucleic acid demethylase activity.

CONCLUSIONS/SIGNIFICANCE

This is one of the first reports that smoking induces an epigenetic modification. A better understanding of the epigenome may help to further elucidate the physiopathology and the development of new therapeutic approaches to tobacco addiction. The results could have a larger impact than cardiovascular damage, considering that MAO-dependent 5-HT catabolism is also involved in addiction, predisposition to cancer, behaviour and mental health.

Canadian Network for Mood and Anxiety Treatments (CANMAT) clinical guidelines for the management of major depressive disorder in adults. III. Pharmacotherapy

BACKGROUND

In 2001, the Canadian Psychiatric Association and the Canadian Network for Mood and Anxiety Treatments (CANMAT) partnered to produce evidence-based clinical guidelines for the treatment of depressive disorders. A revision of these guidelines was undertaken by CANMAT in 2008-2009 to reflect advances in the field.

METHODS

The CANMAT guidelines are based on a question-answer format to enhance accessibility to clinicians. An evidence-based format was used with updated systematic reviews of the literature and recommendations were graded according to Level of Evidence using pre-defined criteria. Lines of Treatment were identified based on criteria that included Levels of Evidence and expert clinical support. This section on "Pharmacotherapy" is one of 5 guideline articles.

RESULTS

Despite emerging data on efficacy and tolerability differences amongst newer antidepressants, variability in patient response precludes identification of specific first choice medications for all patients. All second-generation antidepressants have Level 1 evidence to support efficacy and tolerability and most are considered first-line treatments for MDD. First-generation tricyclic and monoamine oxidase inhibitor antidepressants are not the focus of these guidelines but generally are considered second- or third-line treatments. For inadequate or incomplete response, there is Level 1 evidence for switching strategies and for add-on strategies including lithium and atypical antipsychotics.

LIMITATIONS

Most of the evidence is based on trials for registration and may not reflect real-world effectiveness.

CONCLUSIONS

Second-generation antidepressants are safe, effective and well tolerated treatments for MDD in adults. Evidence-based switching and add-on strategies can be used to optimize response in MDD that is inadequately responsive to monotherapy.

Short-term antidepressant treatment modulates amygdala response to happy faces

RATIONALE

We have previously demonstrated that antidepressant medication facilitates the processing of positive affective stimuli in healthy volunteers. These early effects of antidepressants may be an important component in the therapeutic effects of antidepressant treatment in patients with depression and anxiety.

OBJECTIVES

Here we used functional magnetic resonance imaging in a double-blind, randomised, placebo-controlled between-groups design to investigate the effects of short-term (7-10 days) treatment with the selective serotonin reuptake inhibitor, citalopram, on the amygdala response to positive and negative facial expressions in healthy volunteers.

RESULTS

Citalopram was associated with increased amygdala activation to happy faces relative to placebo control, without changes in levels of mood or anxiety.

CONCLUSIONS

These early, direct effects of antidepressant administration on emotional processing are consistent with a cognitive neuropsychological model of antidepressant action.

Subchronic SSRI administration reduces insula response during affective anticipation in healthy volunteers

The anterior cingulate cortex (ACC) and insula are important neural substrates for the integration of cognitive, emotional, and physiological information, as well as the coordination of responses to anticipated stimuli. Increased neural activation within these structures has been observed in individuals with anxiety and depressive disorders. Selective serotonin reuptake inhibitors (SSRIs) are among the most effective and frequently prescribed anxiolytic agents, yet it is not known whether ACC or insula underlie the effects of these drugs. We examined whether subchronic administration of a SSRI to healthy volunteers attenuates activation in ACC or insula during anticipation, an important emotional process underlying anxiety. Support for this hypothesis would help to understand where and by what process SSRIs may exert beneficial effects as anxiolytics and would provide further mechanistic evidence for functional magnetic resonance imaging (fMRI) as a biomarker for the development of anxiolytics. Fifteen volunteers participated in a double-blind, placebo-controlled, randomized cross-over study. Participants completed a pleasant and aversive picture-cued anticipation task during fMRI after taking either escitalopram (10 mg) or placebo for 21 d. We found that escitalopram significantly decreased activation in bilateral posterior and middle insula during the anticipation condition irrespective of stimulus valence and in medial prefrontal and ACC during anticipation of aversive vs. pleasant images. Reduced insular and ACC activation in healthy controls during anticipation may be integral to the therapeutic efficacy of SSRIs and may provide a mechanistic approach for the use of pharmaco-fMRI in the identification of novel pharmacotherapeutic agents in patient populations.

