Cannabis use and anticipatory pleasure as reported by subjects with early psychosis and community controls

Cannabis and anhedonia: A systematic review

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

The acute and non-acute effects of cannabis on reward processing: A systematic review

Cannabis use has historically been thought to cause amotivation, but the relationship between cannabis and apathy, anhedonia, and reward processing remains poorly characterised. In this systematic review, we evaluated whether cannabis exposure acutely and/or non-acutely was associated with altered reward processing using questionnaire, behavioural, or functional neuroimaging measures. Questionnaire studies demonstrated greater anhedonia in adolescent cannabis users, and some indication of greater apathy in young adult cannabis users. Behavioural studies yielded some evidence of reduced reward learning in adolescent cannabis users, though there were too few studies in this category for reliable conclusions. Finally, longitudinal and acute functional neuroimaging studies showed an association between cannabis and blunted neural responses to reward, which did not emerge consistently in cross-sectional studies. The current results suggest that cannabis use is associated with specific impairments in reward and motivation. Future large-scale, longitudinal studies which use multiple behavioural and neuroimaging measures of reward processing may further clarify the impact of cannabis use on motivational and reward processes, and neural networks.

Relations Among Anhedonia, Reinforcement Learning, and Global Functioning in Help-seeking Youth

Dysfunction in the neural circuits underlying salience signaling is implicated in symptoms of psychosis and may predict conversion to a psychotic disorder in youth at clinical high risk (CHR) for psychosis. Additionally, negative symptom severity, including consummatory and anticipatory aspects of anhedonia, may predict functional outcome in individuals with schizophrenia-spectrum disorders. However, it is unclear whether anhedonia is related to the ability to attribute incentive salience to stimuli (through reinforcement learning [RL]) and whether measures of anhedonia and RL predict functional outcome in a younger, help-seeking population. We administered the Salience Attribution Test (SAT) to 33 participants who met criteria for either CHR or a recent-onset psychotic disorder and 29 help-seeking youth with nonpsychotic disorders. In the SAT, participants must identify relevant and irrelevant stimulus dimensions and be sensitive to different reinforcement probabilities for the 2 levels of the relevant dimension ("adaptive salience"). Adaptive salience attribution was positively related to both consummatory pleasure and functioning in the full sample. Analyses also revealed an indirect effect of adaptive salience on the relation between consummatory pleasure and both role (αβ = .22, 95% CI = 0.02, 0.48) and social functioning (αβ = .14, 95% CI = 0.02, 0.30). These findings suggest a distinct pathway to poor global functioning in help-seeking youth, via impaired reward sensitivity and RL.

A meta-analysis of self-reported anticipatory and consummatory pleasure in the schizophrenia-spectrum

OBJECTIVE

Recent conceptual frameworks propose anhedonia reflects abnormalities in the temporal dynamics of positive emotion in schizophrenia, characterized by intact consummatory and impaired anticipatory pleasure. A comprehensive meta-analysis can directly test this theory using self-report data.

METHOD

A meta-analysis was performed on studies reporting Temporal Experience of Pleasure Scale (TEPS) data from healthy controls and schizophrenia or schizotypy groups. The TEPS was examined as it contains subscales to measure both consummatory and anticipatory pleasure separately. Statistical heterogeneity and study bias were examined. Meta-regressions evaluated moderators.

RESULTS

53 studies were retrieved (7,797 participants). Results revealed small effect sizes for comparisons of combined schizophrenia/schizotypy and control groups for both consummatory and anticipatory pleasure. Within-group comparisons of pleasure conditions were nonsignificant. The percentage of male schizophrenia/schizotypy participants significantly moderated anticipatory and consummatory pleasure for the combined sample and schizotypy alone; male participants were found to report reduced pleasure. There was only minor evidence of bias; sensitivity analysis confirmed result robustness. Exploratory outlier removal for schizophrenia within-group pleasure comparisons revealed a statistically significant difference between reported anticipatory and consummatory pleasure, with consummatory pleasure reduced relative to anticipatory (i.e., in the opposite direction of the majority of experimental research findings).

CONCLUSIONS

These findings provided only modest support for the temporal dynamics of positive emotion conceptualization because they revealed no evidence for: 1) specific anticipatory pleasure deficits in schizophrenia-spectrum participants compared to controls; 2) significant reductions in anticipatory pleasure relative to consummatory pleasure in schizophrenia-spectrum participants.

