Assessing anhedonia in depression: Potentials and pitfalls

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.

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.

Anhedonia and Depressive Disorders

Anhedonia is a core symptom of depression and of several psychiatric disorders. Anhedonia has however expanded from its original definition to encompass a spectrum of reward processing deficits that received much interest in the last decades. It is a relevant risk factor for possible suicidal behaviors, and that it may operate as an independent risk factor for suicidality apart from the episode severity. Anhedonia has also been linked to inflammation with a possible reciprocal deleterious effect on depression. Its neurophysiological bases mainly include alterations in striatal and prefrontal areas, with dopamine being the most involved neurotransmitter. Anhedonia is thought to have a significant genetic component and polygenic risk scores are a possible tool for predicting an individual's risk for developing anhedonia. Traditional antidepressants, such as selective serotonin reuptake inhibitors, showed a limited benefit on anhedonia, also considering their potential pro-anhedonic effect in some subjects. Other treatments may be more effective in treating anhedonia, such as agomelatine, vortioxetine, ketamine and transcranial magnetic stimulation. Psychotherapy is also widely supported, with cognitive-behavioral therapy and behavioral activation both showing benefit. In conclusion, a large body of evidence suggests that anhedonia is, at least partially, independent from depression, therefore it needs careful assessment and targeted treatment.

On the Origins of MAOI Misconceptions: Reaffirming their Role in Melancholic Depression

The first monoamine oxidase inhibitors (MAOIs) used for the treatment of depression in the 1950-60s were credited with treating severe melancholic depression (MeD) successfully and greatly reducing the need for electroconvulsive therapy (ECT). Following the hiatus caused by the then ill-understood cheese reaction, MAOI use was relegated to atypical and treatment-resistant depressions only, based on data from insufficiently probing research studies suggesting their comparatively lesser effectiveness in MeD. The siren attraction of new 'better' drugs with different mechanisms amplified this trend. Following a re-evaluation of the data, we suggest that MAOIs are effective in MeD. Additionally, the broad unitary conceptualisation of major depressive disorder (MDD) in the DSM model diminished the chance of demonstrating distinctive responses to different antidepressant drugs (ADs) such as SSRIs, TCAs, and MAOIs, thereby further reducing the interest in MAOIs. More reliable categorical distinction of MeD, disentangling it from MDD, may be possible if more sensitive measuring instruments (CORE, SMPI) are used. We suggest these issues will benefit from re-appraisement via an inductive reasoning process within a binary (rather than a unitary) model for defining the different depressive disorders, allowing for the use of more reliable diagnostic criteria for MeD in particular. We conclude that MAOIs remain essential for, inter alia, TCA-resistant MeD, and should typically be used prior to ECT; additionally, they have a role in maintaining remission in cases treated with ECT (and ketamine/esketamine). We suggest that MAOIs should be utilized earlier in treatment algorithms and with greater regularity than is presently the case.

Personality predicts pre-COVID-19 to COVID-19 trajectories of transdiagnostic anxiety and depression symptoms

This study aimed to characterize within-person pre-COVID-19 and coronavirus pandemic (COVID-19) transdiagnostic anxiety and depression symptom trajectories in emerging adults and determine the roles of neuroticism and behavioral activation in predicting these COVID-19-related changes. We recruited a sample of 342 emerging adults (aged 18-19 at baseline) who were screened on neuroticism and behavioral activation and completed symptom questionnaires on multiple occasions before and after the start of the pandemic. We examined estimates of the symptom factors of General Distress, Anhedonia-Apprehension, and Fears at each wave. The stress amplification model predicts a multiplicative neuroticism-adversity interaction with those high on neuroticism showing the greatest symptom increases to the pandemic. The stably elevated negative affect model is an additive model and predicts that persons high on neuroticism will display elevated symptoms at every wave. General Distress and Anhedonia-Apprehension showed large increases from the pre-COVID-19 to COVID-19 transition then decreased thereafter. The increase brought the average General Distress score to clinical levels at the first COVID-19 wave. There was a small decrease in Fears from the pre-COVID-19 to COVID-19 transition followed by a large increase. Thus, COVID-19 was associated with both increases in psychological symptoms and some resilience. Neuroticism positively predicted the pre-COVID-19 to COVID-19 transition change in Fears but was associated with a dampening of increases in General Distress and Anhedonia-Apprehension. The results disconfirmed the stress amplification model of neuroticism but partially supported the stably elevated negative affect model. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Striatal dopamine in anhedonia: A simultaneous [11C]raclopride positron emission tomography and functional magnetic resonance imaging investigation

BACKGROUND

Anhedonia is hypothesized to be associated with blunted mesocorticolimbic dopamine (DA) functioning in samples with major depressive disorder. The purpose of this study was to examine linkages between striatal DA, reward circuitry functioning, anhedonia, and, in an exploratory fashion, self-reported stress, in a transdiagnostic anhedonic sample.

METHODS

Participants with (n = 25) and without (n = 12) clinically impairing anhedonia completed a reward-processing task during simultaneous positron emission tomography and magnetic resonance (PET-MR) imaging with [11C]raclopride, a DA D2/D3 receptor antagonist that selectively binds to striatal DA receptors.

RESULTS

Relative to controls, the anhedonia group exhibited decreased task-related DA release in the left putamen, caudate, and nucleus accumbens and right putamen and pallidum. There were no group differences in task-related brain activation (fMRI) during reward processing after correcting for multiple comparisons. General functional connectivity (GFC) findings revealed blunted fMRI connectivity between PET-derived striatal seeds and target regions in the anhedonia group. Associations were identified between anhedonia severity and the magnitude of task-related DA release to rewards in the left putamen, but not mesocorticolimbic GFC.

CONCLUSIONS

Results provide evidence for reduced striatal DA functioning during reward processing and blunted mesocorticolimbic network functional connectivity in a transdiagnostic sample with clinically significant anhedonia.

Multi-modal assessment of reward functioning in adolescent anhedonia

BACKGROUND

Anhedonia is a core symptom of depression that predicts worse treatment outcomes. Dysfunction in neural reward circuits is thought to contribute to anhedonia. However, whether laboratory-based assessments of anhedonia and reward-related neural function translate to adolescents' subjective affective experiences in real-world contexts remains unclear.

METHODS

We recruited a sample of adolescents (n = 82; ages 12-18; mean = 15.83) who varied in anhedonia and measured the relationships among clinician-rated and self-reported anhedonia, behaviorally assessed reward learning ability, neural response to monetary reward and loss (as assessed with functional magnetic resonance imaging), and repeated ecological momentary assessment (EMA) of positive affect (PA) and negative affect (NA) in daily life.

RESULTS

Anhedonia was associated with lower mean PA and higher mean NA across the 5-day EMA period. Anhedonia was not related to impaired behavioral reward learning, but low PA was associated with reduced nucleus accumbens response during reward anticipation and reduced medial prefrontal cortex (mPFC) response during reward outcome. Greater mean NA was associated with increased mPFC response to loss outcome.

CONCLUSIONS

Traditional laboratory-based measures of anhedonia were associated with lower subjective PA and higher subjective NA in youths' daily lives. Lower subjective PA and higher subjective NA were associated with decreased reward-related striatal functioning. Higher NA was also related to increased mPFC activity to loss. Collectively, these findings demonstrate that laboratory-based measures of anhedonia translate to real-world contexts and that subjective ratings of PA and NA may be associated with neural response to reward and loss.

