Stability of positive and negative symptoms in schizophrenic patients: a 3-year follow-up study

Modelling the longitudinal dynamics of paranoia in psychosis: A temporal network analysis over 20 years

BACKGROUND

Paranoia is a key feature of psychosis that can be highly debilitating. Theories of paranoia mostly interface with short-scale or cross-sectional data models, leaving the longitudinal course of paranoia underspecified.

METHODS

We develop an empirical characterisation of two aspects of paranoia - persecutory and referential delusions - in individuals with psychosis over 20 years. We examine delusional dynamics by applying a Graphical Vector Autoregression Model to data collected from the Chicago Follow-up Study (n = 135 with a range of psychosis-spectrum diagnoses). We adjusted for age, sex, IQ, and antipsychotic use.

RESULTS

We found that referential and persecutory delusions are central themes, supported by other primary delusions, and are strongly autoregressive - the presence of referential and persecutory delusions is predictive of their future occurrence. In a second analysis we demonstrate that social factors influence the severity of referential, but not persecutory, delusions.

IMPLICATIONS

We suggest that persecutory delusions represent central, resistant states in the cognitive landscape, whereas referential beliefs are more flexible, offering an important window of opportunity for intervention. Our data models can be collated with prior biological, computational, and social work to contribute toward a more complete theory of paranoia and provide more time-dependent evidence for optimal treatment targets.

The longitudinal structure of negative symptoms in treatment resistant schizophrenia

BACKGROUND AND HYPOTHESIS

The negative symptoms of schizophrenia are strong prognostic factors but remain poorly understood and treated. Five negative symptom domains are frequently clustered into the motivation and pleasure (MAP) and emotional expression (EE) 'dimensions', but whether this structure remains stable and behaves as a single entity or not remains unclear.

STUDY DESIGN

We examined a cohort of 153 patients taking clozapine for treatment-resistant schizophrenia in a regional mental health clinic. Patients were assessed longitudinally over a mean period of 45 months using validated scales for positive, negative and mood symptoms. Network analyses were performed to identify symptom 'communities' and their stability over time. The influence of common causes of secondary negative symptoms as well as centrality measures were also examined.

STUDY RESULTS

Across patients at baseline, two distinct communities matching the clinical domains of MAP and EE were found. These communities remained highly stable and independent over time. The communities remained stabled when considering psychosis, depression, and sedation severity, and these causes of secondary negative symptoms were clustered into the MAP community. Centrality measures also remained stable over time, with similar centrality measures across symptoms.

CONCLUSIONS

Our results suggest that MAP and EE are independent dimensions that remain highly stable over time in chronic schizophrenia patients treated with clozapine. Common causes of secondary negative symptoms mapped onto the MAP dimension. Our results emphasise the need for clinical trials to address either MAP or EE, and that treating causes of secondary negative symptoms may improve MAP.

Dependence Graphs Based on Association Rules to Explore Delusional Experiences

Methods to estimate dependence graphs among variables, have quickly gained popularity in psychopathology research. To date, multiple methods have been proposed but recent studies report several drawbacks impacting on the validity of the conclusions as it is argued that assumptions and conditions underlying the methods commonly used and the nature of the data is lacking alignment. A particularly important issue is that underlying dynamics potentially present in heterogeneous datasets are disregarded, as the methods focus on the variables but not on individuals. This work also argues that the networks may lack relevant components as current methods ignore connections beyond pairwise interactions between individual symptoms. This study addresses these issues with a novel method for constructing dependence graphs based on applying Association Rules to binary records, which is often the type of records in the psychopathology domain. To demonstrate the benefits, we examine 12 delusional experiences in a sample of 1423 subjects with psychotic disorders. We show that by extracting Association Rules using an algorithm called apriori, in addition to facilitating an intuitive interpretation, previously unseen relevant dependencies are revealed from higher order interactions among psychotic experiences in subgroups of patients.

The deficit syndrome in first-admission patients with psychotic and non-psychotic disorders

The authors study the frequency of primary enduring negative symptoms in first-admission patients with schizophrenic and non-schizophrenic disorders. Carpenter's criteria for distinguishing the primary, enduring negative symptoms from the more transient negative symptoms (secondary to different factors) were applied. Furthermore, they compare negative symptom complexes between first-admission patients and patients with recurrent hospitalizations (within 5 years after first admission). There was a trend for patients with recurrent admissions to show more frequently a deficit syndrome than first-admission patients. Nevertheless, this difference was not significant (χ2 = 0.90). First-admission patients with deficit syndrome had significantly higher affective blunting (P < 0.05) and anhedonia (P < 0.001) than those with recurrent admissions. First-admission subjects with psychotic disorders had significantly higher frequency of deficit syndrome than those first-admission patients with non-psychotic disorders (P < 0.05). These results show that negative symptoms observed in first-admitted non-schizophrenic patients can also be enduring and primary. Thereby this work does not contribute to support the specificity of primary enduring negative symptoms for schizophrenia. Moreover, data suggest, that primary anhedonia and affective blunting can decrease within the first 5 years after discharge.

