[Validation of the French version of the self-evaluation of negative symptoms (SNS)]

INTRODUCTION

Schizophrenia is a disorder affecting 1% of the population and is associated with severe functional impairment. Negative symptoms are responsible for the majority of this impairment, and many patients with schizophrenia have negative symptoms. However, their evaluation is still a challenge. Thus, standardized assessments are needed to facilitate identification of these symptoms. Many tools have been developed, but most are based on observer ratings. Self-evaluation can provide an additional outcome measure and allow patients to be more engaged in their treatment. The Self-evaluation of Negative Symptoms (SNS) has been developed recently. This is a remarkably understandable instrument for patients with schizophrenia as it allows them to readily complete it without assistance, providing information with respect to their own perception of negative symptoms. The SNS is a self-assessment that permits patients to evaluate themselves in 5 dimensions of negative symptoms. This validation study for the SNS revealed good psychometric properties alongside satisfactory acceptance by patients.

AIM

This study was to confirm the validation of the French version of the self-evaluation of negative symptoms (SNS).

METHODS

Patients with schizophrenia or schizoaffective disorder according to the DSM-IV-R, with a stable regimen of anti-psychotic drugs for the last two months, aged more than 18 years old were eligible for the study. Symptoms were rated using the SNS, the Scale for the Assessment of Negative Symptoms (SANS), the Calgary Depression Scale for Schizophrenics (CDSS), the Brief Psychiatric Rating Scale (BPRS) and the Clinical Global Impression and Parkinsonism. Patients were asked to fulfill the SNS twice, 6 weeks apart.

RESULTS

Sixty patients were evaluated. Cronbach's coefficient (α=0.8) showed good internal consistency. The SNS significantly correlated with the SANS (r=0.6), the negative sub-score of the BPRS (r=0.6) and the Clinician Global Impression on the severity of negative symptoms (r=0.7). SNS scores did not correlate with level of insight (r=0.08) or Brief Psychiatric Rating Scale positive sub-scores (r=0.2). SNS scores correlated with CDSS scores. However, we did not find correlation between the first item of the CDSS which evaluates depression and the "diminished emotional range" sub-score of SNS. The test-retest of SNS revealed no changes of scores at two evaluations 6 weeks apart.

CONCLUSION

The acceptance by patients of the SNS was excellent. The French version of the SNS demonstrated a good internal consistency, good convergent validity and good discriminant validity. The study demonstrates the ability of patients with schizophrenia to accurately report their own experiences. Self-assessments of negative symptoms should be more widely employed in clinical practice because they may allow patients with schizophrenia to develop appropriate coping strategies.

[Psychopathological aspects of negative symptoms in schizophrenia]

During the past ten years, research on schizophrenia has witnessed a clear emphasis on studies based on negative symptoms. This interest can be explained in terms of diagnosis, specific treatment, functional prognosis and outcome issues. However, main current approaches consider negative symptoms from an operationalist view, which implies objective and atheoretical descriptions of clinical criteria, observed from a third person perspective. And the understanding of negative symptoms in schizophrenia, still a crucial issue of mental health, remains only partial. From a different perspective, psychopathology - and notably psychiatric phenomenology -, can provide a conceptual and clinical framework, taking into account subjective experience (first person perspective), based on a global understanding of the clinical situation lived by patients with schizophrenia. In the present review, we give a brief survey on the historical aspects of the description of negative symptoms. Then, we introduce the clinical contributions raised by clinical phenomenology. We principally develop Minkowski's notion of loss of vital contact, and Blankenburg's notion of loss of natural evidence. Then we highlight the current debates which are discussed and explored in contemporary psychopathology. In conclusion, we discuss the possible articulation between objective and subjective approaches, in order to better understand pauci-symptomatic forms of schizophrenia.

[Negative symptoms in schizophrenia and substance-related disorders]

Dual diagnosis of schizophrenia and substance-related disorders is common in psychiatric practice. Epidemiologic studies and report have established that the risk of a substance-related disorder was 4 to 5 times higher in a population of psychiatric patients than in the general population. However, little is known on the reason of this relationship and the treatments required. It's well known that a family history of psychosis is a risk factor of schizophrenia. Similarly a family history of substance use disorders increases the risk of using substances. Because the two disorders often occurred together, it could be hypothesized that a genetic risk factor is common. However, recent studies did not confirm this hypothesis and it seems that their genetic risks factor would be unrelated. Evidence now exists describing the different profiles of patients whether they used substance or not. Concerning negative symptoms clinical studies and meta-analyses have described fewer symptoms in schizophrenia patients with a substance use disorder. Among the different explanations that have been addressed, it seems that a lower capability of obtaining the substance could partly explain this relationship. Perhaps because patients with social withdrawal have more difficulties to find and spend the time required to obtain abused substances. At the opposite some products such as cocaine may relieve some symptoms especially anhedonia and alogia. However the link between substance-related disorders and negative symptoms is weak and decreases in more recent studies, probably because negative symptoms as well as addiction disorders are better characterized. Considering that treating psychiatric symptoms may not always lead to a decrease in the substance-related disorders but that patients who give up substances improve their psychotic symptoms, a therapeutic strategy should be planned for these dual disorders patients combining psychiatry and addiction interventions.

[Negative symptoms of schizophrenia: from electrophysiology to electrotherapy]

The aim of this review of the literature is to summarize the state of the knowledge concerning the relationship between negative symptoms in schizophrenia, electrophysiology and electrotherapy. The scientific literature search of international articles was performed during August and September 2015 using the PubMed electronic database. We used the following MeSH terms: "Negative symptoms", "Schizophrenia", "Electrophysiology", "Neurophysiology", "EEG power", "Alpha rhythm", "Transcranial magnetic stimulation", "Transcranial direct current stimulation", "Electroconvulsive therapy", "Neurofeedback", "Vagus Nerve Stimulation", "Deep Brain Stimulation", and "State dependent". Negative symptoms in schizophrenia are associated with altered activity in prefrontal cortex in functional neuroimaging studies. This is in line with electrophysiological measurements that found a change in EEG spectral power in the alpha frequency band over prefrontal brain regions. The notion of functional hypofrontality has led to hypotheses that electrotherapy applied to the prefrontal cortex may be an effective treatment of negative symptoms in schizophrenia. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) were used to increase cortical activity in schizophrenia and achieve a clinical effect on negative symptoms. Three meta-analyses confirmed, with a moderate effect size, that rTMS is an effective treatment option for negative symptoms in schizophrenia. The two subsequently published prospective multicenter studies, however, found opposite results from each other. Two randomized controlled studies suggested that tDCS is an effective treatment option for negative symptoms. There is no study on the efficacy of neurofeedback, vagal nerve stimulation or deep brain stimulation on negative symptoms in schizophrenia. Additional studies are needed to confirm the efficacy of rTMS and tDCS on negative symptoms in schizophrenia. Influencing factors, related to clinical and stimulation parameters, of rTMS and tDCS on negative symptoms should be better investigated. Effects related to electrophysiological brain activity of the patient, especially in the alpha band, during the stimulation should also be better investigated. The action of electrotherapy may be state dependent, and a better understanding of electrophysiological effects of electrotherapy techniques could enable their optimization.

[Negative symptoms in schizophrenia: psychotherapeutic approaches]

Although negative symptoms are recognized as a central feature of schizophrenia, their definition as well as phenomenology have long been a vexing issue. During these last years, a major progress has been made with the delineation of two underlying subdomains of negative symptoms: diminished expression and anhedonia-avolition-apathy. As current guidelines are not always in accord on the efficacy of treatments on negative symptoms, it may be tempting to re-interpret the findings of clinical trials by looking at the effects of treatments on these two subdomains. This could concern both psychotropic treatments and psychotherapeutic interventions. Furthermore, neuroimaging as well as emotional response studies have permitted to better understand the mechanism which could be at the root of diminished expression and anhedonia in schizophrenia. On this basis, new psychotherapeutic methods have been devised which, by specifically targeting these two subdomains, are likely to be more efficient on negative symptoms. Further research is warranted to test their efficacy in randomized controlled trials.

[Use of antidepressants in the treatment of negative symptoms of schizophrenia]

Negative symptoms account for a clinical dimension of schizophrenia. They are partly the cause of functional disability of this disease. Clinical experience shows that antipsychotics have little or no effect on these symptoms. The aim of this review is to gather existing data on the treatment of negative symptoms with antidepressants. The combination of antipsychotics with antidepressants is a therapeutic strategy commonly used for the treatment of these symptoms. The pro-dopaminergic effects of antidepressants explain their effectiveness on negative symptoms. There are many comparative, randomized, controlled studies evaluating the efficacy of antidepressant associated with antipsychotic for the treatment of negative symptoms. Furthermore three meta-analyses have been conducted. The overall results suggest that the use of antidepressants may contribute to clinical improvement of negative symptoms in schizophrenia. The limitations of these studies are the small number of patients included and the definition and assessment of negative symptoms. The existing scales are not sufficiently discriminating. Further research using new measurement tools should help refine these results.

[Negative symptoms and cerebral imaging]

A number of neuroanatomical and neurofonctional abnormalities have been evidenced by cerebral imaging studies in patients suffering from schizophrenia. Nevertheless, those specifically associated with the negative symptoms of this disease are still insufficiently known. This work is a review of selected studies that have assessed the brain correlates of negative symptoms in schizophrenia. Approaches using structural imaging have highlighted reduction of gray matter density or cortical thickness associated with negative symptoms, which is rather sparsely distributed within the frontal and temporal regions, localized nevertheless more particularly in the frontal medial and orbitofrontal areas, as well as the amygdalo-hippocampic complex. These deficits are concurrent with a loss of integrity of the principal paths of white matter tracts between frontal and limbic regions. On the other hand, neurofonctional abnormalities associated with negative symptoms involve especially the frontal areas and limbic striatum. A disturbed functioning within the fronto-striatal loops, related to a striatal dopaminergic deficit, may represent a potential explanatory hypothesis of the negative symptoms of schizophrenia, as suggested by studies using Positron Emission Tomography on this topic or neuroimaging studies on the effects of antipsychotics. A better identification of the cerebral abnormalities associated with the negative dimension of schizophrenia, with regard to the lateralization of these abnormalities or to their changes during the course of the disease, could offer new therapeutic modalities for the treatment of this dimension which, until now, remains few responsive to conventional pharmacological treatments.