Anhedonia as a phenotype for the Val158Met COMT polymorphism in relatives of patients with schizophrenia

Understanding Anhedonia from a Genomic Perspective

Anhedonia, or the decreased ability to experience pleasure, is a cardinal symptom of major depression that commonly occurs within other forms of psychopathology. Supportive of long-held theory that anhedonia represents a genetically influenced vulnerability marker for depression, evidence from twin studies suggests that it is moderately-largely heritable. However, the genomic sources of this heritability are just beginning to be understood. In this review, we survey what is known about the genomic architecture underlying anhedonia and related constructs. We briefly review twin and initial candidate gene studies before focusing on genome-wide association study (GWAS) and polygenic efforts. As large samples are needed to reliably detect the small effects that typically characterize common genetic variants, the study of anhedonia and related phenotypes conflicts with current genomic research requirements and frameworks that prioritize sample size over precise phenotyping. This has resulted in few and underpowered studies of anhedonia-related constructs that have largely failed to reliably identify individual variants. Nonetheless, the polygenic architecture of anhedonia-related constructs identified in these studies has genetic overlap with depression and schizophrenia as well as related brain structure (e.g., striatal volume), providing important clues to etiology that may usefully guide refinement in nosology. As we await the accumulation of larger samples for more well-powered GWAS of reward-related constructs, novel analytic techniques that leverage GWAS summary statistics (e.g., genomic structural equation modeling) may currently be used to help characterize how the genomic architecture of anhedonia is shared and distinct from that underlying other constructs (e.g., depression, neuroticism, anxiety).

Link between childhood trauma and psychotic-like experiences in non-affected siblings of schizophrenia patients: A case-control study

AIM

Prior research has consistently demonstrated a relationship between childhood trauma (CT) exposure and an increased risk of developing psychotic-like experiences (PLE) and disorders. Studying the link between CT and PLE in non-clinical populations with or without genetic risk factors could help elucidate the etiopathogeny of psychotic disorders, by removing the effect of confounding variables related to psychotic-spectrum illnesses.

METHOD

A total of 60 non-affected siblings of patients with schizophrenia and 75 controls (aged 18-35 years) participated in a cross-sectional survey. The Positive Subscale of Community Assessment of Psychotic Experiences (CAPE) and the CT Questionnaire were used.

RESULTS

We found no significant difference with regard to positive dimension of the CAPE between the two groups. Siblings have reported higher CAPE negative symptoms scores than controls (27.9 vs 24.2; P = .015), and more emotional abuse and physical neglect during childhood than controls. After controlling for demographic and psychosocial variables, sexual abuse, emotional neglect and physical neglect were positively related to positive psychotic symptoms in the control group, whereas no dimension of CT has been linked to these symptoms in the sibling group.

CONCLUSION

The link between CT and psychosis seems to be complex, not only dependent on genetic vulnerability or early environmental factors shared by siblings of patients with psychotic disorders, but also several other confounding factors, including other psychopathological symptoms. Prevention strategies for individuals at genetic risk of psychosis should pay particular attention to CT as a potential predictor of sub-clinical depression and psychosis.

The Associations between COMT and MAO-B Genetic Variants with Negative Symptoms in Patients with Schizophrenia

Negative symptoms of schizophrenia, including anhedonia, represent a heavy burden on patients and their relatives. These symptoms are associated with cortical hypodopamynergia and impaired striatal dopamine release in response to reward stimuli. Catechol-O-methyltransferase (COMT) and monoamine oxidase type B (MAO-B) degrade dopamine and affect its neurotransmission. The study determined the association between COMT rs4680 and rs4818, MAO-B rs1799836 and rs6651806 polymorphisms, the severity of negative symptoms, and physical and social anhedonia in schizophrenia. Sex-dependent associations were detected in a research sample of 302 patients with schizophrenia. In female patients with schizophrenia, the presence of the G allele or GG genotype of COMT rs4680 and rs4818, as well as GG haplotype rs4818-rs4680, which were all related to higher COMT activity, was associated with an increase in several dimensions of negative symptoms and anhedonia. In male patients with schizophrenia, carriers of the MAO-B rs1799836 A allele, presumably associated with higher MAO-B activity, had a higher severity of alogia, while carriers of the A allele of the MAO-B rs6651806 had a higher severity of negative symptoms. These findings suggest that higher dopamine degradation, associated with COMT and MAO-B genetic variants, is associated with a sex-specific increase in the severity of negative symptoms in schizophrenia patients.

Personality Traits in Individuals with the Dual Diagnosis of Psychosis and Substance Use Disorders: A Comprehensive Review and Meta-Analysis

Substance abuse comorbidity is highly prevalent and is linked to detrimental outcomes in individuals with psychotic disorder, but the role of personality traits as the underlying mechanism is being increasingly underscored. This study aimed to profile temperamental risks of comorbid substance use disorder in psychotic disorders by performing meta-analyses on personality trait differences between psychotic disorders with comorbidity (dual diagnosis; DD) and without it (psychotic disorders; PSD). Methods: A systematic review of English articles using PubMed, MEDLINE, Scopus, Google Scholar, and ProQuest Dissertation and Theses. Only original empirical studies including participants with diagnosis of psychotic disorders based on structured diagnostic interviews, with and without substance use disorder evaluated with reliable and valid tests were included. Articles were independently extracted by two authors using predefined data fields, including study quality indicators. All pooled analyses were based on random-effect models. Thirteen studies (N = 885) met our inclusion criteria. All effect-size estimates were calculated based on means and standard deviations of included measures. Separate effect size estimates were obtained for four traits in the UPPS model (negative urgency, low premeditation, low perseverance, sensation seeking), four traits in the HS model (unconscientious disinhibition, negative affect, disagreeable disinhibition, positive affect) and trait anhedonia. Results: Negative urgency (four studies with 262 participants; ES = 0.59; 95% confidence interval [CI] [0.34, 0.84]), low premeditation (five studies with 349 participants; ES = 0.60; 95% CI [0.39, 0.80]), sensation seeking (seven studies with 550 participants; ES = 0.63; 95% CI [0.17, 1.09]) and unconscientious disinhibition (five studies with 291 participants; ES = 0.36; 95% CI [0.13, 0.59]) were elevated in DD than PSD. Heterogeneity of sensation seeking was significant (I² = 86.2%). Conclusions: The findings of the current meta-analysis highlight a unique profile of impulsive and externalizing trait personality domains pertaining to DD. The study emphasizes the importance of emotion regulation interventions targeting impulsivity or negative affect (i.e. negative urgency, low premeditation) in substance abuse comorbidity patients.

Molecular Genetic Risk for Psychosis Is Associated With Psychosis Risk Symptoms in a Population-Based UK Cohort: Findings From Generation Scotland

OBJECTIVE

Subthreshold psychosis risk symptoms in the general population may be associated with molecular genetic risk for psychosis. This study sought to optimize the association of risk symptoms with genetic risk for psychosis in a large population-based cohort in the UK (N = 9104 individuals 18-65 years of age) by properly accounting for population stratification, factor structure, and sex.