Anticipatory pleasure for future experiences in schizophrenia spectrum disorders and major depression: A systematic review and meta-analysis

OBJECTIVES

Deficits in anticipating pleasure may be an important dimension of anhedonia and functioning in psychiatric disorders, particularly schizophrenia and depression; however, inconsistent findings have limited the conclusions that can be drawn. We conducted the first systemic review and meta-analysis of the extant literature for research comparing psychiatric groups to healthy control groups on anticipatory pleasure.

METHODS

Academic Search Complete, Science Direct, and CINAHL databases were systematically searched up to 9 June 2018 for relevant peer-reviewed articles, book chapters, and dissertations. Reference lists were also hand searched. A total of 36 studies were included in the review.

RESULTS

A moderate-sized deficit was observed in schizophrenia spectrum disorders (k = 32, 1,851 patients and 1,449 controls, g = -0.42 [95% CI = -0.53 to -0.31], p < .001), and a large deficit in major depression (k = 415 patients and 506 controls, g = -0.87 [95% CI = -1.23 to -0.51], p < .001), with this effect being significantly larger for depression (p < .05). Meta-regression showed that heterogeneity was partially explained in schizophrenia spectrum by longer duration of illness and lower cognitive functioning predicting larger deficits. In depression, some evidence was found that ruling out a history of psychiatric illness in controls may be related to larger effects. There was evidence for small study bias inflating estimates in schizophrenia spectrum disorders.

CONCLUSIONS

Deficits in anticipatory pleasure are manifest in these disorders, and significantly more so in major depression. These findings indicate a possible therapeutic target to link cognitive, affective, and behavioural factors that precipitate and maintain disorder.

PRACTITIONER POINTS

Anticipatory pleasure is impaired in schizophrenia spectrum and major depression. A particular focus on enhancing anticipatory pleasure may improve motivation for rewarding behaviour and psychosocial functioning. The review contained only a small number of studies for major depression. Given the heterogeneity in effects, there are likely to be more moderators of anticipatory pleasure that require examination.

Individuals with psychosis and a lifetime history of cannabis use show greater deficits in emotional experience compared to non-using peers

Background: While previous research suggests that active cannabis use is a barrier to the emotional experiences of anticipating pleasure and expressing emotion in early psychosis, the relationship between lifetime cannabis use, emotional experience and social function over time has been understudied.Aims: This study sought to characterize the influence of lifetime cannabis use on emotional experience in prolonged psychosis and the influence of the interaction of cannabis use and emotional expression on social function.Methods: Emotional expression, experience of pleasure in the moment, anticipatory anhedonia and social functioning were measured concurrently using the Emotional Expressivity Scale (EES), Temporal Experience of Pleasure Scale (TEPS) and Social Functioning Scale (SFS), respectively. Participants were adults with schizophrenia either with (n = 35) or without (n = 36) a lifetime history of cannabis use.Results: Compared to non-using participants, individuals with a history of cannabis use expressed lesser abilities to express emotion, were less likely to expect pleasure and had poorer social function. Cannabis use moderated the relationship between anticipatory pleasure and prosocial activities.Conclusions: Lifetime cannabis use in schizophrenia may be associated with greater deficits in emotional expressivity, anticipation of pleasure and social function. Cannabis use may disrupt the relationship between anticipatory pleasure and social functioning.

Progress of negative symptoms over the initial 5 years of a first episode of psychosis

BACKGROUND

Specialized early intervention (EI) following a first episode of psychosis (FEP) are effective at reducing negative symptoms, although its trajectory warrants systematic assessment. However, findings are equivocal as to whether extended gains are made post 2 years of EI and whether there is additional benefit of extending EI for an additional 3 years.

METHODS

Data on 178 FEP patients, from a randomized controlled trial of a 3-year extension of EI service v. transfer to regular care following 2 years of EI service, were used for this report. Repeated measures analysis of variance were conducted separately for the initial 2 years of treatment in an EI service, and for the 3-year post-randomization to examine trajectories of negative symptoms over the two periods in the two arms of the study.

