Anhedonia in schizophrenia and major depression: state or trait?

The Measurement of Positive Valence Forms of Empathy and Their Relation to Anhedonia and Other Depressive Symptomatology

Construct validity of a brief self-report measure of "positive-valence empathy" (the tendency to exude positive emotion as a means to stimulate positive affect in others, and/or to vicariously share in another's positive emotion; Light et al., 2009) was attained utilizing a sample of 282 healthy adults. Positive-valence empathy may have unique predictive ability for differentiating depression versus depression with anhedonia. Confirmatory factor analyses revealed a two-factor structure for the final 15-item Light-Moran Positive Empathy Scale (PES), with an 8-item "Empathic Happiness" subscale (e.g., "I find that other people's happiness easily rubs off on me") and a 7-item "Empathic Cheerfulness" subscale (e.g., "I enjoy making others feel good"). "Empathic Happiness" was a significantly better predictor of overall depressive symptomatology (Beck et al., 1996) than anhedonia (Snaith et al., 1995). The Light-Moran PES-15 may have real-world impact and predictive utility for well-being.

Predicting Predischarge Anhedonia Among Inpatients With Schizophrenia and Schizoaffective Disorders: A Large-scale Analysis

This study sought to evaluate predischarge anhedonia level and its predictors in 125 inpatients with schizophrenia and schizoaffective disorders. Consecutively admitted inpatients were assessed before discharge from the hospital using the Specific Loss of Interest and Pleasure Scale (SLIPS) and a battery of measures for clinical and psychosocial variables. When symptoms, distress, and social anhedonia scores were controlled, the SLIPS score inversely correlated with self-constructs, social support, quality of life, recovery, and unmet needs. Using two cutoff points of the data set of SLIPS, we identified three groups: 19 (15.2%) patients reported "no loss of pleasure"; 46 (36.8%), "some loss of pleasure"; and 60 (48.0%), "marked diminishment of pleasure." The SLIPS score is predicted by sensitivity, unmet needs, deficient interpersonal pleasure, poor quality of life, and friend support. The study underlines the importance of assessing anhedonia and related psychosocial factors in patients with serious mental illness.

Metabolic syndrome, depression and anhedonia among young adults

The aim of this study was to assess the association between anhedonia and metabolic syndrome (MetS) in a well-characterized community sample of individuals with a current depressive episode. This is a cross-sectional study with young adults aged 24-30 years old. Depressive episode and the presence of anhedonia was assessed using the Mini International Neuropsychiatric Interview - Plus version (MINI Plus). The MetS was assessed using the National Cholesterol Education Program Adult Treatment Panel III (NCEP/ATP III). The sample included 931 subjects, being 22 had depression without anhedonia, whereas 55 had depression with anhedonia. MetS was more prevalent among subjects with depression and anhedonia (43.6%) when compared to individuals without anhedonia and population control group. Moreover, subjects with depression and anhedonia have a significant increase of levels of glucose, triglycerides, total-cholesterol and LDL-cholesterol, as well as significant decreased in the HDL-cholesterol level. The present study showed that individuals with depression and anhedonia present higher prevalence of MetS. Our study suggests that the use of the concept of anhedonia may contribute to a better understanding of the complex relationship between depression and metabolic syndrome.

An experimental investigation into the use of eye-contact in social interactions in women in the acute and recovered stages of anorexia nervosa

OBJECTIVE

People with anorexia nervosa (AN) report significant difficulties in social functioning and a growing literature is beginning to explain some of the differences in social skills that might underlie the social challenges experienced by patients. One vital area of social functioning that has been largely neglected to date is how eye-contact is used in the context of social stimuli and in social situations.

METHODS

This cross-sectional, experimental study used eye-tracking to measure the frequency and duration of eye-contact made with the eye region of interest (ROI) of (1) static social stimuli (man and woman Ekman faces displaying basic emotions); (2) moving social stimuli (a video of two actors conversing); and (3) during a real-life social interaction in 75 women (25 with AN, 25 recovered from AN, and 25 non-AN controls; mean age = 27.18, SD = 6.19).

RESULTS

Participants showed greater eye-contact during a real-life social interaction than when viewing static social stimuli. Those with AN made contact with the eye ROI of the static and moving social stimuli and during a real-life social interaction significantly less often and for significantly less time than non-AN controls. Those recovered from AN showed greater eye-contact than the acute group but significantly less eye-contact with the eye ROI across the static and moving social stimuli and during the real-life social interaction than non-AN controls.

DISCUSSION

These findings contribute new knowledge regarding the types of social skills that people with AN may need additional support with to allow them to make greater use of social support in their recovery.

The characterization of social anhedonia and its correlates in schizophrenia and schizoaffective patients

Although social hedonic capacity is often assessed in clinical settings, its operational definitions have not been evaluated for concurrent validity. One hundred and twenty-five patients with schizophrenia and schizoaffective disorder were classified according to their self-reported social hedonic functioning into three groups on the basis of their total scores on the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS). Participants were assessed before discharge using questionnaires and psychiatric rating scales. Using an empirically based cutoff score, we identified three groups: an intact social hedonic group (WNL), a socially anhedonic group (SA), and a socially hypohedonic group (i.e., those with scores intermediate between normal functioning and aberrantly low functioning, H). The SA patients were significantly different from the two other groups (WNL and H) by their higher severity of psychopathology, lower levels of self-efficacy, and less self-esteem. The SA patients also reported less perceived social support, poorer quality of life, and less subjective recovery. Our findings indicate that social anhedonia is a meaningful target for intervention. Further implications of our findings are discussed.

Dopamine dysregulation hypothesis: the common basis for motivational anhedonia in major depressive disorder and schizophrenia?

Abnormalities in reward processing are crucial symptoms of major depressive disorder (MDD) and schizophrenia (SCH). Recent neuroscientific findings regarding MDD have led to conclusions about two different symptoms related to reward processing: motivational and consummatory anhedonia, corresponding, respectively, to impaired motivation to obtain rewards ('wanting'), and diminished satisfaction from consuming them ('liking'). One can ask: which of these is common for MDD and SCH. In our review of the latest neuroscientific studies, we show that MDD and SCH do not share consummatory anhedonia, as SCH patients usually have unaltered liking. Therefore, we investigated whether motivational anhedonia is the common symptom across MDD and SCH. With regard to the similarities and differences between the neural mechanisms of MDD and SCH, here we expand the current knowledge of motivation deficits and present the common underlying mechanism of motivational anhedonia - the dopamine dysregulation hypothesis - stating that any prolonged dysregulation in tonic dopamine signaling that exceeds the given equilibrium can lead to striatal dysfunction and motivational anhedonia. The implications for further research and treatment of MDD and SCH are also discussed.

Neuroscience of apathy and anhedonia: a transdiagnostic approach

Apathy and anhedonia are common syndromes of motivation that are associated with a wide range of brain disorders and have no established therapies. Research using animal models suggests that a useful framework for understanding motivated behaviour lies in effort-based decision making for reward. The neurobiological mechanisms underpinning such decisions have now begun to be determined in individuals with apathy or anhedonia, providing an important foundation for developing new treatments. The findings suggest that there might be some shared mechanisms between both syndromes. A transdiagnostic approach that cuts across traditional disease boundaries provides a potentially useful means for understanding these conditions.