A critical review of human endotoxin administration as an experimental paradigm of depression

The syndrome called depression may represent the common final pathway at which different aetiopathogenic processes converge. One such aetiopathogenic process is innate immune system activation. Some depressed patients have increased levels of inflammatory cytokines and other immunologic abnormalities. It is not known whether immune system activation contributes to the pathogenesis of depressive symptoms. Supporting this possibility is the observation that in both rodents and humans, exogenous immune stimuli such as endotoxin can produce symptoms that resemble depression. A new approach to depression research would be to use immune stimuli to elicit depressive symptoms in humans. Here we review each of the symptoms elicited in humans by endotoxin administration, and compare this model to two other immune depression paradigms: interferon-alpha treatment and typhoid vaccine administration, to assess to what degree endotoxin administration represents a valid model of immune depression. We also review corresponding behavioral changes in rodents and the potential molecular pathways through which immune system activation produces each symptom.

Efficacy, tolerability and side-effect profile of fluvoxamine for major depression: meta-analysis

Fluvoxamine, one of the oldest selective serotonin reuptaking inhibitors, is commonly prescribed to patients with major depression. Several studies have reviewed the efficacy and tolerability of fluvoxamine for the treatment of major depression. However, these reviews are outdated, have not been systematic and/or suffered from several methodological weaknesses. We conducted a systematic review to synthesize the best available evidence on the efficacy of fluvoxamine for adult patients suffering from major depression in comparison with other active antidepressive agents. Relevant randomized controlled trials were identified through a comprehensive search. The primary outcome was a relative risk of response, and the secondary outcome was a relative risk of remission. Tolerability and side-effect profile were also examined. Fifty-three trials were included. There were no large differences between fluvoxamine and any other antidepressants in terms of efficacy and tolerability. There is evidence of differing side effect profiles, especially when comparing gastrointestinal side effects between fluvoxamine and tricyclics. Clinicians should focus on practically or clinically relevant differences including those in side-effect profiles.

Evidence for IL-1 receptor blockade as a therapeutic strategy for the treatment of depression

Uncontrollable stress, a major precipitant of depression in humans and in animal paradigms, impairs hippocampal neurogenesis, which is necessary for the behavioral effects of antidepressants in models of depression that require chronic treatment. However, the mechanisms underlying these anti-neurogenic and behavioral effects of stress have not been elucidated. Proinflammatory cytokines are thought to be contributing factors to stress and have been implicated in stress-related mood disorders such as major depression. In particular, IL-1 beta has been proposed to be a key mediator in a variety of behavioral actions of stress. Notably, the administration of a IL-1 receptor antagonist (IL-1Ra) blocks the stress-like effects of IL-1 beta in both cellular and behavioral models. This review highlights the increasing interest in the relationship between IL-1 beta, neurogenesis, stress and depression, and discusses the potential of IL-1Ra or other cytokine antagonists as new candidates for the treatment of depression.

How long should a trial of escitalopram treatment be in patients with major depressive disorder, generalised anxiety disorder or social anxiety disorder? An exploration of the randomised controlled trial database

OBJECTIVE

To extend the knowledge of course of improvement in patients with major depressive disorder (MDD), social anxiety disorder (SAD) or generalised anxiety disorder (GAD) participating in randomised placebo-controlled trials (RCTs) and to infer the optimal duration of initial escitalopram treatment in clinical practice, after which intervention might be reasonable in case of non-response.

METHODS

Post hoc analysis of pooled clinical trial database for escitalopram in MDD (14 studies), GAD (4 studies) and SAD (2 studies). 'Onset' of action was defined as a 20% or more decrease from baseline score in disorder-specific psychopathological rating scales: 'response' as a 50% or more decrease from baseline score.

RESULTS

In MDD, the probability of responding at week 8 if no onset was apparent at week 2 was 43%; in patients with an onset of effect the probability was nearly 80%. Similar patterns were observed in GAD and SAD. The chance of responding beyond week 4 in MDD, GAD and SAD was 20% or less if no effect had occurred by week 2.

CONCLUSIONS

The pattern of response in these RCTs suggests that in patients with MDD, GAD or SAD in wider clinical practice, a period of at least 4 weeks is worthwhile before considering further intervention.

Effect of a single dose of citalopram on amygdala response to emotional faces

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) are typically thought to have a delay of several weeks in the onset of their clinical effects. However, recent reports suggest they may have a much earlier therapeutic onset. A reduction in amygdala responsivity has been implicated in the therapeutic action of SSRIs.

