Assessing anhedonia in depression: Potentials and pitfalls

Cannabis and anhedonia: A systematic review

This paper employs a systematic review to examine the correlation between anhedonia and marijuana use, exploring whether individuals with anhedonia use marijuana as a coping mechanism or if marijuana use plays a role in the onset of anhedonia. The search utilised PubMed and Web of Science databases, following PRISMA guidelines for paper selection. A total of 21 papers were selected to address this inquiry, and assessments were carried out using the Risk of Bias in Non-randomized Studies of Exposures (ROBINS-E) tool. The results revealed that 17 studies exhibited moderate and low risk of bias. The evaluation encompassed a total of 12,427 participants, including both animals and humans. Experimental animal studies focused on exploring the association between cannabidiol (CBD) and anhedonia, while human studies primarily employed observational research, examining various forms of anhedonia in individuals with or without mental disorders such as depression or psychosis. These studies also delved into understanding the effects of anhedonia during adolescence and explored the causal relationship between these concepts. The findings indicate a reciprocal rather than unidirectional relationship, establishing that initial anhedonia predisposes individuals to cannabis use, and subsequent consumption significantly intensifies the anhedonia experienced. Particularly, the studies placed special emphasis on adolescents and individuals with mental disorders.

New insights about the antidepressant-like effects of riparin A in a chronic murine model of depression

Riparin A is a synthetic form of natural riparins. Acute scale studies that take into consideration the structure-activity relationship have shown preliminary evidence of antidepressant and anxiolytic effects of riparin A, similar to that already known for other riparins. However, for better pharmacological characterization of this new compound, further studies are required. The aim of this work was to evaluate the effect of chronic treatment with riparin A (10 mg/kg; intraperitoneally) on depressive-like behavior in the forced swimming test and tail suspension test, as well as the reduction of anhedonia in the sucrose preference test, and on anxiety-like behavior in the open field and elevated plus maze apparatus, triggered in rats previously subjected to unpredictable chronic mild stress by 4 weeks. In addition, a pentobarbital-induced sleep time test was also used. Riparin A reduced the duration of immobility in both the forced swimming test and tail suspension test, as well as attenuated the anhedonia in the sucrose preference test. Furthermore, riparin A appears to produce anxiolytic effects in rats exposed to an open field and elevated plus maze, while increasing the alertness/vigilance in rats submitted to pentobarbital-induced sleep time test, without altering their locomotor integrity. Our results suggest that chronic riparin A appears to be a potential pharmacological target for new studies on the control of depression- and anxiety-like behaviors in stressed rats.

Treating Depression to Improve Survival in Coronary Heart Disease: What Have We Learned?

Major depressive disorder is a well-established risk factor for cardiac events in patients with coronary heart disease, but clinical trials have produced little evidence that treating depression reliably improves cardiac event-free survival in these patients. In this review, we offer evidence that certain symptoms that commonly remain after otherwise successful treatment of depression-insomnia, fatigue, and anhedonia-independently predict cardiac events. This may help to explain the failure of previous depression treatment trials to improve cardiac event-free survival even when other symptoms of depression improve. We thus propose that adverse cardiovascular effects that have long been attributed to syndromal depression may be instead caused by persistent fatigue, insomnia, and anhedonia, regardless of whether other symptoms of depression are present. We also identify interventions for these symptoms and call for more research to evaluate their effectiveness in depressed patients with coronary heart disease.

Common and separable neural alterations in adult and adolescent depression - Evidence from neuroimaging meta-analyses

Depression is a highly prevalent and debilitating mental disorder that often begins in adolescence. However, it remains unclear whether adults and adolescents with depression exhibit common or distinct brain dysfunctions during reward processing. We aimed to identify common and separable neurofunctional alterations during receipt of rewards and brain structure in adolescents and adults with depression. A coordinate-based meta-analysis was employed using Seed-based d mapping with permutation of subject images (SDM-PSI). Compared with healthy controls, both age groups exhibited common activity decreases in the right striatum (putamen, caudate) and subgenual ACC. Adults with depression showed decreased reactivity in the right putamen and subgenual ACC, while adolescents with depression showed decreased activity in the left mid cingulate, right caudate but increased reactivity in the right postcentral gyrus. This meta-analysis revealed shared (caudate) and separable (putamen and mid cingulate cortex) reward-related alterations in adults and adolescents with depression. The findings suggest age-specific neurofunctional alterations and stress the importance of adolescent-specific interventions that target social functions.

Association of anhedonia with brain-derived neurotrophic factor and interleukin-10 in major depressive disorder

BACKGROUND

Anhedonia, a core symptom of major depressive disorder (MDD), manifests in two forms: anticipatory and consummatory, reflecting a diminished capacity to anticipate or enjoy pleasurable activities. Prior studies suggest that brain-derived neurotrophic factor (BDNF) and interleukin-10 (IL-10) may play key roles in the emergence of anhedonia in MDD. The specific relationships between these biomarkers and the two forms of anhedonia remain unclear. This study investigated the potential links between BDNF, IL-10, and both forms of anhedonia in MDD patients.

METHODS

This study included 43 participants diagnosed with MDD and 58 healthy controls. It involved detailed assessments of depression and anxiety levels, anticipatory and consummatory pleasure, cognitive functions, and a broad spectrum of plasma biomarkers, such as C-reactive protein, various interleukins, and BDNF. Using partial correlation, variables related to pleasant experiences were identified. Stepwise multiple linear regression analysis was applied to pinpoint the independent predictors of anhedonia in the MDD group.

RESULTS

Demographically, both groups were comparable in terms of age, sex, body mass index, educational year, and marital status. Individuals with MDD displayed markedly reduced levels of anticipatory and consummatory pleasure, higher anxiety, and depression scores compared to healthy controls. Additionally, cognitive performance was notably poorer in the MDD group. These patients also had lower plasma diamine oxidase levels. Analysis linked anhedonia to impaired delayed memory. Regression results identified IL-10 and BDNF as independent predictors of anticipatory and consummatory anhedonia, respectively.

CONCLUSION

These findings demonstrate that anticipatory and consummatory anhedonia are influenced by independent factors, thereby providing critical insights into the distinct neuroimmunological mechanisms that underlie various forms of anhedonia. Clinicl Trial Registration Number: NCT03790085.

Improving Mental Health Outcomes in Patients with Major Depressive Disorder in the Gulf States: A Review of the Role of Electronic Enablers in Monitoring Residual Symptoms

Up to 75% of individuals with major depressive disorder (MDD) may have residual symptoms such as amotivation or anhedonia, which prevent full functional recovery and are associated with relapse. Globally and in the Gulf region, primary care physicians (PCPs) have an important role in alleviating stigma and in identifying and monitoring the residual symptoms of depression, as PCPs are the preliminary interface between patients and specialists in the collaborative care model. Therefore, mental healthcare upskilling programmes for PCPs are needed, as are basic instruments to evaluate residual symptoms swiftly and accurately in primary care. Currently, few if any electronic enablers have been designed to specifically monitor residual symptoms in patients with MDD. The objectives of this review are to highlight how accurate evaluation of residual symptoms with an easy-to-use electronic enabler in primary care may improve functional recovery and overall mental health outcomes, and how such an enabler may guide pharmacotherapy selection and positively impact the patient journey. Here, we show the potential advantages of electronic enablers in primary care, which include the possibility for a deeper "dive" into the patient journey and facilitation of treatment optimisation. At the policy and practice levels, electronic enablers endorsed by government agencies and local psychiatric associations may receive greater PCP attention and backing, improve patient involvement in shared clinical decision-making, and help to reduce the general stigma around mental health disorders. In the Gulf region, an easy-to-use electronic enabler in primary care, incorporating aspects of the Hamilton Depression Rating Scale to monitor amotivation, and aspects of the Montgomery-Åsberg Depression Rating Scale to monitor anhedonia, could markedly improve the patient journey from residual symptoms through to full functional recovery in individuals with MDD.