A study of physical anhedonia as a trait marker in schizophrenia

BACKGROUND

Inability to define the heritable phenotype might be a reason for failure to replicate results in psychiatric genetics. Hence, the use of a candidate symptom approach to identify more homogeneous forms of diseases among affected individuals and subclinical traits among first-degree relatives (FDRs) may increase genetic validity. The objective of the present study was to determine whether physical anhedonia can be used as a marker for individuals at risk of schizophrenia.

MATERIALS AND METHODS

Physical anhedonia scores (measured using Revised Physical Anhedonia Scale [rPAS]) were compared across thirty remitted schizophrenic patients, thirty of their unaffected FDRs, and thirty healthy controls. We compared anhedonia scores among the three main groups using one-way ANOVA.

RESULTS

Physical anhedonia (rPAS) scores of the schizophrenic patient group were significantly higher than that of their FDRs and controls both, and physical anhedonia (rPAS) scores of FDRs were significantly higher than that of healthy controls (F = 115.33, P < 0.001). The subgroups did not differ on various other clinical characteristics.

CONCLUSION

Our data suggest that physical anhedonia is a candidate symptom for schizophrenia.

Adult neurogenesis affects motivation to obtain weak, but not strong, reward in operant tasks

Decreased motivation to seek rewards is a key feature of mood disorders that correlates with severity and treatment outcome. This anhedonia, or apathy, likely reflects impairment in reward circuitry, but the specific neuronal populations controlling motivation are unclear. Granule neurons generated in the adult hippocampus have been implicated in mood disorders, but are not generally considered as part of reward circuits. We investigated a possible role of these new neurons in motivation to work for food and sucrose rewards in operant conditioning tasks using GFAP-TK pharmacogenetic ablation of adult neurogenesis in both rats and mice. Rats and mice lacking adult neurogenesis showed normal lever press responding during fixed ratio training, reward devaluation, and Pavlovian Instrumental Transfer, suggesting no impairment in learning. However, on an exponentially progressive ratio schedule, or when regular chow was freely available in the testing chamber, TK rats and mice showed less effort to gain sucrose tablets. When working for balanced food tablets, which rats and mice of both genotypes strongly preferred over sucrose, the genotype effects on behavior were lost. This decrease in effort under conditions of low reward suggests that loss of adult neurogenesis decreases motivation to seek reward in a manner that may model behavioral apathy.

Anhedonia is associated with suicidal ideation independently of depression: A meta-analysis

BACKGROUND

Anhedonia is considered a suicide risk factor in patients with major affective disorders. Here, we wanted to quantify the association between anhedonia and current suicidal ideation according to the absence/presence of between-group differences for depressive scores and psychiatric disorders.

METHODS

We performed a meta-analysis of data on studies retrieved from Medline, Web of Science, and PsycINFO from 1965 to 2016 using, among others, the terms (suicid* or depression) and anhedonia.

RESULTS

We identified 15 observational case-control studies that investigated the anhedonia differences in individuals with and without current (i.e., within the past week, independently of the lifetime suicidality status) suicidal ideation (defined as thoughts of killing oneself). Overall, 657 subjects with and 6,690 subjects without current suicidal ideation could be compared. Anhedonia level was higher in the group with current suicidal ideation than in the group without, with a medium effect size (standardized mean difference = 0.57, z = 5.43, P < 0.001, 95% confidence interval, CI = 0.37-0.79). The association between anhedonia and current suicidal ideation remained significant when controlling for depression and psychiatric disorders. The anhedonia scales used in the selected studies did not allow investigating consummatory and motivational anhedonia separately.

CONCLUSION

Our major finding is the robust association between anhedonia and current suicidal ideation, independently of depression. This is highly relevant for the clinicians' daily practice and might help improving suicidal risk detection and the development of new therapeutic strategies for suicide prevention.

Anhedonia in depression and schizophrenia: A transdiagnostic challenge

BACKGROUND

Anhedonia, as a dysregulation of the reward circuit, is present in both Major Depressive Disorder (MDD) and schizophrenia (SZ).

AIMS

To elucidate the clinical and neurobiological differences between schizophrenia (SZ) and depression (MDD) in regard to anhedonia, while reconciling the challenges and benefits of assessing anhedonia as a transdiagnostic feature under the Research Domain Criteria (RDoC) framework.

METHODS

In this review, we summarize data from publications examining anhedonia or its underlying reward deficits in SZ and MDD. A literature search was conducted in OVID Medline, PsycINFO and EMBASE databases between 2000 and 2017.

RESULTS

While certain subgroups share commonalities, there are also important differences. SZ may be characterized by a disorganization, rather than a deficiency, in reward processing and cognitive function, including inappropriate energy expenditure and focus on irrelevant cues. In contrast, MDD has been characterized by deficits in anticipatory pleasure, development of reward associations, and integration of information from past experience. Understanding the roles of neurotransmitters and aberrant brain circuitry is necessary to appreciate differences in reward function in SZ and MDD.

CONCLUSION

Anhedonia as a clinical presentation of reward circuit dysregulation is an important and relatively undertreated symptom of both SZ and MDD. In order to improve patient outcomes and quality of life, it is important to consider how anhedonia fits into both diagnoses.

Aripiprazole relieves motivational anhedonia in rats

BACKGROUND

Anhedonia is considered a relevant feature in depression and psychosis, characterized by poor treatment outcome, and associated with deficits in mesolimbic dopaminergic responsiveness. Clinical studies suggest the potential utility of aripiprazole as adjunctive therapy for resistant depression. Since aripiprazole can stabilize the dopaminergic system, in search of tailored therapeutic strategies for reward dysfunctions, we investigated whether the drug restored motivation toward positive stimuli in a rat model.

METHODS

Anhedonia is modeled in non food-deprived 9-week old male Sprague-Dawley rats by exposing them to a chronic unavoidable stress protocol, consisting in repeated exposure to tail-shock or restrain, which disrupts the motivation to acquire a reward-directed behavior and the competence to escape aversive stimuli. We evaluated whether long-term aripiprazole administration (1mg/kg/day, i.p.) restored in chronically stressed rats, a) the disrupted dopaminergic response to sucrose consumption measuring DARPP-32 phosphorylation levels in the nucleus accumbens shell by immunoblotting; b) the motivation to operate in a sucrose self-administration protocol.

RESULTS

Long-term aripiprazole administration restored DARPP-32 phosphorylation changes in response to sucrose and reinstated the motivational drive to acquire the reward in the progressive ratio task. However, it did not restore reactivity to aversive stimuli.

LIMITATIONS

The results obtained in our model may not fully translate to the clinic, as anhedonia is a complex construct in patients, where motivational aspects represent a central but not unique feature.