RESULTS

There were significant improvements in total negative symptoms over the first 2 years of EI F(4.612, 797.905) = 25.263, p &lt; 0.001 and in domains of 'expressivity' and 'motivation'. In the following 3 years, there were further significant improvements in negative symptoms F(4.318, 759.908) = 4.182, p = 0.002 with no difference between groups F(4.318, 759.908) = 1.073, p = 0.371. Changes in negative symptoms over the extension period were driven by expressivity F(4.01, 674.73) = 7.19, p &lt; 0.01, but not motivation F(6.58, 1112.18) = 0.95, p = 0.46.

CONCLUSION

Negative symptoms improve significantly over the first 2 years of EI. Subsequent amelioration was largely the result of expressivity. Motivation deficits remained stable. Extended EI offered no advantage over regular care post-randomization.

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.

Exploration of mental health of health students: Dental and medical formations promote anhedonia

OBJECTIVES

Health students usually report to experience stress during their formation. This is due to their exposure to patient's disease or death, to their learning of interpersonal relationships, and to the discovery of health practitioner's responsibility. Anhedonia represents a deficit in experiencing pleasure that is promoted by stressful living conditions. We hypothesized that health formations promote anhedonia. Our objectives have consisted in measuring anhedonia and analyzing its variation and heterogeneity among health students.

METHODS

The Temporal Experience of Pleasure Scale (TEPS) was used to assess anhedonia and its anticipatory and consummatory dimensions. TEPS corresponds to an 18-item questionnaire, the score of which is based on a 6-point Likert scale. Low score indicates a high anhedonia propensity. Score differences were analyzed by considering gender, curriculum and formation as independent variables. A cluster analysis was used to explore anhedonia heterogeneity among our sample.

RESULTS

We collected 1231 responses. Our data confirm French TEPS as a reliable tool for anhedonia evaluation in dental and medical students. Statistical analyses reveal a significant effect of gender (male>female), curriculum (clinical>preclinical) and formation (dental>medical) on anhedonia propensity. Cluster analysis highlights four sub-groups of students characterized by increasing anhedonia traits and by different gender, formation and curriculum proportions.

CONCLUSION

This work describes the first analysis of anhedonia manifestation during dental and medical studies in France. The consequences of our findings for the comprehension of dental and medical students' mental health during their formation are discussed.

An Examination of the Multi-Faceted Motivation System in Healthy Young Adults

Background: Amotivation is a prevalent symptom in schizophrenia (SZ) and depression (MDD), and is linked to poor functional outcomes in affected individuals. Conceptualizations of motivation have outlined a multi-faceted construct comprised of reward responsiveness, reward expectancy, reward valuation, effort valuation, and action selection/preference-based decision making. To date, findings from studies utilizing variable-centered approaches to examining isolated facets of motivation in SZ and MDD have been inconsistent. Thus, the present study adopted a person-centered approach, and comprehensively examined the reward system in a non-clinical sample in an attempt to explore potential subtypes of motivation impairments, while minimizing the effects of illness-related confounds. Methods: Ninety-six healthy undergraduate students were evaluated for amotivation, schizotypal traits, depressive symptoms, and cognition, and administered objective computerized tasks to measure the different facets of motivation. Cluster analysis was performed to explore subgroups of individuals based on similar motivation task performance. Additionally, correlational analyses were conducted in order to examine inter-relationships between motivation facets, and relations between clinical measures and facets of motivation. Results: Cluster analysis identified two subgroups of individuals with differential motivation performance profiles. Correlational analyses revealed that reward responsiveness was associated with amotivation, depressive symptoms, and negative schizotypy. Further, significant inter-correlations were found between reward responsiveness and reward expectancy, as well as between reward valuation and effort valuation. Conclusions: Our results mark important steps forward in understanding motivation in a non-clinical sample, and guide future dimensional and comprehensive analyses of the multi-faceted reward system. It remains to be seen whether these patterns of results will be similar in clinical populations such as SZ and MDD.