Aticaprant, a kappa opioid receptor antagonist, and the recovered 'interest and pleasure' in the concept of major depressive disorder

Lack of positive mood and anhedonia probably are the most specific depressive symptoms. Anhedonia is a multifaceted concept: the clinical language describes anticipatory/consummatory anhedonia and sensory/social anhedonia while the cognitive neuroscience language describes readiness for reward, energy expenditure to attain reward, updating reward presence and value. Mounting evidence supports the potential of kappa-opioid receptor (KOR) antagonists as novel pharmacotherapies for major depressive disorder : aticaprant is a potent, selective, short-acting KOR antagonist. The fast-fail approach evaluated the impact of aticaprant on the brain circuitry hypothesized to mediate anhedonia and significantly increased fMRI activation in the ventral striatal activation during reward anticipation as compared to placebo; the aticaprant induced changes in the self-reported psychological measures of anhedonia were rather inconsistent. The recently reported results of a phase 2a randomized, double-blind, placebo-controlled trial investigating the efficacy and safety of aticaprant, co-administered to an oral SSRI/SNRI antidepressant in depressed patients who had an inadequate response to 1 or 2 antidepressants. The improvement from baseline favoured the co-administration of aticaprant over the co-administration of placebo at all time points (during 6 weeks), and this was confirmed by higher response rates with aticaprant. A mid-split of patients with higher or lower than median anhedonia also showed that the patients with higher baseline anhedonia had the largest decrease on the MADRS. Tolerability and safety were reassuring. These promising results of the co-administration of aticaprant to an SSRI/SNRI in depressed patients with prominent anhedonia support he further investigation of aticaprant in larger trials.

Effects of anhedonia on health-related quality of life and functional outcomes in major depressive disorder: A systematic review and meta-analysis

BACKGROUND

Major depressive disorder (MDD) is a heterogeneous group of mood disorders. A prominent symptom domain is anhedonia narrowly defined as a loss of interest and ability to experience pleasure. Anhedonia is associated with depressive symptom severity, MDD prognosis, and suicidality. We perform a systematic review and meta-analysis of extant literature investigating the effects of anhedonia on health-related quality of life (HRQoL) and functional outcomes in persons with MDD.

METHODS

A literature search was conducted on PubMed, OVID databases, and SCOPUS for published articles from inception to November 2023, reporting on anhedonia and patient-reported outcomes in persons with MDD. The reported correlation coefficients between anhedonia and self-reported measures of both HRQoL and functional outcomes were pooled using a random effects model.

RESULTS

We identified 20 studies that investigated anhedonia with HRQoL and/or functional outcomes in MDD. Anhedonia as measured by the Snaith-Hamilton Pleasure Scale (SHAPS) scores had a statistically significant correlation with patient-reported HRQoL (r = -0.41 [95 % CI = -0.60, -0.18]) and functional impairment (r = 0.39 [95 % CI = 0.22, 0.54]).

LIMITATIONS

These preliminary results primarily investigate correlations with consummatory anhedonia and do not distinguish differences in anticipatory anhedonia, reward valuation or reward learning; therefore, these results require replication.

CONCLUSIONS

Persons with MDD experiencing symptoms of anhedonia are more likely to have worse prognosis including physical, psychological, and social functioning deficits. Anhedonia serves as an important predictor and target for future therapeutic and preventative tools in persons with MDD.

Anhedonia is associated with overgeneralization of conditioned fear during late adolescence and early adulthood

BACKGROUND

Pavlovian fear paradigms involve learning to associate cues with threat or safety. Aberrances in Pavlovian fear learning correlate with psychopathology, especially anxiety disorders. This study evaluated symptom dimensions of anxiety and depression in relation to Pavlovian fear acquisition and generalization.

METHODS

256 participants (70.31 % female) completed a Pavlovian fear acquisition and generalization paradigm at ages 18-19 and 21-22 years. Analyses focused on indices of learning (self-reported US expectancy, skin conductance). Multilevel models tested associations with orthogonal symptom dimensions (Anhedonia-Apprehension, Fears, General Distress) at each timepoint.

RESULTS

All dimensions were associated with weaker acquisition of US expectancies at each timepoint. Fears was associated with overgeneralization only at age 21-22. General Distress was associated with overgeneralization only at age 18-19. Anhedonia-Apprehension was associated with overgeneralization at ages 18-19 and 21-22.

CONCLUSIONS

Anhedonia-Apprehension disrupts Pavlovian fear acquisition and increases overgeneralization of fear. These effects may emerge during adolescence and remain into young adulthood. General Distress and Fears also contribute to overgeneralization of fear, but these effects may vary as prefrontal mechanisms of fear inhibition continue to develop during late adolescence. Targeting specific symptom dimensions, particularly Anhedonia-Apprehension, may decrease fear generalization and augment interventions built on Pavlovian principles, such as exposure therapy.

Reinforcement learning of altruistic punishment differs between cultures and across the lifespan

Altruistic punishment is key to establishing cooperation and maintaining social order, yet its developmental trends across cultures remain unclear. Using computational reinforcement learning models, we provided the first evidence of how social feedback dynamically influences group-biased altruistic punishment across cultures and the lifespan. Study 1 (n = 371) found that Chinese participants exhibited higher learning rates than Americans when socially incentivized to punish unfair allocations. Additionally, Chinese adults showed slower learning and less exploration when punishing ingroups than outgroups, a pattern absent in American counterparts, potentially reflecting a tendency towards ingroup favoritism that may contribute to reinforcing collectivist values. Study 2 (n = 430, aged 12-52) further showed that such ingroup favoritism develops with age. Chinese participants' learning rates for ingroup punishment decreased from adolescence into adulthood, while outgroup rates stayed constant, implying a process of cultural learning. Our findings highlight cultural and age-related variations in altruistic punishment learning, with implications for social reinforcement learning and culturally sensitive educational practices promoting fairness and altruism.

Cognitive Signatures of Depressive and Anhedonic Symptoms and Affective States Using Computational Modeling and Neurocognitive Testing

BACKGROUND

Deeper phenotyping may improve our understanding of depression. Because depression is heterogeneous, extracting cognitive signatures associated with severity of depressive symptoms, anhedonia, and affective states is a promising approach.

METHODS

Sequential sampling models decomposed behavior from an adaptive approach-avoidance conflict task into computational parameters quantifying latent cognitive signatures. Fifty unselected participants completed clinical scales and the approach-avoidance conflict task by either approaching or avoiding trials offering monetary rewards and electric shocks.

RESULTS

Decision dynamics were best captured by a sequential sampling model with linear collapsing boundaries varying by net offer values, and with drift rates varying by trial-specific reward and aversion, reflecting net evidence accumulation toward approach or avoidance. Unlike conventional behavioral measures, these computational parameters revealed distinct associations with self-reported symptoms. Specifically, passive avoidance tendencies, indexed by starting point biases, were associated with greater severity of depressive symptoms (R = 0.34, p = .019) and anhedonia (R = 0.49, p = .001). Depressive symptoms were also associated with slower encoding and response execution, indexed by nondecision time (R = 0.37, p = .011). Higher reward sensitivity for offers with negative net values, indexed by drift rates, was linked to more sadness (R = 0.29, p = .042) and lower positive affect (R = -0.33, p = .022). Conversely, higher aversion sensitivity was associated with more tension (R = 0.33, p = .025). Finally, less cautious response patterns, indexed by boundary separation, were linked to more negative affect (R = -0.40, p = .005).

CONCLUSIONS

We demonstrated the utility of multidimensional computational phenotyping, which could be applied to clinical samples to improve characterization and treatment selection.

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.

Reduced generalization of reward among individuals with subthreshold depression: Behavioral and EEG evidence

Altered stimulus generalization has been well-documented in anxiety disorders; however, there is a paucity of research investigating this phenomenon in the context of depression. Depression is characterized by impaired reward processing and heightened attention to negative stimuli. It is hypothesized that individuals with depression exhibit reduced generalization of reward stimuli and enhanced generalization of loss stimuli. Nevertheless, no study has examined this process and its underlying neural mechanisms. In the present study, we recruited 25 participants with subthreshold depression (SD group) and 24 age-matched healthy controls (HC group). Participants completed an acquisition task, in which they learned to associate three distinct pure tones (conditioned stimuli, CSs) with a reward, a loss, or no outcome. Subsequently, a generalization session was conducted, during which similar tones (generalization stimuli, GSs) were presented, and participants were required to classify them as a reward tone, a loss tone, or neither. The results revealed that the SD group exhibited reduced generalization errors in the early phase of generalization, suggesting a diminished ability to generalize reward-related stimuli. The event-related potential (ERP) results indicated that the SD group exhibited decreased generalization of positive valence to reward-related GSs and heightened generalization of negative valence to loss-related GSs, as reflected by the N1 and P2 components. However, the late positive potential (LPP) was not modulated by depression in reward generalization or loss generalization. These findings suggested that individuals with subthreshold depression may have a blunted or reduced ability to generalize reward stimuli, shedding light on potential treatment strategies targeting this particular process.

