A single dose of mirtazapine modulates neural responses to emotional faces in healthy people

Acute neural effects of the mood stabiliser lamotrigine on emotional processing in healthy volunteers: a randomised control trial

Lamotrigine is an effective mood stabiliser, largely used for the management and prevention of depression in bipolar disorder. The neuropsychological mechanisms by which lamotrigine acts to relieve symptoms as well as its neural effects on emotional processing remain unclear. The primary objective of this current study was to investigate the impact of an acute dose of lamotrigine on the neural response to a well-characterised fMRI task probing implicit emotional processing relevant to negative bias. 31 healthy participants were administered either a single dose of lamotrigine (300 mg, n = 14) or placebo (n = 17) in a randomized, double-blind design. Inside the 3 T MRI scanner, participants completed a covert emotional faces gender discrimination task. Brain activations showing significant group differences were identified using voxel-wise general linear model (GLM) nonparametric permutation testing, with threshold free cluster enhancement (TFCE) and a family wise error (FWE)-corrected cluster significance threshold of p < 0.05. Participants receiving lamotrigine were more accurate at identifying the gender of fearful (but not happy or angry) faces. A network of regions associated with emotional processing, including amygdala, insula, and the anterior cingulate cortex (ACC), was significantly less activated in the lamotrigine group compared to the placebo group across emotional facial expressions. A single dose of lamotrigine reduced activation in limbic areas in response to faces with both positive and negative expressions, suggesting a valence-independent effect. However, at a behavioural level lamotrigine appeared to reduce the distracting effect of fear on face discrimination. Such effects may be relevant to the mood stabilisation effects of lamotrigine.

Social Psychopharmacology: Novel Approaches to Treat Deficits in Social Motivation in Schizophrenia

BACKGROUND AND HYPOTHESIS

Diminished social motivation is a negative symptom of schizophrenia and leads to severe functional consequences for many patients suffering from the illness. However, there are no effective medications available to treat this symptom. Despite the lack of approved treatments for patients, there is a growing body of literature on the effects of several classes of drugs on social motivation in healthy volunteers that may be relevant to patients. The aim of this review is to synthesize these results in an effort to identify novel directions for the development of medications to treat reduced social motivation in schizophrenia.

STUDY DESIGN

In this article, we review pharmacologic challenge studies addressing the acute effects of psychoactive drugs on social motivation in healthy volunteers and consider how these findings may be applied to deficits in social motivation in schizophrenia. We include studies testing amphetamines and 3,4-methylenedioxymethamphetamine (MDMA), opioids, cannabis, serotonergic psychedelics, antidepressants, benzodiazepines, and neuropeptides.

STUDY RESULTS

We report that amphetamines, MDMA, and some opioid medications enhance social motivation in healthy adults and may represent promising avenues of investigation in schizophrenia.

CONCLUSIONS

Given the acute effects of these drugs on behavioral and performance-based measures of social motivation in healthy volunteers, they may be particularly beneficial as an adjunct to psychosocial training programs in patient populations. It remains to be determined how these medications affect patients with deficits in social motivation, and in which contexts they may be most effectively administered.

Acute neural effects of fluoxetine on emotional regulation in depressed adolescents

BACKGROUND

Adolescent major depressive disorder (MDD) is associated with disrupted processing of emotional stimuli and difficulties in cognitive reappraisal. Little is known however about how current pharmacotherapies act to modulate the neural mechanisms underlying these key processes. The current study therefore investigated the neural effects of fluoxetine on emotional reactivity and cognitive reappraisal in adolescent depression.

METHODS

Thirty-one adolescents with MDD were randomised to acute fluoxetine (10 mg) or placebo. Seventeen healthy adolescents were also recruited but did not receive any treatment for ethical reasons. During functional magnetic resonance imaging (fMRI), participants viewed aversive images and were asked to either experience naturally the emotional state elicited ('Maintain') or to reinterpret the content of the pictures to reduce negative affect ('Reappraise'). Significant activations were identified using whole-brain analysis.

RESULTS

No significant group differences were seen when comparing Reappraise and Maintain conditions. However, when compared to healthy controls, depressed adolescents on placebo showed reduced visual activation to aversive pictures irrespective of the condition. The depressed adolescent group on fluoxetine showed the opposite pattern, i.e. increased visuo-cerebellar activity in response to aversive pictures, when compared to depressed adolescents on placebo.

CONCLUSIONS

These data suggest that depression in adolescence may be associated with reduced visual processing of aversive imagery and that fluoxetine may act to reduce avoidance of such cues. This could reflect a key mechanism whereby depressed adolescents engage with negative cues previously avoided. Future research combining fMRI with eye-tracking is nonetheless needed to further clarify these effects.

Influence and interaction of resting state functional magnetic resonance and tryptophan hydroxylase-2 methylation on short-term antidepressant drug response

BACKGROUND

Most antidepressants have been developed on the basis of the monoamine deficiency hypothesis of depression, in which neuronal serotonin (5-HT) plays a key role. 5-HT biosynthesis is regulated by the rate-limiting enzyme tryptophan hydroxylase-2 (TPH2). TPH2 methylation is correlated with antidepressant effects. Resting-state functional MRI (rs-fMRI) is applied for detecting abnormal brain functional activity in patients with different antidepressant effects. We will investigate the effect of the interaction between rs-fMRI and TPH2 DNA methylation on the early antidepressant effects.

METHODS

A total of 300 patients with major depressive disorder (MDD) and 100 healthy controls (HCs) were enrolled, of which 60 patients with MDD were subjected to rs-fMRI. Antidepressant responses was assessed by a 50% reduction in 17-item Hamilton Rating Scale for Depression (HAMD-17) scores at baseline and after two weeks of medication. The RESTPlus software in MATLAB was used to analyze the rs-fMRI data. The amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), fractional ALFF (fALFF), and functional connectivity (FC) were used, and the above results were used as regions of interest (ROIs) to extract the average value of brain ROIs regions in the RESTPlus software. Generalized linear model analysis was performed to analyze the association between abnormal activity found in rs-fMRI and the effect of TPH2 DNA methylation on antidepressant responses.

RESULTS

Two hundred ninety-one patients with MDD and 100 HCs were included in the methylation statistical analysis, of which 57 patients were included in the further rs-fMRI analysis (3 patients were excluded due to excessive head movement). 57 patients were divided into the responder group (n = 36) and the non-responder group (n = 21). Rs-fMRI results showed that the ALFF of the left inferior frontal gyrus (IFG) was significantly different between the two groups. The results showed that TPH2-1-43 methylation interacted with ALFF of left IFG to affect the antidepressant responses (p = 0.041, false discovery rate (FDR) corrected p = 0.149).

CONCLUSIONS

Our study demonstrated that the differences in the ALFF of left IFG between the two groups and its association with TPH2 methylation affect short-term antidepressant drug responses.

The Effect of the 5-HT4 Agonist, Prucalopride, on a Functional Magnetic Resonance Imaging Faces Task in the Healthy Human Brain

Depression is a common and often recurrent illness with significant negative impact on a global scale. Current antidepressants are ineffective for up to one third of people with depression, many of whom experience persistent symptomatology. 5-HT₄ receptor agonists show promise in both animal models of depression and cognitive deficit. We therefore studied the effect of the 5-HT₄ partial agonist prucalopride (1 mg daily for 6 days) on the neural processing of emotional faces in 43 healthy participants using a randomised placebo-controlled design. Participants receiving prucalopride were more accurate at identifying the gender of emotional faces. In whole brain analyses, prucalopride was also associated with reduced activation in a network of regions corresponding to the default mode network. However, there was no evidence that prucalopride treatment produced a positive bias in the neural processing of emotional faces. Our study provides further support for a pro-cognitive effect of 5-HT₄ receptor agonism in humans. While our current behavioural and neural investigations do not suggest an antidepressant-like profile of prucalopride in humans, it will be important to study a wider dose range in future studies.

