Individuals with psychometric schizotypy show similar social but not physical anhedonia to patients with schizophrenia

Mental time travel for self and others in individuals with a high level of schizotypy

Mental time travel (MTT) is the ability to project oneself to the past or future through mental simulation. Moreover, MTT can involve self-related or other-related information. This study aimed to compare MTT in individuals with high levels of schizotypy and that in their counterparts with low levels of schizotypy. Participants with high (n = 37) and low (n = 37) levels of schizotypy completed an MTT task with four conditions [2 (Condition: self vs. other) × 2 (Time orientation: past vs. future)]. They were required to recall past events that had happened to themselves or to a non-intimate person, and to imagine possible future events that might happen to themselves or to a non-intimate person, related to cue words. Outcome measures included specificity, vividness, sense of experience, emotional valence, emotional intensity, proportion of first-person visual perspective in events, and difficulty in event generation. A 2 (Group: high vs. low levels of schizotypy) × 2 (Condition) × 2 (Time orientation) mixed analysis of variance was conducted on each index. Results showed that self-related MTT was more specific than other-related MTT in low levels of schizotypy participants but not in high levels of schizotypy participants. Participants with a high level of schizotypy reported fewer specific events, and reported events with lower vividness and positive emotion than did those with a low level of schizotypy. Self-related MTT showed higher levels of phenomenological characteristics than did other-related MTT. In conclusion, individuals with a high level of schizotypy have altered MTT, and cannot benefit from the self-advantage effect on the specificity of MTT.

Social Anhedonia and Intergroup Processes: A Multi-Study Investigation of Known and Novel Group Memberships

Introduction: Group memberships play an important role in promoting psychological well-being and supporting social functioning. However, studies suggest that individuals with social anhedonia, a characteristic defined by limited pleasure from social bonds, may show abnormalities in their desire to cultivate positive feelings, such as belongingness, from social groups. Still, these abnormalities have not been studied in the context of intergroup processes, leaving the relation between social anhedonia and subjective evaluations of group memberships unclear. Methods: Across three studies (Ns = 124-659), we examined associations between social anhedonia and affective and cognitive attitudes about different types of ingroups and outgroups using self-report and behavioral measures. Results: Taken together, results indicate that social anhedonia is associated with less positive and more negative feelings and beliefs about most ingroups and outgroups from everyday life, as well as negatively biased stereotyping of many prominent social groups. At the same time, individuals with either extremely high or low levels of social anhedonia did not report significantly different intergroup attitudes when group memberships were experimentally manipulated in a minimal group setting. Discussion: Overall, these findings suggest that social anhedonia is associated with less positive and more negative subjective evaluations of long-established, real-world ingroups, but not of a newly formed ingroup that requires little motivation or social engagement to maintain group membership. Aberrant feelings and attitudes toward one's ingroups are consistent with the theory that social anhedonia is related to anomalies in the need to belong within social groups from everyday life and could inform psychosocial interventions for related psychopathologies.

Proactive and reactive cognitive control for emotional conflict in individuals with high schizotypy: An ERP study

OBJECTIVE

The present study aimed to examine how individuals with high schizotypy, a high risk group of schizophrenia patients, resolve emotional conflict in proactive and reactive control and the underlying neural mechanisms.

METHODS

Thirty-two individuals with high schizotypy and 30 matched individuals with low schizotypy completed an emotional face-word Stroop task with electroencephalographic data recorded. The proportion of incongruent trials was manipulated in the task to induce proactive control (mostly incongruent trials context, MI context) or reactive control (mostly congruent trials context, MC context). Two event-related potential (ERP) components (N170 and N2) were examined, which represent face processing and cognitive control processes, respectively.

RESULTS

In the MC context, significantly decreased N2 and N170 amplitudes were found in high schizotypy individuals compared with low schizotypy individuals, suggesting abnormal neural activity of reactive control in high schizotypy individuals. No significant differences were found between the two groups in the MI context.