AIMS

To investigate the effect of a single dose of an SSRI on the amygdala response to emotional faces.

METHOD

Twenty-six healthy volunteers were randomised to receive a single oral dose of citalopram (20 mg) or placebo. Effects on the processing of facial expressions were assessed 3 h later using functional magnetic resonance imaging.

RESULTS

Volunteers treated with citalopram displayed a significantly reduced amygdala response to fearful facial expressions compared with placebo.

CONCLUSIONS

Such an immediate effect of an SSRI on amygdala responses to threat supports the idea that antidepressants have an earlier onset of therapeutically relevant effects than conventionally thought.

Attention deficit-hyperactivity disorder and early-onset bipolar disorder: two facets of one entity?

Early-onset bipolar disorder (BD) and attention-deficithyperactivity disorder (ADHD) have recently been the subject of highly controversial debate, due to theories regarding underlying pathophysiological processes and a clinical overlap of symptoms. Epidemiological data, clinical aspect, neuroimaging, neurochemical, and genetic studies suggest that there may be a possible relationship between biological factors and clinical characteristic in the development of symptoms. However, longitudinal data supporting the hypothesis of a diagnostic shift from BD to ADHD symptoms and vice versa are currently not available. These would be essential to enable further investigations into whether these two disorders possibly represent two different aspects of an underlying common psychopathophysioiogical entity.

Acute and chronic effects of citalopram on 5-HT1A receptor-labeling by [18F]MPPF and -coupling to receptors-G proteins

Selective serotonin reuptake inhibitors take several weeks to produce their maximal therapeutic antidepressant effect. This delay has been attributed to the gradual desensitization of somatodendritic serotonin 5-HT(1A) autoreceptors. We evaluated adaptive changes of 5-HT(1A) receptors after acute and chronic citalopram challenges in rat. Small animal positron emission tomography trial and quantitative ex vivo autoradiography studies using [(18)F]MPPF were employed, as well as in vitro 8-OH-DPAT-stimulated [(35)S]-GTPgammaS binding assay. Additionally, 5-HT(1A) receptor knock-out mice were used to assess the specificity of [(18)F]MPPF. Acute treatment with citalopram did not alter [(18)F]MPPF binding in dorsal raphe nucleus (DR), frontal cortex, or hippocampus. The absence of [(18)F]MPPF binding in the brain of 5-HT(1A) knock-out mice demonstrates the specificity of MPPF for 5-HT(1A) receptor brain imaging, but the high affinity of [(18)F]MPPF compared to 5-HT suggests that it would only be displaced by dramatic increases in extracellular 5-HT. Chronic citalopram did not modify 5-HT(1A) receptor density in any of the brain regions studied. In addition, this treatment did not modify 8-OH-DPAT-stimulated [(35)S]-GTPgammaS binding in DR, although a significant increase was observed in frontal cortex and hippocampus. [(18)F]MPPF appears to be an efficient radioligand to quantify specifically 5-HT(1A) receptor density in brain imaging. The delayed therapeutic efficacy of citalopram did not appear to be linked to either a downregulation of 5-HT(1A) receptors or to a 5-HT(1A) receptor-G protein decoupling process in serotonergic neurons, but to increased functional sensitivity of postsynaptic 5-HT(1A) receptors.

Comparative efficacy and acceptability of 12 new-generation antidepressants: a multiple-treatments meta-analysis

BACKGROUND

Conventional meta-analyses have shown inconsistent results for efficacy of second-generation antidepressants. We therefore did a multiple-treatments meta-analysis, which accounts for both direct and indirect comparisons, to assess the effects of 12 new-generation antidepressants on major depression.

METHODS

We systematically reviewed 117 randomised controlled trials (25 928 participants) from 1991 up to Nov 30, 2007, which compared any of the following antidepressants at therapeutic dose range for the acute treatment of unipolar major depression in adults: bupropion, citalopram, duloxetine, escitalopram, fluoxetine, fluvoxamine, milnacipran, mirtazapine, paroxetine, reboxetine, sertraline, and venlafaxine. The main outcomes were the proportion of patients who responded to or dropped out of the allocated treatment. Analysis was done on an intention-to-treat basis.

FINDINGS

Mirtazapine, escitalopram, venlafaxine, and sertraline were significantly more efficacious than duloxetine (odds ratios [OR] 1.39, 1.33, 1.30 and 1.27, respectively), fluoxetine (1.37, 1.32, 1.28, and 1.25, respectively), fluvoxamine (1.41, 1.35, 1.30, and 1.27, respectively), paroxetine (1.35, 1.30, 1.27, and 1.22, respectively), and reboxetine (2.03, 1.95, 1.89, and 1.85, respectively). Reboxetine was significantly less efficacious than all the other antidepressants tested. Escitalopram and sertraline showed the best profile of acceptability, leading to significantly fewer discontinuations than did duloxetine, fluvoxamine, paroxetine, reboxetine, and venlafaxine.

