Current perspectives in treating negative symptoms of schizophrenia: A narrative review (Review)

Pharmacological Treatments of Negative Symptoms in Schizophrenia-An Update

Schizophrenia is a chronic psychotic disorder comprising positive symptoms, negative symptoms, and cognitive deficits. Negative symptoms are associated with stigma, worse functional outcomes, and a significant deterioration in quality of life. Clinical diagnosis is challenging despite its significance, and current treatments offer little improvement in the burden of negative symptoms. This article reviews current pharmacological strategies for treating negative symptoms. Dopaminergic, glutamatergic, serotonergic, noradrenergic, cholinergic, anti-inflammatory compounds, hormones, and psychostimulants are explored. Finally, we review pharmacological global treatment guidelines for negative symptoms. In general, switching to a second-generation antipsychotic seems to be most often recommended for patients with schizophrenia on first-generation antipsychotics, and an add-on antidepressant is considered when depression is also present. However, the treatment of negative symptoms remains an unmet need. Future, larger clinical studies and meta-analyses are needed to establish effective pharmacological agents for the effective treatment of negative symptoms.

A review on the pharmacology of cariprazine and its role in the treatment of negative symptoms of schizophrenia

Management of negative symptoms is one of the most challenging and important unmet needs of schizophrenia treatment. Negative symptoms together with positive symptoms result in significant psychosocial impairment and poor quality of life. Existing studies on atypical antipsychotics reported limited treatment adherence due to higher prevalence of treatment-emergent adverse events, such as diabetes, weight gain, hyperlipidemia, hyperprolactinemia and hypertension. A compound with greater affinity for dopamine D2/D3 receptors may improve negative symptoms, mood, and cognitive impairment associated with schizophrenia. In 2015, the US FDA has approved cariprazine, a partial D2/D3 agonist for treatment of schizophrenia, mania or mixed episodes. Midlands and Lancashire Commissioning Support Unit, UK (2019) has particularly suggested cariprazine for the treatment of predominant negative symptoms of schizophrenia. India's Central Drugs Standard Control Organization (CDSCO) has approved cariprazine in 2021 for the treatment of schizophrenia, manic or mixed episodes associated with bipolar I disorder. A ten-fold greater affinity for D3 receptors and partial agonism to serotonin receptors, along with longer half-life make cariprazine distinct when compared with other atypical antipsychotics. Cariprazine is also reported to have fewer incidents of metabolic and hormonal adverse events, and has been shown to provide better relapse prevention. Recent evidence indicates promising effect of cariprazine in ameliorating negative symptoms as well as psychotic symptoms in patients with schizophrenia. In addition, improved adherence to treatment (adjunctive/monotherapy) with cariprazine in patients having inadequate response to an ongoing antipsychotic treatment has also been clinically established. This review presents the evidence-based safety and efficacy of cariprazine for treatment of predominant negative symptoms of schizophrenia.

Brexpiprazole in patients with schizophrenia with or without substance use disorder: an observational study

Background

Partial dopamine D2 receptor agonists are used for psychotic symptoms in adults with schizophrenia spectrum disorders. Recently, interest surged for partial dopamine D2 receptor agonists in substance use disorders (SUDs). Since it is believed that SUDs decrease the efficacy of pharmacotherapy of underlying psychiatric disorders, we tested the efficacy of the partial D2 agonist brexpiprazole in patients with schizophrenia who were either comorbid with a SUD (SUD group) or not comorbid (non-SUD) to assess treatment response and the effect of brexpiprazole on substance craving in SUD.

Methods

We included patients with DSM-5/DSM-5-TR schizophrenia (using SCID-5-CV) aged 18-66 years with either comorbid SUD or non-SUD to treat with brexpiprazole 4 mg/day for 6 months during February-October 2022. Patients were assessed with the Clinical Global Impressions-Severity (CGI-S) scale, the 24-item Brief Psychiatric Rating Scale (BPRS), and the Positive And Negative Syndrome Scale (PANSS) at baseline, weekly for the first 2 months and monthly for the next four. Furthermore, we assessed substance craving in SUD with a visual analog scale for craving (VAScrav) at the same timepoints.