CONCLUSIONS

These results provide initial evidence for dissociation of neural activity of proactive and reactive control on emotional conflict in individuals with high schizotypy.

SIGNIFICANCE

The current findings provide important insight into the emotional conflict resolution in the schizophrenia spectrum.

The Transdiagnostic Nature of Social Anhedonia: Historical and Current Perspectives

In this chapter, we trace the historical roots of the social anhedonia (SoA) construct to current conceptualizations. We first describe the aspects of SoA that distinguish it from anhedonia in general. We summarize evidence that SoA is a transdiagnostic symptom and risk factor. Although several forms of psychopathology are associated with elevated rates of self-reported SoA, one unresolved issue is whether the processes and mechanisms underlying SoA in one disorder are the same as the processes and mechanisms underlying SoA seen in another disorder. We assert that there may be different causal factors underlying SoA across disorders. Considering both the principles of equifinality and multifinality, we offer an integrative model for social reward processing. This conceptualization considers roles for the following: attention; social cognition, including, but not limited to, social skills; reward learning and valuation; working memory; anticipation, prediction, and remembering; and motivation and effort. We conclude that SoA may be caused by multiple underlying impairments, all of which may serve as targets for intervention. This conceptualization is provided as an impetus for further research in the area.

Altered activation and functional connectivity in individuals with social anhedonia when envisioning positive future episodes

BACKGROUND

Anticipatory pleasure deficits are closely correlated with negative symptoms in schizophrenia, and may be found in both clinical and subclinical populations along the psychosis continuum. Prospection, which is an important component of anticipatory pleasure, is impaired in individuals with social anhedonia (SocAnh). In this study, we examined the neural correlates of envisioning positive future events in individuals with SocAnh.

METHODS

Forty-nine individuals with SocAnh and 33 matched controls were recruited to undergo functional MRI scanning, during which they were instructed to simulate positive or neutral future episodes according to cue words. Two stages of prospection were distinguished: construction and elaboration.

RESULTS

Reduced activation at the caudate and the precuneus when prospecting positive (v. neutral) future events was observed in individuals with SocAnh. Furthermore, compared with controls, increased functional connectivity between the caudate and the inferior occipital gyrus during positive (v. neutral) prospection was found in individuals with SocAnh. Both groups exhibited a similar pattern of brain activation for the construction v. elaboration contrast, regardless of the emotional context.

CONCLUSIONS

Our results provide further evidence on the neural mechanism of anticipatory pleasure deficits in subclinical individuals with SocAnh and suggest that altered cortico-striatal circuit may play a role in anticipatory pleasure deficits in these individuals.

Chemosensory Anhedonia in Patients With Schizophrenia and Individuals With Schizotypy: A Questionnaire Study

Anhedonia, the loss or decline of the ability to enjoy pleasure, is an important clinical characteristic of schizophrenia. Schizotypal traits refer to the appearance of subclinical symptoms of schizophrenia across normal people. Still, few studies have investigated chemosensory anhedonia in schizophrenia patients and schizotypy individuals. Seventy-one schizophrenia patients (SCZ), 162 schizotypy individuals (SCT) as selected by the Schizotypal Personality Questionnaire (SPQ), and 182 healthy controls (HC) participated in our study. We used the Positive and Negative Syndrome Scale (PANSS) to measure the clinical symptoms of schizophrenia patients. All participants completed the Chemosensory Pleasure Scale (CPS), which was used to assess participants' smell and taste hedonic capacities. We found that the three groups differed in chemosensory anhedonia. The SCZ group presented more severe chemosensory anhedonia than the SCT group, and the SCT group presented more severe chemosensory anhedonia than the HC group. We also found that chemosensory hedonic capacity was negatively correlated with negative schizotypal traits in the SCT group. Our results suggested that chemosensory anhedonia is an important characteristic of schizophrenia spectrum disorders.