Impact of ibuprofen and peroxisome proliferator-activated receptor gamma on emotion-related neural activation: A randomized, placebo-controlled trial

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen have shown initial promise in producing antidepressant effects. This is perhaps due to these drugs being peroxisome proliferator-activated receptor gamma (PPARγ) agonists, in addition to their inhibition of cyclooxygenase enzymes. Some, albeit mixed, evidence suggests that PPARγ agonists have antidepressant effects in humans and animals. This double-blind, placebo-controlled, pharmacologic functional magnetic resonance imaging (ph-fMRI) study aimed to elucidate the impact of ibuprofen on emotion-related neural activity and determine whether observed effects were due to changes in PPARγ gene expression. Twenty healthy volunteers completed an emotional face matching task during three fMRI sessions, conducted one week apart. Placebo, 200 mg, or 600 mg ibuprofen was administered 1 h prior to each scan in a pseudo-randomized order. Peripheral blood mononuclear cells were collected at each session to isolate RNA for PPARγ gene expression. At the doses used, ibuprofen did not significantly change PPARγ gene expression. Ibuprofen dose was associated with decreased blood oxygen level-dependent (BOLD) activation in the dorsolateral prefrontal cortex and fusiform gyrus during emotional face processing (faces-shapes). Additionally, PPARγ gene expression was associated with increased BOLD activation in the insula and transverse and superior temporal gyri (faces-shapes). No interaction effects between ibuprofen dose and PPARγ gene expression on BOLD activation were observed. Thus, results suggest that ibuprofen and PPARγ may have independent effects on emotional neurocircuitry. Future studies are needed to further delineate the roles of ibuprofen and PPARγ in exerting antidepressant effects in healthy as well as clinical populations.

Cognitive neuropsychological theory of antidepressant action: a modern-day approach to depression and its treatment

Depression is a leading cause of disability worldwide and improving its treatment is a core research priority for future programmes. A change in the view of psychological and biological processes, from seeing them as separate to complementing one another, has introduced new perspectives on pathological mechanisms of depression and treatment mode of action. This review presents a theoretical model that incorporated this novel approach, the cognitive neuropsychological hypothesis of antidepressant action. This model proposes that antidepressant treatments decrease the negative bias in the processing of emotionally salient information early in the course of antidepressant treatment, which leads to the clinically significant mood improvement later in treatment. The paper discusses the role of negative affective biases in the development of depression and response to antidepressant treatments. It also discusses whether the model can be applied to other antidepressant interventions and its potential translational value, including treatment choice, prediction of response and drug development.

Trait Sensitivity to Negative and Positive Feedback Does Not Interact With the Effects of Acute Antidepressant Treatment on Hedonic Status in Rats

Aberrant cognition plays a pivotal role in the development and maintenance of depression. One of the most important cognitive distortions associated with depression is aberrant sensitivity to performance feedback. Under clinical conditions, this sensitivity can be measured using the probabilistic reversal learning (PRL) test, which has also been recently implemented in animal studies. Although the evidence for the coexistence of depression and altered feedback sensitivity is relatively coherent, it is unclear whether this sensitivity can influence the effectiveness of antidepressant treatment. In the present research, we investigated how trait sensitivity to negative and positive feedback interacts with the effects of acute antidepressant treatment on hedonic status in rats. We tested a cohort of rats with a series of 10 PRL tests, and based on this screening, we classified each animal as sensitive or insensitive to negative and positive feedback. Subsequently, in the Latin square design, we evaluated the effects of a single administration of two antidepressant drugs (each at three different doses: agomelatine: 5, 10, and 40 mg/kg; mirtazapine 0.5, 1, and 3 mg/kg) on the hedonic status of rats in the sucrose preference tests. There was no statistically significant interaction between trait sensitivity to feedback and the effects of acute antidepressant treatment on hedonic status in rats.

Subchronic treatment with St John's wort produces a positive shift in emotional processing in healthy volunteers

BACKGROUND

The neurocognitive model of antidepressant treatment in depression states that antidepressants work by producing relatively immediate positive shifts in emotional processing, which translate into clinical improvement with time. St John's Wort has shown antidepressant potential in randomised controlled trials; however, its pharmacological actions are broad and it is unknown whether treatment also produces changes in emotional processing.

AIMS

We investigated whether short-term treatment with St John's wort has similar effects on emotional processing to those reported with other antidepressants such as selective serotonergic reuptake inhibitors.

METHODS

Forty-eight healthy participants were given St John's wort or placebo treatment for seven days. On day 7 they completed a battery of tasks to measure emotional processing and other elements of cognition.

RESULTS

St John's wort treatment produced similar changes to other antidepressants, for example reducing recognition of disgusted faces and attention to fearful faces, while increasing memory for positive words. We failed to find evidence for an effect of St John's wort on other aspects of cognition including working memory.

CONCLUSIONS

These findings lend support to the theory that the production of early positive biases in emotional processing may be a common feature of all clinically effective antidepressants with diverse pharmacological mechanisms.

A single dose of fluoxetine reduces neural limbic responses to anger in depressed adolescents

Depression in adolescence is frequently characterised by symptoms of irritability. Fluoxetine is the antidepressant with the most favourable benefit:risk ratio profile to treat adolescent depression, but the neural mechanisms underlying antidepressant drugs in the young brain are still poorly understood. Previous studies have characterised the neural effects of long-term fluoxetine treatment in depressed adolescents, but these are limited by concurrent mood changes and a lack of placebo control. There is also recent evidence suggesting that fluoxetine reduces the processing of anger in young healthy volunteers, which is consistent with its effect for the treatment of irritability in this age group, but this remains to be investigated in depressed adolescents. Here we assessed the effects of a single, first dose of 10 mg fluoxetine vs. placebo on neural response to anger cues using fMRI in a sample of adolescents with Major Depressive Disorder (MDD) who had been recently prescribed fluoxetine. As predicted, adolescents receiving fluoxetine showed reduced activity in response to angry facial expressions in the amygdala-hippocampal region relative to placebo. Activity in the dorsal anterior cingulate cortex (dACC) was also increased. No changes in symptoms were observed. These results demonstrate, for the first time in depressed adolescents, that fluoxetine has immediate neural effects on core components of the cortico-limbic circuitry prior to clinical changes in mood. The effect on anger is consistent with our previous work and could represent a key mechanism through which fluoxetine may act to alleviate irritability symptoms in adolescent depression.

Mirtazapine for chronic breathlessness? A review of mechanistic insights and therapeutic potential

INTRODUCTION

Chronic breathlessness is a common and distressing symptom of advanced disease with few effective treatments. Central nervous system mechanisms are important in respiratory sensation and control. Consequently, drugs which may modify processing and perception of afferent information in the brain may have a role. Antidepressants have been proposed; however, current evidence is limited. Of potentially suitable antidepressants, mirtazapine is an attractive option given its tolerability profile, low cost, and wide availability, along with additional potential benefits. Areas covered: The paper provides an overview of the physiology of breathlessness, with an emphasis on central mechanisms, particularly the role of fear circuits and the associated neurotransmitters. It provides a potential rationale for how mirtazapine may improve chronic breathlessness and quality of life in patients with advanced disease. The evidence was identified by a literature search performed in PubMed through to October 2018. Expert opinion: Currently, there is insufficient evidence to support the routine use of antidepressants for chronic breathlessness in advanced disease. Mirtazapine is a promising candidate to pursue, with definitive randomized controlled trials required to determine its efficacy and safety in this setting.

Cognitive neuropsychological theory: Reconciliation of psychological and biological approaches for depression

New antidepressants and individualized approaches to treatment, matching specific therapies to individual patients, are urgently needed. For this, a better understanding of processes underpinning the development of depressive symptoms and response to medications are required. The cognitive neuropsychological model offers a novel approach uniquely combining biological and psychological approaches to explain how antidepressants exert their effect, why there is a delay in the onset of their clinical effect, and how changes in emotional processing are an essential step for a clinical antidepressant effect to take place. The paper presents the model and its underpinnings in the form of research in both healthy and depressed individuals, as well as the potential for its practical use.