Results

The total sample was 86 (85 analysable) 18- to 64-year-old (mean 39.32 ± 14.09) patients with schizophrenia [51 men (59.3%) and 35 women (40.7%)], of whom 48 SUD (55.8%) (37 men and 11 women) and 38 non-SUD (44.2%) (14 men and 24 women). No serious or persistent adverse events developed over the study period, but one patient dropped out for subjective akathisia. Results indicated the main effects of time with improvements over the course of the study for CGI-S, BPRS, and PANSS in both SUD and non-SUD groups and the entire sample, and for VAScrav in SUD. Brexpiprazole was associated with similar significant improvements in both groups at the 6 month endpoint compared to baseline.

Conclusion

Treatment with brexpiprazole for 6 months improved psychotic symptoms in patients with schizophrenia, independently from whether they belonged to the SUD or the non-SUD group; hence, SUD comorbidity did not confer treatment resistance to brexpiprazole. Furthermore, in the SUD group, we observed reduced substance craving.

Neonatal phencyclidine as a model of sex-biased schizophrenia symptomatology in adolescent mice

Sex-biased differences in schizophrenia are evident in several features of the disease, including symptomatology and response to pharmacological treatments. As a neurodevelopmental disorder, these differences might originate early in life and emerge later during adolescence. Considering that the disruption of the glutamatergic system during development is known to contribute to schizophrenia, we hypothesized that the neonatal phencyclidine model could induce sex-dependent behavioral and neurochemical changes associated with this disorder during adolescence. C57BL/6 mice received either saline or phencyclidine (5, 10, or 20 mg/kg) on postnatal days (PN) 7, 9, and 11. Behavioral assessment occurred in late adolescence (PN48-50), when mice were submitted to the open field, social interaction, and prepulse inhibition tests. Either olanzapine or saline was administered before each test. The NMDAR obligatory GluN1 subunit and the postsynaptic density protein 95 (PSD-95) were evaluated in the frontal cortex and hippocampus at early (PN30) and late (PN50) adolescence. Neonatal phencyclidine evoked dose-dependent deficits in all analyzed behaviors and males were more susceptible. Males also had reduced GluN1 expression in the frontal cortex at PN30. There were late-emergent effects at PN50. Cortical GluN1 was increased in both sexes, while phencyclidine increased cortical and decreased hippocampal PSD-95 in females. Olanzapine failed to mitigate most phencyclidine-evoked alterations. In some instances, this antipsychotic aggravated the deficits or potentiated subthreshold effects. These results lend support to the use of neonatal phencyclidine as a sex-biased neurodevelopmental preclinical model of schizophrenia. Olanzapine null effects and deleterious outcomes suggest that its use during adolescence should be further evaluated.

Efficacy and safety of adjunctive therapy with fingolimod in patients with schizophrenia: A randomized, double-blind, placebo-controlled clinical trial

OBJECTIVES

Studies have suggested that fingolimod, a sphingosine-1-phosphate receptor modulator, exerts neuroprotective and anti-inflammatory effects. Although fingolimod is approved for the treatment of relapsing-remitting multiple sclerosis, limited studies have investigated its effects in patients with schizophrenia. This study investigated the efficacy and safety of fingolimod adjuvant to risperidone in schizophrenia treatment.

METHODS

This eight-week, randomized, double-blinded, placebo-controlled trial included 80 (clinical trials registry code: IRCT20090117001556N137) patients with chronic schizophrenia. Participants were assigned to two equal arms and received risperidone plus either fingolimod (0.5 mg/day) or a matched placebo. The positive and negative symptom scale (PANSS) was used to measure and compare the effectiveness of treatment strategies at baseline and weeks 2, 4, 6, and 8. Treatment side effects were also compared.

RESULTS

Seventy participants completed the trial (35 in each arm). The baseline characteristics of the groups were comparable (P-value > 0.05). There were significant time-treatment interaction effects on negative symptoms (P-value = 0.003), general symptoms (P-value = 0.037), and the PANSS total score (P-value = 0.035), suggesting greater improvement in symptoms following the fingolimod adjuvant therapy. In contrast, the longitudinal changes in positive and depressive symptoms were similar between the groups (P-values > 0.05). Regarding the safety of treatments, there were no differences in extrapyramidal symptoms [assessed by the extrapyramidal symptom rating scale (ESRS)] or frequency of other complications between the fingolimod and the placebo groups (P-values > 0.05).