CONCLUSIONS

This study demonstrates that aripiprazole relieved motivational anhedonia in a stress-induced model and warrants further studies to ascertain whether this activity is clinically relevant for antipsychotic or adjunctive antidepressant treatments.

Anhedonia and individual differences in orbitofrontal cortex sulcogyral morphology

Three types of orbitofrontal cortex (OFC) sulcogyral patterns that have been identified in the population, and the distribution of these three types in clinically diagnosed schizophrenic patients has been found to be distinct from the normal population. Schizophrenia is associated with increased levels of social and physical anhedonia. In this study, we asked whether variation in anhedonia in a neurologically normal population is associated with altered sulcogyral pattern frequency. OFC sulcogyral type was classified and anhedonia was measured in 58 normal young adults, and the relationship between OFC sulcogyral type and anhedonia was explored. In line with other studies conducted in chronic schizophrenia, individuals with higher levels of physical anhedonia demonstrated atypical sulcogyral patterns. Individuals with higher physical anhedonia showed a reduced incidence of Type I OFC and an increased incidence of Type II OFC in the left hemisphere compared to individuals with lower physical anhedonia. These findings support the notion that Type I OFC sulcogyral pattern is protective of anhedonia compared to Type II, even in individuals that are not schizophrenic. Overall, these results support the view that symptoms and neural indices typically associated with neuropsychiatric disorders actually reflect quantitative traits that are continuously distributed throughout the general population. Hum Brain Mapp 37:3873-3881, 2016. © 2016 Wiley Periodicals, Inc.

Divergent anomaly in mesocorticolimbic dopaminergic circuits might be associated with different depressive behaviors, an animal study

BACKGROUND

The mesocorticolimbic dopamine system, which originates from the ventral tegmental area (VTA) and projects primarily to the prefrontal cortex (PFC), olfactory tubercle (OT), nucleus accumbens (NAc), dorsal striatum (ST), and the amygdala (AMy), plays a pivotal role in determining individual motivation and sensitivity to rewards, namely, anhedonia. Not all depressive individuals exhibited anhedonia, thus, it is natural to speculate that the heterogenous manifestations of depression might be related to the mesocorticolimbic dopamine system. Maternal deprivation (MD) and chronic unpredictable stress (CUPS) are two well-established depressogenic stressors, and they were proven to induce different depressive phenotypes.

METHODS

The depressive and anxiety-like behaviors of MD and CUPS-treated rats were measured by classical behavioral tests including open field, forced swimming, and sucrose preference test. The expression of D1-5 dopamine receptors and DAT mRNA and protein in the mesocorticolimbic dopamine system of rats exposed to MD and CUPS were measured by real-time PCR and Western blot, respectively.

RESULTS

Severe anhedonia was observed in MD but not CUPS rats. Divergent expression of D1 and D2 receptors and DAT mRNA and protein in the mesocorticolimbic dopamine system were found between MD and CUPS rats. Significant correlations between different depressive behaviors and D1-/D2-like receptors and DAT protein levels in the mesocorticolimbic dopamine system were observed.

CONCLUSION

Different depressive behaviors of rats such as anhedonia, passive coping behavior, and declined exploratory interest might be related to divergent dopaminergic pathways. Anhedonia is associated with the dysfunction of VTA-NAc and VTA-OT dopaminergic pathways, the passive coping behavior is related to the dysregulation of VTA-PFC and VTA-AMy pathways, and individual exploratory interest is associated with abnormal activity of VTA-PFC and VTA-ST pathways.

Association between habenula dysfunction and motivational symptoms in unmedicated major depressive disorder

The lateral habenula plays a central role in reward and punishment processing and has been suggested to drive the cardinal symptom of anhedonia in depression. This hypothesis is largely based on observations of habenula hypermetabolism in animal models of depression, but the activity of habenula and its relationship with clinical symptoms in patients with depression remains unclear. High-resolution functional magnetic resonance imaging (fMRI) and computational modelling were used to investigate the activity of the habenula during a probabilistic reinforcement learning task with rewarding and punishing outcomes in 21 unmedicated patients with major depression and 17 healthy participants. High-resolution anatomical scans were also acquired to assess group differences in habenula volume. Healthy individuals displayed the expected activation in the left habenula during receipt of punishment and this pattern was confirmed in the computational analysis of prediction error processing. In depressed patients, there was a trend towards attenuated left habenula activation to punishment, while greater left habenula activation was associated with more severe depressive symptoms and anhedonia. We also identified greater habenula volume in patients with depression, which was associated with anhedonic symptoms. Habenula dysfunction may contribute to abnormal response to punishment in patients with depression, and symptoms such as anhedonia.

Neural substrates of trait impulsivity, anhedonia, and irritability: Mechanisms of heterotypic comorbidity between externalizing disorders and unipolar depression

Trait impulsivity, which is often defined as a strong preference for immediate over delayed rewards and results in behaviors that are socially inappropriate, maladaptive, and short-sighted, is a predisposing vulnerability to all externalizing spectrum disorders. In contrast, anhedonia is characterized by chronically low motivation and reduced capacity to experience pleasure, and is common to depressive disorders. Although externalizing and depressive disorders have virtually nonoverlapping diagnostic criteria in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, heterotypic comorbidity between them is common. Here, we review common neural substrates of trait impulsivity, anhedonia, and irritability, which include both low tonic mesolimbic dopamine activity and low phasic mesolimbic dopamine responding to incentives during reward anticipation and associative learning. We also consider how other neural networks, including bottom-up emotion generation systems and top-down emotion regulation systems, interact with mesolimbic dysfunction to result in alternative manifestations of psychiatric illness. Finally, we present a model that emphasizes a translational, transdiagnostic approach to understanding externalizing/depression comorbidity. This model should refine ways in which internalizing and externalizing disorders are studied, classified, and treated.

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.

Down-regulation of cholinergic signaling in the habenula induces anhedonia-like behavior

Dysfunction of cholinergic signaling in the brain has long been believed to be associated with depressive disorders. However, the functional impact of habenular cholinergic signaling on the specified depressive behaviors is not well understood. Here, we demonstrated that the expression levels of cholinergic signaling genes (CHAT, VACHT, CHT, CHRNA3, CHRNB3 and CHRNB4) were down-regulated in a chronic restraint stress (CRS) rat model of depression, in which rats display depression-like behaviors such as anhedonia and mood despair. Moreover, knockdown of CHAT in the rat habenula was sufficient to evoke anhedonia-like behavior. The anhedonia-like behavior induced by CHAT knockdown was not reversed by chronic administration of the selective serotonin reuptake inhibitor fluoxetine. To determine whether habenular cholinergic signaling is associated with regulation of dopamine neurons in the ventral tegmental area (VTA) and serotonin neurons in the dorsal raphe nucleus (DRN), we used CHAT::cre transgenic mice expressing the Designer Receptors Exclusively Activated by Designer Drugs (DREADD). Pharmacogenetic activation of habenular cholinergic neurons induces the excitation of dopamine neurons in the VTA and reduces the immunoreactivity of 5-hydroxytryptamine (5-HT) in the DRN. Habenular cholinergic gene down-regulation was recapitulated in the postmortem habenula of suicide victims diagnosed with major depressive disorder (MDD).