INTERPRETATION

Clinically important differences exist between commonly prescribed antidepressants for both efficacy and acceptability in favour of escitalopram and sertraline. Sertraline might be the best choice when starting treatment for moderate to severe major depression in adults because it has the most favourable balance between benefits, acceptability, and acquisition cost.

A new paradigm for the prediction of antidepressant treatment response

Current treatment of Major Depressive Disorder utilizes a trial-and-error sequential treatment strategy that results in delays in achieving response and remission for a majority of patients. Protracted ineffective treatment prolongs patient suffering and increases health care costs. In addition, long and unsuccessful antidepressant trials may diminish patient expectations, reinforce negative cognitions, and condition patients not to respond during subsequent antidepressant trials, thus contributing to further treatment resistance. For these reasons, it is critical to identify reliable predictors of antidepressant treatment response that can be used to shorten or eliminate lengthy and ineffective trials. Research on possible endophenotypic as well as genomic predictors has not yet yielded reliable predictors. The most reliable predictors identified thus far are symptomatic and physiologic characteristics of patients that emerge early in the course of treatment. We propose here the term "response endophenotypes" (REs) to describe this class of predictors, defined as latent measurable symptomatic or neurobiologic responses of individual patients that emerge early in the course of treatment, and which carry strong predictive power for individual patient outcomes. Use of REs constitutes a new paradigm in which medication treatment trials that are likely to be ineffective could be stopped within 1 to 2 weeks and other medication more likely to be effective could be started. Data presented here suggest that early changes in symptoms, quantitative electroencephalography, and gene expression could be used to construct effective REs. We posit that this new paradigm could lead to earlier recovery from depressive illness and ultimately produce profound health and economic benefits.

The relationship between antidepressant and analgesic responses: findings from six placebo-controlled trials assessing the efficacy of duloxetine in patients with major depressive disorder

OBJECTIVE

Debate continues regarding whether onset of analgesia is faster than antidepressant effect in antidepressants with both properties. Duloxetine hydrochloride (from here on referred to as duloxetine) is effective in both major depressive disorder and diabetic peripheral neuropathic pain. This post-hoc analysis of six placebo-controlled duloxetine trials in patients with major depressive disorder was designed to compare onset of antidepressant activity to pain relief.

RESEARCH DESIGN AND METHODS

Duloxetine was administered at 40-120 mg/day versus placebo for up to 9 weeks in outpatient clinic settings. The primary depression measure was the HAMD(17) and pain severity was measured using visual analog scale (VAS) measuring overall pain, headache, back and shoulder pain, and pain while awake. The time course of improvement was profiled using repeated measures modeling and Kaplan-Meier product limit estimation.

RESULTS

In all but one case, significant reductions in HAMD(17) and VAS scores were seen within 2 weeks of treatment. Median time to VAS response was consistently shorter across all VAS measures than that to HAMD(17) response in both placebo- and duloxetine-treated patients with at least modest levels of pain at study entry. Regression analyses consistently demonstrated little association between analgesic and antidepressant responses. Limitations of these findings include that the studies used in these analyses did not require the patients to enroll with any specific level of pain. Moreover, the type of pain exhibiting at presentation was not routinely identified; therefore, the impact of different pain types on these findings is unknown.

CONCLUSIONS

Duloxetine's analgesic effect is independent of the drug's antidepressant effect. Additionally, faster onset of the analgesic effect appears to be a population-specific phenomenon that is unmodified in the presence of active agents.

The effects of reboxetine on emotional processing in healthy volunteers: an fMRI study

Recent neuropsychological studies in healthy volunteers suggest that antidepressants enhance the processing of positive emotional information. However, the neural substrates underpinning these changes have not been fully elucidated. The current study, therefore, used functional magnetic resonance imaging (fMRI) to map brain systems activated during successful categorization and subsequent recognition of self-referent positive and negative personality characteristics in healthy volunteers following short-term (7 days) repeated administration of the selective noradrenergic reuptake inhibitor reboxetine. Twenty-four healthy volunteers were randomly assigned to 7-day double-blind intervention with reboxetine or placebo. On day 7, neural responses during the categorization and subsequent recognition of positive and negative characteristics were assessed using fMRI. Questionnaires monitoring mood, hostility and anxiety were given before and during this intervention. During categorization, reboxetine was associated with greater activation to positive words, relative to negative words, in left precuneus and right inferior frontal gyrus. By contrast, at subsequent recognition reboxetine was associated with reduced response to positive words, relative to negative words, in left precuneus, anterior cingulate and medial frontal gyrus. These changes in the neural processing of positive and negative words occurred in the absence of significant differences in ratings of mood and anxiety. Such adaptations in the neural processing of emotional information support the hypothesis that antidepressants have early effects on emotional processing in a manner which would be expected to reverse negative biases in depression.

