Where's the fun in that? Broadening the focus on reward function in depression

The interacting effects of depression symptoms and sweet flavoring on the rewarding and reinforcing value of cigarillo use among young adults

Background

Young adults 18-24 years old have the highest prevalence of cigarillo use, exposing young adults to comparable or higher nicotine levels and many of the same toxicants as combustible cigarettes. Identifying individual and product characteristics that increase the potential for persistent use is warranted. We sought to examine the interacting effects of depression symptoms and sweet flavoring on the rewarding and reinforcing value of cigarillo use.

Methods

86 young adults (18-24 years old, 73.3 % male, 38.4 % White, 33.7 % Black, and 27.9 % Other) completed three laboratory visits assessing the subjective rewarding value (exposure paradigm), relative reinforcing value (computerized choice task), and absolute reinforcing value (ad libitum cigarillo smoking session) of sweet-flavored versus non-flavored cigarillos. Depression symptoms were measured with the 20-item Center for Epidemiologic Studies of Depression Scale and treated as a continuous variable.

Results

General linear models with the appropriate family link tested differences in depressive symptomology for each outcome. Irrespective of flavor, greater cigarillo subjective reward was reported across increasing depressive symptomology (B=.0.03 [95%CI=0.00, 0.05], p=.017). Across symptom levels, no significant differences were observed in the subjective reward and relative and absolute reinforcing values of sweet-flavored versus non-flavored cigarillos (p's >.05).

Conclusions

Young adults with elevated depression find cigarillos more rewarding but not more reinforcing. They are not more vulnerable than young adults with lower symptom levels to sweet cigarillo flavoring. Public health prevention campaigns and tobacco product regulations aimed at preventing the initiation and escalation of young adult cigarillo use may impact young adults broadly.

Annual Research Review: Neuroimmune network model of depression: a developmental perspective

Depression is a serious public health problem, and adolescence is an 'age of risk' for the onset of Major Depressive Disorder. Recently, we and others have proposed neuroimmune network models that highlight bidirectional communication between the brain and the immune system in both mental and physical health, including depression. These models draw on research indicating that the cellular actors (particularly monocytes) and signaling molecules (particularly cytokines) that orchestrate inflammation in the periphery can directly modulate the structure and function of the brain. In the brain, inflammatory activity heightens sensitivity to threats in the cortico-amygdala circuit, lowers sensitivity to rewards in the cortico-striatal circuit, and alters executive control and emotion regulation in the prefrontal cortex. When dysregulated, and particularly under conditions of chronic stress, inflammation can generate feelings of dysphoria, distress, and anhedonia. This is proposed to initiate unhealthy, self-medicating behaviors (e.g. substance use, poor diet) to manage the dysphoria, which further heighten inflammation. Over time, dysregulation in these brain circuits and the inflammatory response may compound each other to form a positive feedback loop, whereby dysregulation in one organ system exacerbates the other. We and others suggest that this neuroimmune dysregulation is a dynamic joint vulnerability for depression, particularly during adolescence. We have three goals for the present paper. First, we extend neuroimmune network models of mental and physical health to generate a developmental framework of risk for the onset of depression during adolescence. Second, we examine how a neuroimmune network perspective can help explain the high rates of comorbidity between depression and other psychiatric disorders across development, and multimorbidity between depression and stress-related medical illnesses. Finally, we consider how identifying neuroimmune pathways to depression can facilitate a 'next generation' of behavioral and biological interventions that target neuroimmune signaling to treat, and ideally prevent, depression in youth and adolescents.

Differentiating the abnormalities of social and monetary reward processing associated with depressive symptoms

BACKGROUND

Reward dysfunction is a major dimension of depressive symptomatology, but it remains obscure if that dysfunction varies across different reward types. In this study, we focus on the abnormalities in anticipatory/consummatory processing of monetary and social reward associated with depressive symptoms.

METHODS

Forty participants with depressive symptoms and forty normal controls completed the monetary incentive delay (MID) and social incentive delay (SID) tasks with event-related potential (ERP) recording.

RESULTS

In the SID but not the MID task, both the behavioral hit rate and the ERP component contingent negative variation (CNV; indicating reward anticipation) were sensitive to the interaction between the grouping factor and reward magnitude; that is, the depressive group showed a lower hit rate and a smaller CNV to large-magnitude (but not small-magnitude) social reward cues compared to the control group. Further, these two indexes were correlated with each other. Meanwhile, the ERP components feedback-related negativity and P3 (indicating reward consumption) were sensitive to the main effect of depression across the MID and SID tasks, though this effect was more prominent in the SID task.

CONCLUSIONS

Overall, we suggest that depressive symptoms are associated with deficits in both the reward anticipation and reward consumption stages, particularly for social rewards. These findings have a potential to characterize the profile of functional impairment that comprises and maintains depression.

Pleasure, Reward Value, Prediction Error and Anhedonia

In order to develop effective treatments for anhedonia we need to understand its underlying neurobiological mechanisms. Anhedonia is conceptually strongly linked to reward processing, which involves a variety of cognitive and neural operations. This chapter reviews the evidence for impairments in experiencing hedonic response (pleasure), reward valuation and reward learning based on outcomes (commonly conceptualised in terms of "reward prediction error"). Synthesising behavioural and neuroimaging findings, we examine case-control studies of patients with depression and schizophrenia, including those focusing specifically on anhedonia. Overall, there is reliable evidence that depression and schizophrenia are associated with disrupted reward processing. In contrast to the historical definition of anhedonia, there is surprisingly limited evidence for impairment in the ability to experience pleasure in depression and schizophrenia. There is some evidence that learning about reward and reward prediction error signals are impaired in depression and schizophrenia, but the literature is inconsistent. The strongest evidence is for impairments in the representation of reward value and how this is used to guide action. Future studies would benefit from focusing on impairments in reward processing specifically in anhedonic samples, including transdiagnostically, and from using designs separating different components of reward processing, formulating them in computational terms, and moving beyond cross-sectional designs to provide an assessment of causality.

Response to unexpected social inclusion: A study using the cyberball paradigm

BACKGROUND

Dysfunctional expectations are considered core characteristics of Major Depressive Disorder (MDD) and should be focused in psychotherapy. Dysfunctional expectations are especially pronounced in the interpersonal area (social expectations). In the present study, we examine the effect of unexpected social inclusion (expectation violation) on the change of generalized and specific depression-typical social expectations.

METHOD

We conducted an online study to investigate the impact of social inclusion after a period of social exclusion (unexpected social inclusion) on social expectation change (sample size 144) in a non-clinical sample. Depressive symptoms were assessed via self-reporting. Participants took part in two rounds of the online ball-game Cyberball. In the first round, all participants were socially excluded by their two co-players (acquisition of negative social expectations). In the second round, participants were either once more excluded (expectation confirmation) or included equally (expectation violation) by the same co-players. Specific and generalized social expectations were assessed after each round.

RESULTS

Specific and generalized social expectations increased following expectation violation. Even though depressive symptoms were related to lower levels of social expectations, we found that depressive symptoms did not moderate expectation change after positive expectation violations.

