Evidence for two distinct domains of negative symptoms: Confirming the factorial structure of the CAINS

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.

Social pleasure in daily life: A meta-analysis of experience sampling studies in schizophrenia

Social anhedonia is considered a key feature of schizophrenia that leads to impaired social functioning. Although traditional laboratory measures assess non-current social pleasure, researchers have begun using experience sampling methods (ESM) to measure current, or consummatory, experiences of social pleasure in daily life. A recent meta-analysis examined deficits in consummatory social pleasure in schizophrenia and found vast heterogeneity in effect sizes across ESM studies. Thus, this meta-analysis aimed to extend those results by testing moderators of this effect. Meta-analysis of 14 ESM studies suggests those with psychotic disorders exhibit a moderate deficit in consummatory social pleasure compared to healthy controls. Yet, this effect was significantly moderated by the type of measure used to assess social pleasure. Measures that directly assessed positive emotional experience during socialization yielded small effects that failed to reach significance; indirect measures of other social factors related to pleasure yielded large, significant effects. This suggests daily social anhedonia observed in psychotic disorders is not due to reduced experience of positive emotion. Instead, social anhedonia may be driven by other elements of social functioning. Most clinical variables did not influence effects, but there was a trend such that patient groups with lower cognitive functioning exhibited greater pleasure deficits. Inconsistent reporting across studies limited our ability to examine other real-world variables that may contribute to deficits in social pleasure. Yet, results show different ESM items used to measure social pleasure do not assess the same construct. Future research is needed to validate ESM measures and standardize protocols across studies.

Do People With Schizophrenia Enjoy Social Activities as Much as Everyone Else? A Meta-analysis of Consummatory Social Pleasure

BACKGROUND

The "emotion paradox" of schizophrenia suggests people with schizophrenia demonstrate deficits when reporting anticipated and retrospective pleasure; yet, in-the-moment, consummatory pleasure is largely intact. It is uncertain how these findings extend to social situations. This meta-analysis aimed to (1) determine the mean difference in consummatory social pleasure between people with schizophrenia and healthy controls, and (2) examine moderators of this effect, including study design and clinical characteristics of participants.

DESIGN

A literature search using PsycINFO, Web of Science, Pubmed, and EMBASE databases was conducted. Studies measuring consummatory social pleasure using experience sampling methods and laboratory social simulations were included. Random effects meta-analyses were conducted using Hedge's g.

RESULTS

Meta-analysis of 26 studies suggests people with schizophrenia exhibited a small, significant deficit in consummatory social pleasure (g = -0.38, 90% CI [-0.53, -0.22]). There was significant heterogeneity in effect sizes; magnitude was moderated by study design and type of measure used to assess social pleasure.

CONCLUSIONS

Overall, people with schizophrenia seem to exhibit less consummatory social pleasure than controls. However, this deficit is smaller than in studies of anticipated and retrospective pleasure. Thus, consummatory social pleasure may not be quite as impaired in people with schizophrenia as traditional anhedonia research suggests. Moreover, pleasure deficits observed in people with schizophrenia may result from differences in the quality of their daily social experiences rather than differences in their capacity for social pleasure. Results have important implications for clinical interventions that address barriers to social engagement, low-pleasure beliefs, and cognitive remediation to treat schizophrenia.

The Associations of Neutrophil-Lymphocyte, Platelet-Lymphocyte, Monocyte-Lymphocyte Ratios and Immune-Inflammation Index with Negative Symptoms in Patients with Schizophrenia

Neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), monocyte-lymphocyte ratio (MLR) and systemic immune-inflammation index (SII index) are increasingly used as indicators of inflammation in different conditions, including schizophrenia. However, their relationship with negative symptoms, including anhedonia, is largely unknown. Included were 200 patients with schizophrenia and 134 healthy controls (HC), assessed for physical anhedonia (PA), using the Revised Physical Anhedonia Scale (RPAS), and social anhedonia (SA) by the Revised Social Anhedonia Scale (RSAS). Patients were rated by the Positive and Negative Syndrome Scale (PANSS), the Clinical Assessment Interview for Negative Symptoms (CAINS) and the Brief Negative Symptom Scale (BNSS). Most of the negative symptoms were in a weak to moderate positive correlations with blood cell inflammatory ratios, namely, between NLR and MLR with PANSS negative scale, CAINS, and BNSS, and in male patients, between PLR and PANSS negative scale and CAINS. Fewer correlations were detected in females, but also in a positive direction. An exception was SA, given the negative correlation between its severity and the SII index in females, and its presence and higher PLR in males. While different negative symptoms were associated with subclinical inflammation, the relationship between SA and lower inflammatory markers deserves further exploration.

Psychopathological networks in psychosis: Changes over time and clinical relevance. A long-term cohort study of first-episode psychosis

BACKGROUND

First-episode psychosis is a critical period for early interventions to reduce the risk of poor outcomes and relapse as much as possible. However, uncertainties about the long-term outcomes of symptomatology remain to be ascertained.

METHODS

The aim of the present study was to use network analysis to investigate first-episode and long-term stages of psychosis at three levels of analysis: micro, meso and macro. The sample was a cohort of 510 patients with first-episode psychoses from the SEGPEP study, who were reassessed at the long-term follow-up (n = 243). We used the Comprehensive Assessment of Symptoms and History for their assessments and lifetime outcome variables of clinical relevance.

RESULTS

Our results showed a similar pattern of clustering between first episodes and long-term follow-up in seven psychopathological dimensions at the micro level, 3 and 4 dimensions at the meso level, and one at the macro level. They also revealed significant differences between first-episode and long-term network structure and centrality measures at the three levels, showing that disorganization symptoms have more influence in long-term stabilized patients.

CONCLUSIONS

Our findings suggest a relative clustering invariance at all levels, with the presence of two domains of disorganization as the most notorious difference over time at micro level. The severity of disorganization at the follow-up was associated with a more severe course of the psychosis. Moreover, a relative stability in global strength of the interconnections was found, even though the network structure varied significantly in the long-term follow-up. The macro level was helpful in the integration of all dimensions into a common psychopathology factor, and in unveiling the strong relationships of psychopathological dimensions with lifetime outcomes, such as negative with poor functioning, disorganization with high antipsychotic dose-years, and delusions with poor adherence to treatment. These results add evidence to the hierarchical, dimensional and longitudinal structure of psychopathological symptoms and their clinical relevance in first-episode psychoses.

Revisiting the latent structure of negative symptoms in schizophrenia: Evidence from two second-generation clinical assessments

BACKGROUND

Negative symptoms are core symptom of schizophrenia, and many previous research studied the latent structure of negative symptoms based on a single measurement scale. Applying two second-generation negative symptom scales to the same sample can address measurement-invariance of latent structure.

METHODS

Three-hundred-and-five schizophrenia patients were assessed using the CAINS and the BNSS. Confirmatory Factor Analysis (CFA) tested four competing factor-models: (1) a 1-factor model; (2) a 2-factor model comprising the motivation and pleasure (MAP) domain and the diminished expression (EXP) domain; (3) a 5-factor model comprising anhedonia, avolition, asociality, blunted affect and alogia; (4) a hierarchical model comprising the "first-order" 5-domain factors and the "second-order" MAP & EXP factors.

RESULTS

The CFA results for the data of the CAINS showed that the 2-factor model had the best data fit over the other competing models. The CFA using the BNSS data in the same sample also supported the superiority of the 2-factor model. Lastly, after combining the items of the BNSS and CAINS together in the same sample for CFA, the 2-factor model prevailed over the other competing models.

CONCLUSIONS

The 2-factor model appears to be measurement-invariant latent structure of negative symptoms. The novel method of combining the items of the CAINS and BNSS might have circumvented the possible imperfect construct of a single scale. Our findings support the MAP and EXP factors as the latent structure for negative symptoms.

