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

The clinical effectiveness of using a predictive algorithm to guide antidepressant treatment in primary care (PReDicT): an open-label, randomised controlled trial

Depressed patients often do not respond to the first antidepressant prescribed, resulting in sequential trials of different medications. Personalised medicine offers a means of reducing this delay; however, the clinical effectiveness of personalised approaches to antidepressant treatment has not previously been tested. We assessed the clinical effectiveness of using a predictive algorithm, based on behavioural tests of affective cognition and subjective symptoms, to guide antidepressant treatment. We conducted a multicentre, open-label, randomised controlled trial in 913 medication-free depressed patients. Patients were randomly assigned to have their antidepressant treatment guided by a predictive algorithm or treatment as usual (TaU). The primary outcome was the response of depression symptoms, defined as a 50% or greater reduction in baseline score of the QIDS-SR-16 scale, at week 8. Additional prespecified outcomes included symptoms of anxiety at week 8, and symptoms of depression and functional outcome at weeks 8, 24 and 48. The response rate of depressive symptoms at week 8 in the PReDicT (55.9%) and TaU (51.8%) arms did not differ significantly (odds ratio: 1.18 (95% CI: 0.89-1.56), P = 0.25). However, there was a significantly greater reduction of anxiety in week 8 and a greater improvement in functional outcome at week 24 in the PReDicT arm. Use of the PReDicT test did not increase the rate of response to antidepressant treatment estimated by depressive symptoms but did improve symptoms of anxiety at week 8 and functional outcome at week 24. Our findings indicate that personalisation of antidepressant treatment may improve outcomes in depressed patients.

Paliperidone Compared with Haloperidol on the Theory of Mind Tasks in Schizophrenia: A Pilot Trial

PURPOSE

Theory of mind (ToM) is an important part of social cognitive function and is associated with medial prefrontal cortical (mPFC) activity. This study aimed to evaluate the efficacy of paliperidone in improving ToM task performance in patients with schizophrenia compared with haloperidol.

PATIENTS AND METHODS

This study was a single-center, single-blinded (assessor), parallel-group randomized clinical trial of patients with schizophrenia randomized to paliperidone or haloperidol. ToM was assessed at weeks 0, 8, 12, and 16 using the first-order belief, higher-order belief, faux-pas, and Reading the Mind in the Eyes tests. The primary outcome was the change in the ToM performance scores from baseline to after 16 weeks of treatment.

RESULTS

The participants received paliperidone (n = 29) or haloperidol (n = 31). For the first-order belief task, there were no between-group differences (P > 0.05) but time differences in both groups (P < 0.05). For the higher-order belief task, there were no between-group differences (P > 0.05), but there were time differences in both groups (P < 0.05) and a time×group interaction in the paliperidone group only (P < 0.05). For the faux-pas task, there was a difference between groups at week 16 (P < 0.05), and the improvement in time was significant for the paliperidone group only (P < 0.05). For the Reading the Mind in the Eyes task, there was an improvement over time for the paliperidone group only (P < 0.05). Safety was manageable in both groups.

CONCLUSION

Paliperidone treatment might be more effective than haloperidol in improving ToM task performance in schizophrenia.

TRIAL REGISTRATION

chictr.org.cn_identifier ChiCTR-IPR-15007635.

Using early changes in cold cognition to predict response to vortioxetine in major depressive disorder

Antidepressant pharmacotherapy dominates current treatment in psychiatry, including treatment for major depressive disorder (MDD). However, the current trial-and-error process of medication selection contributes to treatment failure and unnecessarily exposes patients to lengthy and insufficient treatment trials. Notably, improvements in measures of cognition have been demonstrated to occur early during treatment and prior to improvements in clinical state. Cognitions have been categorized based on emotional valence (i.e., cold versus hot cognitions). Cold cognitions describe cognitive operations that are relevant to the processing of non-emotional information. The current analysis investigates whether early changes in cold cognition can predict response after 8 weeks of vortioxetine treatment in adults with MDD. This was secondary analysis of an 8-week, open-label study. Cognition was assessed at week 0 and week 2 to measure early cognitive change. Depressive symptom severity was assessed at week 0 and week 8 to measure treatment response. Eighty-one subjects were analyzed using binomial logistic regression models. Early change in cognition was a non-significant predictor of response (p = 0.845, SE = 0.599, OR = 1.124), which may have resulted from high data variability. The overall predictive accuracy of the model was low (sensitivity = 37.5%, specificity = 89.8%, PPV = 70.6%, NPV = 68.8%). Future studies should include larger samples and stratify patients based on potentially moderating variables, such as baseline cognitive impairment and occupation. Stratification would likely produce more homogenous samples, reducing the amount of variability observed for early cognitive change.

Medial prefrontal disengagement during self-focus in formerly depressed patients prone to rumination

BACKGROUND

Medial prefrontal cortex (MPFC) activity during self-referential processing has been associated with rumination and found aberrant in depression. We investigated whether this aberrant activity reflects a trait marker that persists in remitted patients.

METHODS

Twenty-five patients fully remitted from major depression for at least 6 months, and 29 matched healthy controls were scanned with fMRI while presented with personality trait words in two conditions: Self condition asked whether the trait described themselves; General condition asked whether the trait was generally desirable. Contrasts-of-interest were examined in a factorial model and rumination correlates were examined in 2-sample t-tests with Ruminative Response Style score as covariate. All findings were reported at a conservative p < 0.05, with whole-brain peak-level family-wise error correction.

RESULTS

Self-referential processing increased anterior cortical midline activity to a similar extent in both groups. Dorsal anterior cingulate cortex (MNI(x,y,z) = -12,20,26) and dorsal MPFC (MNI(x,y,z) = -6,46,40) activity during self-referential processing was positively associated with rumination in healthy control subjects and negatively associated with rumination in remitted patients.

LIMITATIONS

A longitudinal design tracking the relationship between rumination and MPFC activity would have aided the interpretation of our findings as to whether high ruminators are exhibiting an adaptive process to maintain remission or whether it represents a maladaptive process considering that high ruminators have an increased vulnerability for relapse.