METHODS

The newly expanded Generation Scotland: Scottish Family Health Study includes 5391 females and 3713 males with age M [SD] = 45.2 [13] with both risk symptom data and genetic data. Subthreshold psychosis symptoms were measured using the Schizotypal Personality Questionnaire-Brief (SPQ-B) and calculation of polygenic risk for schizophrenia was based on 11 425 349 imputed common genetic variants passing quality control. Follow-up examination of other genetic risks included attention-deficit hyperactivity disorder (ADHD), autism, bipolar disorder, major depression, and neuroticism.

RESULTS

Empirically derived symptom factor scores reflected interpersonal/negative symptoms and were positively associated with polygenic risk for schizophrenia. This signal was largely sex specific and limited to males. Across both sexes, scores were positively associated with neuroticism and major depressive disorder.

CONCLUSIONS

A data-driven phenotypic analysis enabled detection of association with genetic risk for schizophrenia in a population-based sample. Multiple polygenic risk signals and important sex differences suggest that genetic data may be useful in improving future phenotypic risk assessment.

Neural anomalies during vigilance in schizophrenia: Diagnostic specificity and genetic associations

Impaired vigilance is a core cognitive deficit in schizophrenia and may serve as an endophenotype (i.e., mark genetic liability). We used a continuous performance task with perceptually degraded stimuli in schizophrenia patients (N = 48), bipolar disorder patients (N = 26), first-degree biological relatives of schizophrenia patients (N = 55) and bipolar disorder patients (N = 28), as well as healthy controls (N = 68) to clarify whether previously reported vigilance deficits and abnormal neural functions were indicative of genetic liability for schizophrenia as opposed to a generalized liability for severe psychopathology. We also examined variation in the Catechol-O-methyltransferase gene to evaluate whether brain responses were related to genetic variation associated with higher-order cognition. Relatives of schizophrenia patients had an increased rate of misidentification of nontarget stimuli as targets when they were perceptually similar, suggestive of difficulties with contour perception. Larger early visual responses (i.e., N1) were associated with better task performance in patients with schizophrenia consistent with enhanced N1 responses reflecting beneficial neural compensation. Additionally, reduced N2 augmentation to target stimuli was specific to schizophrenia. Both patients with schizophrenia and first-degree relatives displayed reduced late cognitive responses (P3b) that predicted worse performance. First-degree relatives of bipolar patients exhibited performance deficits, and displayed aberrant neural responses that were milder than individuals with liability for schizophrenia and dependent on sex. Variation in the Catechol-O-methyltransferase gene was differentially associated with P3b in schizophrenia and bipolar groups. Poor vigilance in schizophrenia is specifically predicted by a failure to enhance early visual responses, weak augmentation of mid-latency brain responses to targets, and limited engagement of late cognitive responses that may be tied to genetic variation associated with prefrontal dopaminergic availability. Experimental results illustrate specific neural functions that distinguish schizophrenia from bipolar disorder and provides evidence for a putative endophenotype that differentiates genetic liability for schizophrenia from severe mental illness more broadly.

Exploring the Relationship of Transdiagnostic Mood and Psychosis Symptom Domains with Motor Dysfunction

BACKGROUND

A number of motor abnormalities have been reported in psychotic disorders, including dyskinesia and psychomotor slowing. There is also evidence for many of the same motor abnormalities in biological first-degree relatives and accruing evidence for motor abnormalities in bipolar disorder. In addition to motor dysfunction, there are also shared symptom domains amongst these populations.

OBJECTIVES

We explored the associations of (1) current and lifetime psychosis and mood symptom domains and (2) domains of psychosis proneness with various domains of motor function in a transdiagnostic sample (n = 149).

METHOD

Individuals with schizophrenia, schizoaffective disorder, or bipolar disorder, biological first-degree relatives of individuals with a psychotic disorder, and controls completed measures of psychomotor speed and movement fluidity, and neural activity related to motor preparation (stimulus-locked lateralized readiness potential, S-LRP) and execution (response-locked LRP) was assessed using EEG. All participants completed the Brief Psychiatric Rating Scale; patients were additionally assessed for lifetime psychosis and mood episode symptoms, and relatives and controls completed the Chapman psychosis proneness scales.

RESULTS

Multiple regression revealed levels of current negative symptoms and mania were significantly positively associated with psychomotor slowing even after accounting for current antipsychotic medication dosage and duration of illness. S-LRP onset latency was significantly positively associated with magical ideation.

CONCLUSION

Domains of motor function are associated with various mood and psychosis symptom domains in a transdiagnostic sample, which may provide insight into brain abnormalities relevant to the expression of symptoms across disorders.

The remediation effects of working memory training in schizophrenia patients with prominent negative symptoms

Introduction: Negative symptoms, particularly amotivation and anhedonia, are important predictors of poor functional outcome in patients with schizophrenia. There has been interest in the efficacy and mechanism of non-pharmacological interventions to alleviate these symptoms. The present study aimed to examine the remediation effect of working memory (WM) training in patients with schizophrenia with prominent negative symptoms.Methods: Thirty-one schizophrenia patients with prominent negative symptoms were recruited and assigned to either a WM training group or a treatment-as-usual (TAU) control group. The WM training group underwent 20 sessions of training using the dual n-back task over one month. A functional neuroimaging paradigm of the Affective Incentive Delay (AID) task was administered before and after the training intervention to evaluate the remediation effect of the intervention.Results: Our results showed that the WM training group demonstrated significant improvement in the WM training task and inattention symptoms. Compared with the TAU group, increased brain activations were observed at the right insula and the right frontal sub-gyral after WM training in the training group.Conclusions: These findings support the efficacy of WM training in ameliorating hedonic dysfunction in schizophrenia patients with prominent negative symptoms.

A Transdiagnostic Perspective on Social Anhedonia

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

Instrument-based assessment of motor function yields no evidence of dyskinesia in adult first-degree biological relatives of individuals with schizophrenia and schizoaffective disorder

There is accruing evidence of spontaneous dyskinesia in individuals with schizophrenia that is independent of medication exposure. Dyskinetic motor behavior is also present in individuals who are at high risk of schizophrenia and appears to have prognostic value for the development of psychosis. Nonetheless, it remains unclear whether dyskinesia is present in first-degree relatives of individuals with schizophrenia and thus associated with genetic liability for schizophrenia (i.e., an endophenotype), or whether the motor abnormality is a biomarker specific to the disease state spectrum. There is also limited information about links between dyskinesia and clinically relevant phenomena such as symptoms and cognition. Because dyskinesia marking genetic liability is likely to be subtle, we used sensitive instrument-based measurement of handwriting fluency to quantify dyskinesia in medicated individuals with schizophrenia or schizoaffective disorder, unaffected first-degree biological relatives of individuals with schizophrenia and schizoaffective disorder, and control participants. Results indicated that medicated individuals with schizophrenia or schizoaffective disorder exhibited more dyskinesia than both relatives and controls, with no difference between relatives and controls. Dyskinesia in individuals with schizophrenia or schizoaffective disorder was unrelated to current antipsychotic medication dosage, but associated with worse working memory function and greater positive formal thought disorder. These results provide evidence that dyskinesia is not associated with unexpressed genetic liability for schizophrenia.