A randomized, double-blind, and placebo-controlled trial of quetiapine augmentation of fluoxetine in major depressive disorder

The objective of this study was to investigate whether quetiapine, when compared with placebo, can speed the onset of action and improve the quality of response to fluoxetine treatment in patients suffering from major depressive disorder. A total of 114 patients with major depressive disorder were enrolled in an 8-week treatment study. Patients were initiated on a course of fluoxetine treatment and randomized to quetiapine or placebo. Quetiapine was flexibly dosed starting at 25 mg to a maximum of 100 mg daily. Mixed-effects regression showed that quetiapine plus fluoxetine did not achieve 50% reduction in the Montgomery-Asberg Depression Rating Scale score or improvement in Hamilton Anxiety Scale, Clinical Global Improvement (CGI)-Severity, and CGI-Improvement scores sooner than the fluoxetine plus placebo group; however both groups improved in all scores over time. Mixed-effects linear regression of insomnia scores showed that the quetiapine plus fluoxetine group improved significantly more rapidly compared with the fluoxetine plus placebo group. The study indicates that quetiapine plus fluoxetine did not achieve a reduction in the Montgomery-Asberg Depression Rating Scale score or improvement in Hamilton Anxiety Scale or CGI scores from baseline sooner than the fluoxetine plus placebo group. The combination of quetiapine and fluoxetine, however, improved sleep over fluoxetine alone over the first few weeks of treatment.

Evidence-based guidelines for treating depressive disorders with antidepressants: a revision of the 2000 British Association for Psychopharmacology guidelines

A revision of the 2000 British Association for Psychopharmacology evidence-based guidelines for treating depressive disorders with antidepressants was undertaken to incorporate new evidence and to update the recommendations where appropriate. A consensus meeting involving experts in depressive disorders and their management was held in May 2006. Key areas in treating depression were reviewed, and the strength of evidence and clinical implications were considered. The guidelines were drawn up after extensive feedback from participants and interested parties. A literature review is provided, which identifies the quality of evidence to inform the recommendations, the strength of which are based on the level of evidence. These guidelines cover the nature and detection of depressive disorders, acute treatment with antidepressant drugs, choice of drug versus alternative treatment, practical issues in prescribing and management, next-step treatment, relapse prevention, treatment of relapse, and stopping treatment.

Rapid onset of antidepressant action: a new paradigm in the research and treatment of major depressive disorder

OBJECTIVE

Current therapeutics of depression are similar in their time to antidepressant action and often take weeks to months to achieve response and remission, which commonly results in considerable morbidity and disruption in personal, professional, family, and social life, as well as risk for suicidal behavior. Thus, treatment strategies presenting a rapid improvement of depressive symptoms--within hours or even a few days--and whose effects are sustained would have an enormous impact on public health. This article reviews the published data related to different aspects of rapid improvement of depressive symptoms.

DATA SOURCES

Literature for this review was obtained through a search of the MEDLINE database (1966-2007) using the following keywords and phrases: rapid response, antidepressant, time to, glutamate, sleep, therapeutics, latency, and depression. The data obtained were organized according to the following topics: clinical relevance and time course of antidepressant action, interventions showing evidence of rapid response and its potential neurobiological basis, and new technologies for better understanding rapid anti-depressant actions.

DATA SYNTHESIS

A limited number of prospective studies evaluating rapid antidepressant actions have been conducted. Currently, only a few interventions have been shown to produce antidepressant response in hours or a few days. The neurobiological basis of these rapid antidepressant actions is only now being deciphered.

CONCLUSIONS

Certain experimental treatments can produce antidepressant response in a much shorter period of time than existing medications. Understanding the molecular basis of these experimental interventions is likely to lead to the development of improved therapeutics rather than simply furthering our knowledge of current standard antidepressants.

