Concepts and methods when considering negative symptom course

The relationship between human development and prevalence of deficit schizophrenia: Results from a systematic review and meta-analysis

This study examined the relationship between the prevalence of deficit schizophrenia (DS) and a country's Human Development Index (HDI). A systematic review and meta-analysis of the literature published in the last decade were conducted to acquire data on the worldwide prevalence of deficit syndrome in schizophrenia cohorts and examine the correlation between DS prevalence and the HDI of the countries in the review. Twenty-six studies meeting our eligibility criteria provided prevalence data on DS in 14 countries with both low-to-middle and high-incomes, ranging from 14.34%-to 61.57%. The pooled prevalence of DS was 32.19% (95% CI = 26.17 to 38.52). Statistical analysis yielded a correlation coefficient (r) of -0.518 (95% CI = -0.754 to -0.164; p = 0.007), indicating a moderate inverse correlation between DS prevalence and HDI. This relationship remained significant in partial correlation analysis after controlling for potential sources of bias in the DS estimates (r = -0.489, p = 0.013). Our results show that schizophrenia cohorts from low-to-middle-income countries are more prone to primary and enduring negative symptoms, and contribute to the emerging evidence questioning the axiom that schizophrenia in the developing world has a better course than in high-income countries.

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.

Early-Stage Negative Symptom Trajectories and Relationships With 13-Year Outcomes in First-Episode Nonaffective Psychosis

Negative symptoms are a key treatment target in early psychosis intervention. There is a paucity of research examining longitudinal course of negative symptoms across the initial years of treatment for first-episode psychosis using individual-based trajectory analysis. No study has been conducted investigating differential relationships of early-stage negative symptom trajectories with long-term distal outcomes. This study examined patterns and baseline predictors of negative symptom trajectories over the first 3 years of treatment in 138 patients aged 18-55 years presenting with first-episode nonaffective psychosis, using latent class growth analysis based on symptom ratings measured at 4 different time points (baseline, 1, 2, and 3 years). We further explored prospective relationships of identified trajectory classes with functional and negative symptom outcomes at 13-year follow-up. Our results revealed 3 distinct negative symptom trajectories including minimal-stable (59.6%), mild-stable (29.4%), and high-increasing (11.0%) trajectories. Poorer premorbid adjustment, more severe global cognitive impairment, and depressive symptoms at baseline were found to predict high-increasing trajectory. Among 3 trajectory classes, patients in high-increasing trajectory had the worst functional and negative symptom outcomes at 13-year follow-up, with post hoc analyses demonstrating significant outcome differences between high-increasing and minimal-stable trajectories. Our findings thus affirm a heterogeneous course of negative symptoms in first-episode psychosis and indicate that early-stage negative symptom trajectories are critically associated with long-term outcomes. Patients displaying persistently high negative symptom levels in the initial 3 years of treatment may represent a specific subgroup who necessitates an extended period of early intervention specifically targeting at negative symptoms to promote early functional recovery.

Correspondence between negative symptoms and potential sources of secondary negative symptoms over time

There has been a debate in the literature about the distinction between primary and secondary negative symptoms of schizophrenia. Our aim was to study the associations between negative symptoms and potential sources of secondary negative symptoms over time. A sample of 275 participants with at least mid-moderate negative symptoms was randomized into body psychotherapy or Pilates class in a previous study. No significant differences were found between groups over time and changes in the symptom domains were modest. The present investigation considers the longitudinal correlation between variables of interest at baseline, 3 and 9 months follow-up. Measures were the Clinical Assessment Interview for Negative Symptoms (CAINS), the Positive and Negative Symptom Scale (PANSS), the Calgary Depression Scale (CDSS) and the Simpson-Angus Extrapyramidal side-effects Scale (SAS). Mixed models were computed to test the longitudinal association between these variables. In a sensitivity analysis, the dosages of antipsychotic, illness duration and allocated intervention were taken into account. Overall, the course of extrapyramidal side-effects, depressive and positive symptoms was significantly related to the course of negative symptoms. Only extrapyramidal effects were longitudinally correlated to expressive negative symptoms. The sensitivity analyses showed unaltered results for positive symptoms and depression but a lack of association between extrapyramidal effects and the CAINS outcomes. In conclusion, the unambiguous interpretation between primary and secondary negative symptoms may lead to refined treatment approaches for schizophrenia and to increased effects of the interventions.

Is the Prevalence of the Deficit Syndrome in Schizophrenia Higher than Estimated? Results of a Meta-Analysis

The primary and enduring presence of negative symptoms observed in a relatively homogeneous subgroup of patients with schizophrenia led to the concept of deficit syndrome (DS). Until date, it is considered that 20-25% of schizophrenia cohorts have DS. The aim of this meta-analysis was to determine the current prevalence of DS, including international and most recent studies. Thirteen observational studies met the inclusion criteria, comprising 2092 patients from eight countries. Pooled proportion of the DS subgroup was 32.64%, higher than previously reported. Based on our outcomes, up to one-third of patients with schizophrenia might have idiopathic and stable negative symptoms. This significant proportion of patients should be well represented in clinical trial's samples.

The course of negative symptoms in first-episode schizophrenia and its predictors: A prospective two-year follow-up study

AIMS

This study aimed to investigate the course of negative symptoms and its stability over a two-year period following a first-episode schizophrenia (FES) and the possible predictors of higher severity in this symptomatology after this period.

METHODS

In this longitudinal two-year prospective follow-up study we included 268 patients with a FES, according to DSM-IV. Analysis of variance was conducted in patients who completed the full follow-up to study changes in negative symptoms over three visits. Regression analyses were conducted to show correlates and potential predictors of negative symptoms at two-year follow-up.

RESULTS

There was a significant effect for time in negative symptomatology, which was less severe at one-year follow-up after a FES and remained stable up to two years (Time 1>Time 2>Time 3); F(2,151)=20.45, p<0.001. Poorer premorbid adjustment (p=0.01) and higher negative symptoms at baseline (p<0.001) made a significant contribution to the changes in the negative symptoms severity at two-years after a FES (R²=0.21, p<0.001).

CONCLUSIONS

We found a reduction in the negative symptomatology at one-year after a FES. This change remained stable at two-year. Our results suggested that the presence of this symptomatology early in the course of the illness, together with a poorer premorbid adjustment, predict more severe negative symptoms at mid-term outcome.