M. Staging of Schizophrenia With the Use of PANSS: An International Multi-Center Study

INTRODUCTION

A specific clinically relevant staging model for schizophrenia has not yet been developed. The aim of the current study was to evaluate the factor structure of the PANSS and develop such a staging method.

METHODS

Twenty-nine centers from 25 countries contributed 2358 patients aged 37.21 ± 11.87 years with schizophrenia. Analysis of covariance, Exploratory Factor Analysis, Discriminant Function Analysis, and inspection of resultant plots were performed.

RESULTS

Exploratory Factor Analysis returned 5 factors explaining 59% of the variance (positive, negative, excitement/hostility, depression/anxiety, and neurocognition). The staging model included 4 main stages with substages that were predominantly characterized by a single domain of symptoms (stage 1: positive; stages 2a and 2b: excitement/hostility; stage 3a and 3b: depression/anxiety; stage 4a and 4b: neurocognition). There were no differences between sexes. The Discriminant Function Analysis developed an algorithm that correctly classified >85% of patients.

DISCUSSION

This study elaborates a 5-factor solution and a clinical staging method for patients with schizophrenia. It is the largest study to address these issues among patients who are more likely to remain affiliated with mental health services for prolonged periods of time.

Positive and negative symptoms in schizophrenia: A longitudinal analysis using latent variable structural equation modelling

BACKGROUND

Recent network models of schizophrenia propose it is the consequence of mutual interaction between its symptoms. While cross-sectional associations between negative and positive symptoms are consistent with this idea, they may merely reflect their involvement in the diagnostic process. Longitudinal analyses however may allow the identification of possible causal relationships. The European Schizophrenia Cohort (EuroSC) provides data suitable for this purpose.

METHODS

EuroSC includes 1208 patients randomly sampled from outpatient services in France, Germany and the UK. Initial measures were repeated after 12 and 24 months. Latent variable structural equation modelling was used to investigate the direction of effect between positive and negative symptoms assessed with the Positive and Negative Syndrome Scale, controlling for the effects of depressed mood and antipsychotic medication.

RESULTS

The structural model provided acceptable overall fit [χ² (953) = 2444.32, P < 0.001; CFI = 0.909; RMSEA = 0.046 (90% CI: 0.043, 0.048); SRMR = 0.052]. Both positive and negative symptoms were persistent, and strongly auto-correlated. There were also persistent cross-sectional associations between positive and negative symptoms. While the path from latent positive to negative symptoms from T1 to T2 approached conventional levels of statistical significance (P = 0.051), that from T2 to T3 did not (P = 0.546). Pathways in the reverse direction were uniformly non-significant.

CONCLUSIONS

There was no evidence that negative symptoms predict later positive symptoms. The prediction of negative symptoms by positive symptoms was ambiguous. We discuss implications for conceptualization of schizophrenic processes.

A two-stage cognitive theory of the positive symptoms of psychosis. Highlighting the role of lowered decision thresholds

OBJECTIVES

We outline a two-stage heuristic account for the pathogenesis of the positive symptoms of psychosis.

METHODS

A narrative review on the empirical evidence of the liberal acceptance (LA) account of positive symptoms is presented.

HYPOTHESIS

At the heart of our theory is the idea that psychosis is characterized by a lowered decision threshold, which results in the premature acceptance of hypotheses that a nonpsychotic individual would reject. Once the hypothesis is judged as valid, counterevidence is not sought anymore due to a bias against disconfirmatory evidence as well as confirmation biases, consolidating the false hypothesis. As a result of LA, confidence in errors is enhanced relative to controls. Subjective probabilities are initially low for hypotheses in individuals with delusions, and delusional ideas at stage 1 (belief formation) are often fragile. In the course of the second stage (belief maintenance), fleeting delusional ideas evolve into fixed false beliefs, particularly if the delusional idea is congruent with the emotional state and provides "meaning". LA may also contribute to hallucinations through a misattribution of (partially) normal sensory phenomena. Interventions such as metacognitive training that aim to "plant the seeds of doubt" decrease positive symptoms by encouraging individuals to seek more information and to attenuate confidence. The effect of antipsychotic medication is explained by its doubt-inducing properties.

LIMITATIONS

The model needs to be confirmed by longitudinal designs that allow an examination of causal relationships. Evidence is currently weak for hallucinations.