The Prevalence of Negative Symptoms Across the Stages of the Psychosis Continuum

BACKGROUND

Patients in every stage of the psychosis continuum can present with negative symptoms. While no treatment is currently available to address these symptoms, a more refined characterization of their course over the lifetime could help in elaborating interventions. Previous reports have separately investigated the prevalence of negative symptoms within each stage of the psychosis continuum. Our aim in this review is to compare those prevalences across stages, thereby disclosing the course of negative symptoms.

METHODS

We searched several databases for studies reporting prevalences of negative symptoms in each one of our predetermined stages of the psychosis continuum: clinical or ultra-high risk (UHR), first-episode of psychosis (FEP), and younger and older patients who have experienced multiple episodes of psychosis (MEP). We combined results using the definitions of negative symptoms detailed in the Brief Negative Symptom Scale, a recently developed tool. For each negative symptom, we averaged and weighted by the combined sample size the prevalences of each negative symptom at each stage.

RESULTS

We selected 47 studies totaling 1872 UHR, 2947 FEP, 5039 younger MEP, and 669 older MEP patients. For each negative symptom, the prevalences showed a comparable course. Each negative symptom decreased from the UHR to FEP stages and then increased from the FEP to MEP stages.

CONCLUSIONS

Certain psychological, environmental, and treatment-related factors may influence the cumulative impact of negative symptoms, presenting the possibility for early intervention to improve the long-term course.

Classification of social anhedonia using temporal and spatial network features from a social cognition fMRI task

Previous studies have suggested that the degree of social anhedonia reflects the vulnerability for developing schizophrenia. However, only few studies have investigated how functional network changes are related to social anhedonia. The aim of this fMRI study was to classify subjects according to their degree of social anhedonia using supervised machine learning. More specifically, we extracted both spatial and temporal network features during a social cognition task from 70 subjects, and used support vector machines for classification. Since impairment in social cognition is well established in schizophrenia-spectrum disorders, the subjects performed a comic strip task designed to specifically probe theory of mind (ToM) and empathy processing. Features representing both temporal (time series) and network dynamics were extracted using task activation maps, seed region analysis, independent component analysis (ICA), and a newly developed multi-subject archetypal analysis (MSAA), which here aimed to further bridge aspects of both seed region analysis and decomposition by incorporating a spotlight approach.We found significant classification of subjects with elevated levels of social anhedonia when using the times series extracted using MSAA, indicating that temporal dynamics carry important information for classification of social anhedonia. Interestingly, we found that the same time series yielded the highest classification performance in a task classification of the ToM condition. Finally, the spatial network corresponding to that time series included both prefrontal and temporal-parietal regions as well as insula activity, which previously have been related schizotypy and the development of schizophrenia.

Delay discounting and affective priming in individuals with negative schizotypy

Previous studies have demonstrated that patients with schizophrenia and individuals with schizotypy experience decreased anticipatory pleasure. However, it is unclear whether this decrease is contributed by altered reward processing at the proximal or distal future. In order to investigate the preference for receiving rewards in the proximal or distal future for individuals with schizophrenia spectrum disorders, individuals with either high or low levels of negative schizotypy performed a delay discounting task under positive, neutral and negative affective priming conditions. Compared with individuals with low levels of negative schizotypy, individuals with high levels of schizotypy exhibited increased delay discounting, preferring to choose immediate but smaller rewards instead of delayed but larger rewards across all three affective priming conditions. Negative affective priming elevated discounting for both groups compared with both the positive and neutral affective conditions. After dividing delayed temporal distance into the proximal and distal future, the results showed that individuals with high levels of negative schizotypy exhibited more preference for immediate but smaller rewards in the distal instead of proximal future compared with controls. Our results suggest that individuals with high levels of negative schizotypy have altered anticipatory reward processing, which is mainly attributed to alterations in representing rewards in the distal future. These findings extend the alterations in representing reward values from schizophrenia patients to schizotypal individuals, and suggest that diminished anticipatory pleasure in schizophrenia spectrum disorders may be due to changes in processing anticipatory rewards in the distal future.