Exploring the prediction of emotional valence and pharmacologic effect across fMRI studies of antidepressants

Background

Clinically approved antidepressants modulate the brain's emotional valence circuits, suggesting that the response of these circuits could serve as a biomarker for screening candidate antidepressant drugs. However, it is necessary that these modulations can be reliably detected. Here, we apply a cross-validated predictive model to classify emotional valence and pharmacologic effect across eleven task-based fMRI datasets (n = 306) exploring the effect of antidepressant administration on emotional face processing.

Methods

We created subject-level contrast of parameter estimates of the emotional faces task and used the Shen whole-brain parcellation scheme to define 268 subject-level features that trained a cross-validated gradient-boosting machine protocol to classify emotional valence (fearful vs happy face visual conditions) and pharmacologic effect (drug vs placebo administration) within and across studies.

Results

We found patterns of brain activity that classify emotional valence with a statistically significant level of accuracy (70% across-all-subjects; range from 50 to 87% across-study). Our classifier failed to consistently discriminate drug from placebo. Subject population (healthy or unhealthy), treatment group (drug or placebo), and drug administration protocol (dose and duration) affected this accuracy with similar populations better predicting one another.

Conclusions

We found limited evidence that antidepressants modulated brain response in a consistent manner, however found a consistent signature for emotional valence. Variable functional patterns across studies suggest that predictive modeling can inform biomarker development in mental health and in pharmacotherapy development. Our results suggest that case-controlled designs and more standardized protocols are required for functional imaging to provide robust biomarkers for drug development.

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The emotional faces task can evaluate the brain's fMRI response to antidepressants.

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We found a consistent signature for emotional valence across 11 such datasets.

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We found limited evidence for consistent antidepressant response.

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Case-controlled designs and more standardized protocols could increase this yield.

Single dose of mirtazapine modulates whole-brain functional connectivity during emotional narrative processing

The link between neurotransmitter-level effects of antidepressants and their clinical effect remain poorly understood. A single dose of mirtazapine decreases limbic responses to fearful faces in healthy subjects, but it is unknown whether this effect applies to complex emotional situations and dynamic connectivity between brain regions. Thirty healthy volunteers listened to spoken emotional narratives during functional magnetic resonance imaging (fMRI). In an open-label design, 15 subjects received 15mg of mirtazapine two hours prior to fMRI while 15 subjects served as a control group. We assessed the effects of mirtazapine on regional neural responses and dynamic functional connectivity associated with valence and arousal. Mirtazapine attenuated responses to unpleasant events in the right fronto-insular cortex, while modulating responses to arousing events in the core limbic regions and the cortical midline structures (CMS). Mirtazapine decreased responses to unpleasant and arousing events in sensorimotor areas and the anterior CMS implicated in self-referential processing and formation of subjective feelings. Mirtazapine increased functional connectivity associated with positive valence in the CMS and limbic regions. Mirtazapine triggers large-scale changes in regional responses and functional connectivity during naturalistic, emotional stimuli. These span limbic, sensorimotor, and midline brain structures, and may be relevant to the clinical effectiveness of mirtazapine.

The effects of drugs on human models of emotional processing: an account of antidepressant drug treatment

Human models of emotional processing suggest that the direct effect of successful antidepressant drug treatment may be to modify biases in the processing of emotional information. Negative biases in emotional processing are documented in depression, and single or short-term dosing with conventional antidepressant drugs reverses these biases in depressed patients prior to any subjective change in mood. Antidepressant drug treatments also modulate emotional processing in healthy volunteers, which allows the consideration of the psychological effects of these drugs without the confound of changes in mood. As such, human models of emotional processing may prove to be useful for testing the efficacy of novel treatments and for matching treatments to individual patients or subgroups of patients.

Fronto-limbic effective connectivity as possible predictor of antidepressant response to SSRI administration

The timely selection of the optimal treatment for depressed patients is critical to improve remission rates. The detection of pre-treatment variables able to predict differential treatment response may provide novel approaches for treatment selection. Selective serotonin reuptake inhibitors (SSRIs) modulate the fronto-limbic functional response and connectivity, an effect preceding the overt clinical antidepressant effects. Here we investigated whether the cortico-limbic connectivity associated with emotional bias measured before SSRI administration predicts the efficacy of antidepressant treatment in MDD patients. fMRI and Dynamic Causal Modeling (DCM) were combined to study if effective connectivity might differentiate healthy controls (HC) and patients affected by major depression who later responded (RMDD, n=21), or failed to respond (nRMDD, n=12), to 6 weeks of escitalopram administration. Sixteen DCMs exploring connectivity between anterior cingulate cortex (ACC), ventrolateral prefrontal cortex (VLPFC), Amygdala (Amy), and fusiform gyrus (FG) were constructed. Analyses revealed that nRMDD had reduced endogenous connectivity from Amy to VLPFC and to ACC, with an increased connectivity and modulation of the ACC to Amy connectivity when processing of fearful emotional stimuli compared to HC. RMDD and HC did not significantly differ among themselves. Pre-treatment effective connectivity in fronto-limbic circuitry could be an important factor affecting antidepressant response, and highlight the mechanisms which may be involved in recovery from depression. These results suggest that fronto-limbic connectivity might provide a neural biomarker to predict the clinical outcome to SSRIs administration in major depression.

Early changes in emotional processing as a marker of clinical response to SSRI treatment in depression

Antidepressant treatment reduces behavioural and neural markers of negative emotional bias early in treatment and has been proposed as a mechanism of antidepressant drug action. Here, we provide a critical test of this hypothesis by assessing whether neural markers of early emotional processing changes predict later clinical response in depression. Thirty-five unmedicated patients with major depression took the selective serotonin re-uptake inhibitor (SSRI), escitalopram (10 mg), over 6 weeks, and were classified as responders (22 patients) versus non-responders (13 patients), based on at least a 50% reduction in symptoms by the end of treatment. The neural response to fearful and happy emotional facial expressions was assessed before and after 7 days of treatment using functional magnetic resonance imaging. Changes in the neural response to these facial cues after 7 days of escitalopram were compared in patients as a function of later clinical response. A sample of healthy controls was also assessed. At baseline, depressed patients showed greater activation to fear versus happy faces than controls in the insula and dorsal anterior cingulate. Depressed patients who went on to respond to the SSRI had a greater reduction in neural activity to fearful versus happy facial expressions after just 7 days of escitalopram across a network of regions including the anterior cingulate, insula, amygdala and thalamus. Mediation analysis confirmed that the direct effect of neural change on symptom response was not mediated by initial changes in depressive symptoms. These results support the hypothesis that early changes in emotional processing with antidepressant treatment are the basis of later clinical improvement. As such, early correction of negative bias may be a key mechanism of antidepressant drug action and a potentially useful predictor of therapeutic response.

Effects of psychotropic drugs used in the treatment of anxiety disorders on the recognition of facial expressions of emotion: Critical analysis of literature

Deficits in recognition of facial expressions of emotion (RFEE) play a central role in the manifestation of anxiety disorders (AD). We systematically reviewed the literature to determine effects of drugs used in AD treatment on RFEE, based on outcomes of accuracy rate, reaction time, and intensity. Electronic databases, including Pubmed, PsycINFO, and Scielo, were used without time constraints. Twenty-six clinical/experimental studies on healthy subjects, focusing on 11 drugs, published in English, Portuguese, and Spanish, were selected. We found that increased recognition of happiness was associated with acute use of citalopram, fluoxetine, duloxetine, and reboxetine. Increased and decreased recognition of negative emotions were associated with the use of selective serotonin and/or norepinephrine reuptake inhibitors, respectively. Benzodiazepine favored recognition of negative emotions. Differences in reaction time were rarely observed. Stimuli with distinct emotion intensities produced similar effects. Specific changes occurred in RFEE depending on the drug, its administration route and dose, and emotion valence. Evidences indicate significant effects on emotional processing relevant to clinical practice, particularly in treating patients with emotional disorders.