Anhedonia as a transdiagnostic symptom across psychological disorders: a network approach

BACKGROUND

Anhedonia is apparent in different mental disorders and is suggested to be related to dysfunctions in the reward system and/or affect regulation. It may hence be a common underlying feature associated with symptom severity of mental disorders.

METHODS

We constructed a cross-sectional graphical Least Absolute Shrinkage and Selection Operator (LASSO) network and a relative importance network to estimate the relationships between anhedonia severity and the severity of symptom clusters of major depressive disorder (MDD), anxiety sensitivity (AS), attention-deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD) in a sample of Dutch adult psychiatric patients (N = 557).

RESULTS

Both these networks revealed anhedonia severity and depression symptom severity as central to the network. Results suggest that anhedonia severity may be predictive of the severity of symptom clusters of MDD, AS, ADHD, and ASD. MDD symptom severity may be predictive of AS and ADHD symptom severity.

CONCLUSIONS

The results suggest that anhedonia may serve as a common underlying transdiagnostic psychopathology feature, predictive of the severity of symptom clusters of depression, AS, ADHD, and ASD. Thus, anhedonia may be associated with the high comorbidity between these symptom clusters and disorders. If our results will be replicated in future studies, it is recommended for clinicians to be more vigilant about screening for anhedonia and/or depression severity in individuals diagnosed with an anxiety disorder, ADHD and/or ASD.

Objective measures of reward sensitivity and motivation in people with high v. low anhedonia

BACKGROUND

Anhedonia - a diminished interest or pleasure in activities - is a core self-reported symptom of depression which is poorly understood and often resistant to conventional antidepressants. This symptom may occur due to dysfunction in one or more sub-components of reward processing: motivation, consummatory experience and/or learning. However, the precise impairments remain elusive. Dissociating these components (ideally, using cross-species measures) and relating them to the subjective experience of anhedonia is critical as it may benefit fundamental biology research and novel drug development.

METHODS

Using a battery of behavioural tasks based on rodent assays, we examined reward motivation (Joystick-Operated Runway Task, JORT; and Effort-Expenditure for Rewards Task, EEfRT) and reward sensitivity (Sweet Taste Test) in a non-clinical population who scored high (N = 32) or low (N = 34) on an anhedonia questionnaire (Snaith-Hamilton Pleasure Scale).

RESULTS

Compared to the low anhedonia group, the high anhedonia group displayed marginal impairments in effort-based decision-making (EEfRT) and reduced reward sensitivity (Sweet Taste Test). However, we found no evidence of a difference between groups in physical effort exerted for reward (JORT). Interestingly, whilst the EEfRT and Sweet Taste Test correlated with anhedonia measures, they did not correlate with each other. This poses the question of whether there are subgroups within anhedonia; however, further work is required to directly test this hypothesis.

CONCLUSIONS

Our findings suggest that anhedonia is a heterogeneous symptom associated with impairments in reward sensitivity and effort-based decision-making.

Better Biomarkers, Faster Drugs, Stronger Models: Progress Towards Precision Psychiatry

The 21st century has brought novel therapies and new therapeutic targets for major depressive disorder (MDD). Until recently all antidepressant medications targeted monoamines-serotonin, norepinephrine, and dopamine- and their regulatory systems. But growing evidence has suggested that individuals who fail to respond to a monoaminergic treatment are likely to fail to respond to other monoaminergic options. The emergence in recent years of treatment targets beyond the monoaminergic systems (e.g. κ-opioid antagonists, ketamine and other NMDA modulators, neurosteroids) has cultivated hopes for not only greater efficacy in treating depression, but also improved precision in targeting specific phenotypes and symptoms. Concurrently, an expanding repertoire of diagnostic and assessment tools-such as smartphone-based experience sampling and brain imaging-is moving the field toward more reliable and symptom-specific measurement with greater descriptive and prescriptive power. Taken together, these diagnostic tools and treatment options herald a new era of "precision psychiatry"-the selection and implementation of an optimal treatment for an individual patient's particular needs. Anhedonia offers an example of the new precision psychiatry. Anhedonia has moved from merely one among several criteria for depression to a transdiagnostic psychopathology which can be understood neurobiologically, assessed quantitatively, and centered as a primary target in research and development of novel pharmacotherapies. We describe functional testing of reward circuits in the development of kappa-opioid antagonists for anhedonia. This offers a lens for understanding how and under what circumstances other novel treatments, such as psychedelics, might find a place in the future landscape of precision psychiatric care.

Reduced anhedonia following internet-based cognitive-behavioral therapy for depression is mediated by enhanced reward circuit activation

BACKGROUND

Major depressive disorder (MDD) is a highly prevalent psychiatric condition, yet many patients do not receive adequate treatment. Novel and highly scalable interventions such as internet-based cognitive-behavioral-therapy (iCBT) may help to address this treatment gap. Anhedonia, a hallmark symptom of MDD that refers to diminished interest and ability to experience pleasure, has been associated with reduced reactivity in a neural reward circuit that includes medial prefrontal and striatal brain regions. Whether iCBT can reduce anhedonia severity in MDD patients, and whether these therapeutic effects are accompanied by enhanced reward circuit reactivity has yet to be examined.

METHODS

Fifty-two MDD patients were randomly assigned to either 10-week iCBT (n = 26) or monitored attention control (MAC, n = 26) programs. All patients completed pre- and post-treatment assessments of anhedonia (Snaith-Hamilton Pleasure Scale; SHAPS) and reward circuit reactivity [monetary incentive delay (MID) task during functional magnetic resonance imaging (fMRI)]. Healthy control participants (n = 42) also underwent two fMRI scans while completing the MID task 10 weeks apart.

RESULTS

Both iCBT and MAC groups exhibited a reduction in anhedonia severity post-treatment. Nevertheless, only the iCBT group exhibited enhanced nucleus accumbens (Nacc) and subgenual anterior cingulate cortex (sgACC) activation and functional connectivity from pre- to post-treatment in response to reward feedback. Enhanced Nacc and sgACC activations were associated with reduced anhedonia severity following iCBT treatment, with enhanced Nacc activation also mediating the reduction in anhedonia severity post-treatment.

CONCLUSIONS

These findings suggest that increased reward circuit reactivity may contribute to a reduction in anhedonia severity following iCBT treatment for depression.

Attention allocation to negatively-valenced stimuli in PTSD is associated with reward-related neural pathways

BACKGROUND

In a recent eye-tracking study we found a differential dwell time pattern for negatively-valenced and neutral faces among patients with posttraumatic stress disorder (PTSD), trauma-exposed healthy control (TEHCs), and healthy control (HC) participants. Here, we explored whether these group differences relate to resting-state functional connectivity (rsFC) patterns of brain areas previously linked to both attention processes and PTSD. These encompass the amygdala, dorsal anterior cingulate cortex (dACC), dorsolateral prefrontal cortex (dlPFC), ventrolateral prefrontal cortex (vlPFC), and nucleus accumbens (NAcc).

METHODS

Ten minutes magnetic resonance imaging rsFC scans were recorded in 17 PTSD patients, 21 TEHCs, and 16 HCs. Participants then completed a free-viewing eye-tracking task assessing attention allocation outside the scanner. Dwell time on negatively-valenced stimuli (DT%) were assessed relative to functional connectivity in the aforementioned seed regions of interest (amygdala, dACC, dlPFC, vlPFC, and NAcc) to whole-brain voxel-wise rsFC.