CONCLUSIONS

The theory may account for positive symptoms in a subgroup of patients. Future directions are outlined.

Could PANSS be a useful tool in the determining of the stages of schizophrenia? A clinically operational approach

Staging in schizophrenia might be an important approach for the better treatment and rehabilitation of patients. The purpose of this study was to empirically devise a staging approach in a sample of stabilized patients with schizophrenia. One hundred and seventy patients aged ≥18 years (mean = 40.7, SD = 11.6) diagnosed by DSM-5 criteria were evaluated with the Positive and Negative Syndrome Scale (PANSS). Principal components analysis (PCA) with varimax rotation was used. The model was examined in the total sample and separately across a hypothesized stage of illness based on three age groups and between the two sexes. The PCA revealed a six factor structure for the total sample: 1) Negative, 2) Positive, 3) Depression and anxiety, 4) Excitement and Hostility, 5) Neurocognition and 6) Disorganization. The separate PCAs by stage of illness and sex revealed different patterns and quality of symptomatology. The Negative and Positive factors were stable across all examined groups. The models corresponding to different stages differed mainly in terms of neurocognition and disorganization and their interplay. Catatonic features appear more prominent in males while in females neurocognition takes two forms; one with disorganization and one with stereotype thinking with delusions. This study suggests that the three arbitrary defined stages of illness (on the basis of age) seem to reflect a progress from a preserved insight and more coherent mental functioning to disorganization and eventually neurocognitive impairment. Sexes differ in terms of the relationship of psychotic features with neurocognition. These results might have significant research and clinical implications.

Investigating the empirical support for therapeutic targets proposed by the temporal experience of pleasure model in schizophrenia: A systematic review

BACKGROUND

Anhedonia and amotivation are substantial predictors of poor functional outcomes in people with schizophrenia and often present a formidable barrier to returning to work or building relationships. The Temporal Experience of Pleasure Model proposes constructs which should be considered therapeutic targets for these symptoms in schizophrenia e.g. anticipatory pleasure, memory, executive functions, motivation and behaviours related to the activity. Recent reviews have highlighted the need for a clear evidence base to drive the development of targeted interventions.

OBJECTIVE

To review systematically the empirical evidence for each TEP model component and propose evidence-based therapeutic targets for anhedonia and amotivation in schizophrenia.

METHOD

Following PRISMA guidelines, PubMed and PsycInfo were searched using the terms "schizophrenia" and "anhedonia". Studies were included if they measured anhedonia and participants had a diagnosis of schizophrenia. The methodology, measures and main findings from each study were extracted and critically summarised for each TEP model construct.

RESULTS

80 independent studies were reviewed and executive functions, emotional memory and the translation of motivation into actions are highlighted as key deficits with a strong evidence base in people with schizophrenia. However, there are many relationships that are unclear because the empirical work is limited by over-general tasks and measures.

CONCLUSIONS

Promising methods for research which have more ecological validity include experience sampling and behavioural tasks assessing motivation. Specific adaptations to Cognitive Remediation Therapy, Cognitive Behavioural Therapy and the utilisation of mobile technology to enhance representations and emotional memory are recommended for future development.

Do negative symptoms of schizophrenia change over time? A meta-analysis of longitudinal data

BACKGROUND

Negative symptoms are a core component of schizophrenia which can severely impact quality of life and functional outcomes. These symptoms are understood to be highly stable but this has not been tested in a meta-analysis, despite the wealth of longitudinal data available.

METHOD

A systematic review of the literature was conducted, with eligible studies pooled into a random-effects meta-analysis. Planned meta-regressions were conducted to evaluate the impact of factors known to induce secondary negative symptoms, in addition to other possible sources of heterogeneity.

RESULTS

The main analysis included 89 samples from 41 studies, totalling 5944 participants. Negative symptoms were found to significantly reduce in all treatment interventions, including in placebo and treatment as usual conditions, with a medium effect size (ES) present across all study conditions (ES = 0.66, 95% confidence interval 0.56-0.77, I(2) = 94.0%). In a multivariate meta-regression, only the type of scale used was found to significantly influence negative symptom change. No difference in outcome was found between studies that excluded patients with a high level of positive or depressive symptoms, compared to those that did not.

CONCLUSIONS

Negative symptoms were found to reduce in almost all schizophrenia outpatient samples. A reduction was found across all conditions, with effect sizes ranging from small to large depending upon the condition type. These findings challenge the convention that negative symptoms are highly stable and suggest that they may improve to a greater extent than what has previously been assumed.