Baseline Perfusion Alterations Due to Acute Application of Quetiapine and Pramipexole in Healthy Adults

BACKGROUND

The dopaminergic system is implicated in many mental processes and neuropsychiatric disorders. Pharmacologically, drugs with dopamine receptor antagonistic and agonistic effects are used, but their effects on functional brain metabolism are not well known.

METHODS

In this randomized crossover, placebo-controlled, and rater-blinded study, 25 healthy adults received an acute dose placebo substance (starch), quetiapine (dopamine receptor antagonist), or pramipexole (dopamine agonist of the nonergoline class) 1 hour before the experiment. Background-suppressed 2D pseudo-continuous arterial spin labeling was used to examine whole-brain baseline cerebral blood flow differences induced by the 3 substances.

RESULTS

We found that quetiapine reduced perfusion in the occipital (early visual areas) and bilateral cerebellar cortex relative to placebo. In contrast, quetiapine enhanced cerebral blood flow (relative to placebo) in the striatal system (putamen and caudate nucleus) but also in the supplementary motor area, insular-, prefrontal- as well as in the pre- and postcentral cortex. Pramipexole increased cerebral blood flow compared with placebo in the caudate nucleus, putamen, middle frontal, supplementary motor area, and brainstem (substantia nigra), but reduced cerebral blood flow in the posterior thalamus, cerebellum, and visual areas. Pramipexole administration resulted in stronger cerebral blood flow relative to quetiapine in the hypothalamus, cerebellum, and substantia nigra.

CONCLUSIONS

Our results indicate that quetiapine and pramipexole differentially modulate regional baseline cerebral blood flow. Both substances act on the dopaminergic system, although they affect distinct regions. Quetiapine altered dopaminergic function in frontal, striatal, and motor regions. In contrast, pramipexole affected cerebral blood flow of the nigrostriatal (striatum and substantia nigra) dopaminergic, but less the fronto-insular system.

Neural effects of social environmental stress - an activation likelihood estimation meta-analysis

BACKGROUND

Social environmental stress, including childhood abuse and deprivation, is associated with increased rates of psychiatric disorders such as schizophrenia and depression. However, the neural mechanisms mediating risk are not completely understood. Functional magnetic resonance imaging (MRI) studies have reported effects of social environmental stress on a variety of brain regions, but interpretation of results is complicated by the variety of environmental risk factors examined and different methods employed.

METHOD

We examined brain regions consistently showing differences in blood oxygen level-dependent (BOLD) response in individuals exposed to higher levels of environmental stress by performing a coordinate-based meta-analysis on 54 functional MRI studies using activation likelihood estimation (ALE), including an overall sample of 3044 participants. We performed separate ALE analyses on studies examining adults (mean age ⩾18 years) and children/adolescents (mean age <18 years) and a contrast analysis comparing the two types of study.

RESULTS

Across both adult and children/adolescent studies, ALE meta-analysis revealed several clusters in which differences in BOLD response were associated with social environmental stress across multiple studies. These clusters incorporated several brain regions, among which the right amygdala was most frequently implicated.

CONCLUSIONS

These findings suggest that a variety of social environmental stressors is associated with differences in the BOLD response of specific brain regions such as the right amygdala in both children/adolescents and adults. What remains unknown is whether these environmental stressors have differential effects on treatment response in these brain regions.

Behavioral and emotional adverse events of drugs frequently used in the treatment of bipolar disorders: clinical and theoretical implications

BACKGROUND

Behavioral and emotional adverse events induced by drugs commonly prescribed to patients with bipolar disorders are of paramount importance to clinical practice and research. However, no reviews on the topic have been published so far.

METHODS

An extensive search was performed. Reports were reviewed if they described behavioral side effects related to pharmacological treatments for bipolar disorders in healthy subjects or patients with different neuropsychiatric disorders. For this review, lithium, antipsychotics, anticonvulsants and selective serotonin reuptake inhibitors were included.

RESULTS

Apathy or emotional blunting, diminished sexual desire, and inability to cry were reported to be associated with exposure to selective serotonin reuptake inhibitors. Neuroleptic-induced deficit syndrome/emotional detachment and obsessive-compulsive symptomatology and decision-making modifications. A lithium-related amotivational syndrome was also reported in the literature. Furthermore, hypersexuality and obsessive-compulsive symptoms have been noted in subjects treated with lamotrigine.

LIMITATIONS

Primary studies on drug-related adverse events are scant so far and most of the data currently available derive from case reports. Moreover, most of the evidence reviewed is based on studies performed on healthy subjects and patients with neuropsychiatric conditions other than bipolar disorders.

DISCUSSION

There is a remarkable dearth of data on behavioral adverse events of pharmacological treatment for bipolar disorders. However, the pieces of evidence available at present, though scant and scattered, suggest that different behavioral adverse events may be related to pharmacological treatment for these disorders. The implications of these findings for research and management of patients with mood disorders are discussed.

Antidepressant drug action--From rapid changes on network function to network rewiring

There has been significant recent progress in understanding the neurobiological mechanisms of antidepressant treatments. The delayed-onset of action of monoamine-based antidepressant drugs have been associated to their ability to slowly increase synaptic plasticity and neuronal excitability via altering neurotrophic signaling (synthesis of BDNF and activation of its receptor TrkB), dematuration of GABAergic interneurons and inhibition of "breaks of plasticity". On the other hand, antidepressants rapidly regulate emotional processing that - with the help of heightened plasticity and appropriate rehabilitation - gradually lead to significant changes on functional neuronal connectivity and clinical recovery. Moreover, the discovery of rapid-acting antidepressants, most notably ketamine, has inspired interest for novel antidepressant developments with better efficacy and faster onset of action. Therapeutic effects of rapid-acting antidepressants have been linked with their ability to rapidly regulate neuronal excitability and thereby increase synaptic translation and release of BDNF, activation of the TrkB-mTOR-p70S6k signaling pathway and increased synaptogenesis within the prefrontal cortex. Thus, alterations in TrkB signaling, synaptic plasticity and neuronal excitability are shared neurobiological phenomena implicated in antidepressant responses produced by both gradually and rapid acting antidepressants. However, regardless of antidepressant, their therapeutic effects are not permanent which suggests that their effects on neuronal connectivity and network function remain unstable and vulnerable for psychosocial challenges.

A single dose of mirtazapine attenuates neural responses to self-referential processing

Increased self-focus is a core factor in the psychopathology of depression. Cortical midline structures (CMS) are implicated in the neurobiology of self, depression and antidepressant treatment response. Mirtazapine, an antidepressant that increases serotonin and norepinephrine release, enhances processing of positive and attenuates processing of negative emotional information in healthy volunteers after a single dose. These early changes, which are opposite to the negative information bias in depression, may be important for the therapeutic effect of mirtazapine. It nevertheless remains unresolved whether/how mirtazapine specifically influences processing of self-referential emotional information.Half of the healthy volunteers (n=15/30) received a single dose of mirtazapine, in an open-label design, two hours before functional magnetic resonance imaging (fMRI), and the other half was scanned as a control group without medication. During fMRI the participants categorized positive and negative self-referential adjectives.Mirtazapine attenuated responses to self-referential processing in the medial prefrontal cortex and the anterior cingulate cortex. Mirtazapine further decreased responses to positive self-referential processing in the posterior cingulate cortex and parietal cortex.These decreased responses of the CMS suggest that mirtazapine may rapidly improve the ability of the CMS to down-regulate self-referential processing. In depressed patients, this could lead to decreased self-focus and rumination, contributing to the antidepressant effect.