Pre-ejection period reactivity to reward is associated with anhedonic symptoms of depression among adolescents

Pre-ejection period (PEP) reactivity to reward has been posited as a specific index of behavioral approach and incentive motivation, suggesting it might be uniquely associated with the affective and motivational deficits of anhedonia. This study evaluated PEP reactivity to a reward task as a predictor of depressive symptoms among adolescents, examining global depressive symptoms as well as specific anhedonic and nonanhedonic symptoms clusters. Participants included 76 adolescents, ages 11-15 years (52% female). This study found marginal support for an association between PEP reactivity to reward and concurrent anhedonia symptoms, but no association with nonanhedonic or the global scale. Findings are discussed in terms of potential associations between peripheral psychophysiological measures and dopaminergic functioning and also the utility of this measure for future research on anhedonia.

A dimensional approach to modeling symptoms of neuropsychiatric disorders in the marmoset monkey

Some patients suffering from the same neuropsychiatric disorder may have no overlapping symptoms whilst others may share symptoms common to other distinct disorders. Therefore, the Research Domain Criteria initiative recognises the need for better characterisation of the individual symptoms on which to focus symptom-based treatment strategies. Many of the disorders involve dysfunction within the prefrontal cortex (PFC) and so the marmoset, due to their highly developed PFC and small size, is an ideal species for studying the neurobiological basis of the behavioural dimensions that underlie these symptoms.Here we focus on a battery of tests that address dysfunction spanning the cognitive (cognitive inflexibility and working memory), negative valence (fear generalisation and negative bias) and positive valence (anhedonia) systems pertinent for understanding disorders such as ADHD, Schizophrenia, Anxiety, Depression and OCD. Parsing the separable prefrontal and striatal circuits and identifying the selective neurochemical modulation (serotonin vs dopamine) that underlie cognitive dysfunction have revealed counterparts in the clinical domain. Aspects of the negative valence system have been explored both at individual- (trait anxiety and genetic variation in serotonin transporter) and circuit-based levels enabling the understanding of generalisation processes, negative biases and differential responsiveness to SSRIs. Within the positive valence system, the combination of cardiovascular and behavioural measures provides a framework for understanding motivational, anticipatory and consummatory aspects of anhedonia and their neurobiological mechanisms. Together, the direct comparison of experimental findings in marmosets with clinical studies is proving an excellent translational model to address the behavioural dimensions and neurobiology of neuropsychiatric symptoms. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 328-353, 2017.

The Predictive Value of the NEO-FFI Items: Parsing the Nature of Social Anhedonia Using the Revised Social Anhedonia Scale and the ACIPS

The goal was to examine the nature of social anhedonia using two validated measures and study their relationship to scores on the NEO-Five Factor Inventory (NEO-FFI). Nearly 1,900 college-aged participants completed the Chapman Revised Social Anhedonia Scale (RSAS), Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS), and the NEO-FFI. Although both the RSAS and ACIPS were associated with the NEO-FFI domains of Extraversion, Agreeableness, and Neuroticism, linear regression analyses revealed that the RSAS and ACIPS were differentially predicted by NEO-FFI item clusters. The RSAS scores were predicted by Sociability, Nonantagonistic Orientation, Positive Affect, and Activity item clusters. The ACIPS scores were predicted by Sociability, Prosocial Orientation, Activity, and Positive Affect item clusters in addition to gender. In summary, it appears that social anhedonia is multidimensional, associated with various personality domains encompassing social approach and withdrawal.

Olfactory identification in patients with schizophrenia - the influence of β-endorphin and calcitonin gene-related peptide concentrations

BACKGROUND

The relationship between the olfactory system and emotional processing is an area of growing interest in schizophrenia research. Both the orbitofrontal cortex and amygdala are involved in the processing of olfactory information, and olfactory deficits may be also influenced by endogenous opioids and calcitonin gene-related peptide (CGRP), which is probably involved in dopaminergic transmission. However, the relationship between endorphins and dopaminergic transmission has not been fully explored.

METHODS

Odor identification performance and valence interaction was evaluated among 50 schizophrenic patients and 50 controls. Schizophrenia symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). All study participants were subjected to the University of Pennsylvania Smell Identification Test (UPSIT), blood β-endorphin (BE) and CGRP measurement.

RESULTS

Insignificantly higher BE concentrations were observed in the patient group, while significantly higher UPSIT scores were seen in controls (mean UPSIT 32.48 vs 26.82). The patients demonstrated significantly more identification errors for pleasant (P=0.000) and neutral (P=0.055) odors than for unpleasant odors. Patients with higher BE concentrations made more identification errors concerning pleasant (R_s=-0.292; P=0.04) and neutral odors (R_s=-0.331; P=0.019). Although the concentration of CGRP was significantly higher in the patient sample (P<0.001), no relationship was observed between concentration and UPSIT performance. A strong negative correlation was observed between PANSS N score and UPSIT total score (R_s=-0.646; P=0.000), between PANSS N score and identification by valence for pleasant and neutral odors (UPSIT n/16: R_s=-0.450, P=0.001; UPSIT n/15: R_s=-0.586, P=0.000), and a weak negative correlation between PANSS N score and identification of unpleasant odors (UPSIT n/9: R_s=-0.325, P=0.021).

CONCLUSIONS

Schizophrenic patients present a unique pattern of smell identification characterized by aberrant hedonic ratings for pleasant odors but not unpleasant ones. Individuals with predominant negative symptoms and higher BE concentrations are most able to identify negative odors.

Treatment for Anhedonia: A Neuroscience Driven Approach

Anhedonia, or loss of interest or pleasure in usual activities, is characteristic of depression, some types of anxiety, as well as substance abuse and schizophrenia. Anhedonia is a predictor of poor long-term outcomes, including suicide, and poor treatment response. Because extant psychological and pharmacological treatments are relatively ineffective for anhedonia, there is an unmet therapeutic need for this high-risk symptom. Current psychological and drug treatments for anxiety and depression focus largely on reducing excesses in negative affect rather than improving deficits in positive affect. Recent advances in affective neuroscience posit that anhedonia is associated with deficits in the appetitive reward system, specifically the anticipation, consumption, and learning of reward. In this paper, we review the evidence for positive affect as a symptom cluster, and its neural underpinnings, and introduce a novel psychological treatment for anxiety and depression that targets appetitive responding. First, we review anhedonia in relation to positive and negative valence systems and current treatment approaches. Second, we discuss the evidence linking anhedonia to biological, experiential, and behavioral deficits in the reward subsystems. Third, we describe the therapeutic approach for Positive Affect Treatment (PAT), an intervention designed to specifically target deficits in reward sensitivity.