Polygenic prediction of the phenome, across ancestry, in emerging adulthood

BACKGROUND

Identifying genetic relationships between complex traits in emerging adulthood can provide useful etiological insights into risk for psychopathology. College-age individuals are under-represented in genomic analyses thus far, and the majority of work has focused on the clinical disorder or cognitive abilities rather than normal-range behavioral outcomes.

METHODS

This study examined a sample of emerging adults 18-22 years of age (N = 5947) to construct an atlas of polygenic risk for 33 traits predicting relevant phenotypic outcomes. Twenty-eight hypotheses were tested based on the previous literature on samples of European ancestry, and the availability of rich assessment data allowed for polygenic predictions across 55 psychological and medical phenotypes.

RESULTS

Polygenic risk for schizophrenia (SZ) in emerging adults predicted anxiety, depression, nicotine use, trauma, and family history of psychological disorders. Polygenic risk for neuroticism predicted anxiety, depression, phobia, panic, neuroticism, and was correlated with polygenic risk for cardiovascular disease.

CONCLUSIONS

These results demonstrate the extensive impact of genetic risk for SZ, neuroticism, and major depression on a range of health outcomes in early adulthood. Minimal cross-ancestry replication of these phenomic patterns of polygenic influence underscores the need for more genome-wide association studies of non-European populations.

Schizotypy-Independent and Schizotypy-Modulated Cognitive Impairments in Unaffected First-Degree Relatives of Schizophrenia-spectrum Patients

Objective

The aim of the study was to compare the neurocognitive profile of unaffected first-degree relatives of schizophrenia patients with control individuals, controlling for different schizotypal traits.

Method

One hundred and fifteen adult unaffected first-degree relatives of schizophrenia-spectrum patients and 122 controls were tested for schizotypy with the Schizotypal Personality Questionnaire. They also underwent a thorough neurocognitive assessment with a range of tasks covering several aspects of executive functioning. Between-group differences in cognition were examined first with multivariate analysis of variance and then with a series of multivariate analyses of covariance, including the schizotypal dimensions as covariates.

Results

The relatives had higher scores on all schizotypal dimensions compared with controls and poorer planning, problem solving, strategy formation and working memory, irrespective of schizotypal traits. They also scored lower in executive working memory and verbal fluency. The difference in executive working memory was sensitive to the effects of paranoid and negative schizotypy (both dimensions abolished the between-group difference) whereas the difference in verbal fluency was sensitive only to the effects of paranoid schizotypy. Neither cognitive-perceptual nor disorganized schizotypy accounted for any differences in neurocognition between relatives and the controls.

Conclusions

Impairments in planning, problem solving, strategy formation and working memory are "core" impairments in the schizophrenia-spectrum, possibly due to high heritability effects in these functions. Impairments in executive working memory and verbal fluency are associated with paranoid and negative schizotypy, possibly due to alterations in a common fronto-temporo-parietal neural network.

Schizotypal and affective traits in the offspring of antenatally depressed mothers - Relationship to family history of psychosis in the Northern Finland 1966 Birth Cohort

BACKGROUND

Maternal depression is relatively common during pregnancy. However, follow-ups of the adult offspring of antenatally depressed mothers are scarce. Previously we found the risk of schizophrenia to be higher in the adult offspring with antenatally depressed mothers and parents with psychosis than in subjects with only one or neither of these risk factors. The aim was to study whether the risk of schizotypal or affective traits differ among adult offspring with antenatally depressed mothers with or without a parental history of psychosis when compared with offspring without antenatally depressed mothers and without parental psychosis.

METHODS

In the general population-based Northern Finland 1966 Birth Cohort (NFBC 1966), the mothers of the cohort members were asked at mid-gestation whether they felt depressed. Parental psychosis (Familial Risk, FR) was detected using the Finnish Care Register for Health Care. In the 31-year field study, seven psychometric questionnaires surveyed schizotypal and affective traits in the offspring. The final sample included 4928 individuals (2203 males).

RESULTS

There were no statistically significant differences in mean scores on the schizotypal and affective scales between offspring with and without antenatally depressed mothers, or between subjects with and without parental psychosis. The scores were not highest in the subjects with both maternal antenatal depressed mood and FR.

CONCLUSION

Surprisingly, maternal depressed mood during pregnancy was unlikely to increase the risk of schizotypy or affective traits in adult offspring, and not even with parental psychosis (FR) in this general population-based birth cohort with about 5000 subjects.

COMT Val(158) Met genotype is associated with reward learning: a replication study and meta-analysis

Identifying mechanisms through which individual differences in reward learning emerge offers an opportunity to understand both a fundamental form of adaptive responding as well as etiological pathways through which aberrant reward learning may contribute to maladaptive behaviors and psychopathology. One candidate mechanism through which individual differences in reward learning may emerge is variability in dopaminergic reinforcement signaling. A common functional polymorphism within the catechol-O-methyl transferase gene (COMT; rs4680, Val(158) Met) has been linked to reward learning, where homozygosity for the Met allele (linked to heightened prefrontal dopamine function and decreased dopamine synthesis in the midbrain) has been associated with relatively increased reward learning. Here, we used a probabilistic reward learning task to asses response bias, a behavioral form of reward learning, across three separate samples that were combined for analyses (age: 21.80 ± 3.95; n = 392; 268 female; European-American: n = 208). We replicate prior reports that COMT rs4680 Met allele homozygosity is associated with increased reward learning in European-American participants (β = 0.20, t = 2.75, P < 0.01; ΔR(2) = 0.04). Moreover, a meta-analysis of 4 studies, including the current one, confirmed the association between COMT rs4680 genotype and reward learning (95% CI -0.11 to -0.03; z = 3.2; P < 0.01). These results suggest that variability in dopamine signaling associated with COMT rs4680 influences individual differences in reward which may potentially contribute to psychopathology characterized by reward dysfunction.

The effects of working memory training on enhancing hedonic processing to affective rewards in individuals with high social anhedonia

Anhedonia is a core feature of the negative symptoms of schizophrenia and is less responsive to antipsychotic medication. Little is known whether anhedonia could be alleviated by cognitive training. The present study aimed to examine whether hedonic deficits observed in individuals with high social anhedonia could be reduced by working memory (WM) training. Thirty-four individuals with high social anhedonia were randomly assigned to either a WM training group or a control group. The WM training group received 20 sessions of dual n-back task training for four weeks. The affective incentive delay task was administered in all participants before the training and one month later. The results showed that individuals who received the WM training showed significant improvement in WM performance (F(19, 304)=55.80, p<0.001) and they also showed significant improvement in approach sensitivity to rewards (p=0.004). These preliminary findings suggest that hedonic processing could be improved through WM training in individuals with high social anhedonia. These results may have important implications for the development of non-pharmacological interventions to alleviate anhedonia in patients with schizophrenia.

