Add-on clinical effects of simvastatin and ondansetron in patients with schizophrenia stabilized on antipsychotic treatment: pilot study

Beneficial adjunctive effects of the 5HT3 receptor antagonist ondansetron on symptoms, function and cognition in early phase schizophrenia in a double-blind, 2 × 2 factorial design, randomised controlled comparison with simvastatin

BACKGROUND

Variable benefits have been reported from the adjunctive use of simvastatin and the 5HT3 receptor antagonist, ondansetron, in patients with schizophrenia. We investigated their independent efficacy and possible synergy to improve negative symptoms of schizophrenia within a single trial.

METHODS

A 6-month, randomised, double-blind, placebo-controlled trial with a 4-arm, 2 × 2 factorial design, in three centres in Pakistan. In total, 303 people with stable treated schizophrenia aged 18-65 were randomly allocated to add-on ondansetron, simvastatin, both or neither. The primary outcome was a Positive and Negative Syndrome Scale (PANSS) negative score at 3 and 6 months.

RESULTS

Mixed model analysis and analysis of covariance revealed no main effects of simvastatin or ondansetron but a significant negative interaction between them (p = 0.03); when given alone, both drugs significantly reduced negative symptoms compared to placebo but they were ineffective in combination. Individual treatment effects versus placebo were -1.9 points (95%CIs -3.23, -0.49; p = 0.01) for simvastatin and -1.6 points for ondansetron (95%CIs -3.00, -0.14; p = 0.03). Combined treatment significantly increased depression and side effects. In those with less than the median 5 years of treatment, ondansetron improved all PANSS subscales, global functioning measures and verbal learning and fluency, whereas simvastatin did not.

CONCLUSION

Small improvement in negative symptoms on simvastatin and ondansetron individually are not synergistic in combination in treating negative symptoms of schizophrenia. Ondansetron showed broad efficacy in patients on stable antipsychotic treatment within 5 years of illness. The findings suggest that ondansetron should be evaluated in patients at risk of psychosis or early in treatment.

Statins as an adjuvant therapy for patients with schizophrenia: An up-to-date systematic review and meta-analysis

BACKGROUND

Evidence suggests that inflammatory processes play a role in the pathophysiology of schizophrenia. Statins exert anti-inflammatory and antioxidant effects and may be effective in improving the symptoms of schizophrenia. This study explored whether statins, as an adjunctive therapy, can alleviate the symptoms of schizophrenia.

METHODS

PubMed, EMBASE, and the Cochrane Library were searched for articles published up to March 2023. The risk-of-bias tool for randomized trials was used to assess study quality. Two researchers independently assessed the risks of bias and extracted data. Pooled data on Positive and Negative Syndrome Scale (PANSS) scores were analyzed. A random-effects model was employed to calculate pooled effect sizes. Statistical heterogeneity across studies was assessed using the I2 statistic. All analyses were performed using RevMan5 and Comprehensive Meta-Analysis software.

RESULTS

Nine trials enrolling 533 patients in total were included. Add-on statin therapy was found to be associated with a significantly better total PANSS score [standardized mean difference (SMD) = -0.42, 95% confidence interval (CI) -0.75 to -0.09, I2 = 72%; P = 0.01] and PANSS negative subscale score (SMD = -0.26, 95% CI -0.45 to -0.07, I2 = 0%; P = 0.009) in comparison with placebo. However, add-on statin therapy did not appear to improve scores for the PANSS positive and general subscales at the study-defined endpoint (6-24 weeks).

CONCLUSIONS

Our meta-analysis indicates that adjunctive statin therapy may confer benefits in ameliorating PANSS negative and total scores. It needs more solid data to confirm the results are related to clinical improvement and functioning.

Add-on Sodium Benzoate and N-Acetylcysteine in Patients With Early Schizophrenia Spectrum Disorder: A Multicenter, Double-Blind, Randomized Placebo-Controlled Feasibility Trial

Background and Hypothesis

Oxidative stress pathways may play a role in schizophrenia through direct neuropathic actions, microglial activation, inflammation, and by interfering with NMDA neurotransmission. N-acetylcysteine (NAC) has been shown to improve negative symptoms of schizophrenia, however, results from trials of other compounds targeting NMDA neurotransmission have been mixed. This may reflect poor target engagement but also that risk mechanisms act in parallel. Sodium Benzoate (NaB) could have an additive with NAC to act on several pathophysiological mechanisms implicated in schizophrenia.