Testing the antidepressant properties of the peptide ARA290 in a human neuropsychological model of drug action

Studies on the neural effects of Erythropoietin (EPO) indicate that EPO may have antidepressant effects. Due to its hematopoietic effects, EPO may cause serious side-effects with repeated administration if patients are not monitored extensively. ARA290 is an EPO-analog peptide without such hematopoietic side-effects but may have neurotrophic and antidepressant effects. The aim of this study was to investigate the possible antidepressant effects of ARA290 in a neuropsychological model of drug action. Healthy participants (N=36) received ARA290 (2mg) or placebo in a double-blind, randomized, parallel-group design. Neural and cognitive effects were assessed one week after administration. Primary outcome measures were the neural processing of fearful vs happy faces and the behavioral recognition of emotional facial expressions. ARA290-treated individuals displayed lower neural responses to happy faces in the fusiform gyrus. ARA290 tended to lower the recognition of happy and disgust facial expressions. Although ARA290 was not associated with a better memory for positive words, it was associated with faster categorization of positive vs negative words. Finally, ARA290 increased attention towards positive emotional pictures. No effects were observed on mood and affective symptoms. ARA290 may modulate some aspects of emotional processing, however, the direction and the strength of its effects do not unequivocally support an antidepressant-like profile for ARA290. Future studies may investigate the effects of different timing and dose.

An increase in joy after two weeks is more specific of later antidepressant response than a decrease in sadness

BACKGROUND

Early improvement in positive emotions-more than decreases in negative emotions-was highly predictive of treatment response in an ecologically valid prospective manner. This result needs replication with simpler assessments to determine whether it can be translated into clinical practice.

METHODS

2049 adult depressed outpatients receiving agomelatine were assessed at inclusion, week 2, and week 6 using the clinician-rated Quick Inventory of Depressive Symptomatology, Sheehan Disability Scale, Clinical Global Impression scale, and Multidimensional Assessment of Thymic States (MATHYS), an auto-questionnaire rating the frequency of emotions, including sadness and joy, over the previous week.

RESULTS

Joy and sadness had a relatively low correlation coefficient at baseline (r=-0.277), joy (r=-0.160) being less correlated with clinical severity than sadness (r=0.317). An increase in joy at week 2 had higher specificity (85.04%) and positive predictive value (70.55%) for treatment response than decreased sadness (57.92% and 66.04%, respectively), and the global capacity of the former to predict remission, either clinical (Yule Q coefficient, 39.96%) or functional (44.35%), was even better compared to the prediction of clinical response (37.38%).

LIMITATIONS

MATHYS retrospectively assesses emotions, with five possible ratings only, relying on self-rated frequencies. With only a 6-week follow-up, conclusions are limited to short-term aspects of clinical and functional remission.

CONCLUSIONS

Early improvement in joy during the first 2 weeks of treatment is strongly specific for treatment response and remission. The frequency of joy captures the predictivity and may deserve further study regarding inclusion in depressive rating scales.

A neurocognitive model for understanding treatment action in depression

The way in which emotion is represented and processed in the human brain is an expanding area of research and has key implications for how we understand and potentially treat affective disorders such as depression. Characterizing the effects of pharmacological manipulations of key neurotransmitter systems can also help reveal the neurochemical underpinnings of emotional processing and how common antidepressant drugs may work in the treatment of depression and anxiety. This approach has revealed that depression is associated with both neural and behavioural biases towards negative over positive stimuli. Evidence from pharmacological challenge studies suggests that antidepressant treatment acts to normalize these biases early on in treatment, resulting in patients experiencing the world in a more positive way, improving their mood over time. This model is supported by evidence from both pharmacological and non-pharmacological interventions. The unique perspective on antidepressant treatment offered by this approach provides some insights into individual response to treatment, as well as novel approaches to drug development.

Effectiveness of resilience training versus cognitive therapy on reduction of depression in female Iranian college students

Depression is the most common mental illness among women. Its prevalence in women is two to three times that of men. The purpose of the present study was to evaluate the effectiveness of resilience training on the reduction of depression in female college students. This semi-empirical study was carried out with two experimental groups and one control group. The research sample was women with symptoms of depression who were 18-22 years of age and living in a college dormitory. One experimental group was given eight 90-minute resilience training sessions, while the other received eight 90-minute cognitive therapy sessions. The control group didn't receive any interventions. The three groups under study were evaluated using the Beck II depression inventory before and after the interventions and two months after the treatment had ended. The three groups didn't have significant differences in age, marital status, or depression scores on the pretest. The resilience training group and cognitive therapy group showed a significant decrease in the average depression score from pretest to posttest and from pretest to follow-up. The main effect of groups, stage, and interaction between groups and stage also were significant (all were p < 0.001). There was no significant difference between effectiveness of resilience training and cognitive therapy on depression but there was a significant difference between these two treatment groups and the control group. The effectiveness of resilience training was just as good as the effectiveness of cognitive therapy. The effects of resilience training on depression remained stable from the posttest to the follow-up, like that of cognitive therapy.

Selective serotonin reuptake inhibition modulates response inhibition in Parkinson's disease

Impulsivity is common in Parkinson's disease even in the absence of impulse control disorders. It is likely to be multifactorial, including a dopaminergic 'overdose' and structural changes in the frontostriatal circuits for motor control. In addition, we proposed that changes in serotonergic projections to the forebrain also contribute to response inhibition in Parkinson's disease, based on preclinical animal and human studies. We therefore examined whether the selective serotonin reuptake inhibitor citalopram improves response inhibition, in terms of both behaviour and the efficiency of underlying neural mechanisms. This multimodal magnetic resonance imaging study used a double-blind randomized placebo-controlled crossover design with an integrated Stop-Signal and NoGo paradigm. Twenty-one patients with idiopathic Parkinson's disease (46-76 years old, 11 male, Hoehn and Yahr stage 1.5-3) received 30 mg citalopram or placebo in addition to their usual dopaminergic medication in two separate sessions. Twenty matched healthy control subjects (54-74 years old, 12 male) were tested without medication. The effects of disease and drug on behavioural performance and regional brain activity were analysed using general linear models. In addition, anatomical connectivity was examined using diffusion tensor imaging and tract-based spatial statistics. We confirmed that Parkinson's disease caused impairment in response inhibition, with longer Stop-Signal Reaction Time and more NoGo errors under placebo compared with controls, without affecting Go reaction times. This was associated with less stop-specific activation in the right inferior frontal cortex, but no significant difference in NoGo-related activation. Although there was no beneficial main effect of citalopram, it reduced Stop-Signal Reaction Time and NoGo errors, and enhanced inferior frontal activation, in patients with relatively more severe disease (higher Unified Parkinson's Disease Rating Scale motor score). The behavioural effect correlated with the citalopram-induced enhancement of prefrontal activation and the strength of preserved structural connectivity between the frontal and striatal regions. In conclusion, the behavioural effect of citalopram on response inhibition depends on individual differences in prefrontal cortical activation and frontostriatal connectivity. The correlation between disease severity and the effect of citalopram on response inhibition may be due to the progressive loss of forebrain serotonergic projections. These results contribute to a broader understanding of the critical roles of serotonin in regulating cognitive and behavioural control, as well as new strategies for patient stratification in clinical trials of serotonergic treatments in Parkinson's disease.

Magnetic resonance imaging predictors of treatment response in late-life depression

In older adults, depression not only results in more years lived with disability than any other disease but it also carries additional risks of suicide, medical comorbidities, and family caregiving burden. Because it can take many months to identify an effective treatment regimen, it is of utmost importance to shorten the window of time and identify early on what medications and dosages will work effectively for individuals having depression. Late-life depression (LLD) has been associated with greater burden of age-related changes (eg, atrophy, white matter ischemic changes, and functional connectivity). Depression in midlife has been shown to alter affective reactivity and regulation, and functional magnetic resonance imaging (fMRI) studies in LLD have replicated the same abnormalities. Effective treatment can normalize these alterations. This article provides a review of the current literature using structural and functional neuroimaging to identify MRI predictors of treatment response in LLD. The majority of the literature on structural MRI has focused on the vascular depression hypothesis, and studies support the view that loss of brain volume and white matter integrity was associated with poorer treatment outcomes. Studies using fMRI have reported that lower task-based activity in the prefrontal cortex and limbic regions was associated with poorer outcome. These imaging markers may be integrated into clinical decision making to attain better treatment outcomes in the future.