The neural transfer effect of working memory training to enhance hedonic processing in individuals with social anhedonia

Anhedonia, the diminished ability to experience pleasure, is a challenging negative symptom in patients with schizophrenia and can be observed in at-risk individuals with schizotypy. Deficits in hedonic processing have been postulated to be related to decreased motivation to engage in potentially rewarding events. It remains unclear whether non-pharmacological interventions, such as cognitive training, could improve anhedonia. The present study aimed to examine the neural mechanism for alleviating hedonic deficits with working memory (WM) training in individuals with social anhedonia. Fifteen individuals with social anhedonia were recruited and received 20 sessions of training on a dual n-back task, five sessions a week. Functional imaging paradigms of the Monetary Incentive Delay (MID) and the Affective Incentive Delay (AID) tasks were administered both before and after the training to evaluate the neural transfer effects on hedonic processing ability. Enhanced brain activations related to anticipation were observed at the anterior cingulate cortex, the left dorsal striatum and the left precuneus with the AID task, and at the dorsolateral prefrontal cortex and the supramarginal gyrus with the MID task. The present findings support that WM training may improve monetary-based and affective-based hedonic processing in individuals with social anhedonia.

Cross-Disorder Psychiatric Genomics

PURPOSE OF REVIEW

The following review provides some description of the movement in cross-disorder psychiatric genomics toward addressing both comorbidity and polygenicity.

RECENT FINDINGS

We attempt to show how dimensional approaches to the phenotype have led to further addressing the problem of comorbidity of psychiatric diagnoses. And we also attempt to show how a dimensional approach to the genome, with different statistical methods from traditional genome-wide association analyses, has begun to resolve the problem of massive polygenicity.

SUMMARY

Cross-disorder research, of any area in psychiatry, arguably has the most potential to inform clinical diagnosis, early detection and prevention strategies, and pharmacological treatment research. Future research might leverage what we now know to inform developmental studies of risk and resilience.

Evidence of structural invariance across three groups of Meehlian schizotypes

According to Meehl’s model of schizotypy, there is a latent personality organization associated with the diathesis for schizophrenia that can be identified in several ways. We sought to examine the structural invariance of four Chapman psychosis–proneness scales (CPPS) across three groups of putative schizotypes, namely, clinically-, biologically-, and psychometrically-identified schizotypes. We examined the factor structure of the Perceptual Aberration (PER), Magical Ideation (MIS), Revised Social Anhedonia (RSAS), and Revised Physical Anhedonia (RPAS) scales in 196 schizophrenia patients, 197 non-psychotic first-degree relatives, and 1,724 non-clinical young adults. The confirmatory factor analyses indicated that the best-fitting model was one in which there is a two-factor model with negative schizotypy (RSAS and RPAS) and positive schizotypy (PER and MIS). All three samples fit the model well, with Comparative Fit Indices>0.95 and Tucker Lewis Indices>0.90. The root mean square error of approximations were all small (P values⩽0.01). We also observed that for both anhedonia scales, the groups’ mean scale scores varied in the hypothesized direction, as predicted by Meehl’s model of schizotypy. All three Chinese samples, namely, the patients (clinical schizotypes), relatives (biologically-identified schizotypes), and non-clinical young adults (containing psychometrically-identified schizotypes) showed the same factorial structure. This finding supports the suitability of the CPPS for cross-cultural and/or genetic investigations of schizotypy.

Neurobiological background of negative symptoms

Studies investigating neurobiological bases of negative symptoms of schizophrenia failed to provide consistent findings, possibly due to the heterogeneity of this psychopathological construct. We tried to review the findings published to date investigating neurobiological abnormalities after reducing the heterogeneity of the negative symptoms construct. The literature in electronic databases as well as citations and major articles are reviewed with respect to the phenomenology, pathology, genetics and neurobiology of schizophrenia. We searched PubMed with the keywords "negative symptoms," "deficit schizophrenia," "persistent negative symptoms," "neurotransmissions," "neuroimaging" and "genetic." Additional articles were identified by manually checking the reference lists of the relevant publications. Publications in English were considered, and unpublished studies, conference abstracts and poster presentations were not included. Structural and functional imaging studies addressed the issue of neurobiological background of negative symptoms from several perspectives (considering them as a unitary construct, focusing on primary and/or persistent negative symptoms and, more recently, clustering them into factors), but produced discrepant findings. The examined studies provided evidence suggesting that even primary and persistent negative symptoms include different psychopathological constructs, probably reflecting the dysfunction of different neurobiological substrates. Furthermore, they suggest that complex alterations in multiple neurotransmitter systems and genetic variants might influence the expression of negative symptoms in schizophrenia. On the whole, the reviewed findings, representing the distillation of a large body of disparate data, suggest that further deconstruction of negative symptomatology into more elementary components is needed to gain insight into underlying neurobiological mechanisms.

Replication study implicates COMT val158met polymorphism as a modulator of probabilistic reward learning

Previous studies suggest that a single nucleotide polymorphism in the catechol-O-methyltransferase (COMT) gene (val158met) may modulate reward-guided decision making in healthy individuals. The polymorphism affects dopamine catabolism and thus modulates prefrontal dopamine levels, which may lead to variation in individual responses to risk and reward. We previously showed, using tasks that index reward responsiveness (measured by responses bias towards reinforced stimuli) and risk taking (measured by the Balloon Analogue Risk Task), that COMT met homozygotes had increased reward responsiveness and, thus, an increased propensity to seek reward. In this study, we sought to replicate these effects in a larger, independent cohort of Caucasian UK university students and staff with similar demographic characteristics (n = 101; 54 females, mean age: 22.2 years). Similarly to our previous study, we observed a significant trial × COMT genotype interaction (P = 0.047; η(2) = 0.052), which was driven by a significant effect of COMT on the incremental acquisition of response bias [response bias at block 3 - block 1 (met/met > val/val: P = 0.028) and block 3 - block 2 (met/met > val/val: P = 0.007)], suggesting that COMT met homozygotes demonstrated higher levels of reward responsiveness by the end of the task. However, we failed to see main effects of COMT genotype on overall response bias or risk-seeking behaviour. These results provide additional evidence that prefrontal dopaminergic variation may have a role in reward responsiveness, but not risk-seeking behaviour. Our findings may have implications for neuropsychiatric disorders characterized by clinical deficits in reward processing such as anhedonia.