Inflammation, glutamate, and glia in depression: a literature review

Multiple lines of evidence suggest that inflammation and glutamate dysfunction contribute to the pathophysiology of depression. In this review we provide an overview of how these two systems may interact. Excess levels of inflammatory mediators occur in a subgroup of depressed patients. Studies of acute experimental activation of the immune system with endotoxin and of chronic activation during interferon-alpha treatment show that inflammation can cause depression. Peripheral inflammation leads to microglial activation which could interfere with excitatory amino acid metabolism leading to inappropriate glutamate receptor activation. Loss of astroglia, a feature of depression, upsets the balance of anti- and pro-inflammatory mediators and further impairs the removal of excitatory amino acids. Microglia activated by excess inflammation, astroglial loss, and inappropriate glutamate receptor activation ultimately disrupt the delicate balance of neuroprotective versus neurotoxic effects in the brain, potentially leading to depression.

Prediction of response within the first 3 days to treatment with paroxetine for depression

OBJECTIVE

In the treatment of depression, clinical and psychopharmacologic aspects have been investigated to predict the response to anti-depressants. Some trials have reported clinical improvement as early as the first week; however, few have investigated the early effects of selective serotonin reuptake inhibitors. The aim of this study was to investigate therapeutic efficacy of paroxetine within the first 3 days of therapy onset.

METHOD

Subjects included 29 outpatients diagnosed at first interview with major depressive disorder according to DSM-IV criteria (June 2003 to January 2007). Paroxetine 5-20 mg/day was administered for at least 2 weeks. Treatment efficacy was defined as a > 50% decrease in Hamilton Rating Scale for Depression (HAM-D) total scores from baseline to the end of the second week. To determine efficacy within the first 3 days, patients completed the HAM-D as a self-rated questionnaire on the first and third days and at the end of the first, second, and fourth weeks.

RESULT

Subjects were divided into 2 groups: successful (17 responders) and failed (12 non-responders). There was a significant difference between the reduction rates of self-rated HAM-D total scores on the third day (p < .01).

CONCLUSION

In patients responding to paroxetine in the early stages of treatment, the prediction of response within the first 3 days using the self-rated HAM-D is suggested.

Time to response for duloxetine 60 mg once daily versus placebo in elderly patients with major depressive disorder

BACKGROUND

Rapid response to antidepressant therapy is desirable and may be particularly critical in elderly patients with major depressive disorder (MDD).

METHODS

Findings are based on post-hoc analyses from a double-blind trial of elderly patients with MDD > or = 65 years, randomly assigned 2:1 to duloxetine 60 mg QD (N = 207) or placebo (N = 104) for 8 weeks. Depression and pain measures included the Geriatric Depression Scale (GDS), 17-item Hamilton Depression Scale (HAMD17), CGI-Severity, and Visual Analog Scale (VAS) for overall pain. The time to response and remission for duloxetine compared with placebo was evaluated using Cox proportional hazards (PH) modeling, Kaplan-Meier estimation, and categorical repeated measures analysis.

RESULTS

Significant improvements of estimated HAMD17 response and remission rates for duloxetine started at week 2 (P = 0.022 and P = 0.033, respectively). Time to HAMD17 response and remission were significantly shorter for duloxetine versus placebo (P 0.10 for all PH treatment-by-age interactions). The placebo-referenced duloxetine HR for time to 50% reduction in overall pain was 1.75 (P = 0.024) for patients with moderate to severe pain.

CONCLUSION

Duloxetine demonstrated a faster time to antidepressant response and improvement in self-reported pain as compared with placebo. CLINICAL TRIAL REGISTRY NUMBER FOR THIS STUDY: NCT00062673, at www.clinicaltrials.gov.

Skeletal effects of serotonin (5-hydroxytryptamine) transporter inhibition: evidence from in vitro and animal-based studies

The regulation of bone metabolism continues to be an area of intense investigation, with recent evidence indicating a potential contribution from the neural system. In particular, the neurotransmitter serotonin (5-hydroxytryptamine [5-HT]) has been hypothesized to play a role in skeletal metabolism via its transporter (5-HTT). The 5-HTT is a plasma membrane transporter that is highly specific for the uptake of extracellular 5-HT, thereby facilitating the intracellular storage and/or degradation of 5-HT. The 5-HTT is clinically important as it is the key target of pharmaceutical agents aimed at treating affective disorders, such as major depressive disorder. By antagonizing the 5-HTT, selective serotonin reuptake inhibitors (SSRIs) potentiate 5-HT activity and effectively relieve the symptoms of depression. However, questions have been raised regarding the potential skeletal effects of SSRIs given the recent identification of a functional 5-HTT and functional 5-HT receptors in bone cells. This paper discusses the preclinical evidence for the skeletal effects of 5-HT and the inhibition of the 5-HTT. In particular, it discusses the: (1) role of 5-HT and the function of the 5-HTT; (2) presence of functional 5-HTTs in bone; (3) potential sources and response mechanisms for 5-HT in bone, and; (4) in vitro and in vivo skeletal effects of 5-HT and 5-HTT inhibition.