Neural Basis of Anhedonia and Amotivation in Patients with Schizophrenia: The Role of Reward System

Anhedonia, the inability to feel pleasure, and amotivation, the lack of motivation, are two prominent negative symptoms of schizophrenia, which contribute to the poor social and occupational behaviors in the patients. Recently growing evidence shows that anhedonia and amotivation are tied together, but have distinct neural correlates. It is important to note that both of these symptoms may derive from deficient functioning of the reward network. A further analysis into the neuroimaging findings of schizophrenia shows that the neural correlates overlap in the reward network including the ventral striatum, anterior cingulate cortex and orbitofrontal cortex. Other neuroimaging studies have demonstrated the involvement of the default mode network in anhedonia. The identification of a specific deficit in hedonic and motivational capacity may help to elucidate the mechanisms behind social functioning deficits in schizophrenia, and may also lead to more targeted treatment of negative symptoms.

PPARα modulation of mesolimbic dopamine transmission rescues depression-related behaviors

Depressive disorders cause a substantial burden for the individual and the society. Key depressive symptoms can be modeled in animals and enable the development of novel therapeutic interventions. Chronic unavoidable stress disrupts rats' competence to escape noxious stimuli and self-administer sucrose, configuring a depression model characterized by escape deficit and motivational anhedonia associated to impaired dopaminergic responses to sucrose in the nucleus accumbens shell (NAcS). Repeated treatments that restore these responses also relieve behavioral symptoms. Ventral tegmental area (VTA) dopamine neurons encode reward and motivation and are implicated in the neuropathology of depressive-like behaviors. Peroxisome proliferator-activated receptors type-α (PPARα) acutely regulate VTA dopamine neuron firing via β2 subunit-containing nicotinic acetylcholine receptors (β2*nAChRs) through phosphorylation and this effect is predictive of antidepressant-like effects. Here, by combining behavioral, electrophysiological and biochemical techniques, we studied the effects of repeated PPARα stimulation by fenofibrate on mesolimbic dopamine system. We found decreased β2*nAChRs phosphorylation levels and a switch from tonic to phasic activity of dopamine cells in the VTA, and increased phosphorylation of dopamine and cAMP-regulated phosphoprotein Mr 32,000 (DARPP-32) in the NAcS. We then investigated whether long-term fenofibrate administration to stressed rats reinstated the decreased DARPP-32 response to sucrose and whether this effect translated into antidepressant-like properties. Fenofibrate restored dopaminergic responses to appetitive stimuli, reactivity to aversive stimuli and motivation to self-administer sucrose. Overall, this study suggests PPARα as new targets for antidepressant therapies endowed with motivational anti-anhedonic properties, further supporting the role of an unbalanced mesolimbic dopamine system in pathophysiology of depressive disorders.

Social functioning in major depressive disorder

Depression is associated with social risk factors, social impairments and poor social functioning. This paper gives an overview of these social aspects using the NIMH Research and Domain Criteria 'Systems for Social Processes' as a framework. In particular, it describes the bio-psycho-social interplay regarding impaired affiliation and attachment (social anhedonia, hyper-sensitivity to social rejection, competition avoidance, increased altruistic punishment), impaired social communication (impaired emotion recognition, diminished cooperativeness), impaired social perception (reduced empathy, theory-of-mind deficits) and their impact on social networks and the use of social media. It describes these dysfunctional social processes at the behavioural, neuroanatomical, neurochemical and genetic levels, and with respect to animal models of social stress. We discuss the diagnostic specificity of these social deficit constructs for depression and in relation to depression severity. Since social factors are importantly involved in the pathogenesis and the consequences of depression, such research will likely contribute to better diagnostic assessments and concepts, treatments and preventative strategies both at the diagnostic and transdiagnostic level.

Anhedonia and general distress show dissociable ventromedial prefrontal cortex connectivity in major depressive disorder

Anhedonia, the reduced ability to experience pleasure in response to otherwise rewarding stimuli, is a core symptom of major depressive disorder (MDD). Although the posterior ventromedial prefrontal cortex (pVMPFC) and its functional connections have been consistently implicated in MDD, their roles in anhedonia remain poorly understood. Furthermore, it is unknown whether anhedonia is primarily associated with intrinsic 'resting-state' pVMPFC functional connectivity or an inability to modulate connectivity in a context-specific manner. To address these gaps, a pVMPFC region of interest was first identified using activation likelihood estimation meta-analysis. pVMPFC connectivity was then examined in relation to anhedonia and general distress symptoms of depression, using both resting-state and task-based functional magnetic resonance imaging involving pleasant music, in current MDD and healthy control groups. In MDD, pVMPFC connectivity was negatively correlated with anhedonia but not general distress during music listening in key reward- and emotion-processing regions, including nucleus accumbens, ventral tegmental area/substantia nigra, orbitofrontal cortex and insula, as well as fronto-temporal regions involved in tracking complex sound sequences, including middle temporal gyrus and inferior frontal gyrus. No such dissociations were observed in the healthy controls, and resting-state pVMPFC connectivity did not dissociate anhedonia from general distress in either group. Our findings demonstrate that anhedonia in MDD is associated with context-specific deficits in pVMPFC connectivity with the mesolimbic reward system when encountering pleasurable stimuli, rather than a static deficit in intrinsic resting-state connectivity. Critically, identification of functional circuits associated with anhedonia better characterizes MDD heterogeneity and may help track of one of its core symptoms.

Diminished facial emotion expression and associated clinical characteristics in Anorexia Nervosa

This study aimed to investigate emotion expression in a large group of children, adolescents and adults with Anorexia Nervosa (AN), and investigate the associated clinical correlates. One hundred and forty-one participants (AN=66, HC= 75) were recruited and positive and negative film clips were used to elicit emotion expressions. The Facial Activation Coding system (FACES) was used to code emotion expression. Subjective ratings of emotion were collected. Individuals with AN displayed less positive emotions during the positive film clip compared to healthy controls (HC). There was no significant difference between the groups on the Positive and Negative Affect Scale (PANAS). The AN group displayed emotional incongruence (reporting a different emotion to what would be expected given the stimuli, with limited facial affect to signal the emotion experienced), whereby they reported feeling significantly higher rates of negative emotion during the positive clip. There were no differences in emotion expression between the groups during the negative film clip. Despite this individuals with AN reported feeling significantly higher levels of negative emotions during the negative clip. Diminished positive emotion expression was associated with more severe clinical symptoms, which could suggest that these individuals represent a group with serious social difficulties, which may require specific attention in treatment.

Hedonic sensitivity to low-dose ketamine is modulated by gonadal hormones in a sex-dependent manner

We recently reported a greater sensitivity of female rats to rapid antidepressant-like effects of ketamine compared to male rats, and that ovarian-derived estradiol (E2) and progesterone (P4) are essential for this response. However, to what extent testosterone may also contribute, and whether duration of response to ketamine is modulated in a sex- and hormone-dependent manner remains unclear. To explore this, we systematically investigated the influence of testosterone, estradiol and progesterone on initiation and maintenance of hedonic response to low-dose ketamine (2.5 mg/kg) in intact and gonadectomized male and female rats. Ketamine induced a sustained increase in sucrose preference of female, but not male, rats in an E2P4-dependent manner. Whereas testosterone failed to alter male treatment response, concurrent administration of P4 alone in intact males enhanced hedonic response low-dose ketamine. Treatment responsiveness in female rats only was associated with greater hippocampal BDNF levels, but not activation of key downstream signaling effectors. We provide novel evidence supporting activational roles for ovarian-, but not testicular-, derived hormones in mediating hedonic sensitivity to low-dose ketamine in female and male rats, respectively. Organizational differences may, in part, account for the persistence of sex differences following gonadectomy and selective involvement of BDNF in treatment response.