Paradoxical effects of short-term antidepressant treatment in fMRI emotional processing models in volunteers with high neuroticism

BACKGROUND

Short-term antidepressant administration has been reported to decrease amygdala response to threat in healthy volunteers and depressed patients. Neuroticism (N) is a risk factor for depression but has also been associated with slow or incomplete remission with antidepressant drug treatment. Our aim was to investigate early selective serotonin reuptake inhibitor (SSRI) administration neural effects on implicit processing of fearful facial expressions in volunteers with high levels of N.

METHOD

Highly neurotic subjects received 20 mg/day citalopram versus placebo for 7 days in a double-blind, between-groups design. On the last day haemoperfusion and functional magnetic resonance imaging (fMRI) data during a gender discrimination task with fearful and happy faces were acquired. A control group of non-neurotic volunteers was also tested.

RESULTS

High-N volunteers had reduced responses to threatening facial expressions across key neural circuits compared to low-N volunteers. SSRI treatment was found to elevate resting perfusion in the right amygdala, increase bilateral amygdalae activation to positive and negative facial expressions and increase activation to fearful versus happy facial expressions in occipital, parietal, temporal and prefrontal cortical areas.

CONCLUSIONS

These results suggest that 7 days of SSRI administration can increase neural markers of fear reactivity in subjects at the high end of the N dimension and may be related to early increases in anxiety and agitation seen early in treatment. Such processes may be involved in the later therapeutic effects through decreased avoidance and increased learning about social 'threat' cues.

Changes in the neural correlates of implicit emotional face processing during antidepressant treatment in major depressive disorder

An emerging hypothesis regarding the mechanisms underlying antidepressant pharmacotherapy suggests that these agents benefit depressed patients by reversing negative emotional processing biases (Harmer, 2008). Neuropsychological indices and functional neuroimaging measures of the amygdala response show that antidepressant drugs shift implicit and explicit processing biases away from the negative valence and toward the positive valence. However, few studies have explored such biases in regions extensively connected with the amygdala, such as the pregenual anterior cingulate cortex (pgACC) area, where pre-treatment activity consistently has predicted clinical outcome during antidepressant treatment. We used functional magnetic resonance imaging (fMRI) to investigate changes in haemodynamic response patterns to positive vs. negative stimuli in patients with major depressive disorder (MDD) under antidepressant treatment. Participants with MDD (n = 10) underwent fMRI before and after 8 wk sertraline treatment; healthy controls (n = 10) were imaged across an equivalent interval. A backward masking task was used to elicit non-conscious neural responses to sad, happy and neutral face expressions. Haemodynamic responses to emotional face stimuli were compared between conditions and groups in the pgACC. The response to masked-sad vs. masked-happy faces (SN-HN) in pgACC in the depressed subjects was higher in the pre-treatment condition than in the post-treatment condition and this difference was significantly greater than the corresponding change across time in the controls. The treatment-associated difference was attributable to an attenuated response to sad faces and an enhanced response to happy faces. Pre-treatment pgACC responses to SN-HN correlated positively with clinical improvement during treatment. The pgACC participates with the amygdala in processing the salience of emotional stimuli. Treatment-associated functional changes in this limbic network may influence the non-conscious processing of such stimuli by reversing the negative processing bias extant in MDD.

Food can lift mood by affecting mood-regulating neurocircuits via a serotonergic mechanism

It is commonly assumed that food can affect mood. One prevalent notion is that food containing tryptophan increases serotonin levels in the brain and alters neural processing in mood-regulating neurocircuits. However, tryptophan competes with other long-neutral-amino-acids (LNAA) for transport across the blood-brain-barrier, a limitation that can be mitigated by increasing the tryptophan/LNAA ratio. We therefore tested in a double-blind, placebo-controlled crossover study (N=32) whether a drink with a favourable tryptophan/LNAA ratio improves mood and modulates specific brain processes as assessed by functional magnetic resonance imaging (fMRI). We show that one serving of this drink increases the tryptophan/LNAA ratio in blood plasma, lifts mood in healthy young women and alters task-specific and resting-state processing in brain regions implicated in mood regulation. Specifically, Test-drink consumption reduced neural responses of the dorsal caudate nucleus during reward anticipation, increased neural responses in the dorsal cingulate cortex during fear processing, and increased ventromedial prefrontal-lateral prefrontal connectivity under resting-state conditions. Our results suggest that increasing tryptophan/LNAA ratios can lift mood by affecting mood-regulating neurocircuits.

Antidepressant treatment and emotional processing: can we dissociate the roles of serotonin and noradrenaline?

The ability to match individual patients to tailored treatments has the potential to greatly improve outcomes for individuals suffering from major depression. In particular, while the vast majority of antidepressant treatments affect either serotonin or noradrenaline or a combination of these two neurotransmitters, it is not known whether there are particular patients or symptom profiles which respond preferentially to the potentiation of serotonin over noradrenaline or vice versa. Experimental medicine models suggest that the primary mode of action of these treatments may be to remediate negative biases in emotional processing. Such models may provide a useful framework for interrogating the specific actions of antidepressants. Here, we therefore review evidence from studies examining the effects of drugs which potentiate serotonin, noradrenaline or a combination of both neurotransmitters on emotional processing. These results suggest that antidepressants targeting serotonin and noradrenaline may have some specific actions on emotion and reward processing which could be used to improve tailoring of treatment or to understand the effects of dual-reuptake inhibition. Specifically, serotonin may be particularly important in alleviating distress symptoms, while noradrenaline may be especially relevant to anhedonia. The data reviewed here also suggest that noradrenergic-based treatments may have earlier effects on emotional memory that those which affect serotonin.

Acute neural effects of selective serotonin reuptake inhibitors versus noradrenaline reuptake inhibitors on emotion processing: Implications for differential treatment efficacy

Clinical research has demonstrated differential efficacy of selective serotonin reuptake inhibitors (SSRIs) and norepinephrine reuptake inhibitors (NRIs), which may relate to differential acute effects these medications have on emotional brain processes. Here we present findings from a Multi-Level Kernel Density Analysis meta-analysis that integrates and contrasts activations from disparate fMRI studies in order to examine whether single dose SSRIs and NRIs have different effects on emotion processing tasks in healthy participants. Seven SSRI and four NRI studies were eligible for inclusion. SSRIs decreased amygdala responses, suggesting reduced emotional reactivity to emotional stimuli, whereas NRIs increased frontal and medial activation, suggesting increased emotion regulation. As hypothesised, an interaction of antidepressant and task type was found, such that SSRIs modulated amygdaloid-hippocampal, medial and frontal activity during both the presentation of faces and pictures, whereas NRIs only modulated the activation in medial and frontal regions during the presentation of pictures. Findings are interpreted within a novel model of the differential effects of SSRIs and NRIs on emotion processing.

Consumption of fermented milk product with probiotic modulates brain activity

BACKGROUND & AIMS

Changes in gut microbiota have been reported to alter signaling mechanisms, emotional behavior, and visceral nociceptive reflexes in rodents. However, alteration of the intestinal microbiota with antibiotics or probiotics has not been shown to produce these changes in humans. We investigated whether consumption of a fermented milk product with probiotic (FMPP) for 4 weeks by healthy women altered brain intrinsic connectivity or responses to emotional attention tasks.