The role of schizotypy in the study of the etiology of schizophrenia spectrum disorders

Schizotypy provides a useful construct for understanding the development of schizophrenia spectrum disorders. As research on the epidemiology of psychotic symptoms and clinical risk for psychosis has expanded, conceptual challenges have emerged to comprehend the nature and borders of the space comprised between personality variation and psychosis. Schizotypy is considered in light of these more recent constructs. It is suggested that rather than being superseded by them due to their higher specificity and predictive power for transition to psychosis, schizotypy integrates them as it constitutes a dynamic continuum ranging from personality to psychosis. The advantages of schizotypy for studying schizophrenia etiology are discussed (eg, it facilitates a developmental approach and the identification of causal, resilience, and compensating factors and offers a multidimensional structure that captures etiological heterogeneity). An overview of putative genetic, biological, and psychosocial risk factors is presented, focusing on communalities and differences between schizotypy and schizophrenia spectrum disorders. The found notable overlap supports etiological continuity, and, simultaneously, differential findings appear that are critical to understanding resilience to schizophrenia. For example, discrepant findings in genetic studies might be interpreted as suggestive of sets of independent genetic factors playing a differential role in schizotypy and schizophrenia: some would influence variation specifically on schizotypy dimensions (ie, high vs low schizotypy, thereby increasing proneness to psychosis), some would confer unspecific liability to disease by impacting neural properties and susceptibility to environmental factors (ie, high vs low resilience to disorder) and some might contribute to disease-specific characteristics. Finally, schizotypy's promise for studying gene-environment interactions is considered.

COMT-by-sex interaction effect on psychosis proneness

Schizotypy phenotypes in the general population share etiopathogenic mechanisms and risk factors with schizophrenia, supporting the notion of psychosis as a continuum ranging from nonclinical to clinical deviance. Catechol-O-methyltransferase (COMT) is a candidate susceptibility gene for schizophrenia that is involved in the regulation of dopamine in the prefrontal cortex. Several recent studies have reported a sex difference in the impact of COMT genotype on psychiatric and cognitive phenotypes and personality traits. The present study investigated the association of COMT Val158Met (rs4680) with psychometric positive and negative schizotypy and psychotic experiences in a sample of 808 nonclinical young adults. The main finding was that sex moderates the association of COMT genotype with the negative dimension of both schizotypy and psychotic experiences. Male subjects carrying the Val allele tended to score higher on the negative dimension of both trait and symptom-like measures. The results from the present study are consistent with recent work suggesting an association between negative schizotypy and diminished prefrontal dopamine availability. They support the idea that a biological differentiation underlies the positive and negative schizotypy dimensions. Additionally, these findings contribute to the growing literature on sex-specific effects of COMT on the predisposition to psychiatric disorders and personality traits.

Self-reported affective traits and current affective experiences of biological relatives of people with schizophrenia

Schizophrenia is characterized by self-reported trait anhedonia but intact hedonic responses during laboratory experiments. Affective traits of first-degree biological relatives may be similar to those of people with schizophrenia, and measures of hedonic response in relatives may be free of antipsychotic medication or cognitive confounds. Relatives also self-report increased anhedonia, yet it is unclear whether, like in patients, this anhedonia is paired with largely intact hedonic self-report. In this study, first-degree relatives of people with schizophrenia (n=33) and nonpsychiatric controls (n=25) completed a wide range of questionnaires and tasks assessing social and physical anhedonia, positive and negative affective experience, and anticipatory and consummatory pleasure. Valence, intensity, frequency, and the arousal of current emotion were assessed. Extraversion and current positive and negative affective state were also examined in relation to self-reported social anhedonia. Relatives evidenced the same disjunction of increased self-reported anhedonia and intact affective response observed in people with schizophrenia. Group differences in anhedonia were not better accounted for by decreased current positive affect, increased current negative affect, or decreased extraversion in relatives. Results suggest that, like people with schizophrenia, first-degree relatives report intact hedonic response on both questionnaire and laboratory measures despite significant elevations in self-reported social anhedonia.

The independence of schizotypy from affective temperaments--a combined confirmatory factor analysis of SPQ and the short TEMPS-A

Sparse evidence of a co-aggregation of the risk of schizophrenia and bipolar disorder provides support for a shared but nonspecific genetic etiology of bipolar disorder and schizophrenia. Temperaments are conceptualized as trait sub-syndromic conditions of major pathologies. This study set out to test the hypothesis of a continuum between schizotypy and affective temperaments versus the alternative hypothesis of their independence based on a cross-sectional, survey design involving 649 (males: 47%) college students. The short 39-item TEMPS-A and the SPQ were used as measures of the affective temperaments and of schizotypy, respectively. Confirmatory factor analyses were applied to a unidimensional model, to a standard correlate traits model, to second-order representations of a common latent structure, and to a bifactor model. Confirmatory bifactor modeling provided evidence against a complete independence of the dimensions subsumed by the affective and the schizotypal traits. The best solution distinguished between two sub-domains grouping positive symptoms and negative symptoms as measured by the SPQ subscales, and a sub-domain related to the affective temperaments as measured by the TEMPS-A. Limitations due to the use of subscales from two different tools should be taken into account.

Prefrontal inefficiency is associated with polygenic risk for schizophrenia

Considering the diverse clinical presentation and likely polygenic etiology of schizophrenia, this investigation examined the effect of polygenic risk on a well-established intermediate phenotype for schizophrenia. We hypothesized that a measure of cumulative genetic risk based on additive effects of many genetic susceptibility loci for schizophrenia would predict prefrontal cortical inefficiency during working memory, a brain-based biomarker for the disorder. The present study combined imaging, genetic and behavioral data obtained by the Mind Clinical Imaging Consortium study of schizophrenia (n = 255). For each participant, we derived a polygenic risk score (PGRS), which was based on over 600 nominally significant single nucleotide polymorphisms, associated with schizophrenia in a separate discovery sample comprising 3322 schizophrenia patients and 3587 control participants. Increased polygenic risk for schizophrenia was associated with neural inefficiency in the left dorsolateral prefrontal cortex after covarying for the effects of acquisition site, diagnosis, and population stratification. We also provide additional supporting evidence for our original findings using scores based on results from the Psychiatric Genomics Consortium study. Gene ontology analysis of the PGRS highlighted genetic loci involved in brain development and several other processes possibly contributing to disease etiology. Our study permits new insights into the additive effect of hundreds of genetic susceptibility loci on a brain-based intermediate phenotype for schizophrenia. The combined impact of many common genetic variants of small effect are likely to better reveal etiologic mechanisms of the disorder than the study of single common genetic variants.

Social deficits induced by peripubertal stress in rats are reversed by resveratrol

Adolescence is increasingly recognized as a critical period for the development of the social system, through the maturation of social competences and of their underlying neural circuitries. The present study sought to test the utility of resveratrol, a dietary phenol recently reported to have mood lifting properties, in modulating social interaction that is deficient following early life adversity. The main aims were to 1) pharmacologically restore normative social investigation levels dampened by peripubertal stress in rats and 2) identify neural pathways engaged by this pharmacological approach. Following peripubertal (P28-42) stress consisting of unpredictable exposures to fearful experiences, at adulthood the subjects' propensity for social exploration was examined in the three-chamber apparatus, comparing time invested in social or non-social investigation. Administered intraperitoneally 30 min before testing, resveratrol (20 mg/kg) normalized the peripubertal stress-induced social investigation deficit seen in the vehicle group, selectively altering juvenile but not object exploration. Examination of prefrontal cortex subregion protein samples following acute resveratrol treatment in a separate cohort revealed that while monoamine oxidase A (MAOA) enzymatic activity remained unaltered, nuclear AKT activation was selectively increased in the infralimbic cortex, but not in the prelimbic or anterior cingulate cortex. In contrast, androgen receptor nuclear localization was increased in the prelimbic cortex, but not in the infralimbic or anterior cingulate cortex. This demonstration that social contact deficits are reversed by resveratrol administration emphasizes a prosocial role for this dietary phenol, and evokes the possibility of developing new treatments for social dysfunctions.