A randomized controlled trial of brief behavioral activation plus savoring for positive affect dysregulation in university students

Rising rates of depression on university campuses accentuate the need for specific intervention. Interventions targeting disturbances in positive affect, in particular, remain sparse, yet such deficits interfere substantially with functioning and further exacerbate or maintain negative symptoms. The current study aimed to evaluate the impact of a virtual, two-session Behavioral Activation augmented with Savoring (BA + S) intervention compared to an Emotional Awareness (EA) control group in increasing positive affect. Sixty university students with low positive affect were randomized to BA + S or EA and completed 21 days of experience-sampling of positive affect. Weekly measures of positive and negative valence symptoms were assessed at baseline, sessions one and two, and at one-week follow-up. Through a prori analyses utilizing multilevel and multivariate multilevel models, our results demonstrate that daily positive affect measured via experience-sampling significantly improved in BA + S, whereas positive affect did not change for those receiving EA, though the interaction of condition and time was not significant. Furthermore, interactions in weekly variables were significant. Increases in positive valence symptoms (affect, anhedonia, etc.) were only reported for students receiving BA + S but not EA. Negative valence symptoms (affect, depression, general distress) improved in both conditions but with superior improvements in BA + S compared to EA. BA + S shows promise for a scalable and accessible intervention to university students with clinical levels of positive and negative affect. ClinicalTrials ID: NCT05234476.

Neural substrates of the interaction between effort-expenditure reward decision-making and outcome anticipation

OBJECTIVE

Reward anticipation is important for future decision-making, possibly due to re-evaluation of prior decisions. However, the exact relationship between reward anticipation and prior effort-expenditure decision-making, and its neural substrates are unknown.

METHOD

Thirty-three healthy participants underwent fMRI scanning while performing the Effort-based Pleasure Experience Task (E-pet). Participants were required to make effort-expenditure decisions and anticipate the reward.

RESULTS

We found that stronger anticipatory activation at the posterior cingulate cortex was correlated with slower reaction time while making decisions with a high-probability of reward. Moreover, the substantia nigra was significantly activated in the prior decision-making phase, and involved in reward-anticipation in view of its strengthened functional connectivity with the mammillary body and the putamen in trial conditions with a high probability of reward.

CONCLUSIONS

These findings support the role of reward anticipation in re-evaluating decisions based on the brain-behaviour correlation. Moreover, the study revealed the neural interaction between reward anticipation and decision-making.

Physiological paradigm for assessing reward prediction and extinction using cortical direct current potential responses in rats

Anticipating positive outcomes is a core cognitive function in the process of reward prediction. However, no neurophysiological method objectively assesses reward prediction in basic medical research. In the present study, we established a physiological paradigm using cortical direct current (DC) potential responses in rats to assess reward prediction. This paradigm consisted of five daily 1-h sessions with two tones, wherein the rewarded tone was followed by electrical stimulation of the medial forebrain bundle (MFB) scheduled at 1000 ms later, whereas the unrewarded tone was not. On day 1, both tones induced a negative DC shift immediately after auditory responses, persisting up to MFB stimulation. This negative shift progressively increased and peaked on day 4. Starting from day 3, the negative shift from 600 to 1000 ms was significantly larger following the rewarded tone than that following the unrewarded tone. This negative DC shift was particularly prominent in the frontal cortex, suggesting its crucial role in discriminative reward prediction. During the extinction sessions, the shift diminished significantly on extinction day 1. These findings suggest that cortical DC potential is related to reward prediction and could be a valuable tool for evaluating animal models of depression, providing a testing system for anhedonia.

Aberrant effort-based reward dynamics in anhedonia

Anhedonia is a transdiagnostic symptom and associated with a spectrum of reward deficits among which the motivational dysfunction is poorly understood. Previous studies have established the abnormal cost-benefit trade-off as a contributor to motivational deficits in anhedonia and its relevant psychiatric diseases. However, it remains elusive how the anhedonic neural dynamics underlying reward processing are modulated by effort expenditure. Using an effort-based monetary incentive delay task, the current event-related potential study examined the neural dynamics underlying the effort-reward interplay in anhedonia using a nonclinical sample who scored high or low on an anhedonia questionnaire. We found that effort prospectively decreased reward effect on the contingent variation negativity and the target-P3 but retrospectively enhanced outcome effect on the feedback-P3 following effort expenditure. Compared to the low-anhedonia group, the high-anhedonia group displayed a diminished effort effect on the target-P3 during effort expenditure and an increased effort-enhancement effect for neutral trials during the feedback-P3 period following effort expenditure. Our findings suggest that anhedonia is associated with an inefficient control and motivation allocation along the efforted-based reward dynamics from effort preparation to effort production.

The Swedish version of the Motivation and Pleasure Scale self-report (MAP-SR): psychometric properties in patients with schizophrenia or depression

PURPOSE

Negative symptoms are commonly regarded as a symptom dimension belonging to schizophrenia spectrum disorders but are also present in depression. The recently developed Clinical Assessment Interview for Negative Symptoms (CAINS) has shown to be reliable and valid. A corresponding self-report questionnaire has also been developed, named the Motivation and Pleasure Scale - Self Report (MAP-SR). The purpose was to evaluate the psychometric properties of the Swedish version of the MAP-SR in patients with either schizophrenia or depression.

MATERIALS AND METHODS

The MAP-SR was translated to Swedish. Participants were 33 patients with schizophrenia spectrum disorders and 52 patients with a depressive disorder and they completed the MAP-SR, the CAINS and other measures assessing adjacent psychopathology, functioning and cognition.

RESULTS

The internal consistency for the MAP-SR was adequate in both groups (schizophrenia spectrum α = .93, depressive disorder α = .82). Furthermore, the MAP-SR had a large correlation to the motivation and pleasure subscale of the CAINS in patients with schizophrenia disorders (r = -0.75, p < .001), however among patients with depression this correlation was medium-to-large (r = -0.48, p < 0.001).

CONCLUSIONS

Findings suggest that the Swedish version of the MAP-SR shows promise as a useful measure of motivation and pleasure, especially in patients with schizophrenia spectrum disorders. Furthermore, results also suggest that the MAP-SR does not assess negative symptoms specifically, but that there is an overlap between depressive and negative symptoms.

Estimating heterogeneity of treatment effect in psychiatric clinical trials

Currently, placebo-controlled clinical trials report mean change and effect sizes, which masks information about heterogeneity of treatment effects (HTE). Here, we present a method to estimate HTE and evaluate the null hypothesis (H0) that a drug has equal benefit for all participants (HTE=0). We developed measure termed 'estimated heterogeneity of treatment effect' or eHTE, which estimates variability in drug response by comparing distributions between study arms. This approach was tested across numerous large placebo-controlled clinical trials. In contrast with variance-based methods which have not identified heterogeneity in psychiatric trials, reproducible instances of treatment heterogeneity were found. For example, heterogeneous response was found in a trial of venlafaxine for depression (peHTE=0.034), and two trials of dasotraline for binge eating disorder (Phase 2, peHTE=0.002; Phase 3, 4mg peHTE=0.011; Phase 3, 6mg peHTE=0.003). Significant response heterogeneity was detected in other datasets as well, often despite no difference in variance between placebo and drug arms. The implications of eHTE as a clinical trial outcomes independent from central tendency of the group is considered and the important of the eHTE method and results for drug developers, providers, and patients is discussed.

Hypoactivation of ventromedial frontal cortex in major depressive disorder: an MEG study of the Reward Positivity

Background

The Reward Positivity (RewP) is sensitive and specific electrophysiological marker of reward receipt. These characteristics make it a compelling candidate marker of dysfunctional reward processing in major depressive disorder. We previously proposed that the RewP is a nexus of multiple aspects of reward variance, and that a diminished RewP in depression might only reflect a deficit in some of this variance. Specifically, we predicted a diminished ventromedial contribution in depression in the context of maintained reward learning.

Methods

Here we collected magnetoencephalographic (MEG) recordings of reward receipt in 43 individuals with major depressive disorder (MDD group) and 38 healthy controls (CTL group). MEG allows effective source estimation due to the absence of volume conduction that compromises electroencephalographic recordings.

Results

The MEG RewP analogue was generated by a broad set of cortical areas, yet only right ventromedial and right ventral temporal areas were diminished in MDD. These areas correlated with a principal component of anhedonia derived from multiple questionnaires. Compellingly, BA25 was the frontal region with the largest representation in both of these effects.