CONCLUSIONS

This study indicated that fingolimod is a safe and effective adjuvant agent for schizophrenia treatment. However, further clinical trials are required to suggest extensive clinical application.

Resting-State Brain Activity Dysfunctions in Schizophrenia and Their Associations with Negative Symptom Domains: An fMRI Study

The aim of the present study was to examine the neurobiological correlates of the two negative symptom domains of schizophrenia, the Motivational Deficit domain (including avolition, anhedonia, and asociality) and the Expressive Deficit domain (including blunted affect and alogia), focusing on brain areas that are most commonly found to be associated with negative symptoms in previous literature. Resting-state (rs) fMRI data were analyzed in 62 subjects affected by schizophrenia (SZs) and 46 healthy controls (HCs). The SZs, compared to the HCs, showed higher rs brain activity in the right inferior parietal lobule and the right temporoparietal junction, and lower rs brain activity in the right dorsolateral prefrontal cortex, the bilateral anterior dorsal cingulate cortex, and the ventral and dorsal caudate. Furthermore, in the SZs, the rs brain activity in the left orbitofrontal cortex correlated with negative symptoms (r = -0.436, p = 0.006), in particular with the Motivational Deficit domain (r = -0.424, p = 0.002), even after controlling for confounding factors. The left ventral caudate correlated with negative symptoms (r = -0.407, p = 0.003), especially with the Expressive Deficit domain (r = -0.401, p = 0.003); however, these results seemed to be affected by confounding factors. In line with the literature, our results demonstrated that the two negative symptom domains might be underpinned by different neurobiological mechanisms.

Management of cognitive and negative symptoms in schizophrenia

Currently available antipsychotics provide only modest benefit in managing the cognitive and negative symptoms of schizophrenia even though these symptoms are often the most impairing in patients' daily lives. Certain antipsychotics may have slight benefits over others, and several nonpharmacologic and pharmacologic adjunctive treatments have been evaluated in recent clinical trials. Recently published meta-analyses and clinical studies of such treatments are reviewed. Potential strategies to manage cognitive and negative symptoms, including deprescribing of medications that may exacerbate these symptoms, are described using theoretical case examples.

Adjuvant palmitoylethanolamide therapy with risperidone improves negative symptoms in patients with schizophrenia: A randomized, double-blinded, placebo-controlled trial

BACKGROUND

Primary negative symptoms of schizophrenia are usually resistant to monotherapy with antipsychotics. The present study sought to assess the efficacy and tolerability of Palmitoylethanolamide (PEA) adjunctive therapy in treatment of negative symptoms in patients with stable schizophrenia.

METHODS

This 8-week (trial timepoints: baseline, week 4, week 8), double-blind, placebo-controlled clinical trial randomized patients with schizophrenia in a 1:1 ratio to compare the efficacy and safety of 600 mg twice a day of PEA and matched placebo alongside a stable dose of risperidone. Outcome measures were the positive and the negative syndrome scale (PANSS), the extrapyramidal symptom rating scale (ESRS), and the Hamilton depression rating scale (HDRS). The primary outcome was change in the negative subscale score during the trial period between the groups. Safety of interventions were controlled and addressed during the trial.

RESULTS

A total of 50 participants completed the trial (25 in each group). Baseline characteristics of the groups were comparable (p>0.05). There was significant effect from time-treatment interaction on negative symptoms (p = 0.012) suggesting greater symptom improvement in the PEA group. In contrast, the longitudinal changes in positive symptoms and depressive symptoms were similar between groups (p values>0.05). Safety assessments showed no significant difference regarding extrapyramidal symptoms, measured by ESRS, and also frequency of other complications between PEA and placebo groups (p values>0.05).

CONCLUSIONS

Adjunctive therapy with PEA and risperidone alleviates schizophrenia-related primary negative symptoms in a safe manner.