Functional connectivity of the default mode network is associated with prospection in schizophrenia patients and individuals with social anhedonia

BACKGROUND

Prospection, which is closely related to negative symptoms in patients with schizophrenia, is mainly associated with the Default Mode Network (DMN). Although abnormalities of the DMN have been reported in schizophrenia patients and at-risk individuals, little is known about the relationship between functional connectivity of the DMN and prospection in these clinical and subclinical populations.

METHOD

Study 1 recruited 40 schizophrenia patients and 29 healthy controls, while 31 individuals with social anhedonia (SocAhn) and 28 controls participated in Study 2. Participants in both studies were asked to complete a prospection task and underwent resting-state functional MRI scans. Eleven regions of interest (ROIs) in the DMN were defined. Functional connectivity between each ROI and whole brain voxels were calculated and compared between groups (schizophrenia vs. control and SocAhn vs. control). Correlation analysis was conducted between altered functional connectivity and prospection variables in the schizophrenia and SocAhn groups.

RESULTS

Schizophrenia patients showed both hyper-connectivity and hypo-connectivity at the medial temporal lobe (MTL) subsystem of the DMN. Decreased connectivity between the ventral medial prefrontal cortex (vMPFC) and the right superior temporal gyrus (rSTG) was correlated with poor thought/emotion details in prospection. In individuals with SocAhn, decreased connectivity between the retrosplenial cortex (Rsp), a region of the MTL subsystem, and the right fusiform gyrus, was found and this was correlated with their prospection performance.

CONCLUSION

Altered functional connectivity of the key nodes of the MTL subsystem was found in both patients with schizophrenia and individuals with SocAhn. Moreover, hypo-connectivity of the vMPFC was found to be correlated with prospection impairments in schizophrenia patients.

Low-pleasure beliefs in patients with schizophrenia and individuals with social anhedonia

Anhedonia in schizophrenia has been suggested to comprise a set of low-pleasure beliefs, defined as beliefs that certain things/activities were not pleasurable or that one does not feel pleasant generally. However, no instrument has been intentionally developed to specifically measure low-pleasure beliefs, and there is a paucity of empirical evidence for low-pleasure beliefs and their relationship with anhedonia in both patients with schizophrenia and individuals with high social anhedonia. We developed and validated the Beliefs About Pleasure Scale (BAPS) using non-clinical (Studies 1, 2 & 3), chronic schizophrenia (Study 2), and first episode schizophrenia (Study 3) samples. Across these studies, we examined psychometric properties of the BAPS, including temporal stability, internal consistency, factor structure, and convergent validity. The 22 BAPS items loaded onto 4 factors, namely the "Devaluation of Pleasure", the "Pleasurable Activity Expectancies", the "Negative Outcomes Expectancies", and the "Attention to Pleasure". The measure demonstrated good internal consistency and convergent validity in each sample. Moreover, both individual with schizophrenia and non-clinical participants with high social anhedonia scored higher on the BAPS than controls (Study 3), supporting construct validity. These findings provide preliminary evidence for the presence of low-pleasure beliefs in both clinical and subclinical groups and suggest that the BAPS has promising initial psychometric properties. The BAPS will be useful for exploring the cognitive component of anhedonia and provides a novel assessment for mechanism of change in psychosocial treatment studies.