Anhedonia is associated with blunted reward sensitivity in first-degree relatives of patients with major depression

BACKGROUND

Anhedonia is a cardinal feature of major depression and is hypothesized to be driven by low motivation, in particular blunted reward sensitivity. It has been suggested to be a marker that represents a genetic predisposition to this disorder. However, little is known about the mechanisms underlying this heightened risk in unaffected first-degree relatives of patients with major depression. We previously demonstrated abnormal reward biases in acutely depressed patients. The present study aimed to examine the development of reward bias in first-degree relatives of patients with major depression.

METHODS

Forty-seven first-degree relatives of patients with major depression (26 females, age 18-52) and 60 healthy controls with no family history of depression (34 females, age 21-48) were recruited. A probabilistically rewarded difficult visual discrimination task, in which participants were instructed about the contingencies, was used to assess blunted reward sensitivity. A response bias towards the more frequently rewarded stimulus (termed "reward bias") was the primary outcome variable in this study. Participants also completed self-reported measures of anhedonia and depressive symptoms.

RESULTS

Compared with the control group, relatives of patients with major depression with sub-clinical depressive symptoms displayed a blunted reward bias. Relatives without symptoms displayed largely intact motivational processing on both self-report and experimental measures. The degree of anhedonia was associated with attenuated reward bias in first-degree relatives of patients with major depression, especially in those with sub-clinical symptoms.

LIMITATIONS

The study did not include a depressed patient group, which restricted our ability to interpret the observed group differences.

CONCLUSIONS

Blunted reward sensitivity may be largely manifested in a subgroup of relatives with high levels of depressive symptoms.

Genetic Moderation of Stress Effects on Corticolimbic Circuitry

Stress exposure is associated with individual differences in corticolimbic structure and function that often mirror patterns observed in psychopathology. Gene x environment interaction research suggests that genetic variation moderates the impact of stress on risk for psychopathology. On the basis of these findings, imaging genetics, which attempts to link variability in DNA sequence and structure to neural phenotypes, has begun to incorporate measures of the environment. This research paradigm, known as imaging gene x environment interaction (iGxE), is beginning to contribute to our understanding of the neural mechanisms through which genetic variation and stress increase psychopathology risk. Although awaiting replication, evidence suggests that genetic variation within the canonical neuroendocrine stress hormone system, the hypothalamic-pituitary-adrenal axis, contributes to variability in stress-related corticolimbic structure and function, which, in turn, confers risk for psychopathology. For iGxE research to reach its full potential it will have to address many challenges, of which we discuss: (i) small effects, (ii) measuring the environment and neural phenotypes, (iii) the absence of detailed mechanisms, and (iv) incorporating development. By actively addressing these challenges, iGxE research is poised to help identify the neural mechanisms underlying genetic and environmental associations with psychopathology.

Anhedonia in schizophrenia: The role of subjective experiences

BACKGROUND

High levels of anhedonia have been found in patients with schizophrenia; specifically they report higher levels of social anhedonia rather than physical anhedonia, and further, in the anticipatory rather than consummatory facets of pleasure. Nonetheless, contrasting results emerged regarding the underlying mechanisms of this deficit. Basic Symptoms (BS) disturb subjective experiences present for most of the illness' course; this impacts patients' daily lives leading to a loss of the ability to organize the experience of the self and the world in a fluid and automatic way. Considering the role played by negative emotions in the subjective evaluation of anhedonia, the aim of the study is to clarify the role of BS in the assessment of anhedonia in a sample of patients with schizophrenia (n=53) compared with healthy controls (n=46).

METHODS

Participants completed a self-administered trait questionnaire evaluating social anhedonia (Revised-Social Anhedonia Scale), physical anhedonia (Physical Anhedonia Scale), and the consummatory and anticipatory pleasure experiences (Temporal Experience of Pleasure Scale). BS were evaluated with the Frankfurter Beschwerde-Frageboden (FBF) whereas psychopathology was assessed with the Positive and Negative Syndromes Scale.

RESULTS

Patients scored higher than healthy controls in social, physical and anticipatory anhedonia, but not in consummatory anhedonia and these relationships were mediated by the FBF. Basic Symptoms of Memory, Overstimulation and Lack of Automatism were related to some facets of anhedonia, independently from depressive symptoms.

CONCLUSIONS

We hypothesize that a subjective cognitive deficit and a reduced ability in information processing, could prevent patients from retaining a positive experience from past pleasant activities. Therefore the lack of pleasure would be, at least in part, related to an avoidance of potentially stressful new scenarios.

Neural reactivity to rewards and losses in offspring of mothers and fathers with histories of depressive and anxiety disorders

Depression appears to be characterized by reduced neural reactivity to receipt of reward. Despite evidence of shared etiologies and high rates of comorbidity between depression and anxiety, this abnormality may be relatively specific to depression. However, it is unclear whether children at risk for depression also exhibit abnormal reward responding, and if so, whether risk for anxiety moderates this association. The feedback negativity (FN) is an event-related potential component sensitive to receipt of rewards versus losses that is reduced in depression. Using a large community sample (N = 407) of 9-year-old children who had never experienced a depressive episode, we examined whether histories of depression and anxiety in their parents were associated with the FN following monetary rewards and losses. Results indicated that maternal history of depression was associated with a blunted FN in offspring, but only when there was no maternal history of anxiety. In addition, greater severity of maternal depression was associated with greater blunting of the FN in children. No effects of paternal psychopathology were observed. Results suggest that blunted reactivity to rewards versus losses may be a vulnerability marker that is specific to pure depression, but is not evident when there is also familial risk for anxiety. In addition, these findings suggest that abnormal reward responding is evident as early as middle childhood, several years prior to the sharp increase in the prevalence of depression and rapid changes in neural reward circuitry in adolescence.

Blunted neural response to rewards as a vulnerability factor for depression: Results from a family study

Depressive disorders are associated with significant economic and public health burdens as well as increased morbidity. Yet, perhaps due to the heterogeneous nature of the disease, prevention and intervention efforts are only moderately efficacious. A better understanding of core mechanisms of depressive disorders might aid in the development of more targeted intervention, and perhaps help identify individuals at risk. One mechanism that may be particularly important to depressive phenotypes is reward insensitivity. Examination of neurobiological correlates of reward-processing, which should relate more directly to the neuropathology of depression, may be helpful in identifying liability for the disorder. To that end, we used a family study design to examine whether a neural response to rewards is a familial risk factor for depression in a sample of probands with a wide range of internalizing psychopathology, as well as their biological siblings. Event-related potentials were recorded during a simple forced-choice gambling paradigm, in which participants could either win or lose small amounts of money. Lower levels of positive affect in probands predicted a reduced neural response to rewards in siblings, even over and above the sibling's own level of positive and negative affect. Additionally, the neural response to rewards was familial (i.e., correlated among siblings). Combined, these analyses suggest that a blunted neural response to rewards may be useful in identifying individuals vulnerable to depressive illnesses.