Temperament and character in remitted and symptomatic patients with schizophrenia: modulation by the COMT Val158Met genotype

While research on remission in schizophrenia has gained attention, personality characteristics associated with remission in schizophrenia have been under-studied. A functional valine-to-methionine (Val158Met) polymorphism in the catechol-O-methyltransferase (COMT) gene is shown to modify clinical presentation of schizophrenia despite weak or no association with the disorder itself. Studies also report that this polymorphism can affect personality traits. We aimed to examine personality traits of remitted patients with schizophrenia as compared to symptomatic patients and healthy controls and to investigate whether the COMT Val158Met polymorphism influences their personality. Scores on the Temperament and Character Inventory were compared between 34 remitted outpatients with schizophrenia, age- and sex-matched 72 symptomatic outpatients with schizophrenia, and matched 247 healthy individuals. The effect of COMT Val158Met polymorphism on personality was examined in each group. The analysis of covariance, controlling for confounding variables, revealed that compared to healthy controls, symptomatic patients exhibited a pervasively altered personality profile whereas remitted patients showed alterations in more limited personality dimensions and demonstrated normal levels of novelty-seeking, reward dependence and cooperativeness. The two-way analysis of covariance, with genotype and sex as between-subject factors and confounders as covariates, revealed that Met carriers demonstrated significantly lower reward dependence and cooperativeness than Val homozygotes in symptomatic patients; while no significant genotype effect was found in remitted patients or in healthy individuals. These findings indicate that remitted patients with schizophrenia have a relatively adaptive personality profile compared to symptomatic patients. The COMT Val158Met polymorphism might have a modulating effect on the relationship between personality and remission.

The paradox of schizotypy: resemblance to prolonged severe mental illness in subjective but not objective quality of life

An interesting paradox has emerged regarding the schizophrenia-spectrum. Put simply, college students with schizotypy (defined as the personality organization reflecting a vulnerability to schizophrenia-spectrum pathology) report experiencing pathology with respect to some key functional domains on a level that is equal to or more severe than older, outpatients with an prolonged psychiatric disorders. Notably, this self-reported pathology is not supported by objective/behavioral performance data, suggesting that the primary deficit is psychological in nature (e.g., metacognition). We evaluated whether this subjective-objective dysjunction extends to quality of life (QOL). Eighty-three college students with schizotypy were compared to 50 outpatients with severe mental illness (SMI) as well as to 82 undergraduate and 34 community control groups in subjective and objective QOL via a modified version of Lehman׳s Quality of Life Interview, which covers a range of QOL domains. The schizotypy and SMI group were equally impoverished in all measures of subjective QOL compared to the college and community control groups. In contrast, the schizotypy group was relatively normal in most measures of objective quality of life compared to the SMI group. The subjective-objective dysjunction appears to extend to QOL, and these differences do not appear to reflect a more global negativistic reporting bias.

Schizotypal personality disorder: a current review

The study of schizotypal personality disorder (SPD) is important clinically, as it is understudied, challenging to treat, often under-recognized or misdiagnosed, and associated with significant functional impairment. SPD also represents an intermediate schizophrenia-spectrum phenotype, and therefore, can provide a better understanding of the genetics, pathogenesis, and treatment of related psychotic illnesses. In this review we discuss recent findings of SPD related to epidemiology and functional impairment, heritability and genetics, working memory and cognitive impairments, social-affective disturbances, and neurobiology. Additionally, we examine the challenges associated with treating patients with SPD, as well as clinical recommendations. Finally, we address future directions and areas in need of further exploration.

The assessment of interpersonal pleasure: introduction of the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS) and preliminary findings

Although several valid measures of pleasure and anhedonia exist, there is a relative paucity of measures that adequately assess pleasure for social interactions. The Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS) is a measure specifically designed to assess hedonic capacity for social and interpersonal pleasure. Various aspects of the validity and reliability of the ACIPS were examined in several ways. First, we assessed the factor structure as well as the internal consistency, convergent, and discriminant validity of the ACIPS in 496 young adults recruited from undergraduate classes. Second, we investigated the temporal stability of the measure by having a subset of the group return for retesting. Results from the factor analysis suggested a three-factor model. The ACIPS was found to be highly reliable in terms of internal consistency and test-retest stability. Further, the ACIPS correlated in a theoretically meaningful way with other measures of pleasure and affect. The current research indicates that the ACIPS is a reliable and valid questionnaire to assess hedonic capacity for social and interpersonal pleasure in nonclinical samples. Suggestions for further clinical and research applications using the ACIPS are offered.

An Overview of the Association between Schizotypy and Dopamine

Schizotypy refers to a constellation of personality traits that are believed to mirror the subclinical expression of schizophrenia in the general population. Evidence from pharmacological studies indicates that dopamine (DA) is involved in the etiology of schizophrenia. Based on the assumption of a continuum between schizophrenia and schizotypy, researchers have begun investigating the association between DA and schizotypy using a wide range of methods. In this article, we review published studies on this association from the following areas of work: (1) experimental investigations of the interactive effects of dopaminergic challenges and schizotypy on cognition, motor control, and behavior (2), dopaminergically supported cognitive functions (3), studies of associations between schizotypy and polymorphisms in genes involved in dopaminergic neurotransmission, and (4) molecular imaging studies of the association between schizotypy and markers of the DA system. Together, data from these lines of evidence suggest that DA is important to the expression and experience of schizotypy and associated behavioral biases. An important observation is that the experimental designs, methods, and manipulations used in this research are highly heterogeneous. Future studies are required to replicate individual observations, to enlighten the link between DA and different schizotypy dimensions (positive, negative, cognitive disorganization), and to guide the search for solid DA-sensitive behavioral markers. Such studies are important in order to clarify inconsistencies between studies. More work is also needed to identify differences between dopaminergic alterations in schizotypy compared to the dysfunctions observed in schizophrenia.