Healthcare Provider Engagement with a Novel Dashboard for Tracking Medication Ingestion: Impact on Treatment Decisions and Clinical Assessments for Adults with Schizophrenia

Purpose

Schizophrenia is a severe, chronic condition accounting for disproportionate healthcare utilization. Antipsychotics can reduce relapse rates, but the characteristics of schizophrenia may hinder medication adherence. A phase 3b open-label clinical trial used aripiprazole tablets with sensor (AS; includes pills with ingestible event-marker, wearable sensor patches and smartphone application) in adults with schizophrenia. This post hoc analysis explored how healthcare providers' (HCPs) usage of a dashboard that provided medication ingestion information impacted treatment decisions and clinical assessments.

Patients and Methods

Participants used AS for 3-6 months. HCPs were instructed to check the dashboard regularly, identify features used, and report impact on treatment decisions. After stratifying HCPs by frequency of dashboard checks and resulting treatment decisions, changes from baseline were calculated for Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression (CGI)-Severity of Illness and CGI-Improvement (CGI-I), and Personal and Social Performance (PSP), and compared using Mann-Whitney U-tests and rank-biserial correlation coefficient (r) effect sizes.

Results

To ensure sufficient opportunity for AS engagement, 113 participants who completed ≥3 months on study were analyzed. HCPs most often accessed dashboard data regarding medication ingestion and missed doses. HCPs recommended adherence counseling and participant education most often. Participants whose HCPs used the dashboard more and recommended adherence counseling and participant education (n=61) improved significantly more than participants with less dashboard-active HCPs (n=49) in CGI-I mean score (2.9 versus 3.4 [p=0.004]), total PANSS (mean change: -9.2 versus -3.1 [p=0.0002]), PANSS positive subscale (-3.2 versus -1.5 [p=0.003]), PANSS general subscale (-4.3 versus -1.2 [p=0.02]), and Marder factor for negative symptoms (-1.9 versus 0.0 [p=0.03]). Most HCPs found the dashboard easy to use (74%) and helpful for improving conversations with participants about their treatment plan and progress (78%).

Conclusion

This provider dashboard may facilitate discussions with patients about regular medication-taking, which can improve patient outcomes.

Low-Dose Ziprasidone in Combination with Sertraline for First-Episode Drug-Naïve Patients with Schizophrenia: a Randomized Controlled Trial

Many patients with schizophrenia (SCZ) discontinue antipsychotics, frequently due to dose-related multiple and severe adverse effects. We hypothesized that a low-dose ziprasidone plus sertraline would reduce serious side effects without affecting treatment efficacy. Therefore, this clinical trial was designed to investigate the efficacy, safety, and tolerability of adding sertraline to ziprasidone in order to substantially reduce ziprasidone dose and potential side effects in first-episode and drug-naive (FEDN) patients with SCZ. This 24-week randomized, double-blinded, controlled clinical trial randomly allocated 452 FEDN SCZ patients to receive a usual dose of ziprasidone (control group) or half the dose of ziprasidone in combination with sertraline (ZS group). Treatment outcome included the Positive and Negative Syndrome Scale (PANSS), the Hamilton Depression Rating Scale (HAMD), CGI-Severity (CGI-S) and the Personal and Social Performance Scale (PSP) at baseline and weeks 2, 4, 8, 12, and 24. Repeated measures ANCOVA showed significant treatment by time interactions on the PANSS general psychopathology and total scores, as well as CGI-S, HAMD, and PSP scores (all p < 0.05). Furthermore, the ZS group had greater reductions in PANSS general psychopathology, total scores, HAMD, and CGI-S (all p < 0.05) and greater increases in the PSP total score (p < 0.01) than the control group. Importantly, adverse effects were lower in the ZS than control group. The reduction in PANSS, CGI-S, or HAMD scores was not correlated with the increase in PSP. Sex and duration of disease predicted PSP improvement from baseline to week 24 in the ZS group. Our FEDN patients with SCZ were effectively treated for their psychotic and depressive symptoms while experiencing significantly fewer adverse effects using half the usual ziprasidone dose when combined with sertraline. ClinicalTrials.gov, NCT04076371.

Role of Curcumin in the Management of Schizophrenia: A Narrative Review

Nutraceutical agents and food supplements are commonly used as treatment adjuncts in neuropsychiatric disorders. Curcumin, a bioactive agent obtained from the rhizome of Curcuma longa, with its antioxidant and anti-inflammatory properties, has gained much research attention in the last few decades. In this narrative review, we intend to summarize the evidence available for curcumin as an add-on agent in the management of schizophrenia. We searched PubMed/EBSCO for both human and animal trials utilizing curcumin in the management of schizophrenia. We obtained ten articles (five preclinical and five clinical) from the focused literature search. Clinical research utilizing curcumin in schizophrenia is limited to negative and cognitive symptoms. Available preclinical studies suggest curcumin's utility in ameliorating extrapyramidal and metabolic side effects when given as an adjunct with antipsychotics. Curcumin, as an add-on agent, appears promising to improve the negative and cognitive symptoms of schizophrenia. Notably, curcumin was tolerable and safe in all the randomized human clinical trials. The poor oral bioavailability is, however, a limiting factor in its widespread use.

"Predictors of Negative Symptom Domains in Outpatients with Schizophrenia: A Cross-Sectional Study"

"Background: Current research suggests that negative symptoms may not be a unitary construct. Factor analytic studies typically found evidence for a two-factor solution of the negative symptom domain: the expressive and the volitional deficit. This study aimed to investigate whether the two-factor solution of negative symptoms is supported across different instruments of evaluation: PANSS and NSA-16 in outpatients with schizophrenia and to explore the relationship between these domains and sociodemographic, clinical, and metabolic outcomes, routinely assessed in daily practice.Another aim was to determine clinical predictors of negative symptoms domains among these variables. Materials and methods: 107 patients with schizophrenia were included in this cross-sectional study. The Principal Component Analysis was used to identify negative symptom domains and Spearman's rank correlation coefficient and multiple regression analyses were used to assess the relationship between the negative symptom domains and clinical variables. Results: PCA indicated a two-component solution explaining 85.2% of the variance for the NSA-16 subscales, reflecting an expressive deficit and an experiential deficit component. Age of onset of the disease and the cognitive deficit were significant predictors of the expressive deficit , body mass index and the number of admissions in the hospital for the experiential deficit. Conclusions: The current findings indicate that the expressive deficit and the experiential deficit should be considered as distinct domains of the psychopathology and should be rated separately"

Assessment and Treatment of Negative Symptoms in Schizophrenia-A Regional Perspective

Clinicians and researchers consider that there are a variety of symptoms that constitute negative symptoms in schizophrenia, and they may use different definitions for the same symptoms. These differences are also reflected in a variety of negative symptom rating scales. Both research and clinical work are negatively affected by the lack of consensus regarding the symptoms that constitute negative symptoms in schizophrenia. Leading research groups have investigated ways to reduce heterogeneity in the domain of negative symptoms in schizophrenia; however, little attention has been paid to regional differences in the concepts of negative symptoms in schizophrenia. The objective of this review was to collect and summarize information about the assessment and treatment of negative symptoms of schizophrenia in Central and Eastern Europe (CEE). Nineteen experts from 17 countries in CEE participated in this project. The participants collected information about their countries, including the following: (1) the most important publications about negative symptoms in schizophrenia (irrespective of the time of their publication); (2) the most frequently used negative symptom of schizophrenia in clinical practice; (3) definitions of frequently used negative symptoms; and (4) treatment of negative symptoms in schizophrenia. The participating experts/countries most frequently reported the following five negative symptoms: avolition, blunted affect, alogia, asociality, and anhedonia. Several experts also considered other symptoms as belonging to the negative symptom domain, such as a decrease in energy level and changes in personality. The importance of evaluating the long-term course and the relationship between negative symptoms and other symptom domains was also noted. No noticeable differences were reported in the treatment of negative symptoms compared to currently published guidelines and algorithms. The most frequently reported negative symptoms included those defined by the NIMH-MATRICS consensus statement on negative symptoms and recently endorsed in a guidance paper of the European Psychiatric Association. The main differences in the concepts, names, and definitions of primary negative symptoms, especially those related to personality changes, and to the evaluation of the long-term course and relationship between different symptom domains in CEE compared to the current English language literature deserve the attention of psychiatrists and other professionals in this field.