Effectiveness of paroxetine in the treatment of acute major depression in adults: a systematic re-examination of published and unpublished data from randomized trials

BACKGROUND

Concern has been raised about the efficacy of antidepressant therapy for major depression in adults. We undertook a systematic review of published and unpublished clinical trial data to determine the effectiveness and acceptability of paroxetine.

METHODS

We searched the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Register, the Cochrane Central Register of Controlled Trials, the GlaxoSmithKline Clinical Trial Register, MEDLINE and EMBASE up to December 2006. Published and unpublished randomized trials comparing paroxetine with placebo in adults with major depression were eligible for inclusion. We selected the proportion of patients who left a study early for any reason as the primary outcome measure because it represents a hard measure of treatment effectiveness and acceptability.

RESULTS

We included in our review 29 published and 11 unpublished clinical trials, with a total of 3704 patients who received paroxetine and 2687 who received with placebo. There was no difference between paroxetine and placebo in terms of the proportion of patients who left the study early for any reason (random effect relative risk [RR] 0.99, 99% confidence interval [CI] 0.88-1.11). Paroxetine was more effective than placebo, with fewer patients who did not experience improvement in symptoms of at least 50% (random effect RR 0.83, 99% CI 0.77-0.90). Significantly more patients in the paroxetine group than in the placebo group left their respective studies because of side effects (random effect RR 1.77, 95% CI 1.44-2.18) or experienced suicidal tendencies (odds ratio 2.55, 95% CI 1.17-5.54).

INTERPRETATION

Among adults with moderate to severe major depression in the clinical trials we reviewed, paroxetine was not superior to placebo in terms of overall treatment effectiveness and acceptability. These results were not biased by selective inclusion of published studies.

[Antidepressants and their onset of action: a major clinical, methodological and pronostical issue]

Although antidepressant medications are effective in about 50-70% of patients with major depressive disorder (MDD), they have a delayed onset of therapeutic effect. This latency is one of the current major limitations of these medications, in that it prolongs the impairments associated with depression, leaves patients vulnerable to an increased risk of suicide, increases the likelihood that a patient will prematurely discontinue therapy, and increases medical costs associated with severe depression. It is becoming increasingly clear that differences may exist between antidepressants and some evidence suggests that some antidepressant agents may begin to work faster than others. Escitalopram, duloxetine, venlafaxine, and mirtazapine have shown statistically significant differences in some measures of antidepressant action within the first two weeks of treatment, both in placebo-controlled trials and in head-to-head comparisons with other antidepressants. Results of the current review should be regarded with certain important limitations in mind. First, differences in times to onset of antidepressant response have been shown in clinical efficacy studies not specifically designed to detect differences in onset of action (post-hoc analysis). Second, results observed in 'pure' clinical trial samples should not be directly generalized to the real clinical practice since it has been proven in clinical settings that less than one in seven depressed patients would be eligible to participate in antidepressant clinical trials. For instance, depressed patients who are suicidal or who score higher than 30 on the 17-item HAM-D are excluded from antidepressant clinical trials. Third, caution is warranted when applying these findings to clinical populations with more severe depressions with respect to the fact that among clinical populations, severity of depression coincides with comorbidity, including such psychiatric disorders as anxiety disorders, personality disorders and substance abuse. In addition, the magnitudes of the size-effects of antidepressants versus placebo are clearly higher in severely depressed patients. Fourth, specific items on depression rating scales may induce greater antidepressant/placebo differences. For instance, the 17-item HAM-D contains three questions pertaining to sleep. It questions the fact that earlier onset may appear not only via a specific antidepressant effect but also via a non-specific effect on anxiety, sleep, physical pain or other accessory symptoms. Thus, current data do not clearly support claims that one drug reduces the symptoms of depression faster than another, though the existing literature suggests that escitalopram displays some superiority in terms of rapidity of action. Given the potential benefits of early-acting antidepressant treatments, the possibility of superior speed of onset of escitalopram presented here merits further study in adequately designed, prospective clinical trials. A definitive demonstration of early onset of action awaits the results of appropriately designed and powered clinical studies, which may include (1) a prospective definition of early onset of action, (2) more focused assessments of core emotional symptoms and cognitive deficits of depression by using specific and sensitive tools, (3) a data-analytic approach capable of capturing the dynamic nature of symptomatic change (for example, survival analysis), and (4) strategies to minimize biases and heterogeneity of response.

