Anhedonia in Anxiety Disorders

When effort pays off: An experimental investigation into action orientation and anxiety as buffering factors between anhedonia and reward motivation

Reward motivation, a construct tied to depression, has been studied using the Effort-Expenditure for Rewards Task (EEfRT). Prior work indicates that anhedonia can reduce reward motivation on the EEfRT, as those with higher levels of anhedonia tend to engage in low reward tasks that require less effort as opposed to expending higher levels of effort to obtain a larger reward. Action orientation has shown to act as a buffer at low levels of anhedonia, but this effect has not been seen at high levels of anhedonia. The current study examined if these findings replicated without a stress manipulation and explored the interaction between anxiety and anhedonia in predicting persistence on the EEfRT using two moderation models. Participants (N =  101) with varying levels of depressive symptoms took part in the study. The first model examined the effects of anhedonia and action orientation on reward motivation. The second model investigated the influence of anhedonia and anxiety on reward motivation. Findings revealed that higher levels of anhedonia were significantly associated with lower reward motivation in both models. Additionally, the interaction between anhedonia and action orientation on reward motivation was significant. Trend analyses revealed that, at low levels of anhedonia, participants generally made more high-effort/high-reward choices or were willing to exude more effort for the possibility of obtaining a greater reward. However, as anhedonia increased, individuals with higher levels of action orientation exhibited greater effort as opposed to those with lower action orientation. The findings indicate that anhedonia has a strong impact on limiting reward motivation. However, high levels of action orientation can mitigate the negative influence of anhedonia on reward motivation.

What do clients think about amplifying positivity? Client change perspectives following a cognitive and behavioural positive activity intervention for anxiety and depression

The positive valence system (PVS) is increasingly recognized as an important target in facilitating recovery from anxiety and depression. Amplification of Positivity (AMP), a cognitive and behavioral intervention, targets the PVS through repeated and intentional activities (e.g., savoring positive experiences, gratitude, and acts of kindness). Initial data demonstrates that AMP engages positive valence targets (e.g., positive affect) and outcomes (e.g., social connectedness) in people seeking treatment for anxiety or depression; however, client perspectives about AMP are not well understood. This study aimed to qualitatively explore clients' experiences to better understand post-treatment client changes and advance the development and effectiveness of AMP and other emerging positive valence focused interventions. Transcripts were analyzed from eleven participants who completed an optional qualitative interview after completing AMP treatment in a randomized controlled trial (NCT04945239). Two superordinate themes with several subthemes emerged. The first theme, Changes in Self , revealed common changes consistent with the core targets of AMP as well as changes less explicitly targeted by AMP. The second theme, The Positivity Pivot , uncovered client's perceptions on the emphasis of positive emotions in treatment. Overall, clients enjoyed and reaped benefits from amplifying positivity; some clients also reported wanting more time and space to discuss negative valence symptoms. People seeking treatment for anxiety or depression are receptive to amplifying positivity and experience mental and social benefits of doing so. Positive valence centered treatments may therefore be valuable for some clients. Treatment protocols that integrate positive and negative-valence targeted approaches may be preferred by some clients.

Validation of the Approach-Avoidance Temperament Questionnaire in Individuals with Anxiety and Depression

The Approach-Avoidance Temperament Questionnaire (ATQ) is a well-established measure assessing heightened sensitivity and reactivity to reward/positive stimuli (approach temperament) and to punishment/negative stimuli (avoidance temperament). These basic dimensions of personality are believed to be important for understanding the etiology and maintenance of anxiety and depressive disorders. Despite the ATQ's potential utility in clinical psychology research, its psychometric properties and factor structure have yet to be examined in a psychiatric sample. The aims of the present study were to 1) conduct confirmatory factor analysis to replicate the ATQ's factor structure in individuals diagnosed with an anxiety or depressive disorder (N = 244), 2) assess internal consistency and convergent and divergent validity, and 3) explore differences in approach and avoidance temperaments in individuals with versus without a diagnosis of anxiety or depression. Results confirmed the original two-factor structure of the ATQ in a clinical sample, with approach and avoidance temperaments representing orthogonal dimensions. The measure demonstrated strong internal consistency, convergent and divergent validity, and predictive validity. Individuals with anxiety and depression scored higher on avoidance items and lower on approach items compared to those without clinical diagnoses. This study supports the use of the ATQ in clinical populations.