CONCLUSIONS

In the present experimental setup including the use of the online ball-game Cyberball, the establishment and change of social expectations can be experimentally manipulated. Under the given circumstances and in a non-clinical sample, negative expectations can be updated after unexpected positive experiences regardless of the number of depressive symptoms. The results are discussed in the context of current models of Major Depressive Disorder (MDD), expectation change, and cognitive behavioral therapy.

Disentangling emotional processing in dysphoria: An ERP and cardiac deceleration study

The present study aimed to investigate emotional processing in dysphoria. To this end, the amplitude of the Late Positive Potential (LPP) and cardiac deceleration were assessed during the passive viewing of affective (pleasant, neutral, and unpleasant) pictures in 26 individuals with dysphoria and in 25 non-depressed controls. The group with dysphoria revealed a smaller LPP amplitude than the group without dysphoria in response to pleasant and neutral, but not unpleasant, stimuli at centro-parieto-occipital sites. Interestingly, whereas both groups showed cardiac deceleration when viewing pleasant compared to neutral pictures (3-6 s time window), only individuals with dysphoria showed a prolonged cardiac deceleration in response to unpleasant stimuli as compared with neutral ones. This study suggests that dysphoria is characterized by reduced motivated attentional allocation to positive information and by sustained intake of unpleasant information. Overall, the present findings provide novel insights into the characterization of valence-specific attentional processes in dysphoria as potential vulnerability factors for clinically significant depression.

The Etiologic, Theory-Based, Ontogenetic Hierarchical Framework of Alcohol Use Disorder: A Translational Systematic Review of Reviews

Modern nosologies (e.g., ICD-11, DSM-5) for alcohol use disorder (AUD) and dependence prioritize reliability and clinical presentation over etiology, resulting in a diagnosis that is not always strongly grounded in basic theory and research. Within these nosologies, DSM-5 AUD is treated as a discrete, largely categorical, but graded, phenomenon, which results in additional challenges (e.g., significant phenotypic heterogeneity). Efforts to increase the compatibility between AUD diagnosis and modern conceptualizations of alcohol dependence, which describe it as dimensional and partially overlapping with other psychopathology (e.g., other substance use disorders) will inspire a stronger scientific framework and strengthen AUD's validity. We conducted a systematic review of 144 reviews to integrate addiction constructs and theories into a comprehensive framework with the aim of identifying fundamental mechanisms implicated in AUD. The product of this effort was the Etiologic, Theory-Based, Ontogenetic Hierarchical Framework (ETOH Framework) of AUD mechanisms, which outlines superdomains of cognitive control, reward, as well as negative valence and emotionality, each of which subsume narrower, hierarchically-organized components. We also outline opponent processes and self-awareness as key moderators of AUD mechanisms. In contrast with other frameworks, we recommend an increased conceptual role for negative valence and compulsion in AUD. The ETOH framework serves as a critical step towards conceptualizations of AUD as dimensional and heterogeneous. It has the potential to improve AUD assessment and aid in the development of evidence-based diagnostic measures that focus on key mechanisms in AUD, consequently facilitating treatment matching.

Behavioral Activation (BA) in the Management of Depression in an Adolescent with Down Syndrome in Dubai

Depression has been commonly treated with psychotherapy and/or pharmacotherapy for several decades. Ongoing research in the field has suggested promise for behavioral activation (BA), a form of psychotherapeutic intervention, as a means of increasing engagement in adaptive activities and developing skills to counter avoidance in individuals suffering from depression. In this case report, we present the treatment course of BA for an adolescent with Down syndrome (DS), presenting with depression. A multidisciplinary approach was utilized in developing a personalized management plan for the patient since the initial presentation. Sessions at the outpatient psychiatry clinic alternated between in-person visits and virtual ones, due to circumstances associated with physical distancing with the COVID-19 pandemic. Parents were included as integral parts of the management plan, and education, strategic implementation of BA, and barriers to care were discussed extensively to support the adolescent through the course of her treatment. Within 6 weeks of introducing BA, positive outcomes were noted in the patient, with the resolution of her clinical depression. In this report, we discuss BA further as a potentially effective therapeutic approach to the treatment of depressive symptoms in children and adolescents with DS and intellectual disabilities.

I, robot: depression plays different roles in human-human and human-robot interactions

Socially engaging robots have been increasingly applied to alleviate depressive symptoms and to improve the quality of social life among different populations. Seeing that depression negatively influences social reward processing in everyday interaction, we investigate this influence during simulated interactions with humans or robots. In this study, 35 participants with mild depression and 35 controls (all from nonclinical populations) finished the social incentive delay task with event-related potential recording, in which they received performance feedback from other persons or from a robot. Compared to the controls, the mild depressive symptom (MDS) group represented abnormalities of social reward processing in the human feedback condition: first, the MDS group showed a lower hit rate and a smaller contingent-negative variation (correlated with each other) during reward anticipation; second, depression level modulated both the early phase (indexed by the feedback-related negativity (FRN)) and the late phase (indexed by the P3) of reward consumption. In contrast, the effect of depression was evident only on FRN amplitude in the robot feedback condition. We suggest that compared to human-human interaction, the rewarding properties of human-robot interaction are less likely to be affected by depression. These findings have implications for the utilization of robot-assisted intervention in clinical practice.

Emotion context insensitivity in depression: Toward an integrated and contextualized approach

Major depressive disorder (MDD) is characterized by pervasive mood disturbance as well as deficits in emotional processing, reactivity, and regulation. There is accumulating evidence that MDD is characterized by emotional patterns consistent with environmental disengagement, as reflected in attenuated positive and negative emotional reactivity, consistent with Emotion Context Insensitivity (ECI) theory. However, MDD individuals vary considerably in the extent to which they exhibit specific alterations in patterns of emotional responding. Emotions are complex, multicomponent processes that invoke responses across multiple functional domains and levels of analysis, including subjective experience, behavior, autonomic regulation, cognition, and neural processing. In this article, I review the current state of the literature on emotional responding and MDD from the lens of ECI. I focus on the importance of assessing emotional indices from multiple levels of analysis across development and contexts. I also discuss methodological and measurement issues that may contribute to inconsistent findings. In particular, I emphasize how psychophysiological measures can help elucidate emotional processes that underlie the pathophysiology of MDD as part of an integrated and contextualized approach.