Behavioral effects of chronic fluoxetine in BALB/cJ mice do not require adult hippocampal neurogenesis or the serotonin 1A receptor

We previously reported that chronic, but not subchronic, treatment with the selective serotonin reuptake inhibitor (SSRI) fluoxetine altered behavior in the forced swimming test (FST) in BALB/cJ mice. We now use this model to investigate mechanisms underlying the delayed onset of the behavioral response to antidepressants, specifically (1) adult hippocampal neurogenesis and (2) expression of the 5-HT1A receptor. Here, we show data validating this model of chronic antidepressant action. We found the FST to be selectively responsive to chronic administration of the SSRI fluoxetine (18 mg/kg/day) and the tricyclic antidepressant desipramine (20 mg/kg/day), but not to the antipsychotic haloperidol (1 mg/kg/day) in BALB/cJ mice. The behavioral effects of fluoxetine emerged by 12 days of treatment, and were affected neither by ablation of progenitor cells of the hippocampus nor by genetic deletion of the 5-HT1A receptor. The effect of fluoxetine in the BALB/cJ mice was also neurogenesis-independent in the novelty-induced hypophagia test. We also found that chronic fluoxetine does not induce an increase in cell proliferation or the number of young neurons as measured by BrdU and doublecortin immunolabeling, respectively, in BALB/cJ mice. These data are in contrast to our previous report using a different strain of mice (129SvEvTac). In conclusion, we find that BALB/cJ mice show a robust response to chronic SSRI treatment in the FST, which is not mediated by an increase in new neurons in the hippocampus, and does not require the 5-HT1A receptor. These findings suggest that SSRIs can produce antidepressant-like effects via distinct mechanisms in different mouse strains.

Limitations of current medical treatments for depression: disturbed circadian rhythms as a possible therapeutic target

The proportion of diagnosed depressives prescribed antidepressants has increased markedly over the last 20 years, mainly following the introduction of the selective serotonin reuptake inhibitors. However, currently available antidepressants have notable limitations, relating to their only moderate efficacy relative to placebo, relatively slow onset of action, possible withdrawal symptoms, and problems of compliance. Sleep disturbances are often used to identify newly presenting depressive patients, and may be part of a more general alteration of bodily rhythms. There are links between pharmacological treatments and circadian rhythms in depression, which might represent another, new option for the development of a therapeutic approach to depression treatment. Many antidepressants affect sleep, some are sedative, and others have been used specifically in severely insomniac depressives. Disturbances in circadian rhythms may be an integral part of depressive mechanisms, and normalising them via an innovative mechanism of antidepressant action may be a fruitful avenue in the search for improved antidepressant agents.

Rapid onset of true antidepressant action

Antidepressant medications generally are considered to have a delayed onset of action; however, recent evidence is beginning to challenge this conventional wisdom. Meta-analysis of placebo-controlled, randomized trials reveals that patients with depression are more likely to experience a clinically significant response with antidepressants than with placebo by the end of the first week of treatment. About one third of the total treatment benefit over 6 weeks is evident by the end of the first week. Early response to antidepressants is not necessarily a placebo response.

The effects of serotonin manipulations on emotional information processing and mood

BACKGROUND

Serotonin is implicated in both mood and cognition. It has recently been shown that antidepressant treatment has immediate effects on emotional information processing, which is much faster than any clinically significant effects. This review aims to investigate whether the effects on emotional information processing are reliable, and whether these effects are related to eventual clinical outcome. Treatment-efficiency may be greatly improved if early changes in emotional information processing are found to predict clinical outcome following antidepressant treatment.

METHODS

Review of studies investigating the short-term effects of serotonin manipulations (including medication) on the processing of emotional information, using PubMed and PsycInfo databases.

RESULTS

Twenty-five studies were identified. Serotonin manipulations were found to affect attentional bias, facial emotion recognition, emotional memory, dysfunctional attitudes and decision making. The sequential link between changes in emotional processing and mood remains to be further investigated.

LIMITATIONS

The number of studies on serotonin manipulations and emotional information processing in currently depressed subjects is small. No studies yet have directly tested the link between emotional information processing and clinical outcome during the course of antidepressant treatment.

CONCLUSIONS

Serotonin function is related to several aspects of emotional information processing, but it is unknown whether these changes predict or have any relationship with clinical outcome. Suggestions for future research are provided.