Conclusions

These findings not only advance our understanding underlying the computation of the RewP, but they also dovetail with convergent findings from other types of functional source imaging in depression, as well as from deep brain stimulation treatments. Together, these discoveries suggest that the RewP may be a valuable marker for objective assessment of reward affect and its disruption in major depression.

Validation of a touchscreen probabilistic reward task for mice: A reverse-translated assay with cross-species continuity

The Probabilistic Reward Task (PRT) is a laboratory-based technique used to objectively quantify responsivity to reward. The PRT was initially designed to identify reinforcement learning deficits in clinical populations and subsequently was reverse-translated for use in preclinical studies with rats and monkeys. In this task, subjects make visual discriminations and asymmetric probabilistic contingencies are arranged such that correct responses to one stimulus (rich) are reinforced more often than correct responses to the other (lean). Numerous studies have demonstrated that healthy subjects reliably develop a response bias toward the richly rewarded stimulus, whereas humans with anhedonia and laboratory animals with a history of chronic stress exhibit a blunted response bias. This is important because anhedonia, the loss of responsivity to previously rewarding stimuli, is a behavioral phenotype that is a cardinal feature of multiple neuropsychiatric conditions and is without approved pharmacotherapeutic options. To aid in addressing this critical treatment gap, this report describes validation of the first PRT designed for mice, which are a commonly utilized species in preclinical research toward neuropsychiatric medications development. Results reveal orderly psychophysical functions in response to asymmetric probabilistic contingencies in mice, with signal detection outcomes comparable to previous PRT findings in humans, rats, and monkeys. Taken together, such robust cross-species continuity in task performance confirms that the mouse is well-positioned to serve in bidirectional research efforts between human and animal laboratories. These efforts may accelerate the development of treatment options for anhedonia in the different neuropsychiatric conditions in which it is prominent.

Assessing the Link Between General Causality Orientations and Problem Gambling, and the Mediational Role of Nonattachment, Greed, and Anhedonia

Gambling is common in the US, yet nearly one in three players experience gambling-related problems. Using Self-Determination Theory, this study explores how three causality orientations-autonomous, controlled, and impersonal-affect the severity of problem gambling. The study further investigates the mediating roles of nonattachment, dispositional greed, and anhedonia to illuminate how these orientations relate to problem gambling. The data from 675 participants (59% male; Mean age = 40.4 years, SD = 12.9) via Amazon's Mechanical Turk were collected following a screening procedure to identify at-risk players. Findings showed that dispositional greed mediated the impact of a controlled orientation on problem gambling severity, while anhedonia mediated the effect of impersonal orientation. Unexpectedly, nonattachment did not explain the effect of autonomous orientation on problem gambling, though a negative association was still observed. This research enhances understanding of how individual differences and causality orientations contribute to problem gambling behavior. The implications are discussed.

Measurement invariance of the Personality Inventory for DSM-5 across sex

Introduction

There has been an international movement towards dimensional models of personality disorders (PDs) in the last decades, which culminated in the publication of the Alternative Model of Personality Disorders (AMPD) in the Emerging Measures and Models section of the DSM-5. This model was accompanied by a APA-sanctioned Personality Inventory for DSM-5 (PID-5) for the assessment of the AMPD pathological personality traits. One major issue with the assessment of personality disorders pertains to sex differences, and measurement invariance across sex in assessment instruments for PDs is necessary in order to ensure non-biased evaluations and to make valid comparisons between men and women. This study aimed to provide more information on measurement invariance across sex for the PID-5, using both the original scoring approach provided by the authors of the instrument and the scoring approach suggested by the APA in the published version of the PID-5.

Methods

This study was conducted with a sample of 2273 participants from the general Québec (Canada) adult population aged 18 to 90 years (M = 46.59; SD = 16.32; 51.8% women).

Results

The original scoring approach model showed good fit to data after freeing paths between certain traits and reached strict invariance. The APA scoring approach also showed good fit to data and reached strict invariance, but needed an adjustment (path freed between Emotional lability and Impulsivity in men) to reach scalar invariance.

Discussion

In line with previous research, the PID-5 is invariant across sex and the five-factor structure adjusts well to data. The APA scoring approach appears to attenuate the cross-loading problem observed with the original scoring approach. In light of these results, we recommend using the APA scoring approach to derive domain scores.

Aberrant reward learning, but not negative reinforcement learning, is related to depressive symptoms: an attentional perspective

BACKGROUND

Aberrant reward functioning is implicated in depression. While attention precedes behavior and guides higher-order cognitive processes, reward learning from an attentional perspective - the effects of prior reward-learning on subsequent attention allocation - has been mainly overlooked.

METHODS

The present study explored the effects of reward-based attentional learning in depression using two separate, yet complimentary, studies. In study 1, participants with high (HD) and low (LD) levels of depression symptoms were trained to divert their gaze toward one type of stimuli over another using a novel gaze-contingent music reward paradigm - music played when fixating the desired stimulus type and stopped when gazing the alternate one. Attention allocation was assessed before, during, and following training. In study 2, using negative reinforcement, the same attention allocation pattern was trained while substituting the appetitive music reward for gazing the desired stimulus type with the removal of an aversive sound (i.e. white noise).

RESULTS

In study 1 both groups showed the intended shift in attention allocation during training (online reward learning), while generalization of learning at post-training was only evident among LD participants. Conversely, in study 2 both groups showed post-training generalization. Results were maintained when introducing anxiety as a covariate, and when using a more powerful sensitivity analysis. Finally, HD participants showed higher learning speed than LD participants during initial online learning, but only when using negative, not positive, reinforcement.

CONCLUSIONS

Deficient generalization of learning characterizes the attentional system of HD individuals, but only when using reward-based positive reinforcement, not negative reinforcement.

Distinct neurofunctional alterations during motivational and hedonic processing of natural and monetary rewards in depression - a neuroimaging meta-analysis

Reward processing dysfunctions are considered a candidate mechanism underlying anhedonia and apathy in depression. Neuroimaging studies have documented that neurofunctional alterations in mesocorticolimbic circuits may neurally mediate these dysfunctions. However, common and distinct neurofunctional alterations during motivational and hedonic evaluation of monetary and natural rewards in depression have not been systematically examined. Here, we capitalized on pre-registered neuroimaging meta-analyses to (1) establish general reward-related neural alterations in depression, (2) determine common and distinct alterations during the receipt and anticipation of monetary v. natural rewards, and, (3) characterize the differences on the behavioral, network, and molecular level. The pre-registered meta-analysis (https://osf.io/ay3r9) included 633 depressed patients and 644 healthy controls and revealed generally decreased subgenual anterior cingulate cortex and striatal reactivity toward rewards in depression. Subsequent comparative analyses indicated that monetary rewards led to decreased hedonic reactivity in the right ventral caudate while natural rewards led to decreased reactivity in the bilateral putamen in depressed individuals. These regions exhibited distinguishable profiles on the behavioral, network, and molecular level. Further analyses demonstrated that the right thalamus and left putamen showed decreased activation during the anticipation of monetary reward. The present results indicate that distinguishable neurofunctional alterations may neurally mediate reward-processing alterations in depression, in particular, with respect to monetary and natural rewards. Given that natural rewards prevail in everyday life, our findings suggest that reward-type specific interventions are warranted and challenge the generalizability of experimental tasks employing monetary incentives to capture reward dysregulations in everyday life.

Clinical effects of anodal tDCS and identifying response markers in post-traumatic stress disorder (PTSD): An open-label study

Transcranial direct current stimulation (tDCS) is a promising treatment for post-traumatic stress disorder (PTSD). However, not all patients respond to this type of treatment. The first aim of present study was to examine efficacy of tDCS for PTSD, depression, anxiety, and anhedonia in patients with PTSD. The second aim of this study was to examine the demographic, clinical, and psychological factors that may predict response to tDCS. In this open-label study, 103 PTSD patients underwent 10 sessions of tDCS (2 mA, 20 min). The anodal and cathodal electrodes were placed over the left dorsolateral prefrontal cortex (DLPFC; F3) and right supra-orbital (FP2) Respectively. Clinical outcome measures included Posttraumatic the Stress Disorder Checklist for DSM-5 (PCL-5), the Beck Depression Inventory (BDI-II), the Beck Anxiety Inventory (BAI), and the Snaith-Hamilton Pleasure Scale (SHAPS). There was an overall significant improvement in symptoms of PTSD, depression, anxiety, and anhedonia from pre- to post-treatment. Results also revealed that non-responders had higher severity at baseline for depression, anxiety, and anhedonia. However, higher severity of depression and anhedonia at baseline predicted response status, with higher severity associated with greater likelihood of non-response. tDCS of the left dLPFC and right supra-orbital appears to have a positive effect in reducing PTSD and related symptoms. These initial results could have an important influence on the adoption of anodal tDCS over the left DLPFC for PTSD, by enabling the early identification of patients who respond to tDCS.

Quantification of Plasma Dopamine in Depressed Patients Using Silver-Enriched Silicon Nanowires as SERS-Active Substrates

A decrease in the levels of dopamine (DA)─a key catecholamine biomarker for major depressive disorder─highlights the need for quantitative analysis of biological fluids to aid in the early diagnosis of diverse neuropsychiatric disorders. This study developed silicon nanowires enriched with silver nanoparticles to serve as a surface-enhanced Raman scattering (SERS) substrate to enable precise and sensitive quantification of blood plasma DA levels in humans. The silver-enriched silicon nanowires (SiNWs@Ag) yielded flower-like assemblies with densely populated SERS "hot spots," allowing sensitive DA detection. By correlating DA concentration with Raman intensity at 1156 cm-1, the plasma DA levels in treatment-naïve patients with major depression (n = 18) were 2 orders of magnitude lower than those in healthy controls (n = 18) (6.56 × 10-10 M vs 1.43 × 10-8 M). The plasma DA concentrations differed significantly between the two groups (two-tailed p = 5.77×10-7), highlighting a distinct demarcation between depression patients and healthy controls. Furthermore, the SiNWs@Ag substrate effectively differentiated between DA and norepinephrine (NE) in mixtures at nanomolar levels, demonstrating its selective detection capability. This study represents the first report on the quantitative detection of DA levels in human blood samples from individuals with major depression using an SERS technique, emphasizing its potential clinical utility in the evaluation and diagnosis of neuropsychiatric disorders.

A Delphi consensus on clinical features, diagnosis and treatment of major depressive disorder patients with anhedonia amongst psychiatrists in the Asia-Pacific

Background

Anhedonia, a core diagnostic feature for major depressive disorder (MDD), is defined as the loss of pleasure and interest in daily activities. Its prevalence in MDD patients vary from 35 to 70%. Anhedonia in MDD negatively impacts functioning and is associated with treatment resistance and poorer prognosis for various clinical outcomes. Owing to its complexity, there remains considerable heterogeneity in the conceptualization, diagnosis and clinical management of anhedonia in MDD.

Methods

This modified Delphi panel was conducted to elicit expert opinion and establish consensus on concepts relating to clinical features, diagnosis and treatment of MDD with anhedonia (MDDwA) amongst psychiatrists in the Asia-Pacific region. Seven themes were covered. A three-stage process was adopted for consensus generation (two online survey rounds, followed by a moderated consensus meeting). Statements were developed based on a literature review and input from a steering committee of six regional experts. The panel included 12 psychiatrists practicing in Australia, China, Hong Kong, Japan, South Korea and Taiwan with ≥5 years of specialist clinical experience, including assessment or management of patients with MDDwA.

Results

Overall, consensus was achieved (median ≥8) on 89/103 statements (86%). About half of the statements (55/103, 53%) achieved consensus in Round 1, and 29/36 modified statements achieved consensus in Round 2. At the moderated consensus meeting, five modified statements were discussed by the steering committee and consensus was achieved on all statements (5/5). The findings highlighted a lack of clear and practical methods in clinical practice for assessing anhedonia in MDD patients and limited physician awareness of anhedonia in Asia-Pacific.

Conclusion

Insights from this Delphi consensus provide a reference point for psychiatrists in Asia-Pacific to optimize their strategies for personalized diagnosis and management of patients with MDDwA. Identification of distinct and clinically relevant subtypes in MDD may be valuable for guiding personalized diagnosis and management approaches, including type-specific therapies.

Antidepressant-like Effect of the Eburnamine-Type Molecule Vindeburnol in Rat and Mouse Models of Ultrasound-Induced Depression

Vindeburnol (VIND, RU24722, BC19), a synthetic molecule derived from the eburnamine-vincamine alkaloid group, has many neuropsychopharmacological effects, but its antidepressant-like effects are poorly understood and have only been described in a few patents. To reliably estimate this effect, vindeburnol was studied in a model of long-term variable-frequency ultrasound (US) exposure at 20-45 kHz in male Wistar rats and BALB/c mice. Vindeburnol was administered chronically for 21 days against a background of simultaneous ultrasound exposure at a dose of 20 mg/kg intraperitoneally (IP). Using four behavioral tests, the sucrose preference test (SPT), the social interaction test (SIT), the open field test (OFT), and the forced swimming test (FST), we found that the treatment with the compound diminished depression-like symptoms in mice and rats. The compound restored the ultrasound-related reduced sucrose consumption to control levels and increased social interaction time in mice and rats compared with those in ultrasound-exposed animals. Vindeburnol showed contraversive results of horizontal and vertical activity in both species and generally did not increase locomotor activity. At the same time, the compound showed a specific effect in the FST, significantly reducing the immobility time. Moreover, we found an increase in norepinephrine, dopamine, and its metabolite levels in the brainstem, as well as an increase in dopamine, 3-methoxytyramine, and 3,4-dihydroxyphenylacetic acid levels in the striatum. We also observed a statistically significant increase in tyrosine hydroxylase (TH) levels in the region containing the locus coeruleus (LC). We suggest that using its distinct chemical structure and pharmacological activity as a starting point could boost antidepressant drug discovery.

Dimensional and Categorical Solutions to Parsing Depression Heterogeneity in a Large Single-Site Sample

BACKGROUND

Recent studies have reported significant advances in modeling the biological basis of heterogeneity in major depressive disorder, but investigators have also identified important technical challenges, including scanner-related artifacts, a propensity for multivariate models to overfit, and a need for larger samples with more extensive clinical phenotyping. The goals of the current study were to evaluate dimensional and categorical solutions to parsing heterogeneity in depression that are stable and generalizable in a large, single-site sample.

METHODS

We used regularized canonical correlation analysis to identify data-driven brain-behavior dimensions that explain individual differences in depression symptom domains in a large, single-site dataset comprising clinical assessments and resting-state functional magnetic resonance imaging data for 328 patients with major depressive disorder and 461 healthy control participants. We examined the stability of clinical loadings and model performance in held-out data. Finally, hierarchical clustering on these dimensions was used to identify categorical depression subtypes.

RESULTS

The optimal regularized canonical correlation analysis model yielded 3 robust and generalizable brain-behavior dimensions that explained individual differences in depressed mood and anxiety, anhedonia, and insomnia. Hierarchical clustering identified 4 depression subtypes, each with distinct clinical symptom profiles, abnormal resting-state functional connectivity patterns, and antidepressant responsiveness to repetitive transcranial magnetic stimulation.

CONCLUSIONS

Our results define dimensional and categorical solutions to parsing neurobiological heterogeneity in major depressive disorder that are stable, generalizable, and capable of predicting treatment outcomes, each with distinct advantages in different contexts. They also provide additional evidence that regularized canonical correlation analysis and hierarchical clustering are effective tools for investigating associations between functional connectivity and clinical symptoms.

Assessment of Depression in Adults and Youth

This article selectively reviews the key issues and measures for the assessment of depressive disorders and symptoms in youth and adults. The first portion of the article addresses the nature and conceptualization of depression and some key issues that must be considered in its assessment. Next, the diagnostic interview and clinician- and self-administered rating scales that are most widely used to diagnose, screen for, and assess the severity of depression in adults and youth are selectively reviewed. In addition, the assessment of three transdiagnostic clinical features (anhedonia, irritability, and suicidality) that are frequently associated with both depression and other forms of psychopathology is discussed. The article concludes with some broad recommendations for assessing depression in research and clinical practice and suggestions for future research.

Anhedonia mediates the relationships between childhood trauma and symptom severity of PTSD and depression, but not of social anxiety

BACKGROUND

Childhood trauma is a risk factor for developing multiple forms of psychopathology, including depression, posttraumatic stress disorder (PTSD), and social anxiety. Yet, the mechanisms linking childhood trauma and these psychopathologies remain less clear.

OBJECTIVE

Here we examined whether anhedonia, a reduced ability to experience pleasure, may mediate the relationship between childhood trauma and symptom severity of depression, PTSD, and social anxiety.

METHODS

A total of 230 trauma-exposed participants aged 18-75 were assessed for lifetime trauma exposure, including general and childhood traumatic events, anhedonia, and symptoms of depression, PTSD, and social anxiety.

RESULTS

Controlling for age, gender, and general lifetime trauma exposure, mediation analyses revealed a significant mediation effect of anhedonia for the relationship between childhood trauma and symptom severity of depression and PTSD, but not social anxiety. To better understand these significant mediation effects, we repeated the analyses separately for childhood abuse and neglect, and then for the various subtypes of each type of childhood trauma. Results showed a significant mediation effect of anhedonia on symptoms of both depression and PTSD in individuals who reported high emotional and sexual abuse levels. F Anhedonia was also found to mediate the relationship between both emotional and physical neglect and symptoms of depression and PTSD.

CONCLUSION

These findings refine our understanding of the ways in which childhood traumatic experiences may be associated with different mental health problems by increasing anhedonia. Anhedonia may be an important treatment target in survivors of childhood abuse and neglect.

Altered reward network responses to social touch in major depression

BACKGROUND

Social touch is an integral part of social relationships and has been associated with reward. Major depressive disorder (MDD) is characterized by severe impairments in reward processing, but the neural effects of social touch in MDD are still elusive. In this study, we aimed to determine whether the neural processing of social touch is altered in MDD and to assess the impact of antidepressant therapy.

METHODS

Before and after antidepressant treatment, 53 MDD patients and 41 healthy controls underwent functional magnetic resonance imaging (fMRI) while receiving social touch. We compared neural responses to social touch in the reward network, behavioral ratings of touch comfort and general aversion to interpersonal touch in patients to controls. Additionally, we examined the effect of treatment response on those measures.

RESULTS

Clinical symptoms decreased after treatment and 43.4% of patients were classified as responders. Patients reported higher aversion to interpersonal touch and lower comfort ratings during the fMRI paradigm than controls. Patients showed reduced responses to social touch in the nucleus accumbens, caudate nucleus and putamen than controls, both before and after treatment. Contrary to our hypotheses, these effects were independent of touch velocity. Non-responders exhibited blunted response in the caudate nucleus and the insula compared to responders, again irrespective of time.

CONCLUSIONS

These findings suggest altered striatal processing of social touch in MDD. Persistent dysfunctional processing of social touch despite clinical improvements may constitute a latent risk factor for social withdrawal and isolation.

Neuropsychological Effects of Antidepressants: Translational Studies

Pharmacological treatments that improve mood were first identified serendipitously, but more than half a century later, how these drugs induce their antidepressant effects remains largely unknown. With the help of animal models, a detailed understanding of their pharmacological targets and acute and chronic effects on brain chemistry and neuronal function has been achieved, but it remains to be elucidated how these effects translate to clinical efficacy. Whilst the field has been dominated by the monoamine and neurotrophic hypotheses, the idea that the maladaptive cognitive process plays a critical role in the development and perpetuation of mood disorders has been discussed since the 1950s. Recently, studies using objective methods to quantify changes in emotional processing found acute effects with conventional antidepressants in both healthy volunteers and patients. These positive effects on emotional processing and cognition occur without a change in the subjective ratings of mood. Building from these studies, behavioural methods for animals that quantify similar cognitive affective processes have been developed. Integrating these behavioural approaches with pharmacology and targeted brain manipulations, a picture is beginning to emerge of the underlying mechanisms that may link the pharmacology of antidepressants, these neuropsychological constructs and clinical efficacy. In this chapter, we discuss findings from animal studies, experimental medicine and patients investigating the neuropsychological effects of antidepressant drugs. We discuss the possible neural circuits that contribute to these effects and discuss whether a neuropsychological model of antidepressant effects could explain the temporal differences in clinical benefits observed with conventional delayed-onset antidepressants versus rapid-acting antidepressants.

Personality characteristics, not clinical symptoms, are associated with anhedonia in a community sample: A preliminary investigation

Anhedonia is a salient transdiagnostic psychiatric symptom associated with increased illness severity and chronicity. Anhedonia is also present to varying degrees in non-clinical cohorts. Here, we sought to examine factors influencing expression of anhedonia. Participants (N = 335) were recruited through the Nathan Kline Institute-Rockland Sample, an initiative to deeply phenotype a large community sample across the lifespan. Utilizing a data-driven approach, we evaluated associations between anhedonia severity, indexed by Snaith-Hamilton Pleasure Scale (SHAPS), and 20 physical, developmental, and clinical measures, including Structured Clinical Interview for DSM-IV, Beck Depression Inventory, State-Trait Anxiety Inventory, NEO Five-Factor Inventory-3 (NEO-FFI-3), BMI, Hemoglobin A1C, and demography. Using a bootstrapped AIC-based backward selection algorithm, seven variables were retained in the final model: NEO-FFI-3 agreeableness, extraversion, and openness to experience; BMI; sex; ethnicity; and race. Though median SHAPS scores were greater in participants with psychiatric diagnoses (18.5) than those without (17.0) (U = 12238.5, z = 2.473, p = 0.013), diagnosis and symptom measures were not retained as significant predictors in the final robust linear model. Participants scoring higher on agreeableness, extraversion, and openness to experience reported significantly lower anhedonia. These results demonstrate personality as a mild-to-moderate but significant driver of differences in experiencing pleasure in a community sample.

Establishing the measurement precision of the patient health questionnaire in an adolescent sample

BACKGROUND

Technically sound measures are necessary for accurately identifying youth at risk for depression, but many studies rely on classical test theory metrics or adult samples to evaluate measures. This study examined the use of the PHQ-8, a common and freely available pediatric depression screener, in an adolescent sample using item response theory (IRT).

METHODS

Secondary analyses were conducted on data from a study conducted in Midwestern middle schools in which 1224 youth completed the PHQ-8 as part of a battery of surveys. Polytomous IRT analyses (a Graded Response Model) were used to evaluate the PHQ-8. Items were examined for their ability to distinguish between respondents of different latent depression severity and for differential item functioning (DIF) across demographic categories.

RESULTS

All PHQ-8 items had adequate discriminative abilities. Items measuring anhedonia and psychomotor disturbances performed relatively poorly, and items measuring somatic symptoms (appetite and sleep) were most informative when respondents endorsed extreme response options ("not at all" or "nearly every day"). No DIF was found across grade level or race, but several items were flagged for DIF by gender and student income level.

LIMITATIONS

These results might not be generalizable to a broader youth population due to administration setting and the unique demographic characteristics of this sample (76.0 % African American).

CONCLUSIONS

Tools such as the PHQ-8 are appropriate to quickly screen for depression in adolescents, but further scrutiny of adolescent response patterns is warranted. Future research should examine items measuring anhedonia and psychomotor and somatic disturbances in adolescents.

Alteration of the α5 GABA receptor and 5HTT lead to cognitive deficits associated with major depressive-like behaviors in a 14-day combined stress rat model

INTRODUCTION

Current models used to study the pathophysiology of major depressive disorder (MDD) are laborious and time consuming. This study examined the effect of a 14-day combined stress model (CS; corticosterone injection and restraint stress) in male Sprague-Dawley rats and also compare the effect of CS versus 28-day corticosterone treatment on depressive-like behaviour and cognitive deficits.

MATERIEL AND METHODS

Depressive-like behaviours and cognitive deficits were assessed in the forced swim test (FST), sucrose preference (SPT), Morris water maze (MWM) and novel object recognition (NORT) tests. Real-time PCR and ELISA were respectively used to detect expression of the serotonin transporter (5-HTT), serotonin 1 A receptor (5-HT1A), α5 GABAA receptor, and the concentrations of corticosterone (plasma), GABA and acetylcholinesterase (AChE) in the hippocampus and Prefrontal cortex (PFC).Results CS group showed increased immobility time in the FST, time to reach the MWM platform, higher corticosterone level, and increased expressions of hippocampal and PFC 5-HT1A and α5 GABAA receptors, and AChE compared to their control groups. In contrast, reductions in SPT ratio, discrimination index in NORT, time in target quadrant, and hippocampal 5-HTT expression was noted relative to their control group. Compared to the 28-day corticosterone only group, PFC 5-HT1A, Hippocampal 5-HTT were reduced, while PFC 5-HTT, Hippocampal α5 GABAA receptors, and AChE concentrations were higher in the CS group.

CONCLUSION

Our CS model induced depressive-like behaviour with early cognitive deficits in rats affecting both hippocampus and PFC. The CS model may be useful in investigating new and comprehensive treatment strategies for MDD.

The critical role of gut-brain axis microbiome in mental disorders

The Gut-brain axis is a bidirectional neural and humoral signaling that plays an important role in mental disorders and intestinal health and connects them as well. Over the past decades, the gut microbiota has been explored as an important part of the gastrointestinal tract that plays a crucial role in the regulation of most functions of various human organs. The evidence shows several mediators such as short-chain fatty acids, peptides, and neurotransmitters that are produced by the gut may affect the brain's function directly or indirectly. Thus, dysregulation in this microbiome community can give rise to several diseases such as Parkinson's disease, depression, irritable bowel syndrome, and Alzheimer's disease. So, the interactions between the gut and the brain are significantly considered, and also it provides a prominent subject to investigate the causes of some diseases. In this article, we reviewed and focused on the role of the largest and most repetitive bacterial community and their relevance with some diseases that they have mentioned previously.

Uncovering the Neural Correlates of Anhedonia Subtypes in Major Depressive Disorder: Implications for Intervention Strategies

Major depressive disorder (MDD) represents a serious public health concern, negatively affecting individuals' quality of life and making a substantial contribution to the global burden of disease. Anhedonia is a core symptom of MDD and is associated with poor treatment outcomes. Variability in anhedonia components within MDD has been observed, suggesting heterogeneity in psychopathology across subgroups. However, little is known about anhedonia subgroups in MDD and their underlying neural correlates across subgroups. To address this question, we employed a hierarchical cluster analysis based on Temporal Experience of Pleasure Scale subscales in 60 first-episode, drug-naive MDD patients and 32 healthy controls. Then we conducted a connectome-wide association study and whole-brain voxel-wise functional analyses for identified subgroups. There were three main findings: (1) three subgroups with different anhedonia profiles were identified using a data mining approach; (2) several parts of the reward network (especially pallidum and dorsal striatum) were associated with anticipatory and consummatory pleasure; (3) different patterns of within- and between-network connectivity contributed to the disparities of anhedonia profiles across three MDD subgroups. Here, we show that anhedonia in MDD is not uniform and can be categorized into distinct subgroups, and our research contributes to the understanding of neural underpinnings, offering potential treatment directions. This work emphasizes the need for tailored approaches in the complex landscape of MDD. The identification of homogeneous, stable, and neurobiologically valid MDD subtypes could significantly enhance our comprehension and management of this multifaceted condition.

Striatal correlates of Bayesian beliefs in self-efficacy in adolescents and their relation to mood and autonomy: a pilot study

Major depressive disorder often originates in adolescence and is associated with long-term functional impairment. Mechanistically characterizing this heterogeneous illness could provide important leads for optimizing treatment. Importantly, reward learning is known to be disrupted in depression. In this pilot fMRI study of 21 adolescents (16-20 years), we assessed how reward network disruption impacts specifically on Bayesian belief representations of self-efficacy (SE-B) and their associated uncertainty (SE-U), using a modified instrumental learning task probing activation induced by the opportunity to choose, and an optimal Hierarchical Gaussian Filter computational model. SE-U engaged caudate, nucleus accumbens (NAcc), precuneus, posterior parietal and dorsolateral prefrontal cortex (PFWE < 0.005). Sparse partial least squares analysis identified SE-U striatal activation as associating with one's sense of perceived choice and depressive symptoms, particularly anhedonia and negative feelings about oneself. As Bayesian uncertainty modulates belief flexibility and their capacity to steer future actions, this suggests that these striatal signals may be informative developmentally, longitudinally and in assessing response to treatment.

Amelioration of modified chronic unpredictable stress using Celastrus paniculatus seed oil alone and in combination with fluoxetine

The various stressors in chronic unpredictable stress (CUS) triggers depressive behavior, impairs learning, and decision-making abilities. The present study investigated the effects of Celastrus paniculatus seed oil (CPSO) alone and in combination with fluoxetine (FLU) in modified CUS (mCUS) induced depression in mice. In this study, adult albino mice were subjected to a modified version of CUS protocol having six different stressors and were applied daily consistently for 15 days. The post-treatment with CPSO (50 and 100 mg/kg) and FLU (10 mg/kg) alone and in combination from day 16th to 36th. Group I: normal control; group II: diseased control (mCUS subjected group); group III: CPSO (50 mg/kg); group IV: CPSO (100 mg/kg); group V: CPSO (50 mg/kg)+FLU (10 mg/kg); group VI: CPSO (100 mg/kg)+FLU (10 mg/kg); group VII: FLU (10 mg/kg); group VIII: FLU (20 mg/kg). During experimentation, various behavioral, biochemical, oxidative stress, inflammatory, and neurotransmitters level were checked. The CUS treated mice exhibited increased escaped latency, decreased number of open arm entries, increased immobility time, decreased percentage of sucrose consumption, and number of the boxes crossed as compared to the normal group. The post-treatment with the CPSO 50 + FLU 10, CPSO 100 + FLU 10, FLU 10 significantly (p < 0.05) attenuated behavioral, biochemical, inflammation, corticosteroid, and neurotransmitters level as compared to CPSO 50, CPSO 100, and FLU 20 alone. CPSO along with FLU appreciably achieved anti-depressant effect via lowering stress, inflammation, corticosteroid level, and restoration of neurotransmitters level in mCUS induced depression mice model.

Acute stress selectively blunts reward anticipation but not consumption: An ERP study

Stress-induced dysfunction of reward processing is documented to be a critical factor associated with mental illness. Although many studies have attempted to clarify the relationship between stress and reward, few studies have investigated the effect of acute stress on the temporal dynamics of reward processing. The present study applied event-related potentials (ERP) to examine how acute stress differently influences reward anticipation and consumption. In this study, seventy-eight undergraduates completed a two-door reward task following a Trier Social Stress Task (TSST) or a placebo task. The TSST group showed higher cortisol levels, perceived stress, anxiety, and negative affect than the control group. For the control group, a higher magnitude of reward elicited a reduced cue-N2 but increased stimulus-preceding negativity (SPN), suggesting that controls were sensitive to reward magnitude. In contrast, these effects were absent in the stress group, suggesting that acute stress reduces sensitivity to reward magnitude during the anticipatory phase. However, the reward positivity (RewP) and P3 of both groups showed similar patterns, which suggests that acute stress has no impact on reward responsiveness during the consummatory phase. These findings suggest that acute stress selectively blunts sensitivity to reward magnitude during the anticipatory rather than the consummatory phase.

Protein Plasma Levels of the IGF Signalling System Are Altered in Major Depressive Disorder

The Insulin-like growth factor 2 (IGF-2) has been recently proven to alleviate depressive-like behaviors in both rats and mice models. However, its potential role as a peripheral biomarker has not been evaluated in depression. To do this, we measured plasma IGF-2 and other members of the IGF family such as Binding Proteins (IGFBP-1, IGFBP-3, IGFBP-5 and IGFBP-7) in a depressed group of patients (n = 51) and in a healthy control group (n = 48). In some of these patients (n = 15), we measured these proteins after a period (19 ± 6 days) of treatment with antidepressants. The Hamilton Depressive Rating Scale (HDRS) and the Self-Assessment Anhedonia Scale (SAAS) were used to measure depression severity and anhedonia, respectively. The general cognition state was assessed by the Mini-Mental State Examination (MMSE) test and memory with the Free and Cued Selective Reminding Test (FCSRT). The levels of both IGF-2 and IGFBP-7 were found to be significantly increased in the depressed group; however, only IGF-2 remained significantly elevated after correction by age and sex. On the other hand, the levels of IGF-2, IGFBP-3 and IGFBP-5 were significantly decreased after treatment, whereas only IGFBP-7 was significantly increased. Therefore, peripheral changes in the IGF family and their response to antidepressants might represent alterations at the brain level in depression.

tDCS efficacy and utility of anhedonia and rumination as clinical predictors of response to tDCS in major depressive disorder (MDD)

BACKGROUND

Anhedonia and rumination are mental disorders' transdiagnostic features but remain difficult to treat. Transcranial direct current stimulation (tDCS) is a proven treatment for depression, but its effects on anhedonia and rumination and whether anhedonia and rumination can be used as a predictive biomarker of treatment response is not well known. This study aimed to investigate the tDCS efficacy and identify the predictive role of anhedonia and rumination in response to tDCS in patients with MDD.

METHODS

182 patients received 10 tDCS sessions delivered at 2 mA to left (anode) dorsolateral prefrontal cortex (DLPFC). Hamilton Rating Scale for Depression (HRSD-17), Snaith-Hamilton Pleasure Scale (SHAPS), and the 10-item Ruminative Response Scale (RRS-10) was administered to patients with MDD before treatment, following it, and after two weeks of tDCS.

RESULTS

There was an overall significant improvement in anhedonia from pre- to post-treatment. Regression analyses revealed that responders had higher baseline anhedonia and rumination (reflective pondering) scores. We found that the reduction in HRSD scores after tDCS was significantly associated with anhedonia's baseline values while no relation was found between baseline rumination and tDCS treatment response.

CONCLUSION

These results provide new evidence that pronounced anhedonia may be a significant clinical predictor of response to tDCS. Patients with severe or low baseline rumination had an equal chance of achieving clinical response. Prospective tDCS studies are necessary to validate the predictive value of the derived model.

Effort and Appetitive Responding in Depression: Examining Deficits in Motivational and Consummatory Stages of Reward Processing Using the Effort-Doors Task

Background

Reward sensitivity is a dimensional construct central to understanding the nature of depression. Psychophysiological research on this construct has primarily focused on the reward positivity, an event-related potential (ERP) that indexes consummatory reward sensitivity. This study extended prior research by focusing on ERPs that index the motivational component of reward.

Methods

A novel effort-for-reward task was used to elicit motivational and consummatory ERPs. Groups consisting of 34 participants with depression and 32 participants without depression were compared across a range of reward-related ERPs.

Results

Participants with depression exhibited reduced responsivity to effort completion cues following high effort expenditure, reduced anticipation of rewards after low effort expenditure (i.e., the stimulus preceding negativity), and reduced reward positivity following high effort expenditure. ERPs occurring prior to reward receipt accounted for unique variance in depression status and differentiated between subgroups of depressed individuals.

Conclusions

Findings support the utility of leveraging multiple ERPs that index separate reward processing deficits to better characterize depression and depressive subtypes.

Acculturative Orientations Among Hispanic/Latinx Caregivers in the ABCD Study: Associations With Caregiver and Youth Mental Health and Youth Brain Function

Background

Population-based neuroscience offers opportunities to examine important but understudied sociocultural factors such as acculturation. Acculturation refers to the extent to which an individual retains their cultural heritage and/or adopts the receiving society's culture and is particularly salient among Hispanic/Latinx immigrants. Specific acculturative orientations have been linked to vulnerability to substance use, depression, and suicide and are known to influence family dynamics between caregivers and their children.

Methods

Using data from first- and second-generation Hispanic/Latinx caregivers in the Adolescent Brain Cognitive Development (ABCD) Study (N = 1057), we examined how caregivers' acculturative orientation affects their mental health, as well as the mental health and brain function of their children. Neuroimaging analyses focused on regions associated with self- and affiliation-based social processing (ventromedial prefrontal cortex, insula, and temporoparietal junction).

Results

We identified 2 profiles of caregiver acculturation: bicultural (retains heritage culture while adopting U.S. culture) and detached (discards heritage culture and rejects U.S. culture). Bicultural caregivers exhibited fewer internalizing and externalizing problems than detached caregivers; furthermore, youth exhibited similar internalizing effects across caregiver profiles. In addition, youth with bicultural caregivers displayed increased resting-state brain activity (i.e., fractional amplitude of low-frequency fluctuations and regional homogeneity) in the left insula, which has been linked to psychopathology; however, differences in long-range functional connectivity were not significant.

Conclusions

Caregiver acculturation is an important familial factor that has been linked to significant differences in youth mental health and insula activity. Future work should examine sociocultural and neurodevelopmental changes across adolescence to assess health outcomes and determine whether localized, corticolimbic brain effects are ultimately translated into long-range connectivity differences.

Greater anhedonia scores in healthy individuals are associated with less decline in 24-hour energy expenditure with fasting: Evidence for a link between behavioral traits and spendthrift phenotype

Obesity rates are increasing and affecting mental health. It is important to understand how behavioral traits such as anhedonia are associated with physiologic traits that may predict weight-change in clinical and non-clinical populations. We studied whether 24-hour energy expenditure (24hEE) changes with fasting and overfeeding are associated with anhedonia in a healthy cohort. We performed behavioral assessments (physical anhedonia scale (PAS) and inventory for depressive symptoms (IDS)) followed by measures of 24hEE and urinary catecholamines in a whole-room indirect calorimeter (respiratory chamber) during energy balance, and then randomly during fasting and 2 different overfeeding diets. Participants (n=98) were medically healthy, between 18 and 55 years of age, with normal glucose regulation and weight-stable 6 months before admission. Women were premenopausal and not pregnant. Higher PAS was significantly associated with lesser decrease in 24hEE with fasting and higher urinary catecholamine excretion rates - consistent with spendthrift metabolism. As IDS increased, the association between anhedonia and the change in 24hEE from energy balance to fasting decreased (B-values were lower for change in EE). Here, higher PAS scores may reflect the ability to respond with appropriate homeostatic reactions which balance energy needs. IDS scores blunting this response may explain how anhedonia and depression can lead to weight gain.

Polish adaptation of the Dimensional Anhedonia Rating Scale (DARS) - validation in the clinical sample

Background

Anhedonia is the core symptom of depression. Its presence has been linked to worsened prognosis. The Dimensional Anhedonia Rating Scale (DARS) is a scale measuring desire, motivation, effort and consummatory pleasure across different domains. The aim of this paper was to confirm factor structure, assess reliability and validity of the Polish adaptation of the DARS in a clinical sample of patients with mood disorders and healthy controls (HC).

Methods

The study sample included 161 participants aged 18-65 years - 34 HC, 72 patients with bipolar disorder and 55 with major depressive disorder (in depressive episode or remission). Reliability of the Polish adaptation of the DARS was assessed using Cronbach's α and the average inter-item correlation (AIC). Convergent and divergent validity was established by Pearson's correlations between the DARS and the Snaith-Hamilton Pleasure Scale (SHAPS), the Quick Inventory of Depressive Symptomatology- self-report (QIDS-SR), the Hospital Anxiety and Depression Scale (HADS). The structure of the scale was examined by factor analysis.

Results

The factor structure was consistent with the original scale. Strong internal consistency for the DARS total score (Cronbach's α = 0.95) and all subscales (0.86-0.93) was observed. The DARS demonstrated good convergent (moderate to strong correlations with measures of anhedonia and depression) and divergent validity (weak correlations with anxiety level).

Conclusion

The Polish DARS demonstrated excellent internal consistency and very good validity. The scale is a valuable contribution to the psychometrics of anhedonia measures in patients with mood disorders.

Anhedonia and impulsivity in college alcohol use: A path analysis

OBJECTIVE

Alcohol use is a substantial problem among college students and has several negative consequences. The current study examined the associations between anhedonia and alcohol use and related problems via impulsive behavior (e.g., negative urgency, sensation seeking). We parsed anhedonia into four specific facets: consummatory, anticipatory, recreational, and social anhedonia.

PARTICIPANTS

Six hundred and forty college students aged 18-25 were included in the final analysis.

METHOD

Data were collected via Amazon Mechanical Turk. Self-report inventories assessing for anhedonia, alcohol use, impulsive behavior, and depressed mood were utilized.

RESULTS

Recreational consummatory anhedonia was negatively associated with alcohol use and alcohol-related problems through negative urgency. Recreational consummatory anhedonia also had significant negative associations with alcohol consumption via sensation seeking. Further, social anticipatory anhedonia was positively associated with alcohol use and related problems via negative urgency.

CONCLUSIONS

This study highlights important associations between anhedonia, impulsivity, and alcohol use and related problems.

Stress to inflammation and anhedonia: Mechanistic insights from preclinical and clinical models

Anhedonia, as evidenced by impaired pleasurable response to reward, reduced reward motivation, and/or deficits in reward-related learning, is a common feature of depression. Such deficits in reward processing are also an important clinical target as a risk factor for depression onset. Unfortunately, reward-related deficits remain difficult to treat. To address this gap and inform the development of effective prevention and treatment strategies, it is critical to understand the mechanisms that drive impairments in reward function. Stress-induced inflammation is a plausible mechanism of reward deficits. The purpose of this paper is to review evidence for two components of this psychobiological pathway: 1) the effects of stress on reward function; and 2) the effects of inflammation on reward function. Within these two areas, we draw upon preclinical and clinical models, distinguish between acute and chronic effects of stress and inflammation, and address specific domains of reward dysregulation. By addressing these contextual factors, the review reveals a nuanced literature which might be targeted for additional scientific inquiry to inform the development of precise interventions.