Cross Cultural Validation and Extension of the Clinical Assessment Interview for Negative Symptoms (CAINS) in the Chinese Context: Evidence from a Spectrum Perspective

The Clinical Assessment Interview for Negative Symptoms (CAINS) was designed in accordance with the recent theory and research in social affective neuroscience and to address the psychometric and conceptual limitations of other instruments assessing negative symptoms. The present study aimed to provide a large-scale validation of the CAINS in China and examine its applicability and validity evidence across the schizophrenia spectrum. Using confirmatory factor analysis, our results replicated the original findings in the US development samples that the CAINS possesses a stable 2-factor structure, namely "motivation/pleasure" and "expression". We also found significant correlations between the CAINS and other negative symptom measures. The CAINS demonstrated good discriminant validity in differentiating negative symptoms in people with schizophrenia, nonpsychotic first-degree relatives and people with social anhedonia. People with schizophrenia exhibited significantly higher CAINS subscale scores than first-degree relatives and healthy controls. In addition, first-degree relatives had higher "motivation/pleasure" scores than healthy controls. The "motivation/pleasure" subscale scores of individuals with social anhedonia were also significantly higher than healthy controls.

Perspectives on Machine Learning for Classification of Schizotypy Using fMRI Data

Functional magnetic resonance imaging is capable of estimating functional activation and connectivity in the human brain, and lately there has been increased interest in the use of these functional modalities combined with machine learning for identification of psychiatric traits. While these methods bear great potential for early diagnosis and better understanding of disease processes, there are wide ranges of processing choices and pitfalls that may severely hamper interpretation and generalization performance unless carefully considered. In this perspective article, we aim to motivate the use of machine learning schizotypy research. To this end, we describe common data processing steps while commenting on best practices and procedures. First, we introduce the important role of schizotypy to motivate the importance of reliable classification, and summarize existing machine learning literature on schizotypy. Then, we describe procedures for extraction of features based on fMRI data, including statistical parametric mapping, parcellation, complex network analysis, and decomposition methods, as well as classification with a special focus on support vector classification and deep learning. We provide more detailed descriptions and software as supplementary material. Finally, we present current challenges in machine learning for classification of schizotypy and comment on future trends and perspectives.

Associations of differential schizotypal dimensions with executive working memory: A moderated-mediation analysis

BACKGROUND

Increased schizotypal traits are observed in a percentage of the general population and in the schizophrenia-spectrum and have been associated with impairments in working memory. In this study we examined the effects of four schizotypal dimensions [Negative (NegS), Paranoid (ParS), Cognitive-Perceptual (CPS), Disorganized (DiS)] on executive working memory (EWM), as mediated by set-shifting, planning and control inhibition. We also examined whether these associations are moderated by family-history of psychosis.

METHODS

Our sample consisted of 110 unaffected first-degree relatives of schizophrenia-spectrum patients and 120 control individuals. Schizotypy was assessed with the Schizotypal Personality Questionnaire. Participants were also tested with the Letter-Number Sequencing, Wisconsin Card Sorting, Stroop Color-Word and Stockings of Cambridge tasks. The effects of set-shifting, control inhibition and planning on the relationship between schizotypy and EWM were examined with mediation analyses. Moderated-mediation analyses examined potential moderating effects of group membership (unaffected relative/community participant).

RESULTS

All mediators were significant in the relationship between NegS and EWM. The effects of ParS were mediated only by set-shifting and planning. Planning and control inhibition were the only significant mediators on the effects of CPS and DiS on EWM, respectively. The moderated-mediation analyses revealed that these findings apply only in the community group.

CONCLUSIONS

We found that the effects of different schizotypal dimensions on EWM are mediated by other cognitive processes in individuals without personal/family history of psychosis. This is probably due to either more severe impairments in the cognitive processes of the relatives or restrictions in our sample and study-design.

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.

Impaired Self-Monitoring of Inner Speech in Schizophrenia Patients with Verbal Hallucinations and in Non-clinical Individuals Prone to Hallucinations

BACKGROUND

Previous research has shown that various memory errors reflecting failure in the self-monitoring of speech were associated with auditory/verbal hallucinations in schizophrenia patients and with proneness to hallucinations in non-clinical individuals.

METHOD

We administered to 57 schizophrenia patients and 60 healthy participants a verbal memory task involving free recall and recognition of lists of words with different structures (high-frequency, low-frequency, and semantically organisable words). Extra-list intrusions in free recall were tallied, and the response bias reflecting tendency to make false recognitions of non-presented words was computed for each list.