Neural correlates of change in major depressive disorder anhedonia following open-label ketamine

Anhedonia is a cardinal symptom of major depression and is often refractory to standard treatment, yet no approved medication for this specific symptom exists. In this exploratory re-analysis, we assessed whether administration of rapid-acting antidepressant ketamine was associated specifically with reduced anhedonia in medication-free treatment-refractory patients with major depressive disorder in an open-label investigation. Additionally, participants received either oral riluzole or placebo daily beginning 4 hours post-infusion. A subgroup of patients underwent fluorodeoxyglucose positron emission tomography scans at baseline (1-3 days pre-infusion) and 2 hours post-ketamine infusion. Anhedonia rapidly decreased following a single ketamine infusion; this was sustained for up to three days, but was not altered by riluzole. Reduced anhedonia correlated with increased glucose metabolism in the hippocampus and dorsal anterior cingulate cortex (dACC) and decreased metabolism in the inferior frontal gyrus and orbitofrontal cortex (OFC). The tentative relationship between change in anhedonia and glucose metabolism remained significant in dACC and OFC, and at trend level in the hippocampus, a result not anticipated, when controlling for change in total depression score. Results, however, remain tenuous due to the lack of a placebo control for ketamine. In addition to alleviating overall depressive symptoms, ketamine could possess anti-anhedonic potential in major depressive disorder, which speculatively, may be mediated by alterations in metabolic activity in the hippocampus, dACC and OFC.

Rostral medial prefrontal dysfunctions and consummatory pleasure in schizophrenia: a meta-analysis of functional imaging studies

A large number of imaging studies have examined the neural correlates of consummatory pleasure and anticipatory pleasure in schizophrenia, but the brain regions where schizophrenia patients consistently demonstrate dysfunctions remain unclear. We performed a series of meta-analyses on imaging studies to delineate the regions associated with consummatory and anticipatory pleasure dysfunctions in schizophrenia. Nineteen functional magnetic resonance imaging or positron emission tomography studies using whole brain analysis were identified through a literature search (PubMed and EBSCO; January 1990-February 2014). Activation likelihood estimation was performed using the GingerALE software. The clusters identified were obtained after controlling for the false discovery rate at p<0.05 and applying a minimum cluster size of 200 mm(3). It was found that schizophrenia patients exhibited decreased activation mainly in the rostral medial prefrontal cortex (rmPFC), the right parahippocampus/amygala, and other limbic regions (e.g., the subgenual anterior cingulate cortex, the putamen, and the medial globus pallidus) when consummating pleasure. Task instructions (feeling vs. stimuli) were differentially related to medial prefrontal dysfunction in schizophrenia. When patients anticipated pleasure, reduced activation in the left putamen was observed, despite the limited number of studies. Our findings suggest that the medial prefrontal cortex and limbic regions may play an important role in neural dysfunction underlying deficits in consummatory pleasure in schizophrenia.

A comparative study of anhedonia components between major depression and schizophrenia in Chinese populations

BACKGROUND

Anhedonia is a prominent symptom of major depressive disorder (MDD) and schizophrenia. At present, it is believed that hedonic processing rather consists of the anticipatory and consummatory phase. The aim of this research is to explore the different anhedonia components in MDD and schizophrenia in Chinese populations.

METHODS

A Chinese version of the Temporal Experience of Pleasure Scale (TEPS) was used to evaluate 176 MDD patients, 346 schizophrenia patients, and 268 healthy controls. Additionally, the 17-item Hamilton Depression Rating Scale (HAMD-17) was used for MDD patients, while the Positive and Negative Syndrome Scale (PANSS) was applied for schizophrenia.

RESULTS

The scores of consummatory (TEPS-CON) and anticipatory pleasure (TEPS-ANT) in MDD and schizophrenia were both significantly lower than healthy controls (both P < 0.001). TEPS-CON and TEPS-ANT were negatively correlated with the score of HAMD-17, the duration of illness and admission times in MDD (P < 0.05 or 0.01). TEPS-CON was negatively related to PANSS total scores and negative symptoms (P < 0.05 or 0.01), but no significant correlation was found with duration of illness and admission times in schizophrenia (P > 0.05). There was no significant correlation between TEPS-ANT and any clinical variables (P > 0.05).

CONCLUSIONS

The consummatory and anticipatory pleasures were both impaired in MDD and schizophrenia. Consummatory and anticipatory anhedonia can be considered as a "state" in MDD, but as a "trait" in schizophrenia.

Serotonin transporter clustering in blood lymphocytes predicts the outcome on anhedonia scores in naïve depressive patients treated with antidepressant medication

BACKGROUND

We have shown that serotonin transporter (SERT) clustering in blood lymphocytes is altered in major depression and correlates with pharmacological therapeutic responses measured with the Hamilton scale. In the present report, we extend these results to the self-assessment anhedonia scale, as anhedonia is a cardinal symptom of major depression that is difficult to treat with first-line antidepressants.

METHODS

We collected blood samples from 38 untreated depression patients at the time of enrolment and 8 weeks after pharmacological treatment. We used the self-assessment anhedonia scale to evaluate anhedonia symptoms before and after treatment. We also used quantitative immunocytochemistry to measure SERT clusters in blood lymphocytes.

RESULTS

Evaluation of the distribution of SERT clusters size in the plasma membrane of lymphocytes identified two subpopulations of naive depression patients: Depression I (D-I) and Depression II (D-II). While naïve D-I and D-II patients initially showed similar anhedonia scores, D-II patients showed a good response in anhedonia symptoms after 8 weeks of psychopharmacological treatment, whereas D-I patients failed to show any improvement. Psychopharmacological treatment also induced an increase in the number of SERT clusters in lymphocytes in the D-II group, and this increase correlated with the improvement in anhedonia symptoms.

CONCLUSIONS

SERT clustering in peripheral lymphocytes can be used to identify patient response to antidepressant therapy as ascertained by anhedonia scores.

Anhedonia in depressed patients on treatment with selective serotonin reuptake inhibitor anti-depressant--A two-centered study in Malaysia

OBJECTIVE

Anhedonia is the reduced ability to experience pleasure. It is a core symptom of depression and is particularly difficult to treat. This study aims to compare the level of anhedonia between depressed patients on anti-depressants and healthy subjects.

METHOD

A total of 111 depressed patients on selective serotonin reuptake inhibitor (SSRI) and 82 healthy subjects were recruited from the outpatient psychiatric services at two major general hospitals in a cross-sectional study. Subjects were assessed using the Mini International Neuropsychiatric Interview 5.0.0 or MINI, Beck's Depression Index (BDI), and Snaith-Hamilton Pleasure Scale (SHAPS). Relevant personal and sociodemographic information were also collected.