Study Design

A multicenter, 12 weeks, 2 × 2 factorial design, randomized double-blind placebo-controlled feasibility trial of NaB and NAC added to standard treatment in 68 adults with early schizophrenia. Primary feasibility outcomes included recruitment, retention, and completion of assessments as well as acceptability of the study interventions. Psychosis symptoms, functioning, and cognitive assessments were also assessed.

Study Results

We recruited our desired sample (n = 68) and retained 78% (n = 53) at 12 weeks, supporting the feasibility of recruitment and retention. There were no difficulties in completing clinical outcome schedules. Medications were well tolerated with no dropouts due to side effects. This study was not powered to detect clinical effect and as expected no main effects were found on the majority of clinical outcomes.

Conclusions

We demonstrated feasibility of conducting a clinical trial of NaB and NAC. Given the preliminary nature of this study, we cannot draw firm conclusions about the clinical efficacy of either agent, and a large-scale trial is needed to examine if significant differences between treatment groups emerge.

Trial Registration

ClinicalTrials.gov: NCT03510741.

Augmentation Therapies as Treatments for Coexisting Somatic Problems in Schizophrenia-A Systematic Review

The aim of this review is to appraise the data from available randomized clinical trials (RCT) regarding the possible combinations of neuroleptic and non-antipsychotic treatment which could enhance antipsychotic therapy efficacy whilst simultaneously addressing somatic symptoms in individuals with schizophrenia. A systematic search of the PubMed database up to February 2022 was conducted. Inclusion criteria: randomized controlled trials using augmentation therapy in chronic schizophrenia in adults, written in English, and only studies with psychometric assessments of schizophrenia were incorporated. Exclusion criteria: non-clinical, first episode of schizophrenia, patients on medication other than antipsychotics augmented, and not adjunctive therapy. Overall, 37 studies of 1931 patients with schizophrenia who received a combination of antipsychotic medication with other drugs were selected. A statistically significant reduction of negative and positive symptoms of schizophrenia, measured with the PANSS scale, when using a combination of antipsychotic treatment along with aspirin, simvastatin, N-acetylcysteine, or pioglitazone was found. A combination of antipsychotic medication with aspirin, simvastatin, N-acetylcysteine, or pioglitazone seems to be effective in the reduction of symptoms of schizophrenia in adults, but long-term studies are required to confirm this effect.

Safety and Efficacy of Ondansetron and Simvastatin as Potential Adjunctive Treatment for Patients With Schizophrenia: A Systematic Review of Randomized Controlled Trials

In a generation where advancements in research and understanding have led to remarkable achievements in medicine, it is still unfathomable that, after more than a century, the cause of schizophrenia is still a mystery. While antipsychotics, without a doubt, have brought on an exemplary revolution in the way psychiatric disorders are now treated, there are still imperative deficits that need to be addressed to ultimately enable individuals with schizophrenia to function normally in society. However, without a definite cause of schizophrenia, even though speculation has been made on its inflammatory and neurodegenerative nature, it has provided an unnecessary hindrance to finding further potential treatment modalities for these patients. Nevertheless, some trials are investigating potential adjunctive treatment regimens to antipsychotics, which can help achieve complete remission. Exploring these drugs will have significant implications for managing schizophrenia in future clinical practices. This systematic review was conducted between January 2012 to July 2022 according to Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines to evaluate the safety and efficacy of ondansetron and simvastatin as adjunctive treatment to antipsychotics in adult patients with schizophrenia. This review included nine randomized controlled trials. Overall, both simvastatin and ondansetron, when used as adjunctive treatment in schizophrenia, appear to be safe. Ondansetron showed promising results, with all studies on this drug showing positive overall results on schizophrenia symptoms. On the other hand, simvastatin demonstrated mixed results, which can be attributed to the limited participants in the studies and the shorter duration of the trials. However, more extensive trials with uniform assessment tools are needed to demonstrate concrete evidence of the effectiveness of these drugs, whether alone or in combination with each other or perhaps another drug such as aspirin in schizophrenia.