METHODS

Healthy women with no gastrointestinal or psychiatric symptoms were randomly assigned to groups given FMPP (n = 12), a nonfermented milk product (n = 11, controls), or no intervention (n = 13) twice daily for 4 weeks. The FMPP contained Bifidobacterium animalis subsp Lactis, Streptococcus thermophiles, Lactobacillus bulgaricus, and Lactococcus lactis subsp Lactis. Participants underwent functional magnetic resonance imaging before and after the intervention to measure brain response to an emotional faces attention task and resting brain activity. Multivariate and region of interest analyses were performed.

RESULTS

FMPP intake was associated with reduced task-related response of a distributed functional network (49% cross-block covariance; P = .004) containing affective, viscerosensory, and somatosensory cortices. Alterations in intrinsic activity of resting brain indicated that ingestion of FMPP was associated with changes in midbrain connectivity, which could explain the observed differences in activity during the task.

CONCLUSIONS

Four-week intake of an FMPP by healthy women affected activity of brain regions that control central processing of emotion and sensation.

'It's the way that you look at it'--a cognitive neuropsychological account of SSRI action in depression

The fact that selective serotonin reuptake inhibitors (SSRIs) have antidepressant effects in some patients supports the notion that serotonin plays a role in the mode of action of antidepressant drugs. However, neither the way in which serotonin may alleviate depressed mood  nor the reason why several weeks needs to elapse before the full antidepressant effect of treatment is expressed  is known. Here, we propose a neuropsychological theory of SSRI antidepressant action based on the ability of SSRIs to produce positive biases in the processing of emotional information. Both behavioural and neuroimaging studies show that SSRI administration produces positive biases in attention, appraisal and memory from the earliest stages of treatment, well before the time that clinical improvement in mood becomes apparent. We suggest that the delay in the clinical effect of SSRIs can be explained by the time needed for this positive bias in implicit emotional processing to become apparent at a subjective, conscious level. This process is likely to involve the re-learning of emotional associations in a new, more positive emotional environment. This suggests intriguing links between the effect of SSRIs to promote synaptic plasticity and neurogenesis, and their ability to remediate negative emotional biases in depressed patients.

Short-term SSRI treatment normalises amygdala hyperactivity in depressed patients

BACKGROUND

Antidepressant drugs such as selective serotonin re-uptake inhibitors (SSRIs) remediate negative biases in emotional processing in depressed patients in both behavioural and neural outcome measures. However, it is not clear if these effects occur before, or as a consequence of, changes in clinical state.

METHOD

In the present study, we investigated the effects of short-term SSRI treatment in depressed patients on the neural response to fearful faces prior to clinical improvement in mood. Altogether, 42 unmedicated depressed patients received SSRI treatment (10 mg escitalopram daily) or placebo in a randomised, parallel-group design. The neural response to fearful and happy faces was measured on day 7 of treatment using functional magnetic resonance imaging. A group of healthy controls was imaged in the same way.

RESULTS

Amygdala responses to fearful facial expressions were significantly greater in depressed patients compared to healthy controls. However, this response was normalised in patients receiving 7 days treatment with escitalopram. There was no significant difference in clinical depression ratings at 7 days between the escitalopram and placebo-treated patients.

CONCLUSIONS

Our results suggest that short-term SSRI treatment in depressed patients remediates amygdala hyperactivity in response to negative emotional stimuli prior to clinical improvement in depressed mood. This supports the hypothesis that the clinical effects of antidepressant treatment may be mediated in part through early changes in emotional processing. Further studies will be needed to show if these early effects of antidepressant medication predict eventual clinical outcome.

Exaggerated neurobiological sensitivity to threat as a mechanism linking anxiety with increased risk for diseases of aging

Anxiety disorders increase risk for the early development of several diseases of aging. Elevated inflammation, a common risk factor across diseases of aging, may play a key role in the relationship between anxiety and physical disease. However, the neurobiological mechanisms linking anxiety with elevated inflammation remain unclear. In this review, we present a neurobiological model of the mechanisms by which anxiety promotes inflammation. Specifically we propose that exaggerated neurobiological sensitivity to threat in anxious individuals may lead to sustained threat perception, which is accompanied by prolonged activation of threat-related neural circuitry and threat-responsive biological systems including the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system (ANS), and inflammatory response. Over time, this pattern of responding can promote chronic inflammation through structural and functional brain changes, altered sensitivity of immune cell receptors, dysregulation of the HPA axis and ANS, and accelerated cellular aging. Chronic inflammation, in turn, increases risk for diseases of aging. Exaggerated neurobiological sensitivity to threat may thus be a treatment target for reducing disease risk in anxious individuals.

Epistasis between 5-HTTLPR and ADRA2B polymorphisms influences attentional bias for emotional information in healthy volunteers

Individual differences in emotional processing are likely to contribute to vulnerability and resilience to emotional disorders such as depression and anxiety. Genetic variation is known to contribute to these differences but they remain incompletely understood. The serotonin transporter (5-HTTLPR) and α2B-adrenergic autoreceptor (ADRA2B) insertion/deletion polymorphisms impact on two separate but interacting monaminergic signalling mechanisms that have been implicated in both emotional processing and emotional disorders. Recent studies suggest that the 5-HTTLPR s allele is associated with a negative attentional bias and an increased risk of emotional disorders. However, such complex behavioural traits are likely to exhibit polygenicity, including epistasis. This study examined the contribution of the 5-HTTLPR and ADRA2B insertion/deletion polymorphisms to attentional biases for aversive information in 94 healthy male volunteers and found evidence of a significant epistatic effect (p<0.001). Specifically, in the presence of the 5-HTTLPR s allele, the attentional bias for aversive information was attenuated by possession of the ADRA2B deletion variant whereas in the absence of the s allele, the bias was enhanced. These data identify a cognitive mechanism linking genotype-dependent serotonergic and noradrenergic signalling that is likely to have implications for the development of cognitive markers for depression/anxiety as well as therapeutic drug effects and personalized approaches to treatment.

Facial perception bias in patients with major depression

This study used a morphed categorical perception facial expression task to evaluate whether patients with depression demonstrated deficits in distinguishing boundaries between emotions. Forty-one patients with depression and 41 healthy controls took part in this study. They were administered a standardized set of morphed photographs of facial expressions with varying emotional intensities between 0% and 100% of the emotion, in 10% increments to provide a range of intensities from pleasant to unpleasant(e.g. happy to sad, happy to angry) and approach-avoidance (e.g. angry to fearful). Compared with healthy controls, the patients with depression demonstrated a rapid perception of sad expressions in happy-sad emotional continuum and demonstrated a rapid perception of angry expressions in angry-fearful emotional continuum. In addition, when facial expressions shifted from happy to angry, the depressed patients had a clear demarcation for the happy-angry continuum. Depressed patients had a perceptual bias towards unpleasant versus pleasant expressions and the hypersensitivity to angry facial signals might influence the interaction behaviors between depressed patients and others.

Short-term antidepressant administration reduces negative self-referential processing in the medial prefrontal cortex in subjects at risk for depression

Depression has been associated with changes in responses within the medial prefrontal cortex (mPFC) during emotional information processing. Antidepressant drug treatment has been shown to modify neural responses in healthy volunteers early in treatment within similar circuitry. It is unclear, however, whether the same early effect occurs in depressed patients, before changes in mood. The current study therefore investigated the effects of 7-days administration of the selective serotonin-uptake inhibitor citalopram vs placebo in volunteers (n=29) at a high risk for the development of depression, using the personality phenotype of high neuroticism in a double-blind, between-groups design. On the last day of treatment, resting haemoperfusion and functional magnetic resonance imaging (MRI) data were acquired during a self-referential words categorisation task. A significant activation in a cluster of mPFC areas, including dorsal anterior cingulate and right orbitofrontal cortex was revealed, driven by decreased responses to the negative self-descriptors following citalopram compared with placebo, in the absence of any mood differences. These findings show a normalisation of neural abnormalities in- and at-risk population early in treatment, supporting the theory that antidepressants may indeed act by modifying specific neural dysfunctions correlated to negative cognitive biases.