Investigating consummatory and anticipatory pleasure across motivation deficits in schizophrenia and healthy controls

Anhedonia has traditionally been considered a characteristic feature of schizophrenia, but the true nature of this deficit remains elusive. This study sought to investigate consummatory and anticipatory pleasure as it relates to motivation deficits. Eighty-four outpatients with schizophrenia and 81 healthy controls were administered the Temporal Experience of Pleasure Scale (TEPS), as well as a battery of clinical and cognitive assessments. Multivariate analyses of variance were used to examine the experience of pleasure as a function of diagnosis, and across levels of motivation deficits (i.e. low vs. moderate. vs. high) in schizophrenia. Hierarchical regression analyses were also conducted to evaluate the predictive value of amotivation in relation to the TEPS. There were no significant differences between schizophrenia and healthy control groups for either consummatory or anticipatory pleasure. Within the schizophrenia patients, only those with high levels of amotivation were significantly impaired in consummatory and anticipatory pleasure compared to low and moderate groups, and compared to healthy controls. Further, our results revealed that amotivation significantly predicts both consummatory and anticipatory pleasure, with no independent contribution of group. Utilizing study samples with a wide range of motivation deficits and incorporating objective paradigms may provide a more comprehensive understanding of hedonic deficits.

Implication of reward alterations in the expression of negative symptoms in 22q11.2 deletion syndrome: a behavioural and DTI study

BACKGROUND

Alterations of the reward system have been proposed as one of the core mechanisms underlying the expression of negative symptoms in schizophrenia. Specifically, deficits in specific reward components and white matter (WM) integrity of the reward system have been highlighted. The putative link between negative symptoms and the hedonic experience, or structural connectivity of the reward system has never been examined in the 22q11.2 deletion syndrome (22q11DS), a condition with increased risk for psychosis.

METHOD

Anticipatory and consummatory dimensions of pleasure were assessed in participants with 22q11DS (N = 54) and healthy controls (N = 55). In patients with 22q11DS, the association between pleasure scores and positive or negative symptoms was investigated. Furthermore, WM integrity of the accumbofrontal tract was quantified using diffusion tensor imaging (DTI). Associations between DTI measures, pleasure dimensions and negative symptoms were examined.

RESULTS

Patients with 22q11DS showed reduced anticipatory and consummatory pleasure compared to controls. Furthermore, anticipatory pleasure scores were negatively correlated to negative and positive symptoms in 22q11DS. WM microstructural changes of the accumbofrontal tract in terms of increased fractional anisotropy and reduced radial anisotropy were also identified in patients. However, no significant correlation between the DTI measures and pleasure dimensions or psychotic symptoms was observed.

CONCLUSIONS

This study revealed that participants with 22q11DS differed in their experience of pleasure compared to controls. The anticipatory pleasure component appears to be related to negative and positive symptom severity in patients. Alterations of WM integrity of the accumbofrontal tract seem to be related to myelination abnormalities in 22q11DS patients.

Experiential pleasure deficits in the prodrome: A study of emotional experiences in individuals at ultra-high risk for psychosis and recent-onset schizophrenia

BACKGROUND

Previous studies report deficits in noncurrent but not current pleasure experience in schizophrenia, but little is known about pleasure experiences of the prodrome. This study investigated noncurrent and current pleasure experiences and its relationship with neurocognitive function and self-esteem in ultra-high risk (UHR) for psychosis and recent-onset schizophrenia (ROSPR).

METHODS

Twenty-four UHR, 25 ROSPR and 42 normal controls completed the physical and social anhedonia scales for noncurrent emotional experience and the laboratory-based assessment of valence and arousal evoked by positive, neutral and negative emotional stimuli for current emotional experience. Relationships of current and noncurrent emotional experience, episodic memory and self-esteem were investigated.

RESULTS

For ROSPR, noncurrent pleasure, but not current pleasure evoked by positive stimuli, was diminished. Noncurrent anhedonia in ROSPR was related to episodic memory deficits and low self-esteem. In UHR subjects, both noncurrent pleasure and current pleasure to positive and neutral stimuli were diminished. Noncurrent anhedonia in UHR was not associated with episodic memory nor self-esteem. For arousal, ROSPR patients showed higher arousal than UHR subjects to positive stimuli.

CONCLUSIONS

Findings indicate the presence of experiential hedonic deficits during the prodrome phase. Diminished noncurrent pleasure reports exist in ROSPR, which seems to be associated with cognitive deficits and low self-concept. Future research is needed to probe into further underlying mechanisms.