The Impact of Negative Symptoms and Neurocognition on Functioning in MDD and Schizophrenia

Introduction: Negative symptoms, neurocognitive deficits and functional impairment are prevalent in individuals with major depressive disorder (MDD) and schizophrenia (SCZ). However, unlike neurocognitive deficits, little is known about the role of negative symptoms toward functioning in individuals with MDD. On the other hand, both factors are well-studied in individuals with SCZ. Thus, this study aimed to examine the contributions of negative symptoms and neurocognitive impairments in functioning in individuals with MDD, compared to individuals with SCZ. Methods: Participants included 50 individuals with MDD, 49 individuals with SCZ and 49 healthy controls. The following measures were administered-Negative Symptom Assessment (NSA-16), Brief Assessment of Cognition in Schizophrenia (BACS), Patient Health Questionnaire (PHQ-9), and MIRECC-Global Assessment of Functioning (MIRECC-GAF) to evaluate negative symptoms, neurocognition, depressive symptoms, and functioning respectively. Results: Both MDD and SCZ groups had significantly more severe negative symptoms, depressive symptoms, and poorer functioning than healthy controls. Individuals with SCZ performed significantly poorer on the BACS than the other two groups. Both negative symptoms and neurocognition were significantly correlated with social and occupational functioning in SCZ. Motivation subdomain of the negative symptoms was significantly correlated with occupational functioning, while depressive symptoms correlated with functioning in MDD. Conclusion: Both negative symptoms and neurocognitive deficits appear to play differential roles on individual domains of functioning between MDD and SCZ. Future longitudinal studies with larger sample sizes should be done for a better understanding about the associations between the factors and functioning.

Social Feedback Valence Differentially Modulates the Reward Positivity, P300, and Late Positive Potential

Abnormal social or reward processing is associated with several mental disorders. Although most studies examining reward processing have focused on monetary rewards, recent research also has tested neural reactivity to social rewards (e.g., positive social feedback). However, the majority of these studies only include two feedback valences (e.g., acceptance, rejection). Yet, social evaluation is rarely binary (positive vs. negative) and people often give 'on the fence' or neutral evaluations of others. Processing of this type of social feedback may be ambiguous and impacted by factors such as psychopathology, self-esteem, and prior experiences of rejection. Thus, the present study probed the reward positivity (RewP), P300, and late positive potential (LPP) following acceptance, rejection, and "one the fence" [between acceptance and rejection] feedback in undergraduate students (n = 45). Results indicated that the RewP showed more positive amplitudes following acceptance compared to both rejection and "on the fence" feedback, and the RewP was larger (i.e., more positive) following rejection relative to "on the fence" feedback. In contrast, the P300 did not differ between rejection and "on the fence" feedback, and both were reduced compared to acceptance. The LPP was blunted in response to rejection relative to acceptance and "on the fence" feedback (which did not differ from each other). Exploratory analyses demonstrated that greater self-reported rejection sensitivity was associated with a reduced LPP to acceptance. Taken together, these findings suggest that the neural systems underlying the RewP, P300, and LPP may evaluate "on the fence" social feedback differently, and that individuals high on rejection sensitivity may exhibit reduced attention toward and elaborative processing of social acceptance.

Neurocognitive predictors of self-reported reward responsivity and approach motivation in depression: A data-driven approach

BACKGROUND

Individual differences in reward-related processes, such as reward responsivity and approach motivation, appear to play a role in the nature and course of depression. Prior work suggests that cognitive biases for valenced information may contribute to these reward processes. Yet there is little work examining how biased attention, processing, and memory for positively and negatively valenced information may be associated with reward-related processes in samples with depression symptoms.

METHODS

We used a data-driven, machine learning (elastic net) approach to identify the best predictors of self-reported reward-related processes using multiple tasks of attention, processing, and memory for valenced information measured across behavioral, eye tracking, psychophysiological, and computational modeling approaches (n = 202). Participants were adults (ages 18-35) who ranged in depression symptom severity from mild to severe.

RESULTS

Models predicted between 5.0-12.2% and 9.7-28.0% of held-out test sample variance in approach motivation and reward responsivity, respectively. Low self-referential processing of positively valenced information was the most robust, albeit modest, predictor of low approach motivation and reward responsivity.

CONCLUSIONS

Self-referential processing of positive information is the strongest predictor of reward responsivity and approach motivation in a sample ranging from mild to severe depression symptom severity. Experiments are now needed to clarify the causal relationship between self-referential processing of positively valenced information and reward processes in depression.

New directions in behavioral activation: Using findings from basic science and translational neuroscience to inform the exploration of potential mechanisms of change

Interest in behavioral activation treatments for depression has increased over the past two decades. Behavioral activation treatments have been shown to be effective in treating depression across a variety of populations and settings. However, little is known about the mechanisms of change that may bring about symptom improvement in behavioral activation treatments. Recent developments in the theoretical and empirical literature on behavioral activation treatments have coincided with advances in basic science and translational neuroscience regarding the mechanisms underlying individual differences in responsiveness to reward. Attenuated reward responsiveness has been associated with depression and related clinical outcomes at the self-report, behavioral, and neural levels of analysis. Given that behavioral activation treatments are focused on increasing individuals' contact and engagement with sustainable sources of reward in their environment, it is plausible that behavioral activation treatments bring about improvements in depression symptoms by targeting (low) reward responsiveness directly. This paper integrates findings from the clinical research literature on behavioral activation treatments with insights drawn from basic science and translational neuroscience in order to propose hypotheses about potential mechanisms of change in behavioral activation. Conceptual issues and recommendations for future research on behavioral activation treatments are discussed.

Neural substrates for anticipation and consumption of social and monetary incentives in depression

Depression has been reliably associated with abnormalities in the neural representation of reward and loss. However, most studies have focused on monetary incentives; fewer studies have considered neural representation of social incentives. A direct comparison of non-social and social incentives within the same study would establish whether responses to the different incentives are differentially affected in depression. The functional magnetic resonance imaging study presented here investigated the neural activity of individuals with subthreshold depression (SD) and healthy controls (HCs) while they participated in an incentive delay task offering two types of reward (monetary gain vs social approval) and loss (monetary loss vs social disapproval). Compared to HCs, individuals with SD showed increased subgenual anterior cingulate cortex (sgACC) activity during anticipation of social loss, whereas the response in the putamen was decreased during consumption of social gain. Individuals with SD also exhibited diminished insula responses in consuming social loss. Furthermore, positive connectivity between the insula and ventral lateral pre-frontal cortex (VLPFC) was observed in individuals with SD while negative connectivity was found in HCs when consuming social loss. These results demonstrate neural alterations in individuals with depression, specific to the processing of social incentives, mainly characterised by dysfunction within the ‘social pain network’ (sgACC, insula and VLPFC).

Neural Sensitivity to Social and Monetary Reward in Depression: Clarifying General and Domain-Specific Deficits

Reward dysfunction is thought to be play a critical role in the pathogenesis of depression. Multiple studies have linked depression to abnormal neural sensitivity to monetary rewards, but it remains unclear whether this reward dysfunction is generalizable to other rewards types. The current study begins to address this gap by assessing abnormal sensitivity to both monetary and social rewards in relation to depressive symptoms. We recorded event-related potentials (ERPs) during two incentive delay tasks, one with monetary reward and one with social reward. Both tasks were administered within the same sample, enabling a direct comparison of reward types. ERPs elicited by social and nonsocial rewards were morphologically similar across several stages of processing: cue salience, outcome anticipation, early outcome evaluation, outcome salience. Moderation analyses showed depression was linked with a pattern of general deficits across social and monetary rewards, specifically for the stages of outcome anticipation (stimulus-preceding negativity) and outcome salience (feedback-P3); self-reported reward sensitivity was generally associated with early outcome evaluation (reward positivity). Regression analyses modeling task-specific variance, however, showed a unique association between depression and outcome salience for social rewards, controlling for monetary rewards. The findings from this study underscore the importance of assessing neural sensitivity to multiple reward types in depression, particularly social reward. Characterizing the profile of reward functioning in depression across reward types may help to link laboratory-based deficits to relatively global vs. focal difficulties in real-world functioning.