Antidepressants differentially modify the extinction of an aversive memory task in female rats

Treatment of major depression, posttraumatic stress disorder and other psychopathologies with antidepressants can be associated with improvement of the cognitive deficits related to these disorders. Although the mechanisms of these effects are not completely elucidated, alterations in the extinction of aversive memories are believed to play a role in these psychopathologies. We have recently verified that female rats present low levels of extinction when submitted to the plus-maze discriminative avoidance task. In the present study, female rats were treated long term with clinically used antidepressants (fluoxetine, nortriptyline or mirtazapine) and subjected to the plus-maze discriminative avoidance task to evaluate learning, memory, extinction and anxiety-related behaviors as well as behavioral despair in the forced swimming test. All groups learned the task and exhibited retrieval. Chronic treatment with fluoxetine (but not with the other antidepressants tested) increased extinction of the discriminative task. In the forced swimming test, the animals treated with fluoxetine and mirtazapine showed decreased immobility duration. In conclusion, fluoxetine potentiated extinction, while both fluoxetine and mirtazapine were effective in ameliorating depressive-like behavior in the forced swimming test, suggesting a possible dissociation between the effects on mood and the extinction of aversive memories in female rats.

Neural responses to emotional faces in women recovered from anorexia nervosa

Impairments in emotional processing have been associated with anorexia nervosa. However, it is unknown whether neural and behavioural differences in the processing of emotional stimuli persist following recovery. The aim of this study was to investigate the neural processing of emotional faces in individuals recovered from anorexia nervosa compared with healthy controls. Thirty-two participants (16 recovered anorexia nervosa, 16 healthy controls) underwent a functional magnetic resonance imaging (fMRI) scan. Participants viewed fearful and happy emotional faces and indicated the gender of the face presented. Whole brain analysis revealed no significant differences between the groups to the contrasts of fear versus happy and vice versa. Region of interest analysis demonstrated no significant differences in the neural response to happy or fearful stimuli between the groups in the amygdala or fusiform gyrus. These results suggest that processing of emotional faces may not be aberrant after recovery from anorexia nervosa.

Limbic scars: long-term consequences of childhood maltreatment revealed by functional and structural magnetic resonance imaging

BACKGROUND

Childhood maltreatment represents a strong risk factor for the development of depression and posttraumatic stress disorder (PTSD) in later life. In the present study, we investigated the neurobiological underpinnings of this association. Since both depression and PTSD have been associated with increased amygdala responsiveness to negative stimuli as well as reduced hippocampal gray matter volume, we speculated that childhood maltreatment results in similar functional and structural alterations in previously maltreated but healthy adults.

METHODS

One hundred forty-eight healthy subjects were enrolled via public notices and newspaper announcements and were carefully screened for psychiatric disorders. Amygdala responsiveness was measured by means of functional magnetic resonance imaging and an emotional face-matching paradigm particularly designed to activate the amygdala in response to threat-related faces. Voxel-based morphometry was used to study morphological alterations. Childhood maltreatment was assessed by the 25-item Childhood Trauma Questionnaire (CTQ).

RESULTS

We observed a strong association of CTQ scores with amygdala responsiveness to threat-related facial expressions. The morphometric analysis yielded reduced gray matter volumes in the hippocampus, insula, orbitofrontal cortex, anterior cingulate gyrus, and caudate in subjects with high CTQ scores. Both of these associations were not influenced by trait anxiety, depression level, age, intelligence, education, or more recent stressful life events.

CONCLUSIONS

Childhood maltreatment is associated with remarkable functional and structural changes even decades later in adulthood. These changes strongly resemble findings described in depression and PTSD. Therefore, the present results might suggest that limbic hyperresponsiveness and reduced hippocampal volumes could be mediators between the experiences of adversities during childhood and the development of emotional disorders.

Emotional processing and antidepressant action

Negative affective schema and associated biases in information processing have long been associated with clinical depression. Such an approach has guided the development of successful psychological therapies for this and other emotional disorders. However, until quite recently, there has been a large chasm between the practitioners and scientists working with this approach and those working on the neurobiological basis of depression and its treatment. Recent research, however, has started to bridge this gap and our understanding of the neural processes underpinning these cognitive processes has progressed markedly over the past decade. Moreover, rather than representing separate targets for psychological and biological treatments, novel findings suggest that pharmacological interventions for depression also modify these psychological maintaining factors early in treatment and may be involved in the later emergence of clinically relevant change. Such findings offer the possibility of greater integration between psychological and pharmacological conceptualisations of psychiatric illness and provide an experimental medicine model to generate and test specific predictions. Such a model could be applied to improve treatment development, stratification and combination approaches for patients with depression and provide a framework for considering and overcoming treatment nonresponse.

Excessive daytime sleepiness and fatigue in depressed patients and therapeutic response of a sedating antidepressant

BACKGROUND

Although sleepiness and fatigue are common symptoms in depressed patients, the relationships among sleepiness, fatigue and treatment of depression have not been fully elucidated. The main objective of this study was to investigate the therapeutic effects of a sedating antidepressant on sleepiness and fatigue in patients with depression.

METHODS

Forty-two depressed patients, who met DSM-IV diagnostic criteria, and 32 matched healthy controls participated in the baseline measurements. Sixteen of the depressed patients were treated with mirtazapine. At baseline, daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS) and Stanford Sleepiness Scale (SSS), and fatigue was assessed using the Fatigue Severity Scale (FSS) and Fatigue Impact Scale (FIS). During treatment, Multiple Sleep Latency Test (MSLT), ESS and SSS were used to measure daytime sleepiness, and the FIS, FACES Checklist-Fatigue subscale (FAF) and Fatigue Assessment Instrument (FAI) were used to measure fatigue.

RESULTS

At baseline, there were significant group differences between the depressed and healthy controls on the ESS (P = 0.001), SSS (P<0.001), FSS (P < 0.001) and FIS (P < 0.001). Significant improvement of sleepiness and fatigue measures was seen after treatment with mirtazapine on the MSLT (P = 0.011), ESS (P = 0.021), SSS (P = 0.001), FIS (P = 0.002) and FAF (P = 0.004).

LIMITATIONS

Open-label treatment and relatively small sample size.

CONCLUSION

Daytime sleepiness and fatigue are significant symptoms in depressed patients. Slightly paradoxically, a sedating antidepressant may alleviate these symptoms.

Subthalamic nucleus stimulation affects incentive salience attribution in Parkinson's disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) can induce nonmotor side effects such as behavioral and mood disturbances or body weight gain in Parkinson's disease (PD) patients. We hypothesized that some of these problems could be related to an altered attribution of incentive salience (ie, emotional relevance) to rewarding and aversive stimuli. Twenty PD patients (all men; mean age ± SD, 58.3 ± 6 years) in bilateral STN DBS switched ON and OFF conditions and 18 matched controls rated pictures selected from the International Affective Picture System according to emotional valence (unpleasantness/pleasantness) and arousal on 2 independent visual scales ranging from 1 to 9. Eighty-four pictures depicting primary rewarding (erotica and food) and aversive fearful (victims and threat) and neutral stimuli were selected for this study. In the STN DBS ON condition, the PD patients attributed lower valence scores to the aversive pictures compared with the OFF condition (P < .01) and compared with controls (P < .01). The difference between the OFF condition and controls was less pronounced (P < .05). Furthermore, postoperative weight gain correlated with arousal ratings from the food pictures in the STN DBS ON condition (P < .05 compensated for OFF condition). Our results suggest that STN DBS increases activation of the aversive motivational system so that more relevance is attributed to aversive fearful stimuli. In addition, STN DBS-related sensitivity to food reward stimuli cues might drive DBS-treated patients to higher food intake and subsequent weight gain.