Fragile early visual percepts mark genetic liability specific to schizophrenia

Disruption of visual percepts by a subsequent stimulus (ie, backward masking) has been consistently noted in schizophrenia, with some evidence that this fragility in early perception is present in people with genetic liability for the disorder. Given the potential of backward masking paradigms to mark neural processes that confer risk for schizophrenia, it is important to test the diagnostic specificity of abnormalities in visual perception. To more fully assess whether masking visual stimuli reveals a marker of genetic liability (ie, endophenotype) specific to schizophrenia, we tested 44 people with the disorder, 29 people with bipolar disorder, 56 first-degree biological relatives of people with schizophrenia, 26 first-degree biological relatives of people with bipolar disorder, and 43 nonpsychiatric control participants using a magnocellular-biased visual backward masking procedure that included target-to-mask onset asynchronies ranging from 0 to 80 ms. Relatives of people with schizophrenia who were without schizophrenia spectrum disorders exhibited impaired performance compared with nonpsychiatric control participants and relatives of people with bipolar disorder when a visual mask interrupted early perception (eg, 27 ms). A similar vulnerability of early processes was noted in people with schizophrenia, yet they also had impaired performance when masks occurred at later time points (ie, 80 ms). Performance deficits were not attributable to intellectual function, measures of attention and memory, symptomatology, or medication dosage. Bipolar patients and their relatives failed to exhibit deficits on the backward masking task. Fragility of early visual percepts appears to mark genetic liability specific to schizophrenia and may serve as an endophenotype for the disorder.

Reduced hedonic capacity in euthymic bipolar subjects: a trait-like feature?

BACKGROUND

The aim of our study was to assess hedonic capacity in euthymic bipolar subjects, identifying possible differences compared to remitted unipolar depressed patients and healthy controls.

METHODS

107 subjects with bipolar disorders, 86 with major depressive disorder and 106 healthy controls, homogeneous with respect to demographic characteristics, were enrolled. The following scales were administered: the Snaith-Hamilton pleasure scale (SHAPS), the subscale for 'anhedonia/asociality' of the scale for the assessment of negative symptoms (SANS) and the visual analogue scale (VAS) for hedonic capacity.

RESULTS

Scores on SHAPS total, interests and social interactions, SANS 'anhedonia/asociality' and VAS were all significantly higher in affective disorder patients compared to healthy controls. No difference was found between clinical groups. 20.5% (n=22) of bipolar disorder subjects and 24.5% (n=21) of major depressed subjects showed a significant reduction in hedonic capacity (SHAPS total score ≥ 3), compared to 7.5% (n=8) of healthy controls (χ(2)=12.03; p=.002).

LIMITATIONS

Limitations include heterogeneity with respect to pharmacological status and longitudinal course (i.e., 'single' vs. 'recurrent' affective episodes).

CONCLUSIONS

The major finding of our study is that euthymic bipolar patients and remitted major depressed patients display residual anhedonic symptoms. This suggests that, in affective disorder patients, altered hedonic capacity could represent an enduring trait and that, possibly, dysfunctions in the neurobiological mechanisms underlying hedonic response and reward processing persist, irrespective of mood state.

Odor hedonic capacity and anhedonia in schizophrenia and unaffected first-degree relatives of schizophrenia patients

OBJECTIVE

There is increasing evidence that schizophrenia patients have difficulties in the hedonic appraisal of odors. In a prior study, we assessed olfactory hedonic perception birhinally and found that males with schizophrenia failed to attach the appropriate hedonic valence to a pleasant odor, despite correctly perceiving changes in odor intensity. Female patients, in contrast, exhibited normal responses. The current study extends this work by examining odor valence processing in unaffected first-degree relatives of schizophrenia patients, to determine the extent to which this abnormality may be genetically mediated. We also examine odor valence processing unirhinally, rather than birhinally, to probe possible lateralized differences in patients' hedonic processing deficits.

METHOD

Individuals with schizophrenia (n = 54), first-degree unaffected family members (n = 22), and demographically matched controls (n = 45) were administered the Suprathreshold Amyl Acetate Odor Intensity and Odor Pleasantness Rating Test.

RESULTS

In contrast to family members and controls, both male and female schizophrenia probands underevaluated the hedonic characteristics of amyl acetate at lower concentrations and overevaluated its pleasantness at concentrations perceived as unpleasant by both controls and relatives. These patient-specific differences could not be explained by differences in smoking habit, medication use, or subjective ratings of odor intensity. However, they were associated with increased levels of anhedonia/asociality and negative symptomatology.

CONCLUSIONS

Our findings suggest that both male and female schizophrenia patients have difficulties in the unirhinal appraisal of hedonic valence. Normal responses in unaffected first-degree relatives suggest that this is an environmentally, rather than genetically, mediated abnormality denoting negative symptomatology.

The role of the catechol-O-methyltransferase (COMT) gene in personality and related psychopathological disorders

This review provides a short overview of the most significant biologically oriented theories of human personality. Personality concepts of Eysenck, Gray and McNaughton, Cloninger and Panksepp will be introduced and the focal evidence for the heritability of personality will be summarized. In this context, a synopsis of a large number of COMT genetic association studies (with a focus on the COMT Val158Met polymorphism) in the framework of the introduced biologically oriented personality theories will be given. In line with the theory of a continuum model between healthy anxious behavior and related psychopathological behavior, the role of the COMT gene in anxiety disorders will be discussed. A final outlook considers new research strategies such as genetic imaging and epigenetics for a better understanding of human personality.

COMT val158met predicts reward responsiveness in humans

A functional variant of the catechol-O-methyltransferase (COMT) gene [val158met (rs4680)] is frequently implicated in decision-making and higher cognitive functions. It may achieve its effects by modulating dopamine-related decision-making and reward-guided behaviour. Here we demonstrate that individuals with the met/met polymorphism have greater responsiveness to reward than carriers of the val allele and that this correlates with risk-seeking behaviour. We assessed performance on a reward responsiveness task and the Balloon analogue risk task, which measure how participants (N = 70, western European, university and postgraduate students) respond to reward and take risks in the presence of available reward. Individuals with the met/met genotype (n = 19) showed significantly higher reward responsiveness, F2,64 = 4.02, P = 0.02, and reward-seeking behaviour, F(2,68) = 4.52, P = 0.01, than did either val/met (n = 25) or val/val (n = 26) carriers. These results highlight a scenario in which genotype-dependent reward responsiveness shapes reward-seeking, therefore suggesting a novel framework by which COMT may modulate behaviour.

Alogia and formal thought disorder: differential patterns of verbal fluency task performance

BACKGROUND

There is evidence that alogia and formal thought disorder (FTD), two prominent speech symptoms in schizophrenia, are associated with different patterns of verbal fluency task deficits. Verbal fluency is thought to involve several cognitive mechanisms, including controlled retrieval, semantic memory, and context processing.

METHODS

The current research examined whether alogia and FTD were associated with different patterns of verbal fluency performance and whether these patterns of verbal fluency performance would implicate deficits in controlled retrieval, semantic memory, or context processing. In the current research, 34 people with schizophrenia completed letter and category fluency tasks and detailed ratings of alogia and FTD symptoms were made from typed transcripts.

RESULTS

Overall, alogia was associated with increased response latency between each word on the category fluency task, suggesting an association between alogia and poor controlled retrieval. In contrast, FTD was associated with a decreased proportion of semantically-related words on letter fluency, suggesting an association between FTD and poor context processing.

CONCLUSIONS

Alogia and FTD appear to be associated with unique patterns of fluency performance, implicating separate cognitive mechanisms.