RESULTS

In the male patient subsample, extra-list intrusions were positively associated with verbal hallucinations and inversely associated with negative symptoms. In the healthy participants the extra-list intrusions were positively associated with proneness to hallucinations. A liberal response bias in the recognition of the high-frequency words was associated with verbal hallucinations in male patients and with proneness to hallucinations in healthy men. Meanwhile, a conservative response bias for these high-frequency words was associated with negative symptoms in male patients and with social anhedonia in healthy men.

CONCLUSION

Misattribution of inner speech to an external source, reflected by false recollection of familiar material, seems to underlie both clinical and non-clinical hallucinations. Further, both clinical and non-clinical negative symptoms may exert on verbal memory errors an effect opposite to that of hallucinations.

Emotional Experiences Predict the Conversion of Individuals with Attenuated Psychosis Syndrome to Psychosis: A 6-Month Follow up Study

The present study explored the conversion rate in individuals with Attenuated Psychosis Syndrome (APS) and potential predictor for transition in mainland China. Sixty-three participants identified as APS were followed up 6 months later. The results showed that 17% of individuals with APS converted to full-blown psychosis. The converters exhibited significantly poorer emotional experience and expression than the non-converters at baseline. A further binary logistic regression analysis showed that emotional experience could predict the transition (Wald = 4.18, p = 0.041, 95% CI = 1.04~6.82). The present study suggests an important role of emotional processing in the prediction of the development of full-blown psychosis.

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.

Altered corticostriatal functional connectivity in individuals with high social anhedonia

BACKGROUND

Dysregulation of the striatum and altered corticostriatal connectivity have been associated with psychotic disorders. Social anhedonia has been identified as a predictor for the development of schizophrenia spectrum disorders. The aim of the present study was to examine corticostriatal functional connectivity in individuals with high social anhedonia.

METHOD

Twenty-one participants with high social anhedonia score and 30 with low social anhedonia score measured by the Chinese version of the Revised Social Anhedonia Scale were recruited from university undergraduates (age 17-21 years) to undergo resting-state functional MRI scans. Six subdivisions of the striatum in each hemisphere were defined as seeds. Voxel-wise functional connectivity analyses were conducted between each seed and the whole brain voxels, followed by repeated-measures ANOVA for the group effect.

RESULTS

Participants with high social anhedonia showed hyper-connectivity between the ventral striatum and the anterior cingulate cortex and the insula, and between the dorsal striatum and the motor cortex. Hypo-connectivity in participants with high social anhedonia was also observed between the ventral striatum and the posterior cingulate cortex. Partial correlation analyses further showed that the functional connectivity between the ventral striatum and the prefrontal cortex was associated with pleasure experience and emotional suppression.

CONCLUSIONS

Our findings suggest that altered corticostriatal connectivity can be found in participants with high levels of social anhedonia. Since social anhedonia has been considered a predictor for schizophrenia spectrum disorders, our results may provide novel evidence on the early changes in brain functional connectivity in at-risk individuals.

The neural basis of olfactory function and its relationship with anhedonia in individuals with schizotypy: An exploratory study

Previous studies have established a linkage between olfactory deficits and negative symptoms in schizophrenia. However, it is not known whether olfactory function is associated with hedonic traits in individuals with schizotypy. Seventeen individuals with schizotypy and 18 age- and sex-matched controls participated in this study. Hedonic traits were assessed with the Chapman Scales for Physical and Social Anhedonia (CSAS and CPAS). Olfactory function was assessed with the Sniffin' Stick Test (olfactory threshold, odour discrimination and odour identification). All participants undertook a structural imaging scan for grey matter volume measurements. Individuals with schizotypy had significantly higher CSAS and CPAS scores than healthy controls. They had normal olfactory function. Their odour identification ability was inversely correlated with physical and social anhedonia. The volume of the right parahippocampal gyrus was positively associated with odour identification ability, and negatively associated with physical and social anhedonia. Furthermore, mediation analysis suggested that odour identification ability influences anhedonia through its effect on the right parahippocampal gyrus. No such relationship was found in controls. These findings suggest that there is a relationship between odour identification and anhedonia in individuals with schizotypy, and the association may be mediated by parahippocampal gyrus volume.