RESULTS

As previously reported, group differences occurred in attention allocation to negative-valence stimuli, with longer dwell time on negatively valence stimuli in the PTSD and TEHC groups than the HC group. Higher DT% correlated with weaker NAcc-orbitofrontal cortex (OFC) connectivity in patients with PTSD. Conversely, a positive association emerged in the HC group between DT% and NAcc-OFC connectivity.

CONCLUSIONS

While exploratory in nature, present findings may suggest that reward-related brain areas are involved in disengaging attention from negative-valenced stimuli, and possibly in regulating ensuing negative emotions.

Lactobacillus salivarius and Lactobacillus gasseri supplementation reduces stress-induced sugar craving in mice

OBJECTIVE

Increased intake of sweets or sugar craving may occur in response to chronic stress representing a risk factor for development of eating disorders and obesity. However, no safe treatment of stress-induced sugar craving is available. In this study we analysed effects of two Lactobacillus strains on food and sucrose intake in mice before and during their exposure to a chronic mild stress (CMS).

RESEARCH METHODS & PROCEDURES

C57Bl6 mice were gavaged daily for 27 days with a mix of L. salivarius (LS) LS7892 and L. gasseri (LG) LG6410 strains or with 0.9% NaCl as a control. Following 10 days of gavage, mice were individually placed into the Modular Phenotypic cages, and after 7 days of acclimation were exposed to a CMS model for 10 days. Food, water and 2% sucrose intakes as well as meal pattern were monitored. Anxiety and depressive-like behaviour were analysed by standard tests.

RESULTS

Exposure of mice to CMS was accompanied by increased size of sucrose intake in the control group likely reflecting the stress-induced sugar craving. A consistent, about 20% lower total sucrose intake, was observed in the Lactobacilli-treated group during stress which was mainly due to a reduced number of intakes. Lactobacilli treatment also modified the meal pattern before and during the CMS, showing a decrease of meal number and an increase of meal size with a tendency of reduced total daily food intake. Mild anti-depressive behavioural effects of the Lactobacilli mix were also present.

CONCLUSION

Supplementation of mice with LS LS7892 and LG LG6410 decreases sugar consumption suggesting a potential utility of these strains against stress-induced sugar craving.

The Longitudinal Features of Depressive Symptoms During the COVID-19 Pandemic Among Chinese College Students: A Network Perspective

There is substantial evidence that the Corona Virus Disease 2019 (COVID-19) pandemic increased the risk of depressive symptoms among college students, but the long-term features of depressive symptoms on a symptom level have been poorly described. The current study investigated interaction patterns between depressive symptoms via network analysis. In this longitudinal study, participants included 860 Chinese college students (65.8% female; M_age = 20.6, SD_age = 1.8, range: 17-27) who completed a questionnaire at three-time points three months apart. Results demonstrated that fatigue was the most influential symptom, and the occurrence of fatigue could give rise to other depressive symptoms. In addition to predicting other symptoms, fatigue could be predicted by other symptoms in the measurement. The network structures were similar across time, suggesting that the overall interaction pattern of depressive symptoms was stable over the longitudinal course. These findings suggest that depressive symptoms during the COVID-19 period are associated with the presence of fatigue.

Emotional subtypes in patients with depression: A cluster analysis

Major depressive disorder (MDD) is associated with deficits in emotion experience, expression and regulation. Whilst emotion regulation deficits prolong MDD, emotion expression influences symptomatic presentations, and anticipatory pleasure deficits predict recurrence risk. Profiling MDD patients from an emotion componential perspective can characterize subtypes with different clinical and functional outcomes. This study aimed to investigate emotional subtypes of MDD. A two-stage cluster analysis applied to 150 MDD patients. Clustering variables included emotion experience measured by Temporal Experience of Pleasure Scale, emotion expression measured by Toronto Alexithymia Scale, and emotion regulation measured by Emotion Regulation Questionnaire. We validated the resultant clusters by comparing their symptoms and functioning with that of 50 controls. Cluster 1 (n = 50) exhibited intact emotion experience and expression yet adopted reappraisal rather than suppression strategy, whereas Cluster 2 (n = 66) exhibited generalized emotional deficits. Cluster 3 (n = 34) exhibited emotion expression deficits and adopted both reappraisal and suppression strategies. On validation, Cluster 2 exhibited the worst, but Cluster 1 exhibited the least symptoms and social functioning impairments. Cluster 3 was intermediate among the two other subtypes. Our findings support the existence of different emotional subtypes in MDD patients, and have clinical and theoretical implications for developing future specific treatments for MDD.

The antidepressant actions of ketamine and its enantiomers

Ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist first developed as an anesthetic, has shown significant promise as a medication with rapid antidepressant properties in treatment-resistant depression. However, concerns such as adverse side effects and potential misuse liability have limited its widespread use. Racemic ketamine has two enantiomers-(S)- and (R)-ketamine-that appear to have disparate underlying mechanisms. This brief review summarizes some of the most recent preclinical and clinical research regarding the convergent and divergent prophylactic, immediate, and sustained antidepressant effects of (S)- and (R)-ketamine while addressing potential differences in their side effect and misuse liability profiles. Preclinical research suggests divergent mechanisms underlying (S)- and (R)-ketamine, with (S)-ketamine more directly affecting mechanistic target of rapamycin complex 1 (mTORC1) signaling and (R)-ketamine more directly affecting extracellular signal-related kinase (ERK) signaling. Clinical research suggests that (R)-ketamine has a milder side effect profile than (S)-ketamine and decreases depression rating scale scores, but recent randomized, controlled trials found that it had no significant antidepressant efficacy compared to placebo, suggesting that caution is warranted in interpreting its therapeutic potential. Future preclinical and clinical research is needed to maximize the efficacy of each enantiomer, either by optimizing dose, route of administration, or administration paradigm.

Biological factors influencing depression in later life: role of aging processes and treatment implications

Late-life depression occurring in older adults is common, recurrent, and malignant. It is characterized by affective symptoms, but also cognitive decline, medical comorbidity, and physical disability. This behavioral and cognitive presentation results from altered function of discrete functional brain networks and circuits. A wide range of factors across the lifespan contributes to fragility and vulnerability of those networks to dysfunction. In many cases, these factors occur earlier in life and contribute to adolescent or earlier adulthood depressive episodes, where the onset was related to adverse childhood events, maladaptive personality traits, reproductive events, or other factors. Other individuals exhibit a later-life onset characterized by medical comorbidity, pro-inflammatory processes, cerebrovascular disease, or developing neurodegenerative processes. These later-life processes may not only lead to vulnerability to the affective symptoms, but also contribute to the comorbid cognitive and physical symptoms. Importantly, repeated depressive episodes themselves may accelerate the aging process by shifting allostatic processes to dysfunctional states and increasing allostatic load through the hypothalamic-pituitary-adrenal axis and inflammatory processes. Over time, this may accelerate the path of biological aging, leading to greater brain atrophy, cognitive decline, and the development of physical decline and frailty. It is unclear whether successful treatment of depression and avoidance of recurrent episodes would shift biological aging processes back towards a more normative trajectory. However, current antidepressant treatments exhibit good efficacy for older adults, including pharmacotherapy, neuromodulation, and psychotherapy, with recent work in these areas providing new guidance on optimal treatment approaches. Moreover, there is a host of nonpharmacological treatment approaches being examined that take advantage of resiliency factors and decrease vulnerability to depression. Thus, while late-life depression is a recurrent yet highly heterogeneous disorder, better phenotypic characterization provides opportunities to better utilize a range of nonspecific and targeted interventions that can promote recovery, resilience, and maintenance of remission.

Abnormal functional connectivity of the nucleus accumbens subregions mediates the association between anhedonia and major depressive disorder

BACKGROUND

The nucleus accumbens (Nac) is a crucial brain region in the pathophysiology of major depressive disorder (MDD) patients with anhedonia. However, the relationship between the functional imaging characteristics of Nac subregions and anhedonia remains unclear. Thus, this study aimed to investigate the role of resting-state functional connectivity (rsFC) of the Nac subregions between MDD and anhedonia.

METHODS

We performed resting-state functional magnetic resonance imaging (fMRI) to measure the rsFC of Nac subregions in 55 MDD patients and 30 healthy controls (HCs). A two-sample t test was performed to determine the brain regions with varying rsFC among Nac subregions between groups. Then, correlation analyses were carried out to investigate the relationships between the aberrant rsFC of Nac subregions and the severity of anhedonia. Furthermore, we constructed a mediation model to explain the role of the aberrant rsFC of Nac subregions between MDD and the severity of anhedonia.

RESULTS

Compared with the HC group, decreased rsFC of Nac subregions with regions of the prefrontal cortex, insula, lingual gyrus, and visual association cortex was observed in MDD patients. In the MDD group, the rsFC of the right Nac shell-like subregions with the middle frontal gyrus (MFG)/superior frontal gyrus (SFG) was correlated with consummatory anhedonia, and the rsFC of the Nac core-like subdivisions with the inferior frontal gyrus (IFG)/insula and lingual gyrus/visual association cortex was correlated with anticipatory anhedonia. More importantly, the functional alterations in the Nac subregions mediated the association between anhedonia and depression.

CONCLUSIONS

The present findings suggest that the functional alteration of the Nac subregions mediates the association between MDD and anhedonia, which provides evidence for the hypothesis that MDD patients have neurobiological underpinnings of reward systems that differ from those of HCs.

Effects of Aloe-Emodin on the Expression of Brain Aquaporins and Secretion of Neurotrophic Factors in a Rat Model of Post-Stroke Depression

Post-stroke depression (PSD) is a common complication of stroke that can damage patients' brains. More and more studies have been conducted on PSD in recent years, but the exact mechanism is still not understood. Currently, animal models provide an alternative approach to better understand the pathophysiology of PSD and may also pave the way for the discovery of new treatments for depression. This study investigated the therapeutic effect and mechanism of aloe-emodin (AE) on PSD rats. Previous studies have shown that AE positively affects PSD in rats by improving depression, increasing their activities and curiosities, enhancing the number of neurons, and ameliorating damage to brain tissue. Meanwhile, AE could up-regulate the expression of brain-derived neurotrophic factor (BDNF) and neurotrophic 3 (NTF3), but it could also down-regulate the expression of aquaporins (AQP3, AQP4, and AQP5), glial fibrillary acidic protein (GFAP), and transient receptor potential vanilloid 4 (TRPV4), which is helpful in maintaining homeostasis and alleviating encephaledema. AE may be a prospective solution in the future for the treatment of PSD patients.

"Don't [ruminate], be happy": A cognitive perspective linking depression and anhedonia

Anhedonia, a lack of pleasure in things an individual once enjoyed, and rumination, the process of perseverative and repetitive attention to specific thoughts, are hallmark features of depression. Though these both contribute to the same debilitating disorder, they have often been studied independently and through different theoretical lenses (e.g., biological vs. cognitive). Cognitive theories and research on rumination have largely focused on understanding negative affect in depression with much less focus on the etiology and maintenance of anhedonia. In this paper, we argue that by examining the relation between cognitive constructs and deficits in positive affect, we may better understand anhedonia in depression thereby improving prevention and intervention efforts. We review the extant literature on cognitive deficits in depression and discuss how these dysfunctions may not only lead to sustained negative affect but, importantly, interfere with an ability to attend to social and environmental cues that could restore positive affect. Specifically, we discuss how rumination is associated to deficits in working memory and propose that these deficits in working memory may contribute to anhedonia in depression. We further argue that analytical approaches such as computational modeling are needed to study these questions and, finally, discuss implications for treatment.

Anhedonia in Relation to Reward and Effort Learning in Young People with Depression Symptoms

Anhedonia, a central depression symptom, is associated with impairments in reward processing. However, it is not well understood which sub-components of reward processing (anticipation, motivation, consummation, and learning) are impaired in association with anhedonia in depression. In particular, it is unclear how learning about different rewards and the effort needed to obtain them might be associated with anhedonia and depression symptoms. Therefore, we examined learning in young people (N = 132, mean age 20, range 17-25 yrs.) with a range of depression and anhedonia symptoms using a probabilistic instrumental learning task. The task required participants to learn which options to choose to maximize their reward outcomes across three conditions (chocolate taste, puppy images, or money) and to minimize the physical effort required to obtain the rewards. Additionally, we collected questionnaire measures of anticipatory and consummatory anhedonia, as well as subjective reports of "liking", "wanting" and "willingness to exert effort" for the rewards used in the task. We found that as anticipatory anhedonia increased, subjective liking and wanting of rewards decreased. Moreover, higher anticipatory anhedonia was significantly associated with lower reward learning accuracy, and participants demonstrated significantly higher reward learning than effort learning accuracy. To our knowledge, this is the first study observing an association of anhedonia with reward liking, wanting, and learning when reward and effort learning are measured simultaneously. Our findings suggest an impaired ability to learn from rewarding outcomes could contribute to anhedonia in young people. Future longitudinal research is needed to confirm this and reveal the specific aspects of reward learning that predict anhedonia. These aspects could then be targeted by novel anhedonia interventions.

The Motivation and Energy Inventory (MEI): Analysis of the clinically relevant response threshold in patients with major depressive disorder and emotional blunting using data from the COMPLETE study

BACKGROUND

The Motivation and Energy Inventory (MEI) is a patient-reported scale for assessment of the impact of mental/cognitive energy, social motivation, and physical energy on daily functioning in patients with major depressive disorder (MDD). This analysis was undertaken to establish the clinically relevant response threshold for the MEI in patients with MDD receiving antidepressant treatment.

METHODS

Patients with MDD experiencing inadequate response and emotional blunting on selective serotonin reuptake inhibitor or serotonin-noradrenaline reuptake inhibitor monotherapy (adequate dose for ≥6 weeks) were switched to vortioxetine 10-20 mg/day for 8 weeks. Anchor- and distribution-based methods were used to determine the minimal clinically important difference (MCID) in MEI total score.

RESULTS

After 8 weeks of vortioxetine treatment, mean (standard deviation) change in MEI total score from baseline was 33.0 (27.3) points. At week 8, mean change in MEI total score from baseline was 37.5 (27.8) points in patients no longer reporting emotional blunting and 28.3 (26.2) points in those still experiencing emotional blunting. In patients considered minimally improved (i.e. Clinical Global Impression-Improvement [CGI-I] score of 3 after 8 weeks of vortioxetine), mean change in MEI total score from baseline was 14.7 (19.1) points. In patients defined as responders (CGI-I score of 2 at 8 weeks), mean change in MEI total score was 33.0 (24.7) points.

LIMITATIONS

Short study duration.

CONCLUSIONS

These results provide further validation of the clinical utility of the MEI for assessing treatment response in patients with MDD. The suggested MCID for MEI total score is 15 points.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03835715.

Assessment of patient life engagement in major depressive disorder using items from the Inventory of Depressive Symptomatology Self-Report (IDS-SR)

BACKGROUND

Patient-reported outcomes can measure domains that are personally meaningful, such as life engagement, which reflects motivation, pleasure, and well-being. This study explored whether certain items from the Inventory of Depressive Symptomatology Self-Report (IDS-SR) can capture patient life engagement in major depressive disorder (MDD).

METHODS

IDS-SR life engagement items were identified by a) a panel of expert psychiatrists (n = 4), b) patient interviews (n = 20), and c) a principal component analysis (PCA) to explore clustering of items. Psychometric analyses were performed on potential subscales, and a minimal clinically important difference (MCID) was estimated by anchor- and distribution-based methods. IDS-SR data were obtained from three randomized controlled trials of adjunctive brexpiprazole in MDD.

RESULTS

Expert psychiatrists selected 10 items by consensus from the IDS-SR that might capture patient life engagement (Cronbach's alpha, 0.82; item-total correlations, 0.36-0.58). Patient interviews identified 13 items as moderately to very relevant to life engagement (Cronbach's alpha, 0.85; item-total correlations, 0.35-0.61). The PCA revealed a cluster that included all 10 items selected by psychiatrists and 11 items identified by patients. Expert psychiatrists intentionally distinguished life engagement and core depressive symptoms, although patient insights and the PCA indicated that these aspects of MDD are strongly linked. The 10-item IDS-SR life engagement subscale had an MCID of 3-5 points.

CONCLUSIONS

Different approaches consistently identified a subset of 10 IDS-SR items that can measure life engagement in MDD, which may be suitable to group into an IDS-SR life engagement subscale.

The anticipatory and consummatory interpersonal pleasure scale: Applicability to Chinese OCD patients

As a transdiagnostic symptom, social anhedonia has gained increasing attention. Evidence suggests that obsessive-compulsive disorder (OCD) patients demonstrate social anhedonia. This study examined the psychometric properties of the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS) in an undergraduate sample and Chinese OCD patients. Furthermore, we explored the relationship between clinical symptoms and ACIPS scores. This study involved 3,306 undergraduate students and 293 patients with OCD. Internal consistency and convergent validity of ACIPS were examined. Confirmatory factor analysis (CFA) was applied to determine the best-fitting of potential factor models, and multi-group CFA was used to examine measurement invariance across genders and samples. Additionally, hierarchical linear regression was conducted in order to investigate the relationship between clinical symptoms and ACIPS scores in patients suffering from OCD. ACIPS showed acceptable internal consistency in undergraduate and OCD samples (Cronbach's α = 0.93 and 0.89, respectively). In both samples, the four-factor structure had the best fit index. Scalar invariance was established across undergraduate and OCD samples, while residual invariance was established across genders. In both samples, the ACIPS was significantly correlated with the Revised Social Anhedonia Scale and Beck Depression Inventory. Depression and the severity of obsessive thoughts significantly and negatively correlated with the ACIPS score in OCD patients (p < 0.05). In conclusion, ACIPS is a reliable, effective, simple, and convenient tool for the assessment of social anhedonia. Depression and obsessive thoughts contribute to social anhedonia in OCD patients.

Gender Impacts the Relationship between Mood Disorder Symptoms and Effortful Avoidance Performance

We must often decide how much effort to exert or withhold to avoid undesirable outcomes or obtain rewards. In depression and anxiety, levels of avoidance can be excessive and reward-seeking may be reduced. Yet outstanding questions remain about the links between motivated action/inhibition and anxiety and depression levels, and whether they differ between men and women. Here, we examined the relationship between anxiety and depression scores, and performance on effortful active and inhibitory avoidance (Study 1) and reward seeking (Study 2) in humans. Undergraduates and paid online workers ([Formula: see text] = 545, [Formula: see text] = 310; [Formula: see text] = 368, [Formula: see text] = 450, [Formula: see text] = 22.58, [Formula: see text] = 17-62) were assessed on the Beck Depression Inventory II (BDI) and the Beck Anxiety Inventory (BAI) and performed an instructed online avoidance or reward-seeking task. Participants had to make multiple presses on active trials and withhold presses on inhibitory trials to avoid an unpleasant sound (Study 1) or obtain points toward a monetary reward (Study 2). Overall, men deployed more effort than women in both avoidance and reward-seeking, and anxiety scores were negatively associated with active reward-seeking performance based on sensitivity scores. Gender interacted with anxiety scores and inhibitory avoidance performance, such that women with higher anxiety showed worse avoidance performance. Our results illuminate effects of gender in the relationship between anxiety and depression levels and the motivation to actively and effortfully respond to obtain positive and avoid negative outcomes.

The therapeutic role of ketamine and esketamine in treating psychopathological domains of depression

Over the past two decades, ketamine has emerged as a novel effective and rapid-acting antidepressant. While the vast majority of studies on ketamine have focused on its ability to reduce the severity of depression broadly, its effectiveness in specific domains such as cognition, anhedonia, suicidality, and workplace/social/scholastic functionality has been neglected. Similarly, current treatments (e.g., SSRIs and SNRIs) aim to improve overall depression severity, which often results in the persistence of one or more residual symptom domains and prevents full recovery to premorbid functionality. In this review, we narratively synthesize the literature pertaining to the effectiveness of ketamine in treating key domains of depressive symptomatology (i.e., cognition, anhedonia, suicidality, and psychosocial functionality). Our findings suggest that ketamine is effective across domains varyingly, with the strongest evidence being for its ability to reduce suicidality. The rapid acting nature of ketamine further supports its use in treating suicidality and potentially preventing the completion of suicide. Evidence for the effectiveness of ketamine in other domains is weak, primarily due to a lack of robust studies specifically designed to assess these domains as primary outcomes. Future studies should scrutinize the effects of ketamine on specific domains of depression to optimize its implementation.

Neural sensitivity to peer feedback and depression symptoms in adolescents: a 2-year multiwave longitudinal study

BACKGROUND

Depression risk increases during adolescent development, and individual differences in neural sensitivity to peer feedback (rejection vs. acceptance) may be a key diathesis in understanding stress-related depression risk.

METHODS

At baseline, adolescents (12-14 years old; N = 124) completed clinical interviews and self-report symptom measures, and the Chatroom Task while MRI data were acquired. The majority of participants provided usable MRI data (N = 90; 76% female), which included adolescents with no maternal depression history (low risk n = 64) and those with a maternal depression history (high risk n = 26). Whole-brain regression models probed group differences in neural sensitivity following peer feedback, and whole-brain linear mixed-effects models examined neural sensitivity to peer feedback by peer stress interactions relating to depression symptoms at up to nine longitudinal assessments over 2 years.

RESULTS

Whole-brain cluster-corrected results indicated brain activation moderating the strong positive association between peer interpersonal stress and depression over time. This included activation in the anterior insula, cingulate, amygdala, and striatum during anticipation and receipt of feedback (i.e., rejection vs. acceptance). Moderation effects were stronger when examining peer interpersonal (vs. non-interpersonal) stress and in relation to depression (vs. social anxiety) symptoms.

CONCLUSIONS

Neural responses to peer feedback in key social and incentive processing brain regions may reflect core dispositional risk factors that interact with peer interpersonal stressors to predict adolescent depression symptom severity over time.

Neural deficits in anticipatory and consummatory reward processing are uniquely associated with current depressive symptoms during adolescence

Deficits within the consummatory phase of reward processing are associated with increased depression symptoms and risk; however, few studies have also examined other aspects of reward processing in relation to depression. In the current study, a community sample of 121 adolescents (M_age  = 13.1, Min = 11.14; Max = 15.12; 54% male) completed self-report questionnaires to assess depressive symptoms and the monetary incentive delay (MID) task while EEG was recorded. Results indicated that a reduced cue-P300 as well as a reduced reward positivity (RewP) and feedback negativity (FN) to gain and loss feedback, respectively, were associated with increased depressive symptoms; on the other hand, SPN and feedback P300 were unrelated to depressive symptoms. An exploratory multiple regression analysis revealed that a reduced money cue-P300, a reduced RewP, and a reduced (i.e., less negative) FN, all explained unique variance in depressive symptoms. The current study demonstrates that reduced cue-P300, RewP, and FN amplitudes may reflect distinct deficits in reward processing among adolescents with increased depressive symptoms. Notably, this study is one of the first to leverage the MID task in adolescents in relation to depressive symptoms, allowing for a more in-depth view of the individual differences in reward processing among adolescents with increased depressive symptomatology.

Anhedonia modulates benzodiazepine and opioid demand among persons in treatment for opioid use disorder

Background

Benzodiazepine (BZD) misuse is a significant public health problem, particularly in conjunction with opioid use, due to increased risks of overdose and death. One putative mechanism underlying BZD misuse is affective dysregulation, via exaggerated negative affect (e.g., anxiety, depression, stress-reactivity) and/or impaired positive affect (anhedonia). Similar to other misused substances, BZD consumption is sensitive to price and individual differences. Although purchase tasks and demand curve analysis can shed light on determinants of substance use, few studies have examined BZD demand, nor factors related to demand.

Methods

This ongoing study is examining simulated economic demand for alprazolam (among BZD lifetime misusers based on self-report and DSM-5 diagnosis; n = 23 total; 14 male, 9 female) and each participant's preferred-opioid/route using hypothetical purchase tasks among patients with opioid use disorder (n = 59 total; 38 male, 21 female) who are not clinically stable, i.e., defined as being early in treatment or in treatment longer but with recent substance use. Aims are to determine whether: (1) BZD misusers differ from never-misusers on preferred-opioid economic demand, affective dysregulation (using questionnaire and performance measures), insomnia/behavioral alertness, psychiatric diagnoses or medications, or urinalysis results; and (2) alprazolam demand among BZD misusers is related to affective dysregulation or other measures.

Results

Lifetime BZD misuse is significantly (p < 0.05) related to current major depressive disorder diagnosis, opioid-negative and methadone-negative urinalysis, higher trait anxiety, greater self-reported affective dysregulation, and younger age, but not preferred-opioid demand or insomnia/behavioral alertness. Alprazolam and opioid demand are each significantly positively related to higher anhedonia and, to a lesser extent, depression symptoms but no other measures of negative-affective dysregulation, psychiatric conditions or medications (including opioid agonist therapy or inpatient/outpatient treatment modality), or sleep-related problems.

Conclusion

Anhedonia (positive-affective deficit) robustly predicted increased BZD and opioid demand; these factors could modulate treatment response. Routine assessment and effective treatment of anhedonia in populations with concurrent opioid and sedative use disorder may improve treatment outcomes.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT03696017, identifier NCT03696017.

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.

Transforming experiences: Neurobiology of memory updating/editing

Long-term memory is achieved through a consolidation process where structural and molecular changes integrate information into a stable memory. However, environmental conditions constantly change, and organisms must adapt their behavior by updating their memories, providing dynamic flexibility for adaptive responses. Consequently, novel stimulation/experiences can be integrated during memory retrieval; where consolidated memories are updated by a dynamic process after the appearance of a prediction error or by the exposure to new information, generating edited memories. This review will discuss the neurobiological systems involved in memory updating including recognition memory and emotional memories. In this regard, we will review the salient and emotional experiences that promote the gradual shifting from displeasure to pleasure (or vice versa), leading to hedonic or aversive responses, throughout memory updating. Finally, we will discuss evidence regarding memory updating and its potential clinical implication in drug addiction, phobias, and post-traumatic stress disorder.

Alcohol Use Severity, Anger and Drinking Motives among Firefighters

Background: Firefighters represent an understudied population with high rates of hazardous alcohol use and alcohol use disorder. This population is also at an increased risk of mental health disorders and related symptoms such as anger. Anger is a relatively understudied negative mood state with clinical relevance to alcohol use among firefighters. Anger is associated with greater alcohol use and may spur more approach-motivated reasons for drinking compared to other negative emotions. Objectives: This study sought to examine: 1. whether anger significantly contributes to alcohol use severity in firefighters above and beyond general negative mood; 2. which of four validated drinking motives (e.g., coping, social, enhancement and conformity) act as moderators in the relationship between anger and alcohol use severity in this population. The current study is a secondary analysis of data from a larger study examining health and stress behaviors among firefighters (N = 679) at a large urban fire department in the southern United States. Results: Results revealed that anger was positively associated with alcohol use severity, even after controlling for general negative mood. Further, social and enhancement motives for drinking were significant moderators of the relationship between anger and alcohol use severity. Conclusions: These findings identify anger specifically as an important factor to be considered when assessing alcohol use in firefighters, especially those who are drinking to make social experiences more enjoyable or to enhance their mood. These findings can be used to inform more specialized interventions for alcohol use by targeting anger more specifically in firefighters and other male-dominated first-responder populations.

Depressive symptoms are associated with reduced positivity preferences in episodic memory in aging

Age-related positivity preferences are represented as greater memory benefits for positive and/or reduced benefits for negative material with age. It is unknown if positivity preferences are limited to older adults without depressive symptoms. In this fMRI study, adults across the lifespan with a range of depressive symptoms were scanned as they rated emotional intensity of images and subsequently completed a recognition memory task. Behavioral, univariate, and functional connectivity analyses provided evidence for interactive effects between age and depressive symptoms. With low depressive symptoms, typical age-related emotional preferences emerged: younger age was associated with better memory for negative images, and this benefit was reduced with older age. With increasing depressive symptoms in older age, positivity preferences were reduced, manifesting as improvements in negative memory. The neural data highlighted potential underlying mechanisms, including reductions in prefrontal cortex connectivity reflecting diminished ability to engage regulatory processes to reduce negative affect in older participants with higher depressive symptoms. These findings suggest that depressive symptoms in older adulthood reduce positivity preferences through alterations in neural networks underlying emotion regulation.

Sooner is Better: Longitudinal Relations Between Delay Discounting, and Depression and Anxiety Symptoms among Vietnamese Adolescents

Delay discounting refers to the decline in the present value of an outcome as a function of the delay to its receipt. Research on delay discounting initially focused on substance abuse, generally finding that greater delay discounting is associated with increased risk for and severity of substance abuse. More recently, delay discounting has been linked theoretically and empirically to affective psychopathology, potentially suggesting novel intervention targets for mental health problems such as depression and anxiety. Longitudinal research consequently is critical to determine direction of causality and rule out possible third variable explanations. Only a small number of longitudinal studies have been conducted in this area, however. Furthermore, socio-economic and socio-cultural factors may influence delay discounting and its effects, but thus far the literature is relatively limited in this regard. The present study focused on adolescence, a key time-period for development of delay discounting and emotional problems. Longitudinal relations between delay discounting, and depression and anxiety symptoms were assessed among 414 adolescents in Vietnam, a lower-middle-income Southeast Asian nation with significant cultural divergence from Western countries. In contrast to most cross-sectional studies that have found positive or non-significant correlations, in the present study delay discounting at Time 1 had a negative beta with anxiety and depression symptoms at Time 1, with preference for immediate but smaller rewards (higher discounting) at Time 1 associated with lower anxiety and depression symptoms at Time 2. These results suggest that under certain circumstances, steeper delay discounting may be adaptive and supportive of emotional mental health.

The neurobiology of apathy in depression and neurocognitive impairment in older adults: a review of epidemiological, clinical, neuropsychological and biological research

Apathy is a common condition that involves diminished initiative, diminished interest and diminished emotional expression or responsiveness. It is highly prevalent in the context of a variety of neuropsychiatric disorders and is related to poor health outcomes. Presence of apathy is associated with cognitive and functional decline in dementia. Despite its negative impact on health, there is no definitive treatment for apathy, a clinical reality that may be due in part to lack of knowledge about assessment, neuropsychological features and neurobiological underpinnings. Here, we review and synthesize evidence from clinical, epidemiological, neuropsychological, peripheral biomarker and neuroimaging research. Apathy is a common feature of depression and cognitive disorders and is associated with impairment in executive function. Neuropsychological and neuroimaging studies point to dysfunction of brain circuitry involving the prefrontal cortex, especially the dorsolateral prefrontal cortex circuit, the dorsomedial prefrontal cortex circuit, and the ventromedial prefrontal cortex circuit. However, inconsistent findings, particularly in neuroimaging may be due to heterogeneity of apathy symptoms (with a need to better elucidate subtypes), neuropsychiatric comorbidities, the severity of cognitive impairment and other factors. These factors need to be accounted for in future studies so that biomarker research can make progress. On the whole, the literature on apathy has identified likely neurocognitive, peripheral biomarker and neuroimaging targets for understanding apathy, but also points to the need to address methodological issues that will better inform future studies. In turn, as we learn more about the underpinning of apathy and its subtypes, subsequent research can focus on new neurally based interventions that will strengthen the clinical management of apathy in the context of its comorbidities.

How well do Cognitive Behavioural Therapy and Behavioural Activation for depression repair anhedonia? A secondary analysis of the COBRA randomized controlled trial

A secondary analysis of the COBRA randomized controlled trial was conducted to examine how well Cognitive Behavioural Therapy (CBT) and Behavioural Activation (BA) repair anhedonia. Patients with current major depressive disorder (N = 440) were randomized to receive BA or CBT, and anhedonia and depression outcomes were measured after acute treatment (six months) and at two further follow up intervals (12 and 18 months). Anhedonia was assessed using the Snaith Hamilton Pleasure Scale (SHAPS; a measure of consummatory pleasure). Both CBT and BA led to significant improvements in anhedonia during acute treatment, with no significant difference between treatments. Participants remained above healthy population averages of anhedonia at six months, and there was no further significant improvement in anhedonia at 12-month or 18-month follow up. Greater baseline anhedonia severity predicted reduced repair of depression symptoms and fewer depression-free days across the follow-up period in both the BA and CBT arms. The extent of anhedonia repair was less marked than the extent of depression repair across both treatment arms. These findings demonstrate that CBT and BA are similarly and only partially effective in treating anhedonia. Therefore, both therapies should be further refined or novel treatments should be developed in order better to treat anhedonia.

Patient-reported outcome measures for life engagement in mental health: a systematic review

Background

Life engagement in the context of mental health is a broad term that describes positive health aspects relating to cognition, vitality, motivation and reward, and the ability to feel pleasure—concepts that are meaningful to patients. The aim of this systematic literature review was to identify validated patient-reported outcomes (PROs) that can assess any aspect of life engagement in adults, in the field of general mental health.

Methods

This was a systematic literature review of articles in English from the MEDLINE database (date of search: September 9, 2020). The search strategy had three components: (1) terms to capture PROs; (2) terms to capture mental health; and (3) terms to capture aspects of life engagement. Articles were eligible if they included a PRO that: (1) is named; (2) can be used across mental health disorders; (3) is used to assess any aspect of life engagement; and (4) has undergone psychometric validation and/or qualitative content validation. A list of PROs was extracted.

Results

A total of 1585 records were screened and 233 articles were eligible for inclusion. Within these 233 articles, 49 distinct PROs were identified, two of which specifically captured their authors’ interpretation of life engagement: the Engaged Living Scale (ELS) and the Life Engagement Test (LET). However, while the ELS and LET covered motivation and reward, life fulfillment, and value-based living, neither scale captured the cognitive or vitality aspects of life engagement. The remaining identified PROs generally captured single aspects of life engagement, most commonly motivation/reward/energy–apathy, pleasure–anhedonia, and mental/psychological well-being.

Conclusion

Numerous PROs are available that may capture aspects of life engagement. However, a need remains for a new PRO that can be used in clinical trials to provide a more comprehensive description of the improvements in life engagement that patients with mental health disorders may experience with successful treatment.

Aberrant interhemispheric functional connectivity in major depressive disorder with and without anhedonia

OBJECTIVE

Anhedonia is a core feature of major depressive disorder (MDD), and as a subtype of depression, MDD with anhedonia may have exceptional neurobiological mechanisms. However, the neuropathology of anhedonia in MDD remains unclear. Thus, this study aimed to investigate the brain functional differences between MDD with and without anhedonia.

METHODS

A total of 62 individuals including 22 MDD patients with anhedonia, 20 MDD patients without anhedonia, and 20 healthy controls (HCs) were recruited for this study. All participants underwent 3.0-T functional magnetic resonance imaging scan. Voxel-mirrored homotopic connectivity (VMHC) was employed to quantitatively describe bilateral functional connectivity. Analyses of variance (ANOVA) were performed to obtain brain regions with significant differences among three groups and then post hoc tests were calculated for inter-group comparisons.

RESULTS

The ANOVA revealed significant VMHC differences among three groups in the bilateral middle temporal gyrus (MTG), superior frontal gyrus (SFG), and inferior parietal lobule (IPL) (F = 10.47 ~ 15.09, p &lt; 0.05, AlphaSim corrected). Relative to HCs, MDD with anhedonia showed significantly decreased VMHC in the bilateral MTG (t = -5.368, p &lt; 0.05, AlphaSim corrected), as well as increased VMHC in the bilateral SFG (t = -4.696, p &lt; 0.05, AlphaSim corrected). Compared to MDD without anhedonia, MDD with anhedonia showed significantly decreased VMHC in the bilateral MTG and IPL (t = -5.629 ~ -4.330, p &lt; 0.05, AlphaSim corrected), while increased VMHC in the bilateral SFG (t = 3.926, p &lt; 0.05, AlphaSim corrected). However, no significant difference was found between MDD without anhedonia and HCs.

CONCLUSION

The present findings suggest that MDD with and without anhedonia exhibit different patterns of interhemispheric connectivity. Anhedonia in MDD is related to aberrant interhemispheric connectivity within brain regions involved in the frontal-temporal-parietal circuit.

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.

Enduring effects of early-life adversity on reward processes: A systematic review and meta-analysis of animal studies

Two-thirds of individuals experience adversity during childhood such as neglect, abuse or highly-stressful events. Early-life adversity (ELA) increases the life-long risk of developing mood and substance use disorders. Reward-related deficits has emerged as a key endophenotype of such psychiatric disorders. Animal models are invaluable for studying how ELA leads to reward deficits. However, the existing literature is heterogenous with difficult to reconcile findings. To create an overview, we conducted a systematic review containing multiple meta-analyses regarding the effects of ELA on reward processes overall and on specific aspects of reward processing in animal models. A comprehensive search identified 120 studies. Most studies omitted key details resulting in unclear risk of bias. Overall meta-analysis showed that ELA significantly reduced reward behaviors (SMD: -0.42 [-0.60; -0.24]). The magnitude of ELA effects significantly increased with longer exposure. When reward domains were analyzed separately, ELA only significantly dampened reward responsiveness (SMD: -0.525[-0.786; -0.264]) and social reward processing (SMD: -0.374 [-0.663; -0.084]), suggesting that ELA might lead to deficits in specific reward domains.

Sucrose Preference Test as a Measure of Anhedonic Behavior in a Chronic Unpredictable Mild Stress Model of Depression: Outstanding Issues

Despite numerous studies on the neurobiology of depression, the etiological and pathophysiological mechanisms of this disorder remain poorly understood. A large number of animal models and tests to evaluate depressive-like behavior have been developed. Chronic unpredictable mild stress (CUMS) is the most common and frequently used model of depression, and the sucrose preference test (SPT) is one of the most common tests for assessing anhedonia. However, not all laboratories can reproduce the main effects of CUMS, especially when this refers to a decrease in sucrose preference. It is also unknown how the state of anhedonia, assessed by the SPT, relates to the state of anhedonia in patients with depression. We analyzed the literature available in the PubMed database using keywords relevant to the topic of this narrative review. We hypothesize that the poor reproducibility of the CUMS model may be due to differences in sucrose consumption, which may be influenced by such factors as differences in sucrose preference concentration threshold, water and food deprivation, and differences in animals’ susceptibility to stress. We also believe that comparisons between animal and human states of anhedonia should be made with caution because there are many inconsistencies between the two, including in assessment methods. We also tried to offer some recommendations that should improve the reproducibility of the CUMS model and provide a framework for future research.

Define and characterize the anhedonia in major depressive disorder: An explorative study

BACKGROUND

Although anhedonia is a key symptom of major depressive disorder (MDD), there is neither a concise nor effective method to distinguish and define anhedonia in MDD. The current study attempts to answer two questions based on validating the Dimensional Anhedonia Rating Scale (DARS) in Chinese MDD patients: 1) whether anhedonia subgroup can be identified? 2) whether patients with anhedonia display unique psychosocial and clinical features?

METHODS

In the discovery sample, 533 MDD patients and 124 healthy controls were recruited into a multicenter study. For replication, a further 112 first-episode, drug-naïve MDD patients were recruited. Latent profile analysis (LPA) was used to identify the latent subgroups based on their hedonic function measured by the DARS. According to the categorization, ROC curves were applied to find the cut-off value. Lasso regression was performed to characterize psychological and clinical features linked to anhedonia.

RESULTS

The data-driven approach identified and validated the anhedonia subgroup, and proposed that the cut-off value for distinguishing anhedonia was 28.5 based on the total score of DARS. Lasso regression demonstrated that melancholia, lower levels of positive affect and education, more severe depressive symptoms, older age were associated with anhedonia in MDD patients.

CONCLUSION

This study used a data-driven approach to propose a new and convenient method for distinguishing the anhedonia of MDD patients with unique psychological and clinical features. Identifying the subtype may contribute to pinpointing more specific biomarkers in shedding light on the mechanisms of anhedonia in MDD.

TRIAL REGISTRATION

TNDTAD study, NCT03294525; TOSD study, NCT03148522.

Emotion Context Insensitivity is generalized in individuals with major depressive disorder but not in those with subclinical depression

BACKGROUND

Depressed individuals experience deficits in emotional reactivity. One well-established theory is the Emotion Context Insensitivity (ECI) theory. To better understand impairments in emotional reactivity, we investigated whether the ECI theory is applicable to anticipatory, consummatory, and remembered affect, in both clinical and subclinical depression.

METHODS

Participants were divided into four groups: Major Depressive Disorder Group (MDD, N = 60), Control Group for MDD (Control_MDD, N = 50), Subclinical Depression Group (SD, N = 56), and Control Group for SD (Control_SD, N = 56). The Hamilton Depression Rating Scale and the Beck Depression Inventory were used to assess the severity of depression and anhedonia symptoms. The Monetary Incentive Delay Task evaluated participants' affective responses towards monetary stimuli.

RESULTS

The MDD group was more insensitive to both monetary reward and loss across most types of affect than was the control group. Compared with the controls, the SD group exhibited lower reactivity in anticipatory positive affect but enhanced reactivity in consummatory positive, anticipatory, and remembered negative affect.

LIMITATIONS

Emotional affect was evaluated by subjective ratings, which may lack objectivity. Additionally, laboratory settings and monetary rewards used in this study may cause the results less generalized to daily life and to other types of rewards.

CONCLUSION

The pattern of emotional reactivity in the MDD group was partly consistent with the ECI theory, whereas the SD group showed greater arousal and instability of emotional reactions. These different patterns could facilitate the understanding of emotional reactivity and develop further treatments across the course of depression.

Effects of Tibetan medicine metacinnabar (β-HgS) combined with imipramine or sertraline on depression-like symptoms in mice

Depression is a common mood disorder that has exhibited an increased incidence rate worldwide, but the overall clinical efficacy of antidepressants remains unsatisfactory. In traditional Ayurveda and Tibetan medicines, β-HgS-containing medicines have been used to treat neurological diseases for thousands of years, and our previous study found that β-HgS ameliorated depression-like behaviors in chronic restraint stress (CRS)-treated or chronic unpredictable mild stress (CUMS)-treated mice. Hence, present study investigated the effects of β-HgS combined with the clinical first-line antidepressants, imipramine (IMI) and sertraline (SER), on depression-like symptoms in CRS- and CUMS-co-treated mice. Our results revealed that β-HgS promoted the antidepressant effect of SER on depression-like behavior in mice, and enhanced its effects on promoting glucocorticoid receptor (GR) expression and neuronal proliferation in key hippocampal subregions, as well as increasing interleukin 10 (IL-10) levels and decreasing malondialdehyde levels in the sera of stress-stimulated mice. As for IMI, β-HgS enhanced its effects on preventing atrophy and severe structural damage in the hippocampus, as well as in promoting hippocampal GR levels and neuronal proliferation and serum IL-10 and superoxide dismutase (SOD) levels. Additionally, combination therapy resulted in the increased diversity of important intestinal microbiota compared to that of monotherapy, which may help sustain the health of the digestive tract and reduce inflammation to further enhance the antidepressant effects of IMI and SER in mice.