The role of avoidance motivation in the relationship between reward sensitivity and depression symptoms in adolescents: An ERP study

Blunted neural responses to reward in an EEG paradigm (RewP) are associated with vulnerability to depression, but the pathways linking this biomarker to depressive symptoms are unclear. We examined whether the relationship between reward response (RewP mean amplitude and latency) and depression was in part explained by approach-motivated behaviors in adolescents with varying levels of depression. EEG was collected during a game rigged to provide win/loss trials. Longer RewP latency was associated with depression symptoms only when scores on a measure of avoidance motivation were included. These results suggest that treatments targeting avoidance may decrease vulnerability to depressive episodes.

Excitability and irritability in preschoolers predicts later psychopathology: The importance of positive and negative emotion dysregulation

Emotion dysregulation is a risk factor for the development of a variety of psychopathologic outcomes. In children, irritability, or dysregulated negative affect, has been the primary focus, as it predicts later negative outcomes even in very young children. However, dysregulation of positive emotion is increasingly recognized as a contributor to psychopathology. Here we used an exploratory factor analysis and defined four factors of emotion dysregulation: irritability, excitability, sadness, and anhedonia, in the preschool-age psychiatric assessment collected in a sample of 302 children ages 3-5 years enriched for early onset depression. The irritability and excitability factor scores defined in preschoolers predicted later diagnosis of mood and externalizing disorders when controlling for other factor scores, social adversity, maternal history of mood disorders, and externalizing diagnoses at baseline. The preschool excitability factor score predicted emotion lability in late childhood and early adolescence when controlling for other factor scores, social adversity, and maternal history. Both excitability and irritability factor scores in preschoolers predicted global functioning into the teen years and early adolescence, respectively. These findings underscore the importance of positive, as well as negative, affect dysregulation as early as the preschool years in predicting later psychopathology, which deserves both further study and clinical consideration.

Sex-Dependent Associations among Maternal Depressive Symptoms, Child Reward Network, and Behaviors in Early Childhood

Maternal depression is associated with disrupted neurodevelopment in offspring. This study examined relationships among postnatal maternal depressive symptoms, the functional reward network and behavioral problems in 4.5-year-old boys (57) and girls (65). We employed canonical correlation analysis to evaluate whether the resting-state functional connectivity within a reward network, identified through an activation likelihood estimation (ALE) meta-analysis of fMRI studies, was associated with postnatal maternal depressive symptoms and child behaviors. The functional reward network consisted of three subnetworks, that is, the mesolimbic, mesocortical, and amygdala–hippocampus reward subnetworks. Postnatal maternal depressive symptoms were associated with the functional connectivity of the mesocortical subnetwork with the mesolimbic and amygdala–hippocampus complex subnetworks in girls and with the functional connectivity within the mesocortical subnetwork in boys. The functional connectivity of the amygdala–hippocampus subnetwork with the mesocortical and mesolimbic subnetworks was associated with both internalizing and externalizing problems in girls, while in boys, the functional connectivity of the mesocortical subnetwork with the amygdala–hippocampus complex and the mesolimbic subnetworks was associated with the internalizing and externalizing problems, respectively. Our findings suggest that the functional reward network might be a promising neural phenotype for effects of maternal depression and potential intervention to nurture child behavioral development.

Sex-Specific Effects of Stress on Mood-Related Gene Expression

Women are twice as likely as men to be diagnosed with major depressive disorder (MDD). Recent studies report distinct molecular changes in depressed men and women across mesocorticolimbic brain regions. However, it is unclear which sex-related factors drive distinct MDD-associated pathology. The goal of this study was to use mouse experimental systems to investigate sex-specific mechanisms underlying the distinct molecular profiles of MDD in men and women. We used unpredictable chronic mild stress to induce an elevated anxiety-/depressive-like state and "four core genotypes" (FCG) mice to probe for sex-specific mechanisms. As predicted, based on previous implications in mood, stress impacted the expression of several dopamine-, GABA-, and glutamate-related genes. Some of these effects, specifically in the prefrontal cortex, were genetic sex-specific, with effects in XX mice but not in XY mice. Stress also impacted gene expression differently across the mesocorticolimbic circuit, with increased expression of mood-related genes in the prefrontal cortex and nucleus accumbens, but decreased expression in basolateral amygdala. Our results suggest that females are sensitive to the effects of chronic stress, partly due to their genetic sex, independent of gonadal hormones. Furthermore, these results point to the prefrontal cortex as the node in the mesocorticolimbic circuitry with the strongest female-specific effects.

A Transdiagnostic Perspective on Social Anhedonia

Humans are highly social beings, yet people with social anhedonia experience reduced interest in or reward from social situations. Social anhedonia is a key facet of schizotypal personality, an important symptom of schizophrenia, and increasingly recognized as an important feature in a range of other psychological disorders. However, to date, there has been little examination of the similarities and differences in social anhedonia across diagnostic borders. Here, our goal was to conduct a selective review of social anhedonia in different psychological and life course contexts, including the psychosis continuum, depressive disorder, posttraumatic stress disorder, eating disorders, and autism spectrum disorders, along with developmental and neurobiological factors. Current evidence suggests that the nature and expression of social anhedonia vary across psychological disorders with some groups showing deficient learning about, enjoyment from, and anticipation of the pleasurable aspects of social interactions, while for others, some of these components appear to remain intact. However, study designs and methodologies are diverse, the roles of developmental and neurobiological factors are not routinely considered, and direct comparisons between diagnostic groups are rare-which prevents a more nuanced understanding of the underlying mechanisms involved. Future studies, parsing the wanting, liking, and learning components of social reward, will help to fill gaps in the current knowledge base. Consistent across disorders is diminished pleasure from social situations, subsequent withdrawal, and poorer social functioning in those who express social anhedonia. Nonetheless, feelings of loneliness often remain, which suggests the need for social connection is not entirely absent. Adolescence is a particularly important period of social and neural development and may provide a valuable window on the developmental origins of social anhedonia. Adaptive social functioning is key to recovery from mental health disorders; therefore, understanding the intricacies of social anhedonia will help to inform treatment and prevention strategies for a range of diagnostic categories.

Current perspectives on incentive salience and applications to clinical disorders

Affective neuroscience research has revealed that reward contains separable components of 'liking', 'wanting', and learning. Here we focus on current 'liking' and 'wanting' findings and applications to clinical disorders. 'Liking' is the hedonic impact derived from a pleasant experience, and is amplified by opioid and related signals in discrete sites located in limbic-related brain areas. 'Wanting' refers to incentive salience, a motivation process for reward, and is mediated by larger systems involving mesocorticolimbic dopamine. Deficits in incentive salience may contribute to avolitional features of depression and related disorders, whereas deficits in hedonic impact may produce true anhedonia. Excesses in incentive salience, on the other hand, can lead to addiction, especially when narrowly focused on a particular target. Finally, a fearful form of motivational salience may even contribute to some paranoia symptoms of schizophrenia and related disorders.