Two subdomains of negative symptoms in psychotic disorders: established and confirmed in two large cohorts

Negative symptoms of schizophrenia are normally grouped into a single category. However, the diversity of such symptoms suggests that they are actually made up of more than one dimension. The DSM-V proposes two negative symptom domains, namely expressive deficits and avolition/asociality. We investigated whether the negative symptoms do indeed have two dimensions. An exploratory factor analysis was carried out based on interviews with the PANSS (664 patients). We restricted our analysis to items that had been described as negative symptoms in previous factor analyses. The symptom structure was then tested for stability by performing a confirmatory factor analysis on PANSS interviews from a separate cohort (2172 patients). Exploratory factor analysis yielded a two-factor structure of negative symptoms. The first factor consisted of PANSS items Flat affect, Poor rapport, Lack of spontaneity, Mannerisms and posturing, Motor retardation, and Avolition. The second factor consisted of Emotional withdrawal, Passive/apathetic social withdrawal, and Active social avoidance. The first factor could be related to expressive deficits, reflecting a loss of initiative, and the second factor to social amotivation, related to community interaction. This factor structure supports the DSM-V classification and may be relevant for pathophysiology and treatment of schizophrenia and other psychotic disorders.

Persistence and stability of delusions over time

Traditional descriptions of delusions have emphasized the conviction with which they are held and their resistance to change. This study utilizes data from a large cohort of delusional subjects to assess the persistence and stability of delusional beliefs, and the predictors of change. Data were collected from 1,136 acutely hospitalized psychiatric patients, reinterviewed at 10-week intervals for 1 year. Persistence of delusional beliefs was determined for those delusional subjects with at least one follow-up visit (n = 405), and stability for the subset with delusions at two or more points in time (n = 262). Marked plasticity in delusional beliefs was observed, with one third of delusional subjects at any interview no longer delusional 10 weeks later. Persistence of delusions was associated with schizophrenia, global psychopathology, and having acted on a delusion, among other variables. Most subjects showed variation in the content of their primary delusion over time. Delusions appear to be more fluid over relatively short periods of time than has been suggested by many classic descriptions and contemporary formulations.

How many and which are the psychopathological dimensions in schizophrenia? Issues influencing their ascertainment

During the last two decades, much effort has been made to precisely characterize the symptom dimensions of schizophrenia. A number of dimensional models have been proposed, the most popular of which has been a three-dimensional model consisting of psychotic, negative and disorganizational symptoms. This model, however, has been criticized as too simplistic, and more complex models have been proposed, although to date there has been no consensus as to the number and nature of dimensions necessary to account for the whole range of schizophrenic symptoms. In the present paper, the authors review the main methodological issues which have led to the current confusion about the number of dimensions underlying schizophrenic psychopathology. Among the main issues influencing the delimitation of dimensions are: statistical procedures for determining the number of factors, phase of the illness, level of analysis of symptoms (i.e., symptoms or groups of symptoms), and measurement instrument used. Studies analyzing either a broad range of symptoms or particular symptoms at a finer level have produced a rather complex picture of schizophrenic dimensions. There is evidence supporting the existence of eight major dimensions of psychopathology: psychosis, disorganization, negative, mania, depression, excitement, catatonia and lack of insight. The dimensional structure of symptoms becomes even more complex if one considers that these big dimensions can be further divided into more elementary components. A hierarchical approach for organizing the complex dimensional structure of schizophrenic symptoms is proposed.

Symptom dimensions in the course of childhood-onset schizophrenia

The symptom dimensions of childhood-onset schizophrenia (COS) are described by focussing on the clinical features of 44 patients at onset of illness during the first episode and at follow-up investigation 42 years after onset. All subjects were re-diagnosed according to DSM IV. The symptomatology was evaluated with the Positive and Negative Symptom Scale (PANSS) at onset and at follow-up. Two principal component factor analyses with varimax-rotation were applied to the complete items set of the PANSS. The frequencies of positive, negative, and global symptoms were compared longitudinally in an ANOVA-repeated measures design. The factor analysis revealed 5 orthogonal symptom dimensions (factors) at onset of psychosis: Cognition, social withdrawal, antisocial behaviour, excitement, and reality distortion. At follow-up a five-factor solution was found, too, but different dimensions emerged: a positive, negative, excitement, cognitive, and anxiety/depression component which fits to the 5-factor model of White et al. (1997). The first psychotic episode of EOS is accompanied with more unspecific symptoms such as social withdrawal and antisocial behavior. In the later stages of (COS) the structure of symptom dimensions changes to that known from adult-onset schizophrenia (AOS). The results indicate that COS and AOS are comparable nosological entities and that more than 3 dimensions are required to describe the relevant clinical symptom structure. Positive and global symptoms decreased significantly during the course of illness. The frequencies of negative symptoms did not change which demonstrates their disabling impact.