A Review of Anticipatory Pleasure in Schizophrenia

PURPOSE OF REVIEW

Anhedonia, traditionally defined as a diminished capacity to experience pleasure, has long been considered a core symptom of schizophrenia. However, recent research calls into question whether individuals with schizophrenia are truly anhedonic, suggesting intact subjective and neurophysiological response to rewarding stimuli in-the-moment. Despite a presumably intact capacity to experience pleasure, people with schizophrenia still engage in fewer reward-seeking behaviors. This discrepancy has been explained as a dissociation between "liking" and "wanting", with dopaminergic and prefrontal influences on incentive salience leading hedonic responses to not effectively translate into motivated behavior. In the current review, the literature on a key aspect of the wanting deficit is reviewed, anticipatory pleasure.

RECENT FINDINGS

Results provide consistent evidence for impairment in some aspects of anticipatory pleasure (e.g., prospection, associative learning between reward predictive cues and outcomes), and inconsistent evidence for others (e.g., anticipatory affect and affective forecasting).

SUMMARY

Mechanisms underlying anticipatory pleasure abnormalities in schizophrenia are discussed and a new model of anticipatory pleasure deficits is proposed. Findings suggest that anticipatory pleasure may be a critical component of impairments in wanting that impact motivated behavior in schizophrenia.

Psychometric properties, validity, and reliability of the Temporal Experience of Pleasure Scale state version in an opioid-dependent sample

BACKGROUND

Individuals with substance dependence commonly experience anhedonia. Theories of anhedonia distinguish between anticipatory and consummatory reward deficits, with the Temporal Experience of Pleasure Scale (TEPS) the first self-report scale to separately measure these two constructs. Several psychometric studies have analysed the trait version of the TEPS, but the state version of the TEPS has not been previously validated.

METHODS

We examined the psychometric properties of the state version of the TEPS in 121 individuals with opiate dependence (81% Australian-born), to confirm its 2-factor structure and examine the internal consistency, convergent and divergent validity, test-retest reliability, and performance as a state measure.

RESULTS

Confirmation of the 2-factor solution required removal of two items and allowing correlation between residuals of three pairs of highly-similar items. The resulting consummatory and anticipatory scales correlated strongly with each other (r=.76), suggesting poor divergent validity between them. Nevertheless, the scale showed good internal consistency (Chronbach's α: anticipatory=.90; consummatory=.84; total=.92), convergent (TEPS total and Snaith-Hamilton Pleasure Scale r=-.76) and divergent validity (-.38<r<-.10 for measures of negative affect, anxiety, and alexithymia) with other psychological measures, and test-retest reliability. Changes in TEPS scores between baseline and 1-month follow-up correlated well with changes in scores on other state anhedonia and positive affect measures, suggesting that the TEPS state version functions well as a state measure.

CONCLUSION

In opioid-dependent participants, the TEPS state version appeared to have good validity as a measure of state anhedonia. However, evidence for its ability to distinguish between consummatory and anticipatory anhedonia was weak.

Subjective pleasure experience in patients with recent-onset schizophrenia: A preliminary report

Little is known about subjective pleasure experience in recent-onset schizophrenia, and its relationship with neurocognitive functions. Twenty-seven recent-onset schizophrenia people and 26 controls completed the TEPS and neuropsychological tests. The results showed that schizophrenia people self-reported less anticipatory pleasure than controls. Semantic verbal fluency was apparently correlated with anticipatory pleasure.

Trait Anticipatory Pleasure Predicts Effort Expenditure for Reward

Research in motivation and emotion has been increasingly influenced by the perspective that processes underpinning the motivated approach of rewarding goals are distinct from those underpinning enjoyment during reward consummation. This distinction recently inspired the construction of the Temporal Experience of Pleasure Scale (TEPS), a self-report measure that distinguishes trait anticipatory pleasure (pre-reward feelings of desire) from consummatory pleasure (feelings of enjoyment and gratification upon reward attainment). In a university community sample (N = 97), we examined the TEPS subscales as predictors of (1) the willingness to expend effort for monetary rewards, and (2) affective responses to a pleasant mood induction procedure. Results showed that both anticipatory pleasure and a well-known trait measure of reward motivation predicted effort-expenditure for rewards when the probability of being rewarded was relatively low. Against expectations, consummatory pleasure was unrelated to induced pleasant affect. Taken together, our findings provide support for the validity of the TEPS anticipatory pleasure scale, but not the consummatory pleasure scale.