A comparison of the electrocortical response to monetary and social reward

Affective science research on reward processing has primarily focused on monetary rewards. There has been a growing interest in evaluating the neural basis of social decision-making and reward processing. The present study employed a within-subject design and compared the reward positivity (RewP), an event-related potential component that is present following favorable feedback and absent or reduced following unfavorable feedback, during monetary and social reward tasks. Specifically, 114 participants (75 females) completed a monetary reward task and a novel social reward task that were matched on trial structure, timing, and feedback stimuli in a counterbalanced order. Results indicated that the monetary and social RewP were of similar magnitude, positively correlated and demonstrated comparable psychometric properties, including reliability and dependability. Across both the monetary and social tasks, women demonstrated a greater RewP compared with men. This study provides a novel methodological approach toward examining the electrocortical response to social reward that is comparable to monetary reward.

"Why don't they 'like' me more?": Comparing the time courses of social and monetary reward processing

Humans possess a strong tendency towards social affiliation and interpersonal interaction. Yet, we know far less about how rewards in one's social environment affect functioning as we do with other types of rewards, presumably due to the inherent complexity of measuring social phenomena in laboratory settings. Here, we adapted a social reward paradigm (social incentive delay [SID]) for use in event-related potential (ERP) research, enabling a direct comparison of social and monetary reward processing. We found that social and monetary rewards elicit comparable ERP latencies and scalp topographies across several processing stages (reward cue, outcome anticipation, and outcome evaluation), highlighting the possibility of a common neural network. We also found evidence of latent reward sensitivity, as analogous monetary and social ERPs were correlated and associations were uniquely driven by reward signals. The SID is a promising and viable paradigm that is capable of disentangling multiple stages of social reward processing. The capacity to measure social processes will be critical as we broaden efforts to incorporate multiple contexts in reward sensitivity, which will enable us to gain important new insights into human functioning and dysfunction.

Time-Frequency Reward-Related Delta Prospectively Predicts the Development of Adolescent-Onset Depression

BACKGROUND

A blunted reward positivity (RewP), an event-related potential elicited by feedback indicating monetary gain relative to loss, was recently shown to prospectively predict the development of adolescent-onset depression. Time-frequency-based representations of this activity (e.g., reward-related delta) have also been associated with depression. This study is a reanalysis of the time-domain RewP investigation to examine the incremental value of time-frequency indices in the prediction of adolescent-onset depression.

METHODS

The sample included 444 13- to 15-year-old girls with no lifetime history of a depressive disorder. At baseline, adolescents completed a monetary guessing task, and both time-domain and time-frequency analyses were conducted on the event-related potential response to gain and loss feedback. Lifetime psychiatric history in the adolescent and a biological parent were evaluated with diagnostic interviews, and adolescents' current depressive symptoms were assessed using a self-report questionnaire. Adolescents were interviewed again approximately 18 months later to identify first-onset depressive disorder.

RESULTS

Blunted reward-related delta predicted first-onset depressive disorder 18 months later, independent of the time-domain RewP and psychosocial risk factors (i.e., adolescent baseline depressive symptoms, adolescent and parental psychiatric history). In contrast, loss-related theta did not predict the development of depression. Reward-related delta increased sensitivity (73.8% to 82.8%) and positive predictive value (45.0% to 70.9%) for first-onset depressive disorder when applied in parallel and in series, respectively, with baseline depressive symptoms and the time-domain RewP.

CONCLUSIONS

This study provides evidence that frequency-based representations of event-related potentials provide incremental value in the prediction of psychiatric disorders.

Reward processing and mood-related symptoms: An RDoC and translational neuroscience perspective

BACKGROUND

Two objectives of the NIMH Research Domain Criteria (RDoC) initiative are to identify (a) mechanisms that are common to multiple psychiatric disorders, and (b) mechanisms that are unique to specific psychiatric symptoms, and that reflect markers of differential risk for these symptoms. With respect to these objectives, a brain-behavior dimension that has received considerable attention and that is directly relevant to the Positive Valence Systems domain of the RDoC initiative involves reward processing.

METHODS

The present review paper first examines the relationship between reward processing and mood-related symptoms from an RDoC perspective. We then place this work in a larger context by examining the relationship between reward processing abnormalities and psychiatric symptoms defined broadly, including mood-related symptoms, schizophrenia, and addiction.

RESULTS

Our review suggests that reward hyposensitivity relates to a subtype of anhedonia characterized by motivational deficits in unipolar depression, and reward hypersensitivity relates to a cluster of hypo/manic symptoms characterized by excessive approach motivation in the context of bipolar disorder. Integrating this perspective with research on reward processing abnormalities in schizophrenia and addiction, we further argue that the principles of equifinality and multifinality may be preferable to a transdiagnostic perspective for conceptualizing the relationship between reward processing and psychiatric symptoms defined broadly.

CONCLUSION

We propose that vulnerability to either motivational anhedonia or approach-related hypo/manic symptoms involve extreme and opposite profiles of reward processing. We further propose that an equifinality and multifinality perspective may serve as a useful framework for future research on reward processing abnormalities and psychiatric symptoms.

Dull to Social Acceptance Rather than Sensitivity to Social Ostracism in Interpersonal Interaction for Depression: Behavioral and Electrophysiological Evidence from Cyberball Tasks

Objectives: Impairments in interpersonal relationships in depression present as irritability, pessimism, and withdrawal, and play an important role in the onset and maintenance of the disorder. However, we know little about the neurological causes of this impaired interpersonal function. This study used the event-related brain potential (ERP) version of the Cyberball paradigm to investigate the emotions and neural activities in depressive patients during social inclusion and exclusion simultaneously to explore neuropsychological mechanisms.

Methods: Electrophysiological data were recorded when 27 depressed patients and 23 healthy controls (HCs) performed a virtual ball tossing game (Cyberball) during which the participants believed they were playing with two other co-players over the internet. The Cyberball paradigm included two other conditions; inclusion during which participants received the ball with the same probability as the other players to experience a feeling of acceptance, and exclusion during which the participants experienced a feeling of ostracism when the other two players threw the ball with each other. The Positive and Negative Affect Schedule (PANAS) was used as a baseline and after each block during the Cyberball to assess positive and negative effects. In addition, a brief Need-Threat Scale (NTS) was used to assess the fulfillment of basic needs of subjects after each block and 10 min after ostracism. Moreover, the relationship between the ERP data of depression and clinical symptoms was analyzed.

Results: Exclusion compared to inclusion Cyberball caused a decrease in positive affect and an increase in negative affect. The group differences were only found in the positive affect. Moreover, patients reported a lower level of basic needs than did HCs after social inclusion, but a similar level of basic needs after social exclusion. At the electrophysiological level, patients showed decreased P3 amplitudes compared to HCs in social inclusion, and P3 amplitudes were borderline negatively correlated with their scores of anhedonia symptoms.

Limitations: A limitation of our study was that the subjects' criteria were different.