The backward masking red light effect and schizotypy: the influence of sex

Previous research has shown a unique effect of red light on visual processing related to both schizophrenia and positive schizotypy. The current study examined whether this effect is influenced by sex in a more broadly-defined schizotypy sample. A location backward masking (BM) task with red, green, and gray backgrounds was administered to 34 undergraduate students (59% female) with a high score on the Schizotypal Personality Questionnaire (SPQ) and 38 students (50% female) with a low score. Results revealed that the group by color interaction was significant for the male participants, while it did not approach significance in the females. The male schizotypy participants showed a significant decrease in BM accuracy to the red (vs. green) background, while the male control participants showed a non-significant mean increase in accuracy. A decrease in accuracy to the red background in the male schizotypy participants was related to a higher score on the Social Anxiety subscale of the SPQ. Findings suggest that the previously reported schizophrenia red light effect is limited to males when examining a SPQ-defined sample, and appears to be primarily related to negative schizotypy symptoms. The red light effect continues to show promise as a new endophenotype for schizophrenia-spectrum disorders.

Influence of emotional processing on working memory in schizophrenia

Research on emotional processing in schizophrenia suggests relatively intact subjective responses to affective stimuli "in the moment." However, neuroimaging evidence suggests diminished activation in brain regions associated with emotional processing in schizophrenia. We asked whether given a more vulnerable cognitive system in schizophrenia, individuals with this disorder would show increased or decreased modulation of working memory (WM) as a function of the emotional content of stimuli compared with healthy control subjects. In addition, we examined whether higher anhedonia levels were associated with a diminished impact of emotion on behavioral and brain activation responses. In the present study, 38 individuals with schizophrenia and 32 healthy individuals completed blocks of a 2-back WM task in a functional magnetic resonance imaging scanning session. Blocks contained faces displaying either only neutral stimuli or neutral and emotional stimuli (happy or fearful faces), randomly intermixed and occurring both as targets and non-targets. Both groups showed higher accuracy but slower reaction time for negative compared to neutral stimuli. Individuals with schizophrenia showed intact amygdala activity in response to emotionally evocative stimuli, but demonstrated altered dorsolateral prefrontal cortex (DLPFC) and hippocampal activity while performing an emotionally loaded WM-task. Higher levels of social anhedonia were associated with diminished amygdala responses to emotional stimuli and increased DLPFC activity in individuals with schizophrenia. Emotional arousal may challenge dorsal-frontal control systems, which may have both beneficial and detrimental influences. Our findings suggest that disturbances in emotional processing in schizophrenia relate to alterations in emotion-cognition interactions rather than to the perception and subjective experience of emotion per se.

A multivariate perspective on schizotypy and familial association with schizophrenia: a review

Although generally accepted that schizotypal personality disorder diagnosis is more prevalent among relatives of individuals with schizophrenia and may be associated with genetic liability to schizophrenia, it seems likely that this diagnosis is itself heterogeneous and thus perhaps not as useful in identifying genes that affect schizophrenia risk (i.e. endophenotypes) as it could be. In contrast, symptoms and dimensions of schizotypal personality disorder may be more etiologically homogeneous, and thus more useful in genetic studies. The current review evaluated and consolidated evidence to date regarding specific symptoms and dimensions of schizotypal personality disorder among non-psychotic relatives of schizophrenia patients. Comparisons were made with relatives of affective disorder patients and non-psychiatric controls. Findings indicate strong support for elevation of social-interpersonal schizotypal symptoms among relatives of schizophrenia patients versus other groups along with moderate specificity. Results suggest only a small elevation of cognitive-perceptual and disorganized symptoms in relatives of schizophrenia patients and results for disorganized symptoms were inconsistent across studies. Thus, evidence to date supports further investigation of genetic associations between symptoms of schizotypal personality disorder and schizophrenia, and suggests that social-interpersonal symptoms may be particularly promising in genetic analyses of schizophrenia.

Contribution of nonprimate animal models in understanding the etiology of schizophrenia

Schizophrenia is a severe psychiatric disorder that is characterized by positive and negative symptoms and cognitive impairments. The etiology of the disorder is complex, and it is thought to follow a multifactorial threshold model of inheritance with genetic and neurodevelop mental contributions to risk. Human studies are particularly useful in capturing the richness of the phenotype, but they are often limited to the use of correlational approaches. By assessing behavioural abnormalities in both humans and rodents, nonprimate animal models of schizophrenia provide unique insight into the etiology and mechanisms of the disorder. This review discusses the phenomenology and etiology of schizophrenia and the contribution of current nonprimate animal models with an emphasis on how research with models of neuro transmitter dysregulation, environmental risk factors, neurodevelopmental disruption and genetic risk factors can complement the literature on schizophrenia in humans.

Birth characteristics and schizotypy: evidence of a potential "second hit"

Schizophrenia is associated with a modest increase in winter births as well as increased odds of being born in more densely populated and midrange latitude regions. It is unclear the degree to which these findings hold for individuals with schizotypy, defined in terms of the personality organization that is a potential precursor to schizophrenia-spectrum disorders. This issue is important for understanding whether birth factors contribute to general schizophrenia vulnerability or whether they reflect a secondary "hit" that increases the likelihood of psychosis onset in vulnerable individuals. The present project examined season of birth, birthplace population and birth location in a large group of young adults from the southeastern United States. Individuals with extreme schizotypy scores did not differ from those without schizotypy in season of birth, birthplace latitude or population. However, 60% of individuals within the schizotypy group who reported a diagnosis of schizophrenia or prior hospitalization were born during winter months; a dramatic difference from other individuals within the schizotypy group. We also found that individuals with negative/schizoid traits showed a birthplace population less than half that of other individuals with schizotypy. Season of birth appears to be a "second hit" that is related to expression of psychopathology onset in vulnerable individuals. This finding, and the unexpected inverse relationship between birthplace population and negative/schizoid traits, is discussed.

Psychopathology and personality traits in psychotic patients and their first-degree relatives

Personality dimensions have been associated with symptoms dimensions in schizophrenic patients (SP). In this paper we study the relationships between symptoms of functional psychoses and personality dimensions in SP and their first-degree relatives (SR), in other psychotic patients (PP) and their first-degree relatives (PR), and in healthy controls in order to evaluate the possible clinical dimensionality of these disorders. Twenty-nine SP, 29 SR, 18 PP, 18 PR and 188 controls were assessed using the temperament and character inventory (TCI-R). Current symptoms were evaluated with positive and negative syndrome scale (PANSS) using the five-factor model described previously (positive [PF], negative [NF], disorganized [DF], excitement [EF] and anxiety/depression [ADF]). Our TCI-R results showed that patients had different personality dimensions from the control group, but in relatives, these scores were not different from controls. With regard to symptomatology, we highlight the relations observed between harm avoidance (HA) and PANSS NF, and between self-transcendence (ST) and PANSS PF. From a personality traits-genetic factors point of view, schizophrenia and other psychosis may be initially differentiated by temperamental traits such as HA. The so-called characterial traits like ST would be associated with the appearance of psychotic symptoms.