Inflammatory monocyte gene signature predicts beneficial within group effect of simvastatin in patients with schizophrenia spectrum disorders in a secondary analysis of a randomized controlled trial

Immune dysregulation has been reported in schizophrenia spectrum disorders (SSD). In the past decade, several trials using anti-inflammatory agents for treatment of SSD have been completed, with so far limited success. One such anti-inflammatory agent used is simvastatin. A recent, large-scale, randomized controlled trial with simvastatin augmentation failed to show improvement in the predefined primary outcome. However, baseline inflammatory profiles were not taken into account. Here we employed a data-driven clustering approach to investigate whether patients with an inflammatory monocyte gene signature respond better to add-on simvastatin treatment than those without such a signature, over a treatment period of 2 years. In 61 patients (60 randomized, 1:1 placebo:simvastatin) and healthy controls, a previously validated monocyte gene expression signature was assessed using quantitative polymerase chain reaction. Resulting delta cycle threshold values were used to identify patient clusters. Two major patient clusters with either up- or downregulated pro-inflammatory factors were detected. Linear mixed models showed a significant three-way interaction between the inflammatory cluster, treatment, and time for psychotic symptoms. Only patients treated with simvastatin who were in the inflammatory group, showed a consistent improvement: symptom severity gradually decreased after 3 months and reached significance after 12 and 24 months compared to baseline (p.adj<0.05). The effects were small, and overall between-group effects were not significant. Here, we show that patient stratification based on inflammatory gene expression might be useful to select appropriate treatment augmentation for patients with SSD, highlighting the need for precision medicine approaches. Our findings corroborate the results of the primary analyses, showing that in the overall group, simvastatin was not effective; however, at the individual level the treatment might make a difference.

Neuroinflammation and oxidative stress in schizophrenia: are these opportunities for repurposing?

Purpose: To summarize the main findings on the subject of neuroinflammation and oxidative stress in patients with Schizophrenia (SCZ).Methods: A narrative review of all the relevant papers known to the authors was conducted.Results: SCZ is a chronic, debilitating, neuropsychiatric disorder associated with an immense and adverse impact on both the patient and the caregiver, and impairs the overall quality of life. The current modality of treatment involves the use of antipsychotics to balance the disturbances in the neurotransmitters in the dopaminergic and serotonin pathways in the brain, which have a role to play in SCZ. Contemporary management of SCZ focuses mainly on symptomatic control due to the lack of effective curative treatments.Despite the optimum use of antipsychotics, there is a considerable proportion of the patient population who are poor responders. This has necessitated the exploration of new etiopathologies in order to evolve new modalities of treatment. This narrative review, conducted over a period of 3 months, throws light on the large-scale evidence pointing toward neuroinflammation and oxidative stress as key etiopathological markers that merit further consideration in SCZ, and may even be the basis for devising novel pharmacotherapies for SCZ.Conclusions: This review discusses the various plausible hypotheses, viz., cytokine hypothesis of peripheral inflammation, acute-phase reactants in SCZ, microglial hypothesis of central inflammation, neurogenesis in relation to neuroinflammation, and oxidative stress in SCZ. It also highlights the many opportunities available for repurposing already marketed drugs with anti-inflammatory and antioxidant properties with a view to devising more effective and comprehensive therapies to manage SCZ.

Kidney plays an important role in ketogenesis induced by risperidone and voluntary exercise in juvenile female rats

The positive role of ketone bodies in the treatment for mental disorders has been demonstrated. Ketogenesis can be triggered by not only exercise and diet but also metabolic disorders. This study aimed to explore the role of risperidone and exercise in ketogenesis. Thirty-two juvenile female Sprague Dawley rats were randomly assigned into four groups: Vehicle-Sedentary, Risperidone (0.9 mg/kg; b.i.d)-Sedentary, Vehicle-Exercise (three hours daily access to running wheels) and Risperidone-Exercise groups for four weeks. Exercise-intervention significantly ameliorated the risperidone-induced increase in white adipose mass, fasting plasma triglyceride and insulin levels. Compared to the vehicle-exercise group, the risperidone-exercise group had significantly higher plasma β-hydroxybutyrate (β-HB) level, which had a positive correlation with plasma non-esterified fatty acid levels. Risperidone-treatment upregulated expression of ketogenic key enzyme, mitochondrial 3-hydroxy-3-methyl-glutaryl-CoA synthase 2 (HMGCS2) in the kidney rather than liver. Exercise-intervention significantly enhanced renal carnitine palmitoyltransferase1A (CPT1A) expression. These results suggested that the kidney plays an important role in ketogenesis associated with risperidone and exercise. Therefore, it is important to monitor the levels of plasma ketone bodies while exercise intervention is utilized to prevent risperidone-induced metabolic disorders in young people.

The effect of prednisolone on symptom severity in schizophrenia: A placebo-controlled, randomized controlled trial

OBJECTIVE

Immune dysregulation may be involved in the pathophysiology of schizophrenia. Given the need for new treatment options in schizophrenia, anti-inflammatory medication could be a potential treatment in this illness.