Conclusions: The behavioral and electrophysiological results indicated that the interpersonal problems in depressive patients were mainly due to deficits in processing the pleasurable social stimuli rather than aversive social cues.

ADHD and the Development of Depression: Commentary on the Prevalence, Proposed Mechanisms, and Promising Interventions

Attention-deficit/hyperactivity disorder (ADHD) has been identified as a significant risk factor for the development of later depression. Furthermore, their comorbid presentation results in greater levels of impairment than either disorder in isolation. Research has pointed to several causal mechanisms by which ADHD co-occurs with depression including the persistence of ADHD symptoms, reward responsivity, and emotion dysregulation as well as parenting/family factors and maternal depression. Stemming from this mechanistic research, interventions have been developed in recent years that aim to prevent depression in youth with ADHD. The Behaviorally Enhancing Adolescents Mood (BEAM) Program and The Integrated Parenting Intervention for ADHD (IPI-A) have both demonstrated promising results. Directions for future research are discussed with an emphasis on neurobiological mechanisms and the dissemination/implementation of interventions to reduce risk for depression among youth with ADHD in community care settings.

Planning to make economic decisions in the future, but choosing impulsively now: are preference reversals related to symptoms of ADHD and depression?

A preference for smaller immediate rewards over larger delayed rewards (delay discounting, DD) is common in attention deficit hyperactivity disorder (ADHD), but rarely investigated in depression. Whether this preference is due to sensitivity to reward immediacy or delay aversion remains unclear. To investigate this, we examined whether ADHD and depressive symptoms are associated with preference reversals: a switch from smaller immediate rewards to larger delayed rewards when smaller rewards are also delayed. We also examined whether these symptoms differentially affect DD of losses. In Study 1 undergraduates completed a questionnaire about ADHD symptoms, and performed a hypothetical DD task. In the NOW condition, participants were presented with choices between a small reward available today and a large reward available after one year. In the FUTURE condition both rewards were delayed with +1 year. In Study 2 undergraduates completed questionnaires about ADHD and depressive symptoms and performed a DD task with gains and losses. Participants showed preference reversals in both studies and tasks. Losses were less steeply discounted than gains. ADHD and depressive symptoms did not influence these effects. Depressive symptoms, but not ADHD symptoms, were associated with less economic choices in general. These findings suggest that impulsive choice in depression is not explained by sensitivity to reward immediacy. Copyright © 2016 John Wiley & Sons, Ltd.

Future Research Directions in the Positive Valence Systems: Measurement, Development, and Implications for Youth Unipolar Depression

The Positive Valence Systems (PVS) have been introduced by the National Institute of Mental Health as a domain to help organize multiple constructs focusing on reward-seeking behaviors. However, the initial working model for this domain is strongly influenced by adult constructs and measures. Thus, the present review focuses on extending the PVS into a developmental context. Specifically, the review provides some hypotheses about the structure of the PVS, how PVS components may change throughout development, how family history of depression may influence PVS development, and potential means of intervening on PVS function to reduce onsets of depression. Future research needs in each of these areas are highlighted.

Social Reward in Youth at Risk for Depression: A Preliminary Investigation of Subjective and Neural Differences

OBJECTIVE

Offspring of depressed parents are at risk for developing depression at rates higher than the general population. One potential mechanism linking parent and offspring depression involves attenuated reward function. Despite the importance of social incentives for adolescents, no previous studies have relied on active social incentive reward paradigms in youth at risk for depression. The present study examined differences in youth self- and parent-report measures of and neural response to social reward between youth of mothers with and those of mothers without a history of depression.

METHODS

Imaging data were collected on 10 youth with a depressed parent and 23 youth without depressed parent, which included a task examining neural response to social rewards. Youth and parents also completed self-report measures of social reward.

RESULTS

Offspring of depressed parents had lower levels of parent-reported affiliation and reduced neural response to social reward in the ventral striatum and anterior cingulate cortex than offspring of parents without a history of depression. Higher parent-reported affiliation was associated with greater ventral striatal response to social reward. Data suggest that risk status differences in ventral striatal response to social acceptance may be accounted for by affiliation. No differences were found in youth self-reports of behavior.

CONCLUSIONS

The results suggest that attenuated response to social reward, assessed through neurobiology and behavior, may be mechanistically linked to the etiology and pathophysiology of depression. Targeting social interest and engagement may be a new direction in preventing the onset of depressive disorders in youth.

Increased prefrontal and parietal cortical thickness does not correlate with anhedonia in patients with untreated first-episode major depressive disorders

Cerebral morphological abnormalities in major depressive disorder (MDD) may be modulated by antidepressant treatment and course of illness in chronic medicated patients. The present study examined cortical thickness in patients with untreated first-episode MDD to elucidate the early pathophysiology of this illness. Here, we examined cortical thickness in patients with first-episode MDD (N=27) and healthy controls (N=27) using an automated surface-based method (in FreeSurfer). By assessing the correlation between caudate volume and cortical thickness at each vertex on the cortical surface, a caudate-cortical network was obtained for each group. Subsequent analysis was performed to assess the effect of anhedonia by the Temporal Experience of Pleasure Scale. We observed increased cortical thickness at the right orbital frontal cortex and the left inferior parietal gyrus in MDD patients compared with healthy controls. Furthermore, morphometric correlational analysis using cortical thickness measurement revealed increased caudate-cortical connectivity in the bilateral superior parietal gyrus in MDD patients. All changes were not related to anhedonia. These preliminary findings may reflect disorder manifestation close to illness onset and may provide insight into the early neurobiology of MDD.

Neuroeconomics for the study of social cognition in adolescent depression

Traditional social-cognitive approaches for investigating interpersonal problems in adolescent depression are limited. An important functional domain studied in adolescent depression is reward, but experimental paradigms have largely been non-social. In this paper, we propose the methods and concepts of neuroeconomics may address this gap. We begin by discussing a well-established social reward model for vulnerability to adolescent depression. We then show how neuroeconomics may extend this model by offering the tools to examine the mechanics of social exchanges, in behavioral and neural terms, that maintain (or pose vulnerability to) depression. In doing so, we propose a neureoconomic model of adolescent depression in which depression is defined as a perturbation of interpersonal motivational/reward exchange. This model serves to guide future research.

Reward learning in pediatric depression and anxiety: preliminary findings in a high-risk sample

BACKGROUND

Reward learning has been postulated as a critical component of hedonic functioning that predicts depression risk. Reward learning deficits have been established in adults with current depressive disorders, but no prior studies have examined the relationship of reward learning and depression in children. The present study investigated reward learning as a function of familial depression risk and current diagnostic status in a pediatric sample.

METHOD

The sample included 204 children of parents with a history of depression (n = 86 high-risk offspring) or parents with no history of major mental disorder (n = 118 low-risk offspring). Semistructured clinical interviews were used to establish current mental diagnoses in the children. A modified signal detection task was used for assessing reward learning. We tested whether reward learning was impaired in high-risk offspring relative to low-risk offspring. We also tested whether reward learning was impaired in children with current disorders known to blunt hedonic function (depression, social phobia, PTSD, GAD, n = 13) compared to children with no disorders and to a psychiatric comparison group with ADHD.