Negative and depressive symptoms differentially relate to real-world anticipatory and consummatory pleasure in schizophrenia

It has been suggested that schizophrenia is associated with deficits in anticipatory but not consummatory pleasure, though there is mixed support for this hypothesis. As individuals with schizophrenia can experience both negative and depressive symptoms, symptom heterogeneity in this population could contribute to these mixed hedonic findings. Specifically, while some research suggests that negative symptoms of schizophrenia are related to reduced anticipatory but not consummatory pleasure, research on major depressive disorder suggests that depressive symptoms are associated with both decreased anticipatory and consummatory pleasure. Still, it is unclear whether depressive symptoms are associated with experiences of pleasure in schizophrenia as they are in major depressive disorder. Thus, the present study used Ecological Momentary Assessment (four prompts per day over one week) to investigate the unique relationships of negative and depressive symptoms with daily reports of real-world anticipatory and consummatory pleasure in 63 individuals with schizophrenia. Higher negative symptoms related to reduced anticipatory but not consummatory pleasure. On the other hand, higher depressive symptoms related to reductions in both anticipatory and consummatory pleasure. Overall, these results indicate that negative and depressive symptoms are differentially associated with hedonic experience in schizophrenia, and suggest the need to account for the severity of both these symptom types when examining pleasure in this population. Elucidating the nature of these symptom contributions to hedonic impairments could increase causal understanding of these deficits and contribute to the development of more targeted treatments to enhance motivation and pleasure in schizophrenia.

From Memories of Past Experiences to Present Motivation? A Meta-analysis on the Association Between Episodic Memory and Negative Symptoms in People With Psychosis

Based on findings from cognitive science, it has been theorized that the reductions in motivation and goal-directed behavior in people with psychosis could stem from impaired episodic memory. In the current meta-analysis, we investigated this putative functional link between episodic memory deficits and negative symptoms. We hypothesized that episodic memory deficits in psychosis would be related to negative symptoms in general but would be more strongly related to amotivation than to reduced expressivity. We included 103 eligible studies (13,622 participants) in the analyses. Results revealed significant, moderate negative associations of episodic memory with negative symptoms in general (k = 103; r = -.23; z = -13.40; P ≤ .001; 95% CI [-.26; -.20]), with amotivation (k = 16; r = -.18; z = -6.6; P ≤ .001; 95% CI [-.23; -.13]) and with reduced expressivity (k = 15; r = -.18; z = -3.30; P ≤.001; 95% CI[-.29; -.07]). These associations were not moderated by sociodemographic characteristics, positive symptoms, depression, antipsychotic medication or type of negative symptom scale. Although these findings provide sound evidence for the association between episodic memory deficits and amotivation, the rather small magnitude and the unspecific pattern of this relationship also indicate that episodic memory deficits are unlikely to be the only factor relevant to amotivation. This implicates that future research should investigate episodic memory in conjunction with other factors that could account for the association of episodic memory deficits and amotivation in psychosis.

Impact of Negative Symptoms on Functioning and Quality of Life in First Psychotic Episodes of Schizophrenia

Negative symptoms are not considered a unitary construct encompassing two different domains, diminished expression, and avolition-apathy. The aim of this study was to explore the relationships between each domain and psychosocial functioning and quality of life in people with a first psychotic episode of schizophrenia. In total, 61 outpatients were assessed with the Clinical Assessment Interview for Negative Symptoms (CAINS), The Functioning Assesment Short Test (FAST) and The Quality of Life Scale (QLS). The mean global score for CAINS was 21.5 (SD: 15.6), with a CAINS Avolition-Apathy (MAP) score of 17.0 (SD: 11.8), and CAINS Diminished Expression (EXP) score of 4.5 (SD: 5.0). The mean FAST score was 31.9 (SD: 18.9), and 41.1 (SD: 17.9) for QLS. Linear regression analysis revealed a significant (F(4,53) = 15.65, p < 0.001) relationship between MAP and EXP CAINS’ score and FAST score. CAINS-MAP was more predictive of FAST scores (β = 0.44, p = 0.001) than CAINS-EXP (β = 0.37, p = 0.007). Linear regression analysis for QLS revealed a significant model (F(4,56) = 29.29, p < 0.001). The standardized regression weight for the CAINS-MAP was around three times greater (β = −0.63, p < 0.001) than for CAINS-EXP (β = −0.24, p = 0.024). The two different domains are associated differently with functionality and quality of life.

Cognitive, community functioning and clinical correlates of the Clinical Assessment Interview for Negative Symptoms (CAINS) in psychotic disorders

Negative symptoms are a core dimension of schizophrenia and other psychoses that account for a large degree of the poor functional outcomes related to these disorders. Newer assessment scales for negative symptoms, such as the Clinical Assessment Interview for Negative Symptoms (CAINS), provide evidence for separate dimensions of motivational and pleasure (MAP) and expression (EXP) dimensions. This study was aimed at extending the analysis of the clinical, functional and cognitive correlates of CAINS dimensions in a sample of patients with psychotic disorders (n = 98) and 50 healthy controls.A psychopathological evaluation was conducted by using the Comprehensive Assessment of Symptoms and History (CASH). To assess the extrapyramidal signs, the UKU scale was used. Community functioning was evaluated by means of real-world and functional attainment measures. Additionally, a full neuropsychological test battery was administered. Pearson correlation and hierarchical multiple linear regression analyses were performed to identify the influencing and predictive factors associated with the CAINS dimensions.The MAP and EXP dimensions showed strong associations with the Scale for the Assessment of Negative Symptoms (SANS) items and were not significantly associated with extra-pyramidal or cognitive deficits. The MAP and EXP CAINS dimensions revealed good predictive validity for real-world functioning and functional attainment measures.These findings suggest that the CAINS scale endorses good convergent validity for the assessment of negative symptoms and is very useful in the prediction of psychosocial functioning. In addition, the CAINS dimensions might provide advantages over old assessment scales on disentangling the complex associations between negative symptoms and cognitive impairment.

Deconstructing depression and negative symptoms of schizophrenia; differential and longitudinal immune correlates, and response to minocycline treatment

BACKGROUND

Immune dysfunction has been implicated in negative symptoms of schizophrenia and also in depression. These disorders are frequently co-morbid, with some symptoms such as anhedonia and apathy common to both. The anti-inflammatory agent minocycline may be ineffective in schizophrenia, but more positive effects have been seen in depression. Our aim was to investigate the role of immune dysfunction in depression and sub-domains of negative symptoms in schizophrenia by investigating their intercorrelation and the influence of treatment with minocycline.

METHODS

We analysed longitudinal data from 207 patients within 5 years of onset of schizophrenia, from the randomised double-blind, placebo-controlled trial of minocycline (BeneMin). Symptom ratings and circulating IL-6, C-reactive protein (CRP) and TNF-α concentrations were collected at baseline and repeated over twelve months. The sample was not stratified by CRP prior to randomisation. Positive and Negative Syndrome Scale composite ratings of avolition-apathy and diminished expression, Calgary Depression Scale total scores, and immune markers were examined cross-sectionally using Spearman's rank, and longitudinally by linear mixed effect models that included body mass index and minocycline. Additionally, post hoc analysis of the sample stratified by elevated CRP (>1 mg/l and <10 mg/l at baseline) was carried out to assess whether minocycline had any effect on specific symptoms in an immune active sub-group of patients.

RESULTS

Depression and avolition-apathy were significantly positively related, and depression correlated weakly with IL-6 at baseline. Diminished expression was associated with increased TNF-α both cross-sectionally and longitudinally. CRP was unrelated to any symptom domain. Minocycline did not affect any individual symptom or sub-domain in the full sample or in the immune active sub-group.

DISCUSSION

IL-6 may have some specificity to depression in early schizophrenia. TNF-α may be an indicator of immune dysfunction relevant to negative symptoms, and our longitudinal findings add to this evidence. However, minocycline continues to show very little promise as a treatment for any symptom dimension of early schizophrenia.

What is the Best Latent Structure of Negative Symptoms in Schizophrenia? A Systematic Review

Background

Determining the best latent structure of negative symptoms in schizophrenia could benefit assessment tools, neurobiological research, and targeted interventions. However, no review systematically evaluated studies that assessed and validated latent models of negative symptoms.