RESULTS

There was a significant association between educational level and SHAPS-M scores (P < 0.01) among the participants. Most items in the SHAPS scores were significantly different (P < 0.01) in the depressed subjects treated with anti-depressant compared with the healthy subjects, after adjusting the confounding factors, BDI score, and educational level.

CONCLUSION

Anhedonia often persists in depressed patients despite on SSRI anti-depressant treatment.

Attentional modulation by reward and punishment cues in relation to depressive symptoms

BACKGROUND AND OBJECTIVES

Research indicates that individuals at-risk for depression are characterized by high sensitivity to loss and reduced sensitivity to reward. Moreover, it has been shown that attentional bias plays an important role in depression vulnerability. The current study aimed to examine the interplay between these risk factors for depression by examining the development of attentional bias toward reward and loss signals in dysphoric participants (individuals with elevated levels of depressive symptoms).

METHODS

Shapes were conditioned to reward and loss and subsequently presented in a dot probe task in a sample of dysphoric and nondysphoric participants.

RESULTS

Nondysphoric individuals oriented towards reward-related signals whereas dysphoric individuals failed to develop a reward-related attentional bias. This attentional effect was observed in the absence of group differences in motivational factors. No group differences were found for attentional bias for loss-related signals, despite the fact that dysphoric individuals performed worse in response to losing.

LIMITATIONS

The current sample is not clinical thus generalization to clinical depression is not warranted.

CONCLUSIONS

We argue that impaired early attentional processing of rewards are an important cognitive risk factor for anhedonic symptoms in persons with dysphoria.

Social anhedonia and work and social functioning in the acute and recovered phases of eating disorders

Interpersonal difficulties are proposed to maintain eating disorders (EDs). This study explored whether social anhedonia (SA) was an additional social emotional maintenance factor which might also explain work/social problems in EDs. Additionally, the study explored SA and work and social adjustment in recovered participants. Women with anorexia nervosa (AN; n=105), bulimia nervosa (BN; n=46), recovered from AN (RAN; n=30) and non-ED controls (n=136) completed the Work and Social Adjustment Scale (WSAS) and the Revised Social Anhedonia Scale. ED participants reported greater SA and WSAS scores than non-ED controls; the RAN group reported an intermediate profile. AN participants had poorer work/social adjustment than BN participants. SA was associated with longer illness duration. SA, current severity (BMI) and lifetime severity (lowest adult BMI) significantly predicted work/social difficulties. Recovered participants scoring in the clinical range for SA experienced significantly greater work/social difficulties than recovered participants scoring outside the clinical range for SA. EDs are associated with clinical levels of SA and poor work/social functioning which reduce in recovery. SA may maintain the interpersonal functioning difficulties.

Acute and chronic effects of NMDA receptor antagonists in rodents, relevance to negative symptoms of schizophrenia: a translational link to humans

Negative symptoms of schizophrenia remain an unmet clinical need as they are common, persistent, respond poorly to existing treatments and lead to disability. Blunted affect, alogia, asociality, anhedonia and avolition are regarded as key negative symptoms despite DSM-IV-TR specifying a more limited range. The key to development of improved therapies is improved animal models that mimic the human condition in terms of behaviour and pathology and that predict efficacy of novel treatments in patients. Accumulating evidence shows that NMDA receptor (NMDAR) antagonists mimic cognitive deficits of relevance to schizophrenia in animals, along with associated pathological changes. This review examines evidence for the ability of NMDAR antagonists to mimic anhedonia and asociality, two negative symptoms of schizophrenia, in animals. The use of various species, paradigms and treatment regimens are reviewed. We conclude that sub-chronic treatment with NMDAR antagonists, typically PCP, induces social withdrawal in animals but not anhedonia. NMDAR antagonists have further effects in paradigms such as motivational salience that may be useful for mimicking other aspects of negative symptoms but these require further development. Sub-chronic treatment regimens of NMDAR antagonists also have some neurobiological effects of relevance to negative symptoms. It is our view that a sub-chronic treatment regime with NMDAR antagonists, particularly PCP, with animals tested following a wash-out period and in a battery of tests to assess certain behaviours of relevance to negative symptoms and social withdrawal (the animal equivalent of asociality) is valuable. This will enhance our understanding of the psycho and neuropathology of specific negative symptom domains and allow early detection of novel pharmacological targets.

Nogo-A-deficient Transgenic Rats Show Deficits in Higher Cognitive Functions, Decreased Anxiety, and Altered Circadian Activity Patterns

Decreased levels of Nogo-A-dependent signaling have been shown to affect behavior and cognitive functions. In Nogo-A knockout and knockdown laboratory rodents, behavioral alterations were observed, possibly corresponding with human neuropsychiatric diseases of neurodevelopmental origin, particularly schizophrenia. This study offers further insight into behavioral manifestations of Nogo-A knockdown in laboratory rats, focusing on spatial and non-spatial cognition, anxiety levels, circadian rhythmicity, and activity patterns. Demonstrated is an impairment of cognitive functions and behavioral flexibility in a spatial active avoidance task, while non-spatial memory in a step-through avoidance task was spared. No signs of anhedonia, typical for schizophrenic patients, were observed in the animals. Some measures indicated lower anxiety levels in the Nogo-A-deficient group. Circadian rhythmicity in locomotor activity was preserved in the Nogo-A knockout rats and their circadian period (tau) did not differ from controls. However, daily activity patterns were slightly altered in the knockdown animals. We conclude that a reduction of Nogo-A levels induces changes in CNS development, manifested as subtle alterations in cognitive functions, emotionality, and activity patterns.

Anhedonia in Parkinson's disease patients with and without pathological gambling: a case-control study

Anhedonia is present in Parkinson's Disease (PD) as well as in addictive behaviors. Pathological Gambling (PG) and other Impulse Control Disorders (ICDs) have emerged as iatrogenic complications associated with dopamine replacement therapy. We studied 154 PD patients, divided into three groups: 11 with PG, 23 with other ICDs (compulsive buying, hypersexuality, binge eating), 120 without ICDs. All patients underwent a thorough clinical, neuropsychological and psychiatric evaluation. The PG-group, compared to the ICDs-group and PD-controls, reported a significantly higher incidence of anhedonia (45% vs. 9% vs. 14% respectively), higher Snaith-Hamilton Pleasure Scale (SHAPS) scores (2.0±1.3 vs. 1.0±1.1 vs. 1.0±1.2), higher levels of impulsivity traits as measured by the Barratt Impulsiveness Scale (70.0±10.6 vs. 64.8±11 vs. 60.9±9.3) and more severe frontal dysfunctions (Frontal Assessment Battery, FAB: 12.4±4.9 vs. 15.5±1.6 vs. 14.4±3). A model for PG (incorporating anhedonia, impulsivity levels and frontal impairment) is discussed in the context of the pathophysiology of addictive behaviors. The impairment of hedonic capacity, possibly resulting from an underlying neuropsychological dysfunction, might facilitate loss of control over reward-related behavior, thus favoring the shift towards predominantly habit-based compulsive behaviors.