RESULTS

High- and low-risk youth did not differ in reward learning. However, youth with current anhedonic disorders (depression, social phobia, PTSD, GAD) exhibited blunted reward learning relative to nondisordered youth and those with ADHD.

CONCLUSIONS

Our results are a first demonstration that reward learning deficits are present among youth with disorders known to blunt anhedonic function and that these deficits have some degree of diagnostic specificity. We advocate for future studies to replicate and extend these preliminary findings.

The medial forebrain bundle as a deep brain stimulation target for treatment resistant depression: A review of published data

INTRODUCTION

Despite a wide variety of therapeutic interventions for major depressive disorder (MDD), treatment resistant depression (TRD) remains to be prevalent and troublesome in clinical practice. In recent years, deep brain stimulation (DBS) has emerged as an alternative for individuals suffering from TRD not responding to combining antidepressants, multiple adjunctive strategies and electroconvulsive therapy (ECT). Although the best site for TRD-DBS is still unclear, pilot data suggests that the medial forebrain bundle (MFB) might be a key target to accomplish therapeutic efficacy in TRD patients.

OBJECTIVE

To explore the anatomic, electrophysiologic, neurocognitive and treatment data supporting the MFB as a target for TRD-DBS.

RESULTS

The MFB connects multiple targets involved in motivated behavior, mood regulation and antidepressant response. Specific phenomenology associated with TRD can be linked specifically to the superolateral branch (sl) of the MFB (slMFB). TRD patients who received DBS-slMFB reported high response/remission rates with an improvement in functioning and no significant adverse outcomes in their physical health or neurocognitive performance.

DISCUSSION

The slMFB is an essential component of a network of structural and functional pathways connecting different areas possibly involved in the pathogenesis of mood disorders. Therefore, the slMFB should be considered as an exciting therapeutic target for DBS therapy to achieve a sustained relief in TRD patients.

CONCLUSION

There is an urgent need for clinical trials exploring DBS-slMFB in TRD. Further efforts should pursue measuring baseline pro-inflammatory cytokines, oxidative stress, and cognition as possible biomarkers of DBS-slMFB response in order to aid clinicians in better patient selection.

Personality traits modulate emotional and physiological responses to stress

An individual's susceptibility to psychological and physical disorders associated with chronic stress exposure, for example, cardiovascular and infectious disease, may also be predicted by their reactivity to acute stress. One factor associated with both stress resilience and health outcomes is personality. An understanding of how personality influences responses to acute stress may shed light upon individual differences in susceptibility to chronic stress-linked disease. This study examined the relationships between personality and acute responses to stress in 125 healthy adults, using hierarchical linear regression. We assessed personality traits using the Multidimensional Personality Questionnaire (MPQ-BF), and responses to acute stress (cortisol, heart rate, blood pressure, mood) using a standardized laboratory psychosocial stress task, the Trier Social Stress Test. Individuals with high Negative Emotionality exhibited greater emotional distress and lower blood pressure responses to the Trier Social Stress Test. Individuals with high agentic Positive Emotionality exhibited prolonged heart rate responses to stress, whereas those with high communal Positive Emotionality exhibited smaller cortisol and blood pressure responses. Separate personality traits differentially predicted emotional, cardiovascular, and cortisol responses to a psychosocial stressor in healthy volunteers. Future research investigating the association of personality with chronic stress-related disease may provide further clues to the relationship between acute stress reactivity and susceptibility to disease.

Gender differences in the relationship between affect and adolescent smoking uptake

AIMS

To evaluate gender differences in the role of positive and negative affect on smoking uptake.

DESIGN

Prospective longitudinal cohort study of adolescent health behaviors.

SETTING

Four suburban secondary schools outside Philadelphia, Pennsylvania, USA.

PARTICIPANTS

Adolescents (n = 1357) were surveyed every 6 months for 4 years (age 14-18 years).

MEASUREMENTS

Smoking and affect were measured via survey at each of the eight time-points.

FINDINGS

A two-group associative process latent growth curve model revealed that baseline positive affect was related negatively to smoking progression for females (b = -0.031, Z = -4.00, P < 0.0001) but not for males (P = 0.33). This gender difference was significant, χ(2)((df = 1))  = 8.24, P = 0.0041, indicating that for every standard deviation (SD) decrease in positive affect (SD = 2.90), there was a 10% increase [odds ratio (OR) = 1.10, 95% confidence interval (CI) = 1.04, 1.14] in the odds of smoking progression for females. Baseline negative affect was related significantly and positively to smoking progression for males (b = 0.038, Z =2.874, P = 0.004) and females (b = 0.025, Z =3.609, P < 0.0001), but the gender difference was not significant, χ(2)((df = 1)) = 0.82, P = 0.37. Thus, on average, for every standard deviation (SD = 4.40) increase in baseline negative affect there was a 15% (OR = 1.15, 95% CI = 1.06, 1.26) increase in the odds of smoking progression for males and for females.

CONCLUSIONS

The impact of affect on adolescent smoking uptake varies by gender. Low positive affect (low experience of positive feelings or emotions) for females and high negative affect (high experience of negative feelings or emotions) for both males and females increases the risk for adolescent smoking.

The Adolescent Behavioral Activation Program: Adapting Behavioral Activation as a Treatment for Depression in Adolescence

This study aimed to examine implementation feasibility and initial treatment outcomes of a behavioral activation (BA) based treatment for adolescent depression, the Adolescent Behavioral Activation Program (A-BAP). A randomized, controlled trial was conducted with 60 clinically referred adolescents with a depressive disorder who were randomized to receive either 14 sessions of A-BAP or uncontrolled evidenced-based practice for depression. The urban sample was 64% female, predominantly Non-Hispanic White (67%), and had an average age of 14.9 years. Measures of depression, global functioning, activation, and avoidance were obtained through clinical interviews and/or through parent and adolescent self-report at preintervention and end of intervention. Intent-to-treat linear mixed effects modeling and logistic regression analysis revealed that both conditions produced statistically significant improvement from pretreatment to end of treatment in depression, global functioning, and activation and avoidance. There were no significant differences across treatment conditions. These findings provide the first step in establishing the efficacy of BA as a treatment for adolescent depression and support the need for ongoing research on BA as a way to enhance the strategies available for treatment of depression in this population.

The Role of Depression in the Uptake and Maintenance of Cigarette Smoking

Cigarette smoking and depression both account for significant morbidity, mortality, and economic burden. The prevalence of both smoking and depression increase across mid-to-late adolescence and show high rates of comorbidity. While little is known about why smoking is disproportionately higher among depressed adolescents than adolescents without depression, emerging research has begun to offer some initial insights. The high rates of comorbidity between depression and smoking emphasize the importance of identifying intervention targets to inform smoking prevention efforts for this high-risk group. Interventions during adolescence may lessen the prevalence of depression-prone adult smokers. Depression is over-represented among adult smokers and contributes to lower smoking cessation rates. Negative mood management and pharmacotherapy have been the central focus of smoking cessation interventions for depression-prone populations to date. Converging lines of research highlight novel smoking cessation targets such as the maintenance of positive mood and reward regulation. Smoking cessation research in depression-prone smokers is critical to identify efficacious treatments that will ultimately decrease the excess smoking burden for this population.