Objective

To identify and evaluate existing latent structure models in the literature of negative symptoms and to determine the best model.

Method

Systematic search of MEDLINE, EMBASE, and Scopus on July 19, 2020, for confirmatory factor analysis models of negative symptoms in patients with schizophrenia. The available evidence was assessed through 2 sets of criteria: (1) study design quality—based on negative symptoms assessment and modeling strategy and (2) psychometric quality and model fit—based on fit indices and factor definition quality.

Results

In total, 22 studies (n = 17 086) from 9 countries were included. Studies differed greatly regarding symptom scales, setting, and sample size (range = 86–6889). Dimensional models included 2–6 factors (median = 4). Twelve studies evaluated competing models and adopted appropriate instruments to assess the latent structure of negative symptoms. The 5-factor and hierarchical models outperformed unitary, 2-factor, and 3-factor models on all direct comparisons, and most of the analyses derived from the Brief Negative Symptom Scale. Considering the quality criteria proposed, 5-factor and hierarchical models achieved excellent fit in just one study.

Conclusions

Our review points out that the 5-factor and hierarchical models represent the best latent structure of negative symptoms, but the immaturity of the relevant current literature may affect the robustness of this conclusion. Future studies should address current limitations regarding psychometric properties and also address biological and clinical validity to refine available models.

Retinal functioning and reward processing in schizophrenia

Retinal responses to light, as measured by electroretinography (ERG), have been shown to be reduced in schizophrenia. Data from a prior ERG study in healthy humans indicated that activity of a retinal cell type affected in schizophrenia can be modified by the presence of a food reward. Therefore, we aimed to determine whether ERG amplitudes would be sensitive to the well-documented reward processing impairment in schizophrenia. Flash ERG data from 15 clinically stable people with schizophrenia or schizoaffective disorder and 15 healthy controls were collected under three conditions: baseline, anticipation of a food reward, and immediately after consuming the food reward. At the group level, data indicated that controls' ERG responses varied as a function of salience of the food reward (baseline vs. anticipation vs. consumption) whereas patients' ERG responses did not vary significantly across conditions. Correlations between ERG amplitudes and scores on measures of hedonic capacity (including motivation and pleasure negative symptom ratings for patients) indicated consistent relationships. These data suggest that flash ERG amplitudes may be a sensitive indicator of the integrity of reward processing mechanisms. However, several differences in the direction of findings between this and a prior study in controls point to the need for further investigation of the contributions of a number of key variables to the observed effects.

The Symptom and Domain Structure of Psychotic Disorders: A Network Analysis Approach

Little is understood about the symptom network structure of psychotic disorders. In the current study, we aimed to examine the network structure of psychotic symptoms in a broad and transdiagnostic sample of subjects with psychotic disorders (n = 2240) and to determine whether network structure parameters vary across demographic, sampling method and clinical variables. Gaussian graphical models were estimated for 73 psychotic symptoms assessed using the Comprehensive Assessment of Symptoms and History. A 7-cluster solution (reality distortion, disorganization, catatonia, diminished expressivity, avolition/anhedonia, mania, and depression) best explained the underlying symptom structure of the network. Symptoms with the highest centrality estimates pertained to the disorganization and, to a lesser extent, negative domains. Most bridge symptoms pertained to the disorganization domain, which had a central position within the network and widespread connections with other psychopathological domains. A comparison of networks in subgroups of subjects defined by premorbid adjustment levels, treatment response, and course pattern significantly influenced both network global strength and network structure. The sampling method and diagnostic class influenced network structure but not network global strength. Subgroups of subjects with less densely connected networks had poorer outcomes or more illness severity than those with more densely connected networks. The network structure of psychotic features emphasizes the importance of disorganization symptoms as a central domain of psychopathology and raises the possibility that interventions that target these symptoms may prove of broad use across psychopathology. The network structure of psychotic disorders is dependent on the sampling method and important clinical variables.