CONCLUSIONS

The association between increased anterior cortical midline activity during self-referential processing and rumination differentiated healthy controls from formerly depressed patients. Self-referential neural processing during remission from depression may depend on the cognitive tendencies to ruminate.

Near-infrared spectroscopy reveals neural perception of vocal emotions in human neonates

Processing affective prosody, that is the emotional tone of a speaker, is fundamental to human communication and adaptive behaviors. Previous studies have mainly focused on adults and infants; thus the neural mechanisms underlying the processing of affective prosody in newborns remain unclear. Here, we used near-infrared spectroscopy to examine the ability of 0-to-4-day-old neonates to discriminate emotions conveyed by speech prosody in their maternal language and a foreign language. Happy, fearful, and angry prosodies enhanced neural activation in the right superior temporal gyrus relative to neutral prosody in the maternal but not the foreign language. Happy prosody elicited greater activation than negative prosody in the left superior frontal gyrus and the left angular gyrus, regions that have not been associated with affective prosody processing in infants or adults. These findings suggest that sensitivity to affective prosody is formed through prenatal exposure to vocal stimuli of the maternal language. Furthermore, the sensitive neural correlates appeared more distributed in neonates than infants, indicating a high-level of neural specialization between the neonatal stage and early infancy. Finally, neonates showed preferential neural responses to positive over negative prosody, which is contrary to the "negativity bias" phenomenon established in adult and infant studies.

Short-term escitalopram treatment normalizes aberrant self-referential processing in major depressive disorder

BACKGROUND

Increased self-focus and negative self-concept play an important role in depression. Antidepressants influence self-referential processing in healthy volunteers, but their function in self-processing of depressed patients remains unknown.

METHODS

Thirty-two depressed patients were randomly allocated to receive either escitalopram 10 mg or placebo for one week. After one week, neural responses to positive and negative self-referential adjectives and neutral control stimuli were assessed with functional magnetic resonance imaging. A group of matched healthy volunteers served as a control group.

RESULTS

Escitalopram decreased responses of medial fronto-parietal regions to self-referential words relative to non-emotional control stimuli, driven by increased responses to the control condition. Escitalopram also increased responses in the pre-defined region of the medial prefrontal cortex (MPFC) and the anterior cingulate cortex (ACC) to positive relative to negative words. Importantly, the changes in neural responses occurred before any effect on depressive symptoms, implying a direct effect of escitalopram. Furthermore, the placebo group had decreased responses of the MPFC and the ACC to positive self-referential processing relative to the matched healthy controls. However, neural responses of the escitalopram group and the healthy unmedicated controls were similar.

LIMITATIONS

Differences between the groups in self-reported depression symptoms and personality traits may have influenced the results.

CONCLUSION

One-week treatment with escitalopram normalized aberrant self-referential processing in depressed patients, shifting the focus from the self to the external environment and potentiating positive self-referential processing. This may be an important factor in mechanism of action of antidepressants.

Effects of antidepressant therapy on neural components of verbal working memory in depression

Impairments in verbal working memory are evident in major depression. Verbal working memory is comprised of the components of encoding, maintenance and retrieval. Whether the neural impairments are expressed in specific components, and how pharmacological therapy could modify the neural correlates are not well understood. We investigated the neural correlates of verbal working memory components in depression using the Sternberg task in a longitudinal magnetic resonance imaging study. Serial scans were acquired in 23 patients (mean age 39.8 years) during an acute depressive episode and following 12 weeks of pharmacological therapy with duloxetine and in 22 matched healthy controls (mean age 39.1 years) at the same time points. A significant group by time interaction was evident during the long maintenance phase, extending from the left middle frontal to the middle temporal and caudate regions, in which there was reduced activation in healthy participants at the follow -up scan but there were no changes in patients. Persistent neural engagement during the maintenance phase following treatment was revealed in major depression. The findings emphasize that impairments in verbal working memory may be initiated in the maintenance phase in major depression in order to sustain performance. Further research with larger sample size and using randomized, placebo-controlled double-blind studies are required to confirm our results.

Brain Functional Effects of Psychopharmacological Treatment in Major Depression: a Focus on Neural Circuitry of Affective Processing

In the last two decades, neuroimaging research has reached a much deeper understanding of the neurobiological underpinnings of major depression (MD) and has converged on functional alterations in limbic and prefrontal neural networks, which are mainly linked to altered emotional processing observed in MD patients. To date, a considerable number of studies have sought to investigate how these neural networks change with pharmacological antidepressant treatment. In the current review, we therefore discuss results from a) pharmacological functional magnetic resonance imaging (fMRI) studies investigating the effects of selective serotonin or noradrenalin reuptake inhibitors on neural activation patterns in relation to emotional processing in healthy individuals, b) treatment studies in patients with unipolar depression assessing changes in neural activation patterns before and after antidepressant pharmacotherapy, and c) predictive neural biomarkers of clinical response in depression. Comparing results from pharmacological fMRI studies in healthy individuals and treatment studies in depressed patients nicely showed parallel findings, mainly for a reduction of limbic activation in response to negative stimuli. A thorough investigation of the empirical findings highlights the importance of the specific paradigm employed in every study which may account for some of the discrepant findings reported in treatment studies in depressed patients.

Noradrenaline effects on social behaviour, intergroup relations, and moral decisions

•

The involvement of noradrenaline in moral and social judgments is reviewed.

•

Noradrenergic transmission is causally involved in implicit racial biases, racial face perception, as well as increasing social harm aversion.

•

Fear and anger – mediated by limbic circuit brain activation – might mediate moral and social decisions and acts.

Recent research has begun to elucidate the neural basis of higher order social concepts, such as the mechanisms involved in intergroup relations, and moral judgments. Most theories have concentrated on higher order emotions, such as guilt, shame, or empathy, as core mechanisms. Accordingly, psychopharmacological and neurobiological studies have investigated the effects of manipulating serotonin or oxytocin activity on moral and social decisions and attitudes. However, recently it has been determined that changes in more basic emotions, such as fear and anger, might also have a significant role in social and moral cognition. This article summarizes psychopharmacological and fMRI research on the role of noradrenaline in higher order social cognition suggesting that indeed noradrenergic mediated affective changes might play key – and probably causal – role in certain social attitudes and moral judgments. Social judgments may also be directly influenced by numerous neurotransmitter manipulations but these effects could be mediated by modulation of basic emotions which appear to play an essential role in the formation of social concepts and moral behaviour.

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.

Effect of short-term escitalopram treatment on neural activation during emotional processing

Recent functional magnetic resonance (fMRI) imaging studies have revealed that subchronic medication with escitalopram leads to significant reduction in both amygdala and medial frontal gyrus reactivity during processing of emotional faces, suggesting that escitalopram may have a distinguishable modulatory effect on neural activation as compared with other serotonin-selective antidepressants. In this fMRI study we aimed to explore whether short-term medication with escitalopram in healthy volunteers is associated with reduced neural response to emotional processing, and whether this effect is predicted by drug plasma concentration. The neural response to fearful and happy faces was measured before and on day 7 of treatment with escitalopram (10mg) in 15 healthy volunteers and compared with those in a control unmedicated group (n=14). Significantly reduced activation to fearful, but not to happy facial expressions was observed in the bilateral amygdala, cingulate and right medial frontal gyrus following escitalopram medication. This effect was not correlated with plasma drug concentration. In accordance with previous data, we showed that escitalopram exerts its rapid direct effect on emotional processing via attenuation of neural activation in pathways involving medial frontal gyrus and amygdala, an effect that seems to be distinguishable from that of other SSRIs.

The Antidepressant Treatment Response Index as a Predictor of Reboxetine Treatment Outcome in Major Depressive Disorder

Biomarkers to predict clinical outcomes early during the treatment of major depressive disorder (MDD) could reduce suffering and improve outcomes. A quantitative electroencephalogram (qEEG) biomarker, the Antidepressant Treatment Response (ATR) index, has been associated with outcomes of treatment with selective serotonin reuptake inhibitor antidepressants in patients with MDD. Here, we report the results of a post hoc analysis initiated to evaluate whether the ATR index may also be associated with reboxetine treatment outcome, given that its putative mechanism of action is via norepinephrine reuptake inhibition (NRI). Twenty-five adults with MDD underwent qEEG studies during open-label treatment with reboxetine at doses of 8 to 10 mg daily for 8 weeks. The ATR index calculated after 1 week of reboxetine treatment was significantly associated with overall Hamilton Depression Rating Scale (HAM-D) improvement at week 8 (r=0.605, P=.001), even after controlling for baseline depression severity (P=.002). The ATR index predicted response (≥50% reduction in HAM-D) with 70.6% sensitivity and 87.5% specificity, and remission (final HAM-D≤7) with 87.5% sensitivity and 64.7% specificity. These results suggest that the ATR index may be a useful biomarker of clinical response during NRI treatment of adults with MDD. Future studies are warranted to investigate further the potential utility of the ATR index as a predictor of noradrenergic antidepressant treatment response.

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.

Impact of acute administration of escitalopram on the processing of emotional and neutral images: a randomized crossover fMRI study of healthy women

BACKGROUND

Acute neural effects of antidepressant medication on emotion processing biases may provide the foundation on which clinical outcomes are based. Along with effects on positive and negative stimuli, acute effects on neutral stimuli may also relate to antidepressant efficacy, yet these effects are still to be investigated. The present study therefore examined the impact of a single dose of the selective serotonin reuptake inhibitor escitalopram (20 mg) on positive, negative and neutral stimuli using pharmaco-fMRI.

METHODS

Within a double-blind, randomized, placebo-controlled crossover design, healthy women completed 2 sessions of treatment administration and fMRI scanning separated by a 1-week washout period.

RESULTS

We enrolled 36 women in our study. When participants were administered escitalopram relative to placebo, left amygdala activity was increased and right inferior frontal gyrus (IFG) activity was decreased during presentation of positive pictures (potentiation of positive emotion processing). In contrast, escitalopram was associated with decreased left amygdala and increased right IFG activity during presentation of negative pictures (attenuation of negative emotion processing). In addition, escitalopram decreased right IFG activity during the processing of neutral stimuli, akin to the effects on positive stimuli (decrease in negative appraisal).

LIMITATIONS

Although we used a women-only sample to reduce heterogeneity, our results may not generalize to men. Potential unblinding, which was related to the subjective occurrence of side effects, occurred in the study; however, manipulation check analyses demonstrated that results were not impacted.

CONCLUSION

These novel findings demonstrate that a single dose of the commonly prescribed escitalopram facilitates a positive information processing bias. These findings provide an important lead for better understanding effects of antidepressant medication.

Healthy individuals treated with clomipramine: an fMRI study of brain activity during autobiographical recall of emotions

Various functional magnetic resonance imaging studies addressed the effects of antidepressant drugs on brain functioning in healthy subjects; however, none specifically investigated positive mood changes to antidepressant drug. Sixteen subjects with no personal or family history of psychiatric disorders were selected from an ongoing 4-week open trial of small doses of clomipramine. Follow-up interviews documented clear positive treatment effects in six subjects, with reduced irritability and tension in social interactions, improved decision making, higher self-confidence and brighter mood. These subjects were then included in a placebo-controlled confirmatory trial and were scanned immediately after 4 weeks of clomipramine use and again 4 weeks after the last dose of clomipramine. The functional magnetic resonance imaging (fMRI) scans were run during emotion-eliciting stimuli. Repeated-measures analysis of variance of brain activity patterns showed significant interactions between group and treatment status during induced irritability (P<0.005 cluster-based) but not during happiness. Individuals displaying a positive subjective response do clomipramine had higher frontoparietal cortex activity during irritability than during happiness and neutral emotion, and higher temporo-parieto-occipital cortex activity during irritability than during happiness. We conclude that antidepressants not only induce positive mood responses but also act upon autobiographical recall of negative emotions.

Serotonergic modulation of glutamate neurotransmission as a strategy for treating depression and cognitive dysfunction

Monoamine-based treatments for depression have evolved greatly over the past several years, but shortcomings such as suboptimal efficacy, treatment lag, and residual cognitive dysfunction are still significant. Preclinical and clinical studies using compounds directly targeting glutamatergic neurotransmission present new opportunities for antidepressant treatment, with ketamine having a surprisingly rapid and sustained antidepressant effect that is presumably mediated through glutamate-dependent mechanisms. While direct modulation of glutamate transmission for antidepressant and cognition-enhancing actions may be hampered by nonspecific effects, indirect modulation through the serotonin (5-HT) system may be a viable alternative approach. Based on localization and function, 5-HT can modulate glutamate neurotransmission at least through the 5-HT1A, 5-HT1B, 5-HT3, and 5-HT7 receptors, which presents a rational pharmacological opportunity for modulating glutamatergic transmission without the direct use of glutamatergic compounds. Combining one or more of these glutamate-modulating 5-HT targets with 5-HT transporter inhibition may offer new therapeutic opportunities. The multimodal compounds vortioxetine and vilazodone are examples of this approach with diverse mechanisms, and their different clinical effects will provide valuable insights into serotonergic modulation of glutamate transmission for the potential treatment of depression and associated cognitive dysfunction.

Self-referential processing, rumination, and cortical midline structures in major depression

Major depression is associated with a bias toward negative emotional processing and increased self-focus, i.e., the process by which one engages in self-referential processing. The increased self-focus in depression is suggested to be of a persistent, repetitive and self-critical nature, and is conceptualized as ruminative brooding. The role of the medial prefrontal cortex in self-referential processing has been previously emphasized in acute major depression. There is increasing evidence that self-referential processing as well as the cortical midline structures play a major role in the development, course, and treatment response of major depressive disorder. However, the links between self-referential processing, rumination, and the cortical midline structures in depression are still poorly understood. Here, we reviewed brain imaging studies in depressed patients and healthy subjects that have examined these links. Self-referential processing in major depression seems associated with abnormally increased activity of the anterior cortical midline structures. Abnormal interactions between the lateralized task-positive network, and the midline cortical structures of the default mode network, as well as the emotional response network, may underlie the pervasiveness of ruminative brooding. Furthermore, targeting this maladaptive form of rumination and its underlying neural correlates may be key for effective treatment.

Hippocampal and prefrontal dopamine D1/5 receptor involvement in the memory-enhancing effect of reboxetine

Dopamine modulates cognitive functions through regulation of synaptic transmission and plasticity in the hippocampus and prefrontal cortex (PFC). Thus, dopamine dysfunction in depression may be particularly relevant for the cognitive symptoms. The norepinephrine transporter inhibitor reboxetine facilitates memory processing in both healthy volunteers and in depressed patients and increases dopamine release in both the hippocampus and PFC. We investigated the potential involvement of the hippocampal and PFC dopamine D1/5 receptors in the cognitive effects of reboxetine using the object recognition test in rats. Infusion of the D1/5 antagonist SCH23390 into the dorsal hippocampus or medial PFC prior to the exploration of the objects impaired memory. Conversely, infusion of the D1/5 agonist SKF81297 into the dorsal hippocampus or medial PFC facilitated memory. Reboxetine similarly facilitated recognition memory in healthy rats and the D1/5 antagonist SCH23390 reversed this effect when infused into the dorsal PFC, but not when infused into the hippocampus. Moreover, systemic reboxetine increased the levels of the NMDA subunit GluN2A in the PFC but not in the hippocampus. Finally, we demonstrate that a single dose of reboxetine does not affect immobility in the forced swim test but improves recognition memory in the Flinders sensitive line (FSL) rat model for depression. The present data in rats are in line with effects of reboxetine on memory formation in healthy volunteers and depressed patients and indicate the involvement of PFC dopamine D1/5 receptors.

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.

Study of the catechol-o-methyltransferase (COMT) gene with high aggression in children

The etiology of childhood-onset aggression (COA) is poorly understood, but early COA can be considered as a strong risk factor for adult delinquency and criminal behavior. Callous-unemotional (CU) traits have been proposed as a developmental model of antisocial behavior. Catechol O-methyltransferase (COMT) has been associated with aggression, attention deficit/hyperactivity disorder (ADHD), and other psychiatric disorders. We report an association study between COMT single-nucleotide polymorphisms (SNPs), childhood aggression, and the CU trait in our sample of 144 children with scores at or exceeding the 90th percentile on the aggression subscale of the parent-reported Child Behavior Checklist and the Teacher's Report Form. The genotype analysis of rs6269 showed nominally significant association (P = .019) and rs4818 showed a trend (P = .064) with COA. Trends were observed for rs6269 and rs4818 with CU scores (P < .10) as well. The analyses stratified by ADHD, or gender showed no significant results. This is the first report to our knowledge evaluating COMT SNPs with the phenotype of high aggression in children with a possible role for the COMT marker in CU traits. Given the importance of CU traits in antisocial behavior, further investigation of COMT is warranted.

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.

Effects of amphetamine on reactivity to emotional stimuli

RATIONALE

Most studies of the reinforcing effects of stimulants have focused on the drugs' capacity to induce positive mood (i.e., euphoria). However, recent findings suggest drugs may also alter emotional reactivity to external stimuli, and that this may occur independently of direct effects on mood.

OBJECTIVES

We aimed to examine effects of D: -amphetamine, a prototypic stimulant, on self-reported and psychophysiological reactivity to emotional stimuli as well as overall subjective mood. We predicted that amphetamine would enhance reactivity to pleasant stimuli, particularly, stimuli with social content and that these effects would be independent of the drug's direct effects on mood.

METHODS

Over three sessions, 36 healthy normal adults received placebo, D: -amphetamine 10 and 20 mg under counterbalanced double-blind conditions. At each session, emotional reactivity to standardized positive, neutral, and negative pictures with and without social content was measured in self-reports and facial muscles sensitive to emotional state. Drug effects on cardiovascular variables and subjective mood were also measured.

RESULTS

Amphetamine produced euphoria, feelings of drug effect, and increased blood pressure. Most notably, amphetamine enhanced self-reported positive reactions to all pictures and psychophysiological reactions to positive pictures. These effects were not significantly related to drug-induced mood changes. Contrary to our hypothesis, effects of amphetamine on emotional reactivity were not moderated by social content.

CONCLUSIONS

This study demonstrates a previously unexamined and potentially reinforcing effect of stimulant drugs in humans, distinct from more typically measured euphorigenic effects, and suggests new areas of research in stimulant abuse risk and adaptations occurring during drug dependence.

Medial prefrontal cortex and the self in major depression

Self-focus (i.e. the process by which one engages oneself in self-referential processing) is a core issue in the psychopathology of major depression. The cortical midline structures, including the medial prefrontal cortex (MPFC), play a key role in self-referential processing in healthy subjects. Four functional magnetic resonance imaging studies recently found either an increased or a decreased MPFC activation during self-referential processing in depressed patients compared to healthy controls. Building on critical differences in experimental settings, we argue that these conflicting results are indeed consistent with two modes of elevated MPFC activation in major depression. An elevated tonic ventral MPFC activation, as uncovered by an event-related design, may embody automatic aspects of depressive self-focus, such as attracting attention to self-relevant incoming information. An elevated phasic dorsal MPFC activation, as uncovered by a block-based design, may embody more strategic aspects of depressive self-focus, such as comparing the self with inner standards. Additionally, strategic self-focus in depression may recruit the anterior cingulate cortex and more lateral regions of the prefrontal cortex. An aberrant functional connectivity of the dorsal MPFC may underlie this lack of reciprocal inhibition between the cognitive control network and the default mode network. Altogether, these results suggest that self-focus in depression may emerge as a process competing for brain resources due to a lack of inhibition of the default mode network, resulting in detrimental effects on externally-oriented cognitive processes. Follow-up studies are warranted to determine the trait vs. state nature of these biomarkers and their ability to predict treatment outcome.

Cognitive mechanisms of treatment in depression

Cognitive abnormalities are a core feature of depression, and biases toward negatively toned emotional information are common, but are they a cause or a consequence of depressive symptoms? Here, we propose a 'cognitive neuropsychological' model of depression, suggesting that negative information processing biases have a central causal role in the development of symptoms of depression, and that treatments exert their beneficial effects by abolishing these biases. We review the evidence pertaining to this model: briefly with respect to currently depressed patients, and in more detail with respect to individuals at risk for depression and the effects of antidepressant treatments. As well as being present in currently depressed individuals, negative biases are detectable in those vulnerable for depression due to neuroticism, genetic risk, or previous depressive illness. Recent evidence provides strong support for the notion that both antidepressant drugs and psychological therapies modify negative biases, providing a common mechanism for understanding treatments for depression. Intriguingly, it may even be possible to predict which patients will benefit most from which treatments on the basis of neural responses to negative stimuli. However, further research is required to ascertain whether negative processing biases will be useful in predicting, detecting, and treating depression, and hence in preventing a chronic, relapsing course of illness.

Short-term duloxetine administration affects neural correlates of mood-congruent memory

It is unknown how antidepressants reverse mood-congruent memory bias, a cognitive core factor causing and maintaining depression. Using a double-blind, placebo-controlled, cross-over design, we investigated the effect of a short-term treatment (14 days) with the dual reuptake inhibitor duloxetine on neural correlates of mood-congruent and mood-incongruent memory formation and retrieval in healthy volunteers who underwent a sad mood induction procedure. Duloxetine did not affect acute mood state or memory performance, but interacted with brain processes mediating mood-congruent memory. It decreased activity related to successful memory formation for mood-congruent and -incongruent items in a set of brain regions comprising the putamen and the middle frontal gyrus, as well as the middle and the anterior cingulate cortex. Duloxetine specifically increased amygdala activity related to successful memory retrieval for mood-incongruent items. Here we show that short-term administration of duloxetine affects the neural correlates of emotional memory formation and retrieval in a set of brain regions whose processing is related to affective state and its regulation. While duloxetine suppressed the neural correlates of emotional memory formation in general, it specifically enhanced amygdala processes associated with mood-incongruent memory retrieval. This pattern of results shows how an antidepressant may reduce emotional memory formation and reverse mood-congruent processing biases at retrieval.

Neuroanatomical targets of reboxetine and bupropion as revealed by pharmacological magnetic resonance imaging

RATIONALE

One of the key targets of psychopharmacology research is to determine the potential sites of action of antidepressants in order to characterise their underlying mechanism of action.

OBJECTIVE

Using blood oxygenation level-dependent (BOLD) pharmacological magnetic resonance imaging (phMRI), the neuroanatomical target-sites of reboxetine (a selective noradrenaline reuptake inhibitor) and bupropion (an antidepressant with stimulatory effects on dopamine and potentially on noradrenaline) were mapped.

METHODS

Separate groups of rats were challenged acutely or chronically (daily injections for 14 days) with saline or psychoactive compounds and scanned. Subsequent statistical parametric mapping of the main effects of the drug was performed by identifying changes in the BOLD signal.

RESULTS

Acute reboxetine challenge at a low dose (10 mg/kg i.p.) produced positive BOLD responses specifically in the hypothalamus, whereas a larger dose (30 mg/kg i.p.) produced activations in the hypothalamus, anterior hippocampus and prefrontal cortex. Chronic reboxetine (30 mg/kg i.p.) treatment induced increased BOLD responses in the posterior hippocampus and prefrontal cortex, while no significant contrast changes were observed in the hypothalamus and a significant decrease was apparent in the amygdala. In contrast, acute bupropion (15 and 30 mg/kg i.p.) challenge in both doses produced no significant contrast changes in the regions of interest. However, chronic bupropion treatment (30 mg/kg i.p.) produced robust increases in BOLD responses in the hippocampus, amygdala and prefrontal cortex.

CONCLUSION

In summary, this study demonstrates that reboxetine and bupropion evoke a significant increase in BOLD functional activity in specific regions of the brain, including the hypothalamus, hippocampus, prefrontal cortex and amygdala. Furthermore, the study illustrates the potential value of pharmacological MRI in rodents to delineate pharmacologically induced changes in regional brain function.

Using MRI to measure drug action: caveats and new directions

Investigating pharmacological modulation of brain activity using magnetic resonance imaging (MRI) presents an exciting opportunity to bridge the gap between preclinical and clinical studies, and holds the potential to be a useful tool in the discovery and development of novel therapeutic agents. Most functional MRI studies to date have utilized the blood oxygen level dependent (BOLD) contrast mechanism. Although this has some advantages over other techniques and is widely available, BOLD has two significant limitations for the study of drug effects; it is an indirect measurement of neuronal function, and produces only a relative (non-quantitative) measure of blood dynamics. Here we describe the various experimental manipulations that have been used to reduce the impact of these limitations, and discuss new ways of collecting and analysing imaging data that allow us to assess functional connectivity of the brain. We recommend some complementary techniques (such as arterial spin labelling and magnetoencephalography) that, if used in conjunction with BOLD functional MRI, will increase the interpretability and thus the utility of MRI for pharmacology research.

Efficacy markers in depression

Current antidepressant agents are similar in efficacy to the original drugs discovered in the 1950s. The development of new treatments for depression is, however, limited by the absence of validated human biomarker models to predict efficacy, clinical profile and dosing. Such models need to meet key criteria for biomarkers including sensitivity, specificity and relevance to depression. Here we review studies exploring whether early changes in emotional processing with antidepressant drug administration meet these criteria. A large body of evidence suggests that changes in emotional memory are particularly relevant to depression and to antidepressant drug action whereas changes in attentional processing are sensitive to anxiolytic drugs. These tasks are not consistently affected by agents which have failed in clinical trials in depression, but do show changes in the predicted direction with agents associated either with amelioration or induction of symptoms. Hence, early assessment of novel drugs on emotional processing may predict likely clinical effects and dosing prior to randomized controlled trials. Greater validation is required to assess whether these effects are an obligatory component of effective treatment of depression and whether use of these models can improve the accuracy of go/no-go decisions in drug development.

The effects of antidepressants on human brain as detected by imaging studies. Focus on major depression

Recent brain imaging studies have shed light on understanding the pathogenesis of mood disorders. Evidence of structural, chemical, and functional brain changes, particularly in prefrontal cortex, cingulate, and amygdala, has been revealed in major depressive disorder (MDD). Furthermore, imaging techniques have been applied to monitor the effects of antidepressants (ADs) both in the brains of healthy volunteers and MDD patients. Although with some discrepancies due to the differences in study designs and patient samples, imaging findings have shown that ADs, particularly those having effects on the serotonergic system, modulate the volumes, functions and biochemistry of brain structures, i.e. dorsolateral prefrontal cortex, anterior cingulate and amygdala, which have been demonstrated abnormal in MDD by earlier imaging studies. This paper reviews imaging studies conducted in MDD patients and healthy controls treated with different ADs.

Differential modulation of emotion processing brain regions by noradrenergic and serotonergic antidepressants

RATIONALE

Most widely used antidepressant drugs affect the serotonergic and noradrenergic pathways. However, there are currently no neurobiological criteria for selecting between these targets and predicting the treatment response in individual depressed patients.

OBJECTIVES

The current study is aimed at differentiating brain regions known to be pathophysiologically and functionally involved in depression-related emotion processing with respect to their susceptibility to serotonergic and noradrenergic modulation.

METHODS

In a single-blind pseudo-randomized crossover study, 16 healthy subjects (out of 21 enrolled) were included in analysis after ingesting a single dose of citalopram (a selective serotonin-reuptake inhibitor, 40 mg), reboxetine (a selective noradrenaline-reuptake inhibitor, 8 mg), or placebo at three time points prior to functional magnetic resonance imaging (fMRI). During fMRI, subjects anticipated and subsequently viewed emotional pictures. Effects of serotonergic and noradrenergic modulation versus placebo on brain activity during the perception of negative pictures were analyzed with a repeated measures ANOVA in the whole brain and in specific regions of interest relevant to depression.

RESULTS

Noradrenergic modulation by reboxetine increased brain activity in the thalamus, right dorsolateral prefrontal cortex and occipital regions during the perception of negative emotional stimuli. Citalopram primarily affected the ventrolateral prefrontal cortical regions.

CONCLUSION

The brain regions involved in the processing of negative emotional stimuli were differentially modulated by selective noradrenergic and serotonergic drugs: thalamic activity was increased by reboxetine, whereas citalopram primarily affected ventrolateral prefrontal regions. Thus, dysfunction in these regions, which could be identified in depressed patients, may predict treatment responses to either noradrenergic or serotonergic antidepressants.

Neural activity changes to emotional stimuli in healthy individuals under chronic use of clomipramine

Previous functional magnetic resonance imaging (fMRI) studies examined neural activity responses to emotive stimuli in healthy individuals after acute/subacute administration of antidepressants. We now report the effects of repeated use of the antidepressant clomipramine on fMRI data acquired during presentation of emotion-provoking and neutral stimuli on healthy volunteers. A total of 12 volunteers were evaluated with fMRI after receiving low doses of clomipramine for 4 weeks and again after 4 weeks of washout. Fear-, happiness-, anger-provoking and neutral pictures from the International Affective Picture System (IAPS) were used. Data analysis was performed with statistical parametric mapping (P < 0.05). Paired t-test comparisons for each condition between medicated and unmedicated states showed, to negative valence paradigms, decrease in brain activity in the amygdala when participants were medicated. We also demonstrated, across both positive and negative valence paradigms, consistent decreases in brain activity in the medicated state in the anterior cingulate gyrus and insula. This is the first report of modulatory effects of repeated antidepressant use on the central representation of somatic states in response to emotions of both negative and positive valences in healthy individuals. Also, our results corroborate findings of antidepressant-induced temporolimbic activity changes to emotion-provoking stimuli obtained in studies of subjects treated acutely with such agents.

Emotional processing in bipolar disorder: behavioural and neuroimaging findings

Existing studies revealed that bipolar patients show an altered identification of emotional stimuli (e.g. facial expressions), however, so far modifications in early emotional processes and the regulation of emotions are less clear. In response to emotional stimuli bipolar patients show a dysfunction in a ventral-limbic brain network including the amygdala, insula, striatum, subgenual cingulate cortex, ventrolateral prefrontal cortex and orbitofrontal cortex. In most studies, a relative hypoactivity of dorsal brain structures, including the dorsolateral prefrontal cortex, the dorsal anterior cingulate and the posterior cingulate cortex, has been reported in bipolar patients. This imbalance between the two networks has been proposed to underlie deficient emotion regulation in bipolar disorder.

Antidepressants in healthy subjects: what are the psychotropic/psychological effects?

A wide debate is ongoing regarding whether antidepressant effects should be considered a general property of these agents or whether they exclusively belong to the context of target symptoms. The aim of the present review is to summarize findings on antidepressant influences on healthy volunteers, focusing on changes in psychological and cognitive functions. Differences have been detected between acute and chronic treatments. Acute treatment has been found to lead to positive bias in emotion processing and facilitation in negative emotion recognition. Chronic treatments have been found to stabilise some changes induced by acute treatment, such as increased social behaviours. Regarding antidepressant modulation of affective symptomatology contrasting results have been reported suggesting that the link between action on cognitive processes and mood may be not direct. In fact, meta-analyzing data on mood and anxiety symptoms no difference was detected between subjects receiving placebo and SSRIs. However, meta-analyzing data on negative affects, a significant decrease was detected in subjects receiving SSRIs in comparison with subjects receiving placebo. In summary, antidepressants seem to exert a detectable influence also in healthy subjects.

From facial mimicry to emotional empathy: a role for norepinephrine?

Tendency to mimic others' emotional facial expressions predicts empathy and may represent a physiological marker of psychopathy. Anatomical connectivity between amygdala, cingulate motor cortex (M3, M4), and facial nucleus demonstrates a potential neuroanatomical substrate for mimicry, though pharmacological influences are largely unknown. Norepinephrine modulation selectively impairs negative emotion recognition, reflecting a potential role in processing empathy-eliciting facial expressions. We examined effects of single doses of propranolol (beta-adrenoceptor blocker) and reboxetine (selective norepinephrine reuptake inhibitor) on automatic facial mimicry of sadness, anger, and happiness, and the relationship between mimicry and empathy. Forty-five healthy volunteers were randomized to 40 mg propranolol or 4 mg reboxetine. Two hours after drug subjects viewed and rated facial expressions of sadness, anger, and happiness, while corrugator, zygomatic, and mentalis EMG were recorded. Trait emotional empathy was measured using the Balanced Emotional Empathy Scale. EMG confirmed emotion-specific mimicry and the relationship between corrugator mimicry and empathy. Norepinephrine modulation did not alter mimicry to any expression or influence the relationship between mimicry and empathy. Corrugator but not zygomaticus mimicry predicts trait empathy, consistent with greater anatomical connectivity between amygdala and M3 coding upper facial muscle representations. Although influencing emotion perception, norepinephrine does not influence emotional facial mimicry or its relationship with trait empathy.

Linking the cytokine and neurocircuitry hypotheses of depression: a translational framework for discovery and development of novel anti-depressants

Recent studies suggest a model of depression that links the cytokine hypothesis from the field of psychoneuroimmunology with the neurocircuitry hypothesis derived from burgeoning insight into neurophysiological changes observed in depressed patients. According to the neurocircuitry hypothesis of depression, failure of homeostatic synaptic plasticity in cortical-striatal-limbic nodes of a distributed network of neural circuits involving the sub-genual anterior cingulate cortex is responsible for core symptoms of depression: loss of interest or pleasure (anhedonia) and depressed mood (sadness). According to the cytokine hypothesis of depression, inflammatory cytokines act on neural circuits to evoke the behavioral and physiological changes observed in depression. Synthesis of these hypotheses implicates cytokines released during injury, infection, illness, or psychological stress as a cause of dysregulated synaptic plasticity in cortical-striatal-limbic circuits implicated in depression. These neural circuits process affective and reward-based information for optimal cost-benefit decision-making, a function that may link cytokine-evoked changes in synaptic plasticity to translatable measures of specific behavioral impairments observed in depressed patients. This viewpoint outlines evidence linking the cytokine and neurocircuitry hypotheses of depression to offer a translational model of major depressive disorder suitable for novel drug discovery and development.

NK1 receptor antagonism and emotional processing in healthy volunteers

The neurokinin-1 (NK(1)) receptor antagonist, aprepitant, showed activity in several animal models of depression; however, its efficacy in clinical trials was disappointing. There is little knowledge of the role of NK(1) receptors in human emotional behaviour to help explain this discrepancy. The aim of the current study was to assess the effects of a single oral dose of aprepitant (125 mg) on models of emotional processing sensitive to conventional antidepressant drug administration in 38 healthy volunteers, randomly allocated to receive aprepitant or placebo in a between groups double blind design. Performance on measures of facial expression recognition, emotional categorisation, memory and attentional visual-probe were assessed following the drug absorption. Relative to placebo, aprepitant improved recognition of happy facial expressions and increased vigilance to emotional information in the unmasked condition of the visual probe task. In contrast, aprepitant impaired emotional memory and slowed responses in the facial expression recognition task suggesting possible deleterious effects on cognition. These results suggest that while antagonism of NK(1) receptors does affect emotional processing in humans, its effects are more restricted and less consistent across tasks than those of conventional antidepressants. Human models of emotional processing may provide a useful means of assessing the likely therapeutic potential of new treatments for depression.

Using diffusion models to understand clinical disorders

Sequential sampling models provide an alternative to traditional analyses of reaction times and accuracy in two-choice tasks. These models are reviewed with particular focus on the diffusion model (Ratcliff, 1978) and how its application can aide research on clinical disorders. The advantages of a diffusion model analysis over traditional comparisons are shown through simulations and a simple lexical decision experiment. Application of the diffusion model to a clinically-relevant topic is demonstrated through an analysis of data from nonclinical participants with high- and low-trait anxiety in a recognition memory task. The model showed that after committing an error, participants with high trait anxiety responded more cautiously by increasing their boundary separation, whereas participants with low trait anxiety did not. The article concludes with suggestions for ways to improve and broaden the application of these models to studies of clinical disorders.

Serotonergic and noradrenergic modulation of emotion processing by single dose antidepressants

Serotonergic and noradrenergic pathways are the main targets of antidepressants. Their differential effects on emotion processing-related brain activation are, however, to be further characterized. We aimed at elucidating the neural sites of action of an acute differential serotonergic and noradrenergic influence on an emotion-processing task, which was earlier shown to be associated with depressiveness. In a single-blind pseudo-randomized crossover study, 21 healthy subjects (16 subjects finally included in the analysis) participated to ingest a single dose at three time points of either 40 mg citalopram, a selective serotonin-reuptake inhibitor, 8 mg reboxetine, a selective noradrenaline-reuptake inhibitor, or placebo 2-3 h before functional magnetic resonance imaging (fMRI). During fMRI, subjects performed a task comprising the anticipation and perception of pictures of either 'known' (positive, negative, neutral) or 'unknown' valence (randomly 50% positive or negative). In direct comparison with citalopram and with placebo, reboxetine increased brain activity in the medial thalamus. Citalopram modulated certain prefrontal and insular areas more prominently. Other frontal and parieto-occipital areas were modulated by both drugs. In conclusion, the functional network involved in emotional information processing could be modulated by the acute application of selective noradrenergic and serotonergic drugs revealing a noradrenergic effect in thalamic and frontal areas, and a prefrontal and insular focus of serotonergic modulation. These findings could have implications for future selection criteria concerning personalized antidepressant medication in depression.

Effects of erythropoietin on emotional processing biases in patients with major depression: an exploratory fMRI study

INTRODUCTION

Erythropoietin (Epo) has neurotrophic effects and may be a novel therapeutic agent in the treatment of depression. We have found antidepressant-like effects of Epo on emotional processing and mood in healthy volunteers.

OBJECTIVE

The current study aimed to explore the effects of Epo on the neural processing of emotional information in depressed patients.

MATERIALS AND METHODS

Seventeen patients with acute major depressive disorder were randomised to receive Epo (40,000 IU) or saline iv in a double-blind, parallel-group design. On day 3, we assessed neural responses to positive, negative and neutral pictures during fMRI followed by picture recall after the scan. Mood and blood parameters were assessed at baseline and on day 3.

RESULTS

Epo reduced neural response to negative vs. positive pictures 3 days post-administration in a network of areas including the hippocampus, ventromedial prefrontal and parietal cortex. After the scan, Epo-treated patients showed improved memory compared with those that were given placebo. The effects occurred in the absence of changes in mood or haematological parameters, suggesting that they originated from direct neurobiological actions of Epo.

CONCLUSIONS

These findings are similar to the effects of conventional antidepressants and opposite to the negative biases in depression. The central effects of Epo therefore deserve further investigation as a potential antidepressant mechanism.

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.

A new ethics of psychiatry: neuroethics, neuroscience, and technology

Neuroethics is a new subset of bioethics that addresses ethical issues pertaining to the brain, primarily in the fields of neuroscience, cognitive science, and neuroradiology. Research in brain science is progressing at a phenomenal rate and, as a result, the acquisition and application of knowledge and technology raises ethical questions of a practical and philosophical nature. While neuroethics is developing as a distinct field of study, one area that should be addressed in greater depth is the relevance and potential impact of neurotechnology in psychiatry. New knowledge in the mind-brain conundrum and increasingly sophisticated techniques for imaging and intervening in human cognition, emotion, and behavior pose ethical issues at the intersection of technology and psychiatry. This article presents a broad survey of the new directions in neuroethics, neuroscience, and technology and considers the implications of technological advances for the practice of psychiatry in the new millennium. (Journal of Psychiatric Practice 2009;15:391-401).

Why do antidepressants take so long to work? A cognitive neuropsychological model of antidepressant drug action

BACKGROUND

The neuropharmacological actions of antidepressants are well characterised but our understanding of how these changes translate into improved mood are still emerging.

AIMS

To investigate whether actions of antidepressant drugs on emotional processing are a mediating factor in the effects of these drugs in depression.

METHOD

We examined key published findings that explored the effects of antidepressants on behavioural and functional magnetic resonance imaging (fMRI) measures of emotional processing.

RESULTS

Negative emotional bias has been reliably associated with depression. Converging results suggest that antidepressants modulate emotional processing and increase positive emotional processing much earlier than effects on mood. These changes in emotional processing are associated with neural modulation in limbic and prefrontal circuitry.

CONCLUSIONS

Antidepressants may work in a manner consistent with cognitive theories of depression. Antidepressants do not act as direct mood enhancers but rather change the relative balance of positive to negative emotional processing, providing a platform for subsequent cognitive and psychological reconsolidation.

Modeling a negative response bias in the human amygdala by noradrenergic-glucocorticoid interactions

An emerging theme in the neuroscience of emotion is the question of how acute stress shapes, and distorts, social-emotional behavior. The prevailing neurocircuitry models of social-emotional behavior emphasize the central role of the amygdala. Acute stress leads to increased central levels of norepinephrine (NE) and cortisol (CORT), and evidence suggests that these endogenous neuromodulators synergistically influence amygdala responses to social-emotional stimuli. We therefore hypothesized that amygdala responses to emotional facial expressions would be susceptible to pharmacologically induced increases in central NE and CORT levels. To specifically test this hypothesis, we measured amygdala activation to emotional faces using functional magnetic resonance imaging in 62 healthy subjects under four pharmacological conditions: (1) single oral dose of placebo, (2) 4 mg of the selective NE-reuptake inhibitor reboxetine (RBX), (3) 30 mg of hydrocortisone, or (4) both drugs in combination. We found that a decrease in amygdala activation to positive facial emotion was coupled with an increase in amygdala activation to negative facial emotion in the RBX-CORT combined challenge condition. In conclusion, a pharmacologically induced elevation of central NE and CORT levels in healthy subjects created a negative response bias in the amygdala that did not exist at baseline. Our results implicate a causative role of NE-CORT interactions in the emergence of a negative bias of cognitive and emotional functions which is germane in stress-related affective spectrum disorders.