Deficits in anticipatory but not consummatory pleasure in people with recent-onset schizophrenia spectrum disorders

The majority of studies examining self-reported anticipatory and consummatory pleasure in schizophrenia, as measured on the Temporal Experience of Pleasure Scale (TEPS), have been conducted on chronically ill people with the disorder. In this study, people with a recent-onset schizophrenia spectrum diagnosis (first psychotic episode within one year of study participation) (n=88) and people without a schizophrenia spectrum diagnosis (n=66) were administered the TEPS. People with a schizophrenia spectrum diagnosis reported significantly lower scores of anticipatory, but not consummatory, pleasure on the TEPS compared to the control group. TEPS anticipatory pleasure scores were also significantly, negatively correlated with negative symptoms, but neither TEPS anticipatory nor consummatory pleasure scores were significantly correlated with functioning measures. Our results replicate previous findings with chronically ill people with schizophrenia on the TEPS.

Do reward-processing deficits in schizophrenia-spectrum disorders promote cannabis use? An investigation of physiological response to natural rewards and drug cues

BACKGROUND

Dysfunctional reward processing is present in individuals with schizophrenia-spectrum disorders (SSD) and may confer vulnerability to addiction. Our objective was to identify a deficit in patients with SSD on response to rewarding stimuli and determine whether this deficit predicts cannabis use.

METHODS

We divided a group of patients with SSD and nonpsychotic controls into cannabis users and nonusers. Response to emotional and cannabis-associated visual stimuli was assessed using self-report, event-related potentials (using the late positive potential [LPP]), facial electromyography and skin-conductance response.

RESULTS

Our sample comprised 35 patients with SSD and 35 nonpsychotic controls. Compared with controls, the patients with SSD showed blunted LPP response to pleasant stimuli (p = 0.003). Across measures, cannabis-using controls showed greater response to pleasant stimuli than to cannabis stimuli whereas cannabis-using patients showed little bias toward pleasant stimuli. Reduced LPP response to pleasant stimuli was predictive of more frequent subsequent cannabis use (β = -0.24, p = 0.034).

LIMITATIONS

It is not clear if the deficit associated with cannabis use is specific to rewarding stimuli or nonspecific to any kind of emotionally salient stimuli.

CONCLUSION

The LPP captures a reward-processing deficit in patients with SSD and shows potential as a biomarker for identifying patients at risk of heavy cannabis use.

Do motivation deficits in schizophrenia-spectrum disorders promote cannabis use? An investigation of behavioural response to natural rewards and drug cues

Deficits in incentive motivation are often present in both Schizophrenia Spectrum Disorders (SSD) and substance-use disorders. The current study aims to test whether the presence of such deficits confers vulnerability to cannabis use in individuals with SSD. SSD patients (n=35) and healthy controls (n=35) were each divided into a group with (n=20) and a group without (n=15) current cannabis use disorder. Subjects performed a behavioural task designed for schizophrenia patients in which they could seek exposure to pleasant and cannabis visual stimuli on the basis of internal representations of these stimuli. Intensity of cannabis use was assessed by self-report. SSD patients were significantly less likely than controls to exert effort to try to re-view pleasant stimuli but were not significantly less likely to work to avoid unpleasant stimuli. Lack of response to re-view pleasant stimuli significantly predicted higher subsequent cannabis self-administration in patients but not controls, after controlling for degree of prior exposure to cannabis. Deficits in incentive motivation may be an aspect of SSD which promotes cannabis use in this population.

Persistent negative symptoms in schizophrenia: survey of Canadian psychiatrists

A sample of 206 Canadian psychiatrists who routinely treat patients with psychotic disorders were randomly surveyed regarding their knowledge and practice in relation to persistent negative symptoms of schizophrenia. Large majorities reported observing a high prevalence of persistent negative symptoms that do not respond to available treatments (83%), have a profound impact on functional outcomes (96.5%) and contribute to family burden. Almost half the sample (43%) recognised the importance of formally assessing persistent symptoms and nearly a third (30%) indicated that this was a part of their usual practice. These survey results correspond with recent consensus and highlight the importance and challenge of treating persistent negative symptoms in schizophrenia.