The stability of schizotypy across time and instruments

Little is known about the stability of schizotypy across relatively long time periods and instrumentation. This study assesses the degree of stability between schizotypy and its three factor structure as assessed by the Survey of Attitudes and Experiences (SAE) at age 17, and the Schizotypal Personality Questionnaire (SPQ) at age 23. A sample of 678 at ages 17 and 23 years from a birth cohort in Mauritius were split into two random samples, with initial analyses on the first sample independently replicated on the second sample. Cognitive-perceptual, interpersonal, and disorganized factors at age 17 correlated from 0.28 to 0.32 with their respective factors at age 23. Total scores correlated 0.41 (d=0.90) across this six year time period and increased to 0.58 (d=1.42) after correcting for measurement error. Receiver operating characteristic (ROC) analyses showed an area under the curve value of 0.74, confirmed prediction over time. Findings on predictive validity were closely replicated in the second independent sample. In contrast, social anhedonia at age 17 was unrelated to interpersonal deficits at age 23. Results provide replicable support for the moderate stability of cognitive-perceptual, interpersonal, and disorganized schizotypy across time, instrumentation, and a period of rapid developmental change.

Intact speed of processing in a community-based sample of adults with high schizotypy: A marker of reduced psychosis risk?

Speed of processing is impaired in schizophrenia but intact in schizotypal college students. In view of this disparity, we investigated whether deficient processing speed was associated with schizotypy in adults from the general community. Data were drawn from the Western Australian Family Study of Schizophrenia, including 216 (non-clinical) adults from the general community, and a reference group with schizophrenia spectrum disorder (N=224). Schizotypal traits were assessed with the Schizotypal Personality Questionnaire, whilst processing speed was assessed with a digit-symbol coding task. Community controls had significantly higher digit symbol coding scores than patients with psychosis. However, both correlational and hierarchical regression analysis indicated a lack of association between Cognitive-perceptual, Interpersonal or Disorganized schizotypy traits and digit symbol coding performance. Relative to Australian norms there was also no evidence of a non-linear decline in coding in high schizotypes in young, mature or senior age groups. The results show that speed of information processing is unimpaired in high schizotypes from the general community. The possibility that intact processing speed in at-risk groups confers protection to psychosis onset is discussed. Assessing the trajectory of processing speed throughout development may provide a useful clinical screening tool to distinguish those at heightened risk of developing psychosis.

Distinct structural neural patterns of trait physical and social anhedonia: evidence from cortical thickness, subcortical volumes and inter-regional correlations

Anhedonia is an enduring trait accounting for the reduced capacity to experience pleasure. Few studies have investigated the brain structural features associated with trait anhedonia. In this study, the relationships between cortical thickness, volume of subcortical structures and scores on the Chapman physical and social anhedonia scales were examined in a non-clinical sample (n=72, 35 males). FreeSurfer was used to examine the cortical thickness and the volume of six identified subcortical structures related to trait anhedonia. We found that the cortical thickness of the superior frontal gyrus and the volume of the pallidum in the left hemisphere were correlated with anhedonia scores in both physical and social aspects. Specifically, positive correlations were found between levels of social anhedonia and the thickness of the postcentral and the inferior parietal gyri. Cortico-subcortical inter-correlations between these clusters were also observed. Our findings revealed distinct correlation patterns of neural substrates with trait physical and social anhedonia in a non-clinical sample. These findings contribute to the understanding of the pathologies underlying the anhedonia phenotype in schizophrenia and other psychiatric disorders.