Motivational deficits in effort-based decision making in individuals with subsyndromal depression, first-episode and remitted depression patients

Anhedonia is a hallmark symptom of major depressive disorder (MDD). Preliminary findings suggest that anhedonia is characterized by reduced reward anticipation and motivation of obtaining reward. However, relatively little is known about reward-based decision-making in depression. We tested the hypothesis that anhedonia in MDD may reflect specific impairments in motivation on reward-based decision-making and the deficits might be associated with depressive symptoms severity. In study 1, individuals with and without depressive symptoms performed the modified version of the Effort Expenditure for Rewards Task (EEfRT), a behavioral measure of cost/benefit decision-making. In study 2, MDD patients, remitted MDD patients and healthy controls were recruited for the same procedures. We found evidence for decreased willingness to make effort for rewards among individuals with subsyndromal depression; the effect was amplified in MDD patients, but dissipated in patients with remitted depression. We also found that reduced anticipatory and consummatory pleasure predicted decreased willingness to expend efforts to obtain rewards in MDD patients. For individuals with subsyndromal depression, the impairments were correlated with anticipatory anhedonia but not consummatory anhedonia. These data offer novel evidence that motivational deficits in MDD are correlated with depression severity and predicted by self-reported anhedonia.

Reward and affective regulation in depression-prone smokers

BACKGROUND

There is a disproportionately high smoking prevalence among individuals who are prone to depression. While depression has been conceptualized as a disorder of dysregulated positive affect and disrupted reward processing, little research has been conducted to determine the role of smoking in these processes among depression-prone smokers.

METHODS

Depression-prone smokers (DP+; n = 34) and smokers not depression-prone (DP-; n = 49) underwent two laboratory sessions, one while smoking abstinent and one while smoking ad libitum, to assess the relative reinforcing value of smoking and reward sensitivity. Using experience sampling methods, participants completed self-report measures of subjective reward, positive affect, and negative affect across 3 days while smoking as usual and 3 days while smoking abstinent.

RESULTS

DP+ were two times more likely to work for cigarette puffs versus money in a progressive ratio, choice task (odds ratio 2.05; 95% confidence interval 1.04 to 4.06, p = .039) compared with DP-. Reward sensitivity as measured by the signal detection task did not yield any significant findings. Mixed models regressions revealed a three-way interaction (depression group, smoking phase, and time) for subjective reward, negative affect, and positive affect. For all three of these outcomes, the slopes for DP- and DP+ differed significantly from each other (ps < .05) and the effect of smoking (versus abstinence) over time was greater for DP+ than DP- smokers (ps < .05).

CONCLUSIONS

These findings indicate that the effects of smoking on reward and positive affect regulation are specific to DP+ smokers and highlight novel targets for smoking cessation treatment in this population.

Elevated reward-related neural activation as a unique biological marker of bipolar disorder: assessment and treatment implications

Growing evidence indicates that risk for bipolar disorder is characterized by elevated activation in a fronto-striatal reward neural circuit involving the ventral striatum and orbitofrontal cortex, among other regions. It is proposed that individuals with abnormally elevated reward-related neural activation are at risk for experiencing an excessive increase in approach-related motivation during life events involving rewards or goal striving and attainment. In the extreme, this increase in motivation is reflected in hypomanic/manic symptoms. By contrast, unipolar depression (without a history of hypomania/mania) is characterized by decreased reward responsivity and decreased reward-related neural activation. Collectively, this suggests that risk for bipolar disorder and unipolar depression are characterized by distinct and opposite profiles of reward processing and reward-related neural activation. The objective of the present paper is threefold. First, we review the literature on reward processing and reward-related neural activation in bipolar disorder, and in particular risk for hypomania/mania. Second, we propose that reward-related neural activation reflects a biological marker of differential risk for bipolar disorder versus unipolar depression that may help facilitate psychiatric assessment and differential diagnosis. We also discuss, however, the challenges to using neuroscience techniques and biological markers in a clinical setting for assessment and diagnostic purposes. Lastly, we address the pharmacological and psychosocial treatment implications of research on reward-related neural activation in bipolar disorder.

Elevated reward-related neural activation as a unique biological marker of bipolar disorder: assessment and treatment implications

Growing evidence indicates that risk for bipolar disorder is characterized by elevated activation in a fronto-striatal reward neural circuit involving the ventral striatum and orbitofrontal cortex, among other regions. It is proposed that individuals with abnormally elevated reward-related neural activation are at risk for experiencing an excessive increase in approach-related motivation during life events involving rewards or goal striving and attainment. In the extreme, this increase in motivation is reflected in hypomanic/manic symptoms. By contrast, unipolar depression (without a history of hypomania/mania) is characterized by decreased reward responsivity and decreased reward-related neural activation. Collectively, this suggests that risk for bipolar disorder and unipolar depression are characterized by distinct and opposite profiles of reward processing and reward-related neural activation. The objective of the present paper is threefold. First, we review the literature on reward processing and reward-related neural activation in bipolar disorder, and in particular risk for hypomania/mania. Second, we propose that reward-related neural activation reflects a biological marker of differential risk for bipolar disorder versus unipolar depression that may help facilitate psychiatric assessment and differential diagnosis. We also discuss, however, the challenges to using neuroscience techniques and biological markers in a clinical setting for assessment and diagnostic purposes. Lastly, we address the pharmacological and psychosocial treatment implications of research on reward-related neural activation in bipolar disorder.

Associations among smoking, anhedonia, and reward learning in depression

Depression and cigarette smoking co-occur at high rates. However, the etiological mechanisms that contribute to this relationship remain unclear. Anhedonia and associated impairments in reward learning are key features of depression, which also have been linked to the onset and maintenance of cigarette smoking. However, few studies have investigated differences in anhedonia and reward learning among depressed smokers and depressed nonsmokers. The goal of this study was to examine putative differences in anhedonia and reward learning in depressed smokers (n=36) and depressed nonsmokers (n=44). To this end, participants completed self-report measures of anhedonia and behavioral activation (BAS reward responsiveness scores) and as well as a probabilistic reward task rooted in signal detection theory, which measures reward learning (Pizzagalli, Jahn, & O'Shea, 2005). When considering self-report measures, depressed smokers reported higher trait anhedonia and reduced BAS reward responsiveness scores compared to depressed nonsmokers. In contrast to self-report measures, nicotine-satiated depressed smokers demonstrated greater acquisition of reward-based learning compared to depressed nonsmokers as indexed by the probabilistic reward task. Findings may point to a potential mechanism underlying the frequent co-occurrence of smoking and depression. These results highlight the importance of continued investigation of the role of anhedonia and reward system functioning in the co-occurrence of depression and nicotine abuse. Results also may support the use of treatments targeting reward learning (e.g., behavioral activation) to enhance smoking cessation among individuals with depression.