METHODS

In this double-blind, placebo-controlled clinical trial, patients with schizophrenia, schizoaffective disorder or psychosis NOS were randomized 1:1 to either prednisolone or placebo, in addition to their regular antipsychotic medication. Patients diagnosed with schizophrenia for less than 7 years and on antipsychotics, were treated with prednisolone or placebo, tapered-off within six weeks in the following schedule: 40 mg/day for 3 days and 30 mg/day for 4 days, followed by a decrease of 5 mg/day per week during the remaining 5 weeks. Change in symptom severity relative to baseline was compared between treatment arms, as measured through the Positive and Negative Syndrome Scale total score.

RESULTS

In total, 68 patients signed informed consent and were screened on eligibility criteria, of whom 42 patients were randomized to either prednisolone or placebo, with 39 patients completing the treatment and tapering phase. Due to recruitment difficulties, the study was terminated prematurely. Symptom severity decreased significantly in both the prednisone and placebo treatment arm (p < 0.001). The degree of improvement was not significantly different between treatment arms (p = 0.96). No serious adverse events occurred during the treatment phase.

DISCUSSION

There is no indication that prednisolone has a beneficial effect on symptom severity, as adjunctive treatment in patients with schizophrenia, as compared to placebo.

CONCLUSION

Adjunctive treatment with prednisolone did not improve symptom severity compared to placebo in patients with schizophrenia.

Simvastatin Augmentation for Patients With Early-Phase Schizophrenia-Spectrum Disorders: A Double-Blind, Randomized Placebo-Controlled Trial

Schizophrenia-spectrum disorders (SSD) are associated with increased inflammatory markers, both in brain and periphery. Augmentation with drugs that lower this pro-inflammatory status may improve clinical presentation. Simvastatin crosses the blood-brain barrier, has anti- inflammatory and neuroprotective effects and reduces metabolic syndrome. In this study, we investigated if 12 months of simvastatin augmentation can improve symptoms and cognition in patients with early SSD. This double-blind placebo-controlled trial included 127 SSD patients across the Netherlands, <3 years after their diagnosis. From these, 119 were randomly assigned 1:1 to simvastatin 40 mg (n = 61) or placebo (n = 58), stratified for sex and study site. Primary outcomes were symptom severity and cognition after 12 months of treatment. Depression, symptom subscores, general functioning, metabolic syndrome, movement disorders, and safety were secondary outcomes. Intention to treat analyses were performed using linear mixed models and ANCOVA. No main effect of simvastatin treatment was found on total symptom severity after 12 months of treatment as compared to placebo (X2(1) = 0.01, P = .90). Group differences varied over time (treatment*time X2(4) = 11.2; P = .025), with significantly lower symptom severity in the simvastatin group after 6 months (mean difference = -4.8; P = .021; 95% CI: -8.8 to -0.7) and at 24 months follow-up (mean difference = -4.7; P = .040; 95% CI: -9.3 to -0.2). No main treatment effect was found for cognition (F(1,0.1) = 0.37, P = .55) or secondary outcomes. SAEs occurred more frequently with placebo (19%) than with simvastatin (6.6%). This negative finding corroborates other large scale studies on aspirin, minocycline, and celecoxib that could not replicate positive findings of smaller studies, and suggests that anti-inflammatory augmentation does not improve the clinical presentation of SSD.

Discovery and Development of Non-Dopaminergic Agents for the Treatment of Schizophrenia: Overview of the Preclinical and Early Clinical Studies

Schizophrenia is a chronic psychiatric disorder that affects about 1 in 100 people around the world and results in persistent emotional and cognitive impairments. Untreated schizophrenia leads to deterioration in quality of life and premature death. Although the clinical efficacy of dopamine D2 receptor antagonists against positive symptoms of schizophrenia supports the dopamine hypothesis of the disease, the resistance of negative and cognitive symptoms to these drugs implicates other systems in its pathophysiology. Many studies suggest that abnormalities in glutamate homeostasis may contribute to all three groups of schizophrenia symptoms. Scientific considerations also include disorders of gamma-aminobutyric acid-ergic and serotonergic neurotransmissions as well as the role of the immune system. The purpose of this review is to update the most recent reports on the discovery and development of non-dopaminergic agents that may reduce positive, negative, and cognitive symptoms of schizophrenia, and may be alternative to currently used antipsychotics. This review collects the chemical structures of representative compounds targeting metabotropic glutamate receptor, gamma-aminobutyric acid type A receptor, alpha 7 nicotinic acetylcholine receptor, glycine transporter type 1 and glycogen synthase kinase 3 as well as results of in vitro and in vivo studies indicating their efficacy in schizophrenia. Results of clinical trials assessing the safety and efficacy of the tested compounds have also been presented. Finally, attention has been paid to multifunctional ligands with serotonin receptor affinity or phosphodiesterase inhibitory activity as novel strategies in the search for dedicated medicines for patients with schizophrenia.

Adjunctive ondansetron for schizophrenia: A systematic review and meta-analysis of randomized controlled trials

The serotonin 5-hydroxytryptamine type 3 (5-HT3) receptor has been implicated in the pathogenesis of schizophrenia. This meta-analysis of randomized controlled trials (RCTs) examined the efficacy and safety of adjunctive ondansetron, a potent 5-HT3 receptor antagonist, in the treatment of schizophrenia. Only RCTs examining adjunctive ondansetron for schizophrenia were included. Standardized mean difference (SMD), risk ratio (RR) and their 95% confidence intervals (CIs) were analyzed using RevMan, Version 5.3. Study quality was evaluated with the Cochrane risk of bias and the Jadad scale. Data of 5 RCTs (n = 304) covering 149 patients on ondansetron (4-8 mg/day) and 155 patients on placebo were analyzed. Three RCTs reported "randomized allocation" with a specific description; the weighted Jadad score was 3.8. Adjunctive ondansetron outperformed placebo in the reduction of Positive and Negative Syndrome Scale (PANSS) total score [3 RCTs, n = 171; SMD: -1.06 (95%CI: -2.10, -0.02), p = 0.04, I² = 85%], the negative [4 RCTs, n = 209; SMD: -0.96 (95%CI: -1.71, -0.22), p = 0.01, I² = 80%], and general psychopathology symptom scores [3 RCTs, n = 171; SMD: -0.97 (95%CI: -1.91, -0.02), p = 0.04, I² = 82%], but not in the positive (p = 0.05) and depressive symptom scores (p = 0.91). The difference in PANSS total score remained significant after excluding one outlying RCT [2 RCTs, n = 141; SMD: -0.50 (95%CI: -0.84, -0.16), P = 0.004, I² = 0%]. Four RCTs examined the effect of ondansetron on cognition applying different instruments yielding conflicting findings. Ondansetron was superior over placebo in improving extrapyramidal symptoms, but no group differences were found in overall discontinuation rate and adverse drug reactions. In conclusion, adjunctive ondansetron appears to be efficacious and safe in improving negative symptoms and general psychopathology. The effect of ondansetron on cognitive impairment in schizophrenia needs to be further explored in large-scale RCTs.

Proinflammatory and anti-inflammatory biomarkers in schizophrenia and influence of simvastatin on the interleukin-6

The present study sought to assess biomarkers of inflammation in stable patients with schizophrenia (SZ) on clozapine therapy. We recruited 60 outpatients with SZ and 60 healthy controls, matched for sex and age. Compared with controls, patients had significantly increased concentrations of interleukin-6 and tumor necrosis factor-α. Interestingly, patients on simvastatin had lower interleukin-6 levels compared with patients not on simvastatin and controls. This study corroborated previous evidence for increased inflammatory biomarkers in SZ and detected a potential anti-inflammatory action of simvastatin in patients with a clinical diagnosis of SZ on clozapine therapy.

Association between Serum Lipids and Antipsychotic Response in Schizophrenia

Metabolic abnormalities are serious health problems in individuals with schizophrenia. Paradoxically, studies have noted an association where individuals who gained body weight or who have increased their serum lipids demonstrated a better antipsychotic response. As serum lipids serve as more specific physiological markers than body weight, the objective of this study was to review studies that examined the association between changes in serum lipids and changes in symptoms during antipsychotic treatment in individuals with schizophrenia. A Medline® literature search was performed. Fourteen studies were included and analyzed. Evidence suggests that increases in serum lipids may be associated with decreases in symptoms during antipsychotic treatment. This inverse association may be independent of confounding variables, such as weight gain, and may be most evident during treatment with clozapine. Also, according to recent randomized controlled trials, lipid-lowering agents do not appear to worsen symptoms although this needs to be further investigated in clozapine-treated patients. Future studies should investigate the association in question in a larger population and identify underlying mechanisms.

Statins and Inflammation: New Therapeutic Opportunities in Psychiatry

Statins, which are widely used to treat hypercholesterolemia, have anti-inflammