Clinical, behavioral, and neural measures of reward processing correlate with escitalopram response in depression: a Canadian Biomarker Integration Network in Depression (CAN-BIND-1) Report

Resting EEG source-level connectivity pattern to predict anhedonia improvement with agomelatine treatment in patients with major depression

BACKGROUND

Neuroimaging studies have revealed that dysfunction of reward circuitry in the brain underlies anhedonia, a core symptom of major depressive disorder (MDD) that is related to treatment outcomes. However, the relationship between the brain network at the level of neuronal oscillations and the longitudinal improvement in the severity of anhedonia is still unknown.

METHODS

The study enrolled 84 unmedicated patients with MDD. Anhedonia severity was measured using the Snaith-Hamilton Pleasure Scale (SHAPS). EEG data in the resting state was obtained both at baseline and following an 8-week course of agomelatine 25 mg taken once daily. Whole-brain functional connectivity (FC) of source-level resting-state EEG and FC-derived graph metrics (i.e., global topological properties: global efficiency and local efficiency) were calculated in distinct frequency bands.

RESULTS

SHAPS scores were significantly improved from baseline to 8 weeks. Concurrently, there was a decrease in alpha-1 (8.5-10 Hz) connectivity between the right-hemisphere precuneus (PreC) and the left-hemisphere inferior frontal gyrus (IFG). Reduced alpha-2 (10.5-12 Hz) connectivity between the right-hemisphere transverse temporal gyrus (TTG) and the left-hemisphere superior frontal gyrus (SFG) and middle frontal gyrus (MFG) was observed. Global efficiency in the alpha-1 (p < 0.001) and alpha-2 (p = 0.003) frequency bands and local efficiency in the alpha-1 frequency band (p = 0.003) were reduced. Correlation analyses showed that alpha-1 local efficiency at baseline predicted improvement in SHAPS scores (r = -0.261, p = 0.017).

CONCLUSION

Global topological properties of source-level EEG FC can predict anhedonia improvement during antidepressant treatment, which might help guide treatment decisions and advance precision psychopharmacology.

The association between anhedonia and prefrontal cortex activation in patients with major depression: a functional near-infrared spectroscopy study

This study investigated cerebral blood flow characteristics using functional nearinfrared spectroscopy (fNIRS) in agomelatine-treated depressed patients with anhedonia. The level of anhedonia was assessed by the Snaith Hamilton Rating Scale (SHAPS) and Montgomery Åsberg Depression Rating Scale 5-item (MADRS 5-item) score. All 84 patients were evaluated on the day of the study initiation and followed at week 1, 4 and 8 after the study initiation. Graph theory-based network analysis showed 2-back task-modulated global efficiency (adjusted B = 0.055, 95% CI = 0.043 - 0.066) and local efficiency (adjusted B = 0.066, 95% CI = 0.050 - 0.081) were significantly increased 1 week after treatment compared with the baseline. Furthermore, the increased oxy-hemoglobin (oxy-Hb) values from the baseline to the one week after treatment was positively related to the total MADRAS 5-item score reductions in the left-hemispheric orbitofrontal cortex (r = - 0.307, p = 0.005). Our findings suggest that abnormal functional connectivity over OFC may reflect the pathophysiological characteristics of anhedonia and serve as a clinical biomarker for anhedonia.

Differential Insular Cortex Activation During Reward Anticipation in Major Depressive Disorder With and Without Anxiety

BACKGROUND

Anticipation involves preparatory resource allocation to optimize upcoming responses, linked to insular cortex function. Although individuals with major depressive disorder (MDD) show impairments in anticipatory processing and blunted insula activation, it is unclear whether this pattern holds across MDD with comorbid anxiety disorders (MDD+ANX) and MDD without comorbid anxiety disorders. The monetary incentive delay (MID) task, combined with magnetic resonance imaging (MRI)-guided electroencephalography (EEG) source localization, offers a robust approach to study anticipatory mechanisms in MDD subtypes.

METHODS

Participants with MDD (n = 53) or MDD+ANX (n = 108) and healthy control participants (CTLs; n = 38) completed the MID task during simultaneous EEG-MRI recording. Stimulus-preceding negativity event-related potentials were source localized to identify insular cortical activity differences across groups (MDD, MDD+ANX, CTL), sex (male, female), MID task conditions (gain, loss), hemisphere (left, right), and 6 insular subregions.

RESULTS

Behavioral performance revealed that the CTL group reacted faster than the MDD+ANX group in both gain and loss conditions (p = .03). Insular source analysis showed lower activity in the MDD+ANX (p < .001) and MDD (p = .06) groups than in the CTL group during gain anticipation and lower activity in the MDD+ANX group than in both CTL (p = .003) and MDD (p < .001) groups during loss anticipation.

CONCLUSIONS

Results highlight potential intervention targets for improving anticipatory deficits in MDD+ANX. The MDD+ANX group exhibited distinctive patterns of insular cortical activity, with lower activity during the anticipation of both gain and loss feedback than the CTL and MDD groups, suggesting significant neural alterations. Moreover, in the MDD+ANX group, higher anxiety severity was linked to increased insula activity during loss anticipation, indicating a specific neural correlate of anxiety in this comorbid condition.

The Role of the Serotonergic System in Time Perception: A Systematic Review

Time perception is a fundamental cognitive function essential for adaptive behavior and shared across species. The neural mechanisms underlying time perception, particularly its neuromodulation, remain debated. In this review, we examined the role of the serotonergic system in time perception (at the scale of seconds and minutes), building a translational bridge between human and non-human animal studies. The literature search was conducted according to the PRISMA statement in PubMed, APA PsycINFO, and APA PsycARTICLES. Sixty papers were selected for full-text review, encompassing both human (n = 10) and animal studies (n = 50). Summarizing the reviewed literature, we revealed consistent evidence for the role of serotonin in timing behavior, highlighting its complex involvement across retrospective, immediate, and prospective timing paradigms. Increased serotonergic activation appears to accelerate internal time speed, which we interpret through the dual klepsydra model as accelerated discharge of the temporal accumulator. However, some findings challenge this framework. Additionally, we link impulsivity-associated with decreased serotonergic functioning in our review-to a slower internal time speed. Variability in prospective timing tasks underscores the need for further research into how serotonin modulates reward-based temporal decisions, using novel approaches to disentangle internal time speed, response inhibition, and other factors.

Beyond the serotonin deficit hypothesis: communicating a neuroplasticity framework of major depressive disorder

The serotonin deficit hypothesis explanation for major depressive disorder (MDD) has persisted among clinicians and the general public alike despite insufficient supporting evidence. To combat rising mental health crises and eroding public trust in science and medicine, researchers and clinicians must be able to communicate to patients and the public an updated framework of MDD: one that is (1) accessible to a general audience, (2) accurately integrates current evidence about the efficacy of conventional serotonergic antidepressants with broader and deeper understandings of pathophysiology and treatment, and (3) capable of accommodating new evidence. In this article, we summarize a framework for the pathophysiology and treatment of MDD that is informed by clinical and preclinical research in psychiatry and neuroscience. First, we discuss how MDD can be understood as inflexibility in cognitive and emotional brain circuits that involves a persistent negativity bias. Second, we discuss how effective treatments for MDD enhance mechanisms of neuroplasticity-including via serotonergic interventions-to restore synaptic, network, and behavioral function in ways that facilitate adaptive cognitive and emotional processing. These treatments include typical monoaminergic antidepressants, novel antidepressants like ketamine and psychedelics, and psychotherapy and neuromodulation techniques. At the end of the article, we discuss this framework from the perspective of effective science communication and provide useful language and metaphors for researchers, clinicians, and other professionals discussing MDD with a general or patient audience.

Breakthroughs and challenges for generating brain network-based biomarkers of treatment response in depression

Treatment outcomes widely vary for individuals diagnosed with major depressive disorder, implicating a need for deeper understanding of the biological mechanisms conferring a greater likelihood of response to a particular treatment. Our improved understanding of intrinsic brain networks underlying depression psychopathology via magnetic resonance imaging and other neuroimaging modalities has helped reveal novel and potentially clinically meaningful biological markers of response. And while we have made considerable progress in identifying such biomarkers over the last decade, particularly with larger, multisite trials, there are significant methodological and practical obstacles that need to be overcome to translate these markers into the clinic. The aim of this review is to review current literature on brain network structural and functional biomarkers of treatment response or selection in depression, with a specific focus on recent large, multisite trials reporting predictive accuracy of candidate biomarkers. Regarding pharmaco- and psychotherapy, we discuss candidate biomarkers, reporting that while we have identified candidate biomarkers of response to a single intervention, we need more trials that distinguish biomarkers between first-line treatments. Further, we discuss the ways prognostic neuroimaging may help to improve treatment outcomes to neuromodulation-based therapies, such as transcranial magnetic stimulation and deep brain stimulation. Lastly, we highlight obstacles and technical developments that may help to address the knowledge gaps in this area of research. Ultimately, integrating neuroimaging-derived biomarkers into clinical practice holds promise for enhancing treatment outcomes and advancing precision psychiatry strategies for depression management. By elucidating the neural predictors of treatment response and selection, we can move towards more individualized and effective depression interventions, ultimately improving patient outcomes and quality of life.

Neuroimaging for precision medicine in psychiatry

Although the lifetime burden due to mental disorders is increasing, we lack tools for more precise diagnosing and treating prevalent and disabling disorders such as major depressive disorder. We lack strategies for selecting among available treatments or expediting access to new treatment options. This critical review concentrates on functional neuroimaging as a modality of measurement for precision psychiatry, focusing on major depressive and anxiety disorders. We begin by outlining evidence for the use of functional neuroimaging to stratify the heterogeneity of these disorders, based on underlying circuit dysfunction. We then review the current landscape of how functional neuroimaging-derived circuit predictors can predict treatment outcomes and clinical trajectories in depression and anxiety. Future directions for advancing clinically appliable neuroimaging measures are considered. We conclude by considering the opportunities and challenges of translating neuroimaging measures into practice. As an illustration, we highlight one approach for quantifying brain circuit function at an individual level, which could serve as a model for clinical translation.

Brain Circuit-Derived Biotypes for Treatment Selection in Mood Disorders: A Critical Review and Illustration of a Functional Neuroimaging Tool for Clinical Translation

Although the lifetime burden due to major depressive disorder is increasing, we lack tools for selecting the most effective treatments for each patient. One-third to one-half of patients with major depressive disorder do not respond to treatment, and we lack strategies for selecting among available treatments or expediting access to new treatment options. This critical review concentrates on functional neuroimaging as a modality of measurement for precision psychiatry. We begin by summarizing the current landscape of how functional neuroimaging-derived circuit predictors can forecast treatment outcomes in depression. Then, we outline the opportunities and challenges in integrating circuit predictors into clinical practice. We highlight one standardized and reproducible approach for quantifying brain circuit function at an individual level, which could serve as a model for clinical translation. We conclude by evaluating the prospects and practicality of employing neuroimaging tools, such as the one that we propose, in routine clinical practice.

Ketamine treatment for anhedonia in unipolar and bipolar depression: a systematic review

Ketamine, an N-methyl-D-aspartate receptor antagonist, is a racemic mixture of esketamine and arketamine used to treat unipolar and bipolar depression. Preliminary reports indicate that it may be beneficial for depressed patients reporting symptoms of anhedonia. In this systematic review we aim to assess and analyze the existing body of evidence regarding the therapeutic effects of ketamine on the domain of anhedonia. Electronic databases (PubMed, APA Psycinfo and Web of Science) were searched from inception to November 2023. Protocol was registered in PROSPERO under the identifier CRD42023476603. A total of twenty-two studies, including four randomized-controlled trials and eighteen open-label trials were included. All studies reported alleviation of anhedonia symptoms following ketamine or esketamine administration, regardless of the number of infusions. Several important limitations were included, first and foremost low number of placebo-controlled randomized-controlled trials. This review indicates a potential anti-anhedonic effect of ketamine in patients with depression. Several trials used neuroimaging techniques which confirm ketamine's effect on functional connectivity correlating with the improvement in anhedonia. Despite considerable variations in methodology and the specific brain regions investigated, these studies collectively point towards ketamine's neuroplastic effects in mitigating anhedonia.

Changes of anhedonia and cognitive symptoms in first episode of depression and recurrent depression, an analysis of data from NSSD

BACKGROUND

Anhedonia and cognitive impairment are core features of major depressive disorder (MDD), and are essential to the treatment and prognosis. Here, we aimed to investigate anhedonia and its cognitive correlates between first episode of depression (FED) and recurrent depression (RD), which was part of the National Survey on Symptomatology of Depression.

METHODS

In this study, 1400 drug naïve FED patients and 487 on medicine RD patients were included. Differences of anhedonia, cognitive symptoms and other clinical characteristics between groups were compared via Student's t-test, or the chi-square test as appropriate. Partial correlation analysis was used to analyze the correlations between anhedonia and cognitive symptoms after adjusting for potential confounders. A stepwise logistic regression analysis was performed to identify relapse risk factors among symptomatic variables, demographic factors, clinical characteristics and medication use.

RESULTS

Compared to FED, RD patients displayed more comprehensive depressive, impaired cognitive and anhedonia symptoms. Cognitive symptoms were significantly related with the anhedonia symptoms with varying aspects. Patients taking emotional stabilizers displayed more abnormal cognitive symptoms, followed by benzodiazepines, and finally SSRIs, SNRIs and TCAs. The effect of drug use on anhedonia is not as extensive as that of cognitive symptoms.

CONCLUSION

Collectively, the results of this investigation advance the knowledge on changes in anhedonia and cognitive symptoms in MDD.

LIMITATIONS

As this is a cross sectional study, it is difficult to draw any causal conclusions between cognitive impairment and anhedonia in MDD, and to ascertain the worse cognitive performances identified here were induced by current drug use.

Cognitive-affective processes and suicidality in response to repetitive transcranial magnetic stimulation for treatment resistant depression

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) can elicit 45-55 % response rates and may alleviate suicidality symptoms in treatment resistant depression (TRD). Blunted anticipatory reward sensitivity and negatively biased self-referential processing may predict trajectories of depressive and suicidality symptoms in rTMS for TRD and be modulated during treatment.

METHODS

Fifty-five individuals with TRD received four weeks of low-frequency rTMS applied to the right dorsolateral prefrontal cortex (LFR-rTMS) and were followed until 17 weeks post-baseline. Participants completed behavioral measures of anticipatory reward sensitivity and self-referential processing at baseline and five weeks post-baseline (approximately one-week post-treatment). We examined whether baseline anticipatory reward sensitivity and self-referential processing predicted trajectories of depressive and suicidality symptoms from baseline to follow-up and whether these cognitive-affective variables showed change from baseline to week five.

RESULTS

Anticipatory reward sensitivity and negative self-referential encoding at baseline were associated with higher overall depressive symptoms and suicidality from baseline to 17 weeks post-baseline. At week five, participants self-attributed a higher number of positive traits and a lower number of negative traits and had a lesser tendency to remember negative relative to positive traits they had self-attributed, compared to baseline.

LIMITATIONS

The specificity of these results to LFR-rTMS is unknown in the absence of a comparison group, and our relatively small sample size precluded the interpretation of null results.

CONCLUSIONS

Baseline blunted anticipatory reward sensitivity and negative biases in self-referential processing may be risk factors for higher depressive symptoms and suicidality during and after LFR-rTMS, and LFR-rTMS may modulate self-referential processing.

Biomarkers in Psychiatric Drug Development: From Precision Medicine to Novel Therapeutics

Burden of psychiatric disorders is compounded by their wide prevalence as well as the limited efficacy of currently available treatments and the current approaches for prescribing these treatments. The selection of treatments continues to be subjective and often results in a trial-and-error approach. Emerging research suggests that biological markers (or biomarkers) can be used to develop precision medicine approaches for psychiatric disorders. Furthermore, the biomarkers also promise to elucidate the underlying pathophysiological mechanisms which in turn can be used to develop novel therapeutic treatments. In this chapter we have focused on mood disorders and reviewed studies on electroencephalography (EEG), magnetic resonance imaging (MRI), and blood-based biomarkers that can guide selection of one treatment versus another (treatment-selection biomarker) as well as biomarkers that can guide the development of novel therapeutics. These studies suggest that the use of objective physiological data is poised to alter the landscape of psychiatric diagnosis and treatment. However, practical and economic barriers remain as major hurdles. The key to finding such translational diagnostic and therapeutic biomarkers is a better understanding of the underlying pathophysiology, and despite the tremendous advances in neuroscience, it is clear there remains much left to be elucidated.

Elevated Effort Cost Identified by Computational Modeling as a Distinctive Feature Explaining Multiple Behaviors in Patients With Depression

BACKGROUND

Motivational deficit is a core clinical manifestation of depression and a strong predictor of treatment failure. However, the underlying mechanisms, which cannot be accessed through conventional questionnaire-based scoring, remain largely unknown. According to decision theory, apathy could result either from biased subjective estimates (of action costs or outcomes) or from dysfunctional processes (in making decisions or allocating resources).

METHODS

Here, we combined a series of behavioral tasks with computational modeling to elucidate the motivational deficits of 35 patients with unipolar or bipolar depression under various treatments compared with 35 matched healthy control subjects.

RESULTS

The most striking feature, which was observed independent of medication across preference tasks (likeability ratings and binary decisions), performance tasks (physical and mental effort exertion), and instrumental learning tasks (updating choices to maximize outcomes), was an elevated sensitivity to effort cost. By contrast, sensitivity to action outcomes (reward and punishment) and task-specific processes were relatively spared.

CONCLUSIONS

These results highlight effort cost as a critical dimension that might explain multiple behavioral changes in patients with depression. More generally, they validate a test battery for computational phenotyping of motivational states, which could orientate toward specific medication or rehabilitation therapy, and thereby help pave the way for more personalized medicine in psychiatry.

Neural substrates of reward anticipation and outcome in schizophrenia: a meta-analysis of fMRI findings in the monetary incentive delay task

Dysfunction of the mesocorticolimbic dopaminergic reward system is a core feature of schizophrenia (SZ), yet its precise contributions to different stages of reward processing and their relevance to disease symptomology are not fully understood. We performed a coordinate-based meta-analysis, using the monetary incentive delay task, to identify which brain regions are implicated in different reward phases in functional magnetic resonance imaging in SZ. A total of 17 studies (368 SZ and 428 controls) were included in the reward anticipation, and 10 studies (229 SZ and 281 controls) were included in the reward outcome. Our meta-analysis revealed that during anticipation, patients showed hypoactivation in the striatum, anterior cingulate cortex, median cingulate cortex (MCC), amygdala, precentral gyrus, and superior temporal gyrus compared with controls. Striatum hypoactivation was negatively associated with negative symptoms and positively associated with the proportion of second-generation antipsychotic users (percentage of SGA users). During outcome, patients displayed hyperactivation in the striatum, insula, amygdala, hippocampus, parahippocampal gyrus, cerebellum, postcentral gyrus, and MCC, and hypoactivation in the dorsolateral prefrontal cortex (DLPFC) and medial prefrontal cortex (mPFC). Hypoactivity of mPFC during outcome was negatively associated with positive symptoms. Moderator analysis showed that the percentage of SGA users was a significant moderator of the association between symptom severity and brain activity in both the anticipation and outcome stages. Our findings identified the neural substrates for different reward phases in SZ and may help explain the neuropathological mechanisms underlying reward processing deficits in the disorder.

MRI predictors of pharmacotherapy response in major depressive disorder

Major depressive disorder is among the most prevalent psychiatric disorders, exacting a substantial personal, social, and economic toll. Antidepressant treatment typically involves an individualized trial and error approach with an inconsistent success rate. Despite a pressing need, no reliable biomarkers for predicting treatment outcome have yet been discovered. Brain MRI measures hold promise in this regard, though clinical translation remains elusive. In this review, we summarize structural MRI and functional MRI (fMRI) measures that have been investigated as predictors of treatment outcome. We broadly divide these into five categories including three structural measures: volumetric, white matter burden, and white matter integrity; and two functional measures: resting state fMRI and task fMRI. Currently, larger hippocampal volume is the most widely replicated predictor of successful treatment. Lower white matter hyperintensity burden has shown robustness in late life depression. However, both have modest discriminative power. Higher fractional anisotropy of the cingulum bundle and frontal white matter, amygdala hypoactivation and anterior cingulate cortex hyperactivation in response to negative emotional stimuli, and hyperconnectivity within the default mode network (DMN) and between the DMN and executive control network also show promise as predictors of successful treatment. Such network-focused measures may ultimately provide a higher-dimensional measure of treatment response with closer ties to the underlying neurobiology.

Shared and distinct reward neural mechanisms among patients with schizophrenia, major depressive disorder, and bipolar disorder: an effort-based functional imaging study

Unwillingness to exert effort for rewards has been found in patients with schizophrenia (SCZ), major depressive disorder (MDD), and bipolar disorder (BD), but the underlying shared and distinct reward neural mechanisms remain unclear. This study aimed to compare the neural correlates of such impairments across different diagnoses. The neural responses in an effort-expenditure for reward task (EEfRT) were assessed in 20 SCZ patients, 23 MDD patients, 17 BD patients, and 30 healthy controls (HC). The results found shared activation in the cingulate gyrus, the medial frontal gyrus, and the middle frontal gyrus during the EEfRT administration. Compared to HC, SCZ patients exhibited stronger variations of functional connectivity between the right caudate and the left amygdala, the left hippocampus and the left putamen, with increase in reward magnitude. In MDD patients, an enhanced activation compared to HC in the right superior temporal gyrus was found with the increase of reward magnitude. The variations of functional connectivity between the caudate and the right cingulate gyrus, the left postcentral gyrus and the left inferior parietal lobule with increase in reward magnitude were weaker than that found in HC. In BD patients, the degree of activation in the left precuneus was increased, but that in the left dorsolateral prefrontal cortex was decreased with increase in reward probability compared to HC. These findings demonstrate both shared and distinct reward neural mechanisms associated with EEfRT in patients with SCZ, MDD, and BD, implicating potential intervention targets to alleviate amotivation in these clinical disorders.

Disrupted reward processing in Parkinson's disease and its relationship with dopamine state and neuropsychiatric syndromes: a systematic review and meta-analysis

BACKGROUND

Neuropsychiatric symptoms are common in Parkinson's disease (PD) and predict poorer outcomes. Reward processing dysfunction is a candidate mechanism for the development of psychiatric symptoms including depression and impulse control disorders (ICDs). We aimed to determine whether reward processing is impaired in PD and its relationship with neuropsychiatric syndromes and dopamine replacement therapy.

METHODS

The Ovid MEDLINE/PubMed, Embase and PsycInfo databases were searched for articles published up to 5 November 2020. Studies reporting reward processing task performance by patients with PD and healthy controls were included. Summary statistics comparing reward processing between groups were converted to standardised mean difference (SMD) scores and meta-analysed using a random effects model.

RESULTS

We identified 55 studies containing 2578 participants (1638 PD and 940 healthy controls). Studies assessing three subcomponent categories of reward processing tasks were included: option valuation (n=12), reinforcement learning (n=37) and reward response vigour (n=6). Across all studies, patients with PD on medication exhibited a small-to-medium impairment versus healthy controls (SMD=0.34; 95% CI 0.14 to 0.53), with greater impairments observed off dopaminergic medication in within-subjects designs (SMD=0.43, 95% CI 0.29 to 0.57). Within-subjects subcomponent analysis revealed impaired processing off medication on option valuation (SMD=0.57, 95% CI 0.39 to 0.75) and reward response vigour (SMD=0.36, 95% CI 0.13 to 0.59) tasks. However, the opposite applied for reinforcement learning, which relative to healthy controls was impaired on-medication (SMD=0.45, 95% CI 0.25 to 0.65) but not off-medication (SMD=0.28, 95% CI -0.03 to 0.59). ICD was the only neuropsychiatric syndrome with sufficient studies (n=13) for meta-analysis, but no significant impairment was identified compared tonon-ICD patients (SMD=-0.02, 95% CI -0.43 to 0.39).

CONCLUSION

Reward processing disruption in PD differs according to subcomponent and dopamine medication state, and warrants further study as a potential treatment target and mechanism underlying associated neuropsychiatric syndromes.

Beyond Response: Aiming for Quality Remission in Depression

To define treatment response in depression as at least a 50% reduction in total symptom severity is to accept that up to half of patients will continue to have residual symptoms, most commonly low mood/loss of interest, cognitive problems, lack of energy, and difficulty sleeping. In fact, patients' goals for treatment are to return to premorbid levels of functioning. This highlights the importance of assessing both functional outcomes and symptom improvement when evaluating the efficacy of antidepressant medication. Not all patients who achieve symptomatic response/remission will achieve a functional response/remission. In two studies (one with agomelatine and one with escitalopram), 54% of patients receiving agomelatine and 47% of those receiving escitalopram achieved a symptomatic response, and 53% of patients in each study achieved a functional response. However, 42% of patients receiving agomelatine and 35% of those receiving escitalopram had both a symptomatic and a functional response. The four symptoms of depression with the most marked effect on function are sad mood, impaired concentration, fatigue, and loss of interest. Low energy is particularly associated with poor occupational functioning, highlighting the importance of ongoing assessment of patients with depression, focusing particular attention on the symptoms that affect their ability to function, such as fatigue. Depending on the type of residual symptoms, some patients may benefit from combination therapy, such as adding dopamine modulator therapy. Antidepressant therapy is only effective if patients continue to take their medication, and high rates of early discontinuation have been reported. Therefore, when selecting treatment for depression, physicians can maximize the likelihood of adherence and persistence by taking into account both the antidepressant efficacy of treatment, its adverse effects and acceptability to patients.

Neuronally-enriched exosomal microRNA-27b mediates acute effects of ibuprofen on reward-related brain activity in healthy adults: a randomized, placebo-controlled, double-blind trial

This double-blind, randomized, within-subjects design evaluated whether acute administration of an anti-inflammatory drug modulates neuron-specific, inflammation-modulating microRNAs linked to macroscopic changes in reward processing. Twenty healthy subjects (10 females, 10 males) underwent a functional magnetic resonance imaging scan while performing a monetary incentive delay (MID) task and provided blood samples after administration of placebo, 200 mg, or 600 mg of ibuprofen. Neuronally-enriched exosomal microRNAs were extracted from serum and sequenced. Results showed that: (1) 600 mg of ibuprofen exhibited higher miR-27b-3p, miR-320b, miR-23b and miR-203a-3p expression than placebo; (2) higher mir-27b-3p was associated with lower insula activation during MID loss anticipation; and (3) there was an inverse relationship between miR-27b-3p and MID gain anticipation in bilateral putamen during placebo, a pattern attenuated by both 200 mg and 600 mg of ibuprofen. These findings are consistent with the hypothesis that miR-27b could be an important messaging molecule that is associated with regulating the processing of positive or negative valenced information.

Anhedonia in Depression and Bipolar Disorder

Anhedonia is a hallmark feature of depression and is highly prevalent among individuals with mood disorders. The history and neurobiology of anhedonia has been most extensively studied in the context of unipolar Major Depressive Disorder (MDD), with converging lines of evidence indicating that marked anhedonia heralds a more chronic and treatment-refractory illness course. Furthermore, findings from neuroimaging studies suggest that anhedonia in MDD is associated with aberrant reward-related activation in key brain reward regions, particularly blunted reward anticipation-related activation in the ventral striatum. However, the ongoing clinical challenge of treating anhedonia in the context of Bipolar Disorder (BD) also highlights important gaps in our understanding of anhedonia's prevalence, severity, and pathophysiology along the entire mood disorder spectrum. In addition, although current theoretical models posit a key role for reward hyposensitivity in BD depression, unlike studies in MDD, studies in BD do not clearly show evidence for reduced reward-related activation in striatal or other brain regions. Although further research is needed, the evidence to date hints at a divergent pathophysiology for anhedonia in unipolar and bipolar mood disorders, which, if better understood, could lead to significant improvements in the diagnosis and treatment of MDD and BD.

Therapeutic Potential of Vortioxetine for Anhedonia-Like Symptoms in Depression: A Post Hoc Analysis of Data from a Clinical Trial Conducted in Japan

AIM

Anhedonia in major depressive disorder may be resistant to first-line antidepressants. We examined the effect of vortioxetine, a multimodal antidepressant, on anhedonia-like symptoms in Japanese patients with major depressive disorder.

METHODS

This was a post hoc analysis of an 8-week, randomized, double-blind, placebo-controlled, phase 3 study of vortioxetine (10 mg or 20 mg) in Japanese patients aged 20-75 years with recurrent major depressive disorder and a Montgomery-Åsberg Depression Rating Scale (MADRS) total score of at least 26. The primary outcome was the mean change from baseline to week 8 in anhedonia-like symptoms as measured by MADRS anhedonia factor score, composed of: Q1, apparent sadness; Q2, reported sadness; Q6, concentration; Q7, lassitude; and Q8, inability to feel. Mean change in MADRS total score and anhedonia factor score were compared among treatment groups, with data categorized by median baseline anhedonia factor score (0-17 or ≥18).

RESULTS

Data were available for 489 patients. The least-squares mean difference in MADRS anhedonia factor score change from baseline to week 8 versus placebo was -1.34 for vortioxetine 10 mg (P = 0.0300) and -1.77 for vortioxetine 20 mg (P = 0.0044). The least-squares mean difference between vortioxetine and placebo in MADRS total score change from baseline to week 8 was -3.11 (10 mg dose) and -3.37 (20 mg dose) for patients with a higher baseline anhedonia factor score (≥18), and -2.08 (10 mg) and -2.61 (20 mg) for patients with a lower baseline score (0-17).

CONCLUSION

This post hoc analysis suggests that vortioxetine may have therapeutic potential in patients with anhedonia-like symptoms of major depressive disorder. ClinicalTrials.gov identifier for primary study: NCT02389816.

Intrinsic Connectivity Networks of Glutamate-Mediated Antidepressant Response: A Neuroimaging Review

Conventional monoamine-based pharmacotherapy, considered the first-line treatment for major depressive disorder (MDD), has several challenges, including high rates of non-response. To address these challenges, preclinical and clinical studies have sought to characterize antidepressant response through monoamine-independent mechanisms. One striking example is glutamate, the brain's foremost excitatory neurotransmitter: since the 1990s, studies have consistently reported altered levels of glutamate in MDD, as well as antidepressant effects following molecular targeting of glutamatergic receptors. Therapeutically, this has led to advances in the discovery, testing, and clinical application of a wide array of glutamatergic agents, particularly ketamine. Notably, ketamine has been demonstrated to rapidly improve mood symptoms, unlike monoamine-based interventions, and the neurobiological basis behind this rapid antidepressant response is under active investigation. Advances in brain imaging techniques, including functional magnetic resonance imaging, magnetic resonance spectroscopy, and positron emission tomography, enable the identification of the brain network-based characteristics distinguishing rapid glutamatergic modulation from the effect of slow-acting conventional monoamine-based pharmacology. Here, we review brain imaging studies that examine brain connectivity features associated with rapid antidepressant response in MDD patients treated with glutamatergic pharmacotherapies in contrast with patients treated with slow-acting monoamine-based treatments. Trends in recent brain imaging literature suggest that the activity of brain regions is organized into coherent functionally distinct networks, termed intrinsic connectivity networks (ICNs). We provide an overview of major ICNs implicated in depression and explore how treatment response following glutamatergic modulation alters functional connectivity of limbic, cognitive, and executive nodes within ICNs, with well-characterized anti-anhedonic effects and the enhancement of "top-down" executive control. Alterations within and between the core ICNs could potentially exert downstream effects on the nodes within other brain networks of relevance to MDD that are structurally and functionally interconnected through glutamatergic synapses. Understanding similarities and differences in brain ICNs features underlying treatment response will positively impact the trajectory and outcomes for adults suffering from MDD and will facilitate the development of biomarkers to enable glutamate-based precision therapeutics.

Acute Neurofunctional Effects of Escitalopram in Pediatric Anxiety: A Double-Blind, Placebo-Controlled Trial

OBJECTIVE

Amygdala-ventrolateral prefrontal cortex (VLPFC) circuitry is disrupted in pediatric anxiety disorders, yet how selective serotonin reuptake inhibitors (SSRIs) affect this circuitry is unknown. We examined the impact of the SSRI escitalopram on functional connectivity (FC) within this circuit, and whether early FC changes predicted treatment response in adolescents with generalized anxiety disorder (GAD).

METHOD

Resting-state functional magnetic resonance (MR) images were acquired before and after 2 weeks of treatment in 41 adolescents with GAD (12-17 years of age) who received double-blind escitalopram or placebo for 8 weeks. Change in amygdala-based whole-brain FC and anxiety severity were analyzed.

RESULTS

Controlling for age, sex, and pretreatment anxiety, escitalopram increased amygdala-VLPFC connectivity compared to placebo (F = 17.79, p = .002 FWE-corrected). This early FC change predicted 76.7% of the variability in improvement trajectory in patients who received escitalopram (p < .001) but not placebo (p = .169); the predictive power of early amygdala-VLPFC FC change significantly differed between placebo and escitalopram (p = .013). Furthermore, this FC change predicted improvement better than baseline FC or clinical/demographic characteristics. Exploratory analyses of amygdala subfields' FC revealed connectivity of left basolateral amygdala (BLA) -VLPFC (F = 19.64, p < .001 FWE-corrected) and superficial amygdala-posterior cingulate cortex (F = 22.92, p = .001 FWE-corrected) were also increased by escitalopram, but only BLA-VLPFC FC predicted improvement in anxiety over 8 weeks of treatment.

CONCLUSION

In adolescents with GAD, escitalopram increased amygdala-prefrontal connectivity within the first 2 weeks of treatment, and the magnitude of this change predicted subsequent clinical improvement. Early normalization of amygdala-VLPFC circuitry might represent a useful tool for identifying future treatment responders as well as a promising biomarker for drug development.

CLINICAL TRIAL REGISTRATION INFORMATION

Neurofunctional Predictors of Escitalopram Treatment Response in Adolescents With Anxiety; https://www.clinicaltrials.gov/; NCT02818751.

State Anhedonia in Young Healthy Adults: Psychometric Properties of the German Dimensional Anhedonia Rating Scale (DARS) and Effects of the COVID-19 Pandemic

Healthy reward processing is a complex interplay of several components. Recent self-report measures of anhedonia, the decrease or loss of hedonic capacity, take this complexity into account. The Dimensional Anhedonia Rating Scale (DARS) measures interest, motivation, effort and consummatory pleasure across four domains: hobbies, food/drink, social activities and sensory experiences. In the present cross-sectional survey study, we validated the German version of the DARS in a sample of 557 young healthy adults. Factor structure as well as convergent and divergent validity were assessed. As a secondary aim, we examined the effects of the COVID-19 pandemic on state anhedonia and depression severity. Our results suggest good convergent and divergent validity and high internal consistency of the German DARS. The original differentiation of four factors mapping onto the four domains was confirmed and measurement invariance before and during the COVID-19 pandemic was established. We conclude that the DARS is a valid instrument to comprehensively assess state anhedonia in healthy German samples. Future studies should further assess the utility of the German DARS in clinical contexts. In line with many previous studies, participants during the pandemic reported significantly higher levels of depressive symptoms compared to participants in the months before. We found no indication that the COVID-19 pandemic affected state hedonic capacity.

Interest-activity symptom severity predicts response to ketamine infusion in treatment-resistant depression

BACKGROUND

Interest and activity are part of the positive mood domain. Evidence suggests the symptom domain of interest-activity at baseline as a clinical predictor for treatment response to traditional antidepressants. However, whether this domain is related to the response to a single low-dose ketamine infusion remains unclear.

METHODS

Seventy-one patients with treatment-resistant depression were randomized to 3 treatment groups: a single 0.5 or 0.2 mg/kg ketamine or normal saline placebo infusion. Depressive symptoms were measured using the 17-item Hamilton Depression Rating Scale before infusions and at postinfusion period (at 40 min and up to 2 weeks). Low (mild) versus medium versus high (severe) interest-activity symptom domain groups were classified on the basis of the cutoff point of ± 0.4 standard deviation. The effect of baseline interest-activity symptoms on outcomes was tested using generalized estimating equation models.

RESULTS

The interest-activity symptom domain as a continuous variable (β = 8.413, p = .016) was related to the trajectory of depressive symptoms. Stratified by levels of the interest-activity symptom domain, in the low interest-activity, 0.2 mg/kg ketamine infusion (β = 0.013) demonstrated the greatest antidepressant effect (p < .01) compared with 0.5 mg/kg ketamine (β = 0.739) and placebo infusions; however, in the high interest-activity, 0.5 mg/kg ketamine infusion (β = 0.001) demonstrated the best antidepressant effect (p < .01) compared with 0.2 mg/kg ketamine (β = 1.372) and placebo infusions.

DISCUSSION

The symptom domain of interest-activity was an independent predictor for the treatment response to a single low-dose ketamine infusion.

Reward processing in major depressive disorder and prediction of treatment response - Neuropharm study

Major depressive disorder (MDD) is a prevalent brain disorder for which anhedonia is a core symptom, indicating aberrations in the neural processing of reward. The striatum, medial prefrontal cortex (mPFC) and anterior insula (AI) are core reward processing regions. Here we used a reward-related, card-guessing functional magnetic resonance imaging (fMRI) paradigm to assay brain responses to reward in 90 MDD individuals and 58 healthy controls. We evaluated group differences in task-responsive, reward-related striatal, mPFC, and AI reactivity and whether baseline reactivity predicted an eight-week escitalopram antidepressant treatment response in MDD individuals. Thirty-eight MDD individuals also completed the reward paradigm after treatment and we evaluated antidepressant effects on reward reactivity estimates. Multivariate statistical analysis of task-responsive striatum, mPFC and AI brain responses did not reveal statistically significant differences between MDD and HC individuals (p_uncorrected>0.23). Logistic regression models (five-fold cross-validation, statistical significance assessed with permutation testing) also did not support that baseline reward-related brain responses significantly predicted antidepressant treatment response (p_uncorrected>0.39). Finally, reward-related brain responses were not statistically significantly changed over the course of treatment (p_uncorrected>0.27). Our findings in a comparatively large MDD cohort do not support that these reward-related fMRI brain responses are informative biomarkers of MDD or antidepressant treatment response to escitalopram.

Functional neuroimaging biomarkers of resilience in major depressive disorder

PURPOSE OF REVIEW

In this review we provide an overview of definitions and determinants of resilience in the context of neuroimaging research in major depressive disorder (MDD). We summarize emerging literature on functional neuroimaging biomarkers of resilience in MDD and discuss their clinical relevance and implications for future research.

RECENT FINDINGS

Resilience in MDD is characterized by dissociable profiles of activation and functional connectivity within brain networks involved in cognitive control, emotion regulation, and reward processing. Increased activation of frontal cortical brain regions implicated in cognitive appraisal and emotion regulation is a common characteristic of resilient individuals at high risk for MDD and of individuals with MDD with a favorable illness course. Furthermore, significant associations between fronto-striato-limbic functional connectivity and both positively interpreted stressful life events in resilient high-risk individuals and a favorable response to first-line treatments in depressed individuals suggest that neuro-compensatory changes and experience-dependent plasticity underlie resilience in MDD.

SUMMARY

Emerging research has identified functional neuroimaging biomarkers of resilience in MDD. A continued focus on identifying neurobiological underpinnings of resilience, in the context of dynamic environmental and developmental influences, will advance our understanding of resilience and improve approaches to prevention and treatment of MDD.

Behavioral Activation Therapy on Reward Seeking Behaviors in Depressed People: An Experimental study

Introduction: Behavioral activation therapy (BAT) is designed to help individuals’ approach and access sources of positive reinforcement in their life, which can serve a natural antidepressant function and efforts to help depressed people reengage in their life through focused activation strategies.

Methods: In this study, 60 individuals were selected and randomly assigned to intervention and control groups. The intervention group received behavioral activation treatment, including eight treatment sessions and 5 weeks later, a follow-up study was conducted. The data were collected, using a Beck Depression Inventory-II and behavioral activation system (BIS)/ behavioral inhibition system (BAS) Carver and White questionnaires, before the intervention and after the intervention and five weeks after the intervention. SPSS 23 and analysis of covariance (ANCOVA) was used for data analysis.

Results: Results showed a significant increase in the two components of the BAS including reward seeking and response to reward in the intervention group, which indicates an increase in positive affect and appetitive motivation for reward seeking and decreases the risk of depression. Also, the results showed a significant decrease in the BIS and depression in the intervention group, which indicates a decline in experiencing negative emotions.

Conclusion: The implementation of BAT will cause depressed people to try to maximize future rewards and it’s effective in improving the reward seeking and reward response in depressed people because this treatment will increase the positive reinforcement and lead to learning cues that predict possible rewards in environments.