Cross-species translational paradigms for assessing positive valence system as defined by the RDoC matrix

Functions associated with processing reward-related information are fundamental drivers of motivation, learning, and goal-directed behavior. Such functions have been classified as the positive valence system under the Research Domain and Criteria (RDoC) criteria and are negatively impacted across a range of psychiatric disorders and mental illnesses. The positive valence system is composed of three comprehensive categories containing related but dissociable functions that are organized into either Reward Responsiveness, Reward Learning, or Reward Valuation. The presence of overlapping behavioral dysfunction across diagnostic mental disorders is in-part what motivated the RDoC initiative, which emphasized that the study of mental illness focus on investigating relevant behavior and cognitive functions and their underlying mechanisms, rather than separating efforts on diagnostic categories (i.e., transdiagnostic). Moreover, the RDoC approach is well-suited for preclinical neuroscience research, as the rise in genetic toolboxes and associated neurotechnologies enables researchers to probe specific cellular targets with high specificity. Thus, there is an opportunity to dissect whether behaviors and cognitive functions are supported by shared or distinct neural mechanisms. For preclinical research to effectively inform our understandings of human behavior however, the cognitive and behavioral paradigms should have predictive, neurobiological, and pharmacological predictive validity to the human test. Touchscreen-based testing systems provide a further advantage for this endeavor enabling tasks to be presented to animals using the same media and task design as in humans. Here, we outline the primary categories of the positive valence system and review the work that has been done cross-species to investigate the neurobiology and neurochemistry underlying reward-related functioning. Additionally, we provide clinical tasks outlined by RDoC, along with validity and/or need for further validation for analogous rodent paradigms with a focus on implementing the touchscreen-based cognitive testing systems.

The Limbic System in Co-Occurring Substance Use and Anxiety Disorders: A Narrative Review Using the RDoC Framework

Substance use disorders (SUDs) and anxiety disorders (ADs) are highly comorbid, a co-occurrence linked to worse clinical outcomes than either condition alone. While the neurobiological mechanisms involved in SUDs and anxiety disorders are intensively studied separately, the mechanisms underlying their comorbidity remain an emerging area of interest. This narrative review explores the neurobiological processes underlying this comorbidity, using the Research Domain Criteria (RDoC) framework to map disruptions in positive valence, negative valence, and cognitive systems across the three stages of the addiction cycle: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Anxiety and substance use play a reciprocal role at each stage of addiction, marked by significant psychosocial impairment and dysregulation in the brain. A more thorough understanding of the neural underpinnings involved in comorbid SUDs and anxiety disorders will contribute to more tailored and effective therapeutic interventions and assessments.

A parallel-arm, randomized trial of Behavioral Activation Therapy for anhedonia versus mindfulness-based cognitive therapy for adults with anhedonia

BACKGROUND

Anhedonia, deficits in motivation and pleasure, is a transdiagnostic symptom of psychopathology and negative prognostic marker.

METHODS

In this randomized, parallel-arm clinical trial, a novel intervention, Behavioral Activation Treatment for Anhedonia (BATA), was compared to an individually administered Mindfulness-Based Cognitive Therapy (MBCT) in a transdiagnostic cohort of adults with clinically significant anhedonia (ClinicalTrials.gov Identifiers NCT02874534 and NCT04036136). Participants received 8-15 individual psychotherapy sessions, once weekly, with either BATA (n = 61) or MBCT (n = 55) and completed repeated self-report assessment of anhedonia and other internalizing symptoms.

RESULTS

Indicators of treatment feasibility were similar across conditions, though MBCT showed a trend towards greater attrition rates than BATA, with an adjusted odd's ratio of 2.04 [0.88, 4.73]. Treatment effects on the primary clinical endpoint of anhedonia symptoms did not significantly differ, with a 14-week estimated difference on the Snaith Hamilton Pleasure Scale (SHAPS) of -0.20 [-2.25, 1.84] points in BATA compared to MBCT (z = 0.19, p = 0.845, d = 0.05). The expected 14-week change in SHAPS scores across conditions was -7.18 [-8.22, -6.15] points (z = 13.6, p < 0.001, d = 1.69). There were no significant differences in the proportion of participants demonstrating reliable and clinically significant improvements in SHAPS scores, or in the magnitude of internalizing symptom reductions.

LIMITATIONS

Limitations included a modest sample size, lack of longer-term follow up data, and non-preregistered analytic plan.

DISCUSSION

There was no evidence to support superior clinical efficacy of BATA over MBCT in a transdiagnostic cohort of adults with elevated anhedonia. Both interventions reduced anhedonia symptoms to a comparable magnitude of other existing treatments.

The Use of Ketamine for the Treatment of Anhedonia in Depression

Anhedonia, a complex symptom rooted in deficits across reward processes, is primarily linked to depression and schizophrenia but transcends diagnostic boundaries across various mental disorders. Its presence correlates with poorer clinical outcomes, including an increased risk of suicide and diminished response to treatment. The neurobiological underpinnings of anhedonia remain incompletely understood despite advancements in biomarkers and imaging that contribute to deeper insights. Ketamine, known for its rapid-acting antidepressant properties, appears to possess antianhedonic effects through a mechanism of action not fully elucidated. This effect appears to be independent of its antidepressant properties. Explorations into alternative antianhedonic treatments have been underway, yet lingering questions persist, underscoring the imperative need for ongoing research to advance the field.

Amplification of positivity for depression and anxiety: Neural prediction of treatment response

Psychosocial treatments targeting the positive valence system (PVS) in depression and anxiety demonstrate efficacy in enhancing positive affect (PA), but response to treatment varies. We examined whether individual differences in neural activation to positive and negative valence incentive cues underlies differences in benefitting from a PVS-targeted treatment. Individuals with clinically elevated depression and/or anxiety (N = 88, ages 18 to 55) participated in one of two randomized, waitlist-controlled trials of Amplification of Positivity (AMP; NCT02330627, NCT03196544), a cognitive and behavioral intervention targeting the PVS. Participants completed a monetary incentive delay (MID) task during fMRI acquisition at baseline measuring neural activation to the possibility of gaining or losing money. Change in PA from before to after treatment was assessed using the Positive and Negative Affect Schedule. No significant associations were observed between baseline neural activation during gain anticipation and AMP-related changes in PA in regions of interest (striatum and insula) or whole-brain analyses. However, higher baseline striatal and insula activation during loss anticipation was associated with greater increases in PA post-AMP. This study provides preliminary evidence suggesting neural reactivity to negative valence cues may inform who stands to benefit most from treatments targeting the PVS.

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.

Amplification of Positivity Treatment for Anxiety and Depression: A Randomized Experimental Therapeutics Trial Targeting Social Reward Sensitivity to Enhance Social Connectedness

BACKGROUND

Social disconnection is common and causes significant impairment in anxiety and depressive disorders, and it does not respond sufficiently to available treatments. The positive valence system supports social bond formation and maintenance but is often hyporesponsive in people with anxiety or depression. We conducted an experimental therapeutics trial to test the hypothesis that targeting positive valence processes through cognitive and behavioral strategies would enhance responsivity to social rewards, a core mechanism underlying social connectedness.

METHODS

Sixty-eight adults who endorsed clinically elevated anxiety and/or depression with social impairment were randomized 1:1:1 to 5 (n = 23) or 10 (n = 22) sessions of amplification of positivity (AMP) treatment or waitlist (n = 23). Pre- to posttreatment change in striatal activity (primary outcome) during social reward anticipation was measured using functional magnetic resonance imaging, and reactivity to a social affiliation task (secondary) and self-reported social connectedness (exploratory) were examined. Primary analyses compared AMP (doses combined) versus waitlist. A second aim was to compare the effects of different doses.

RESULTS

AMP engaged the hypothesized treatment target, leading to greater striatal activation during anticipation of social rewards versus waitlist (d = 1.01 [95% CI = 0.42-1.61]; largest striatal volume). AMP yielded larger improvements in positive affect and approach behavior during the affiliation task (but not other outcomes) and social connectedness. Larger striatal and social connectedness increases were observed for 5-session versus 10-session AMP (d range = 0.08-1.03).

CONCLUSIONS

Teaching people with anxiety or depression strategies to increase positive thoughts, behaviors, and emotions enhances activity in brain regions that govern social reward processing and promotes social connectedness. Social reward sensitivity may be a transdiagnostic target for remediating social disconnection.

What good are positive emotions for treatment? A replication test of whether trait positive emotionality predicts response to exposure therapy for social anxiety disorder

BACKGROUND

Positive valence emotions serve functions that may facilitate response to exposure therapy - they encourage approach behavior, diminish perceived threat reactivity, and enhance assimilation of new information in memory. Few studies have examined whether positive emotions predict exposure therapy success and extant findings are mixed.

METHODS

We conducted a secondary analysis of an exposure therapy trial for social anxiety disorder to test the hypothesis that patients endorsing higher trait positive emotions at baseline would display the greatest treatment response. N = 152 participants enrolled in a randomized controlled trial of d-cycloserine augmentation completed five sessions of group exposure therapy. Pre-treatment positive emotionality was assessed using the NEO Five-Factor Inventory. Social anxiety symptoms were assessed throughout treatment by blinded evaluators using the Liebowitz Social Anxiety Scale.

RESULTS

Accounting for baseline symptom severity, multilevel growth curve models revealed that patients with higher pre-treatment positive emotionality displayed faster social anxiety symptom reductions and lower scores at 3-month follow-up. This predictive effect remained significant after controlling for baseline depression and extraversion (without the positive emotionality facet).

CONCLUSIONS

These findings add to emerging evidence suggesting that explicitly targeting and enhancing positive emotions during exposure to perceived threat may improve treatment outcomes for anxiety and fear-based disorders.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02066792https://clinicaltrials.gov/ct2/show/NCT02066792.

Norepinephrine system at the interface of attention and reward

Reward learning is key to survival for individuals. Attention plays an important role in the rapid recognition of reward cues and establishment of reward memories. Reward history reciprocally guides attention to reward stimuli. However, the neurological processes of the interplay between reward and attention remain largely elusive, due to the diversity of the neural substrates that participate in these two processes. In this review, we delineate the complex and differentiated locus coeruleus norepinephrine (LC-NE) system in relation to different behavioral and cognitive substrates of reward and attention. The LC receives reward related sensory, perceptual, and visceral inputs, releases NE, glutamate, dopamine and various neuropeptides, forms reward memories, drives attentional bias and selects behavioral strategies for reward. Preclinical and clinical studies have found that abnormalities in the LC-NE system are involved in a variety of psychiatric conditions marked by disturbed functions in reward and attention. Therefore, we propose that the LC-NE system is an important hub in the interplay between reward and attention as well as a critical therapeutic target for psychiatric disorders characterized by compromised functions in reward and attention.

Probabilistic Reinforcement Learning and Anhedonia

Despite the prominence of anhedonic symptoms associated with diverse neuropsychiatric conditions, there are currently no approved therapeutics designed to attenuate the loss of responsivity to previously rewarding stimuli. However, the search for improved treatment options for anhedonia has been reinvigorated by a recent reconceptualization of the very construct of anhedonia, including within the Research Domain Criteria (RDoC) initiative. This chapter will focus on the RDoC Positive Valence Systems construct of reward learning generally and sub-construct of probabilistic reinforcement learning specifically. The general framework emphasizes objective measurement of a subject's responsivity to reward via reinforcement learning under asymmetrical probabilistic contingencies as a means to quantify reward learning. Indeed, blunted reward responsiveness and reward learning are central features of anhedonia and have been repeatedly described in major depression. Moreover, these probabilistic reinforcement techniques can also reveal neurobiological mechanisms to aid development of innovative treatment approaches. In this chapter, we describe how investigating reward learning can improve our understanding of anhedonia via the four RDoC-recommended tasks that have been used to probe sensitivity to probabilistic reinforcement contingencies and how such task performance is disrupted in various neuropsychiatric conditions. We also illustrate how reverse translational approaches of probabilistic reinforcement assays in laboratory animals can inform understanding of pharmacological and physiological mechanisms. Next, we briefly summarize the neurobiology of probabilistic reinforcement learning, with a focus on the prefrontal cortex, anterior cingulate cortex, striatum, and amygdala. Finally, we discuss treatment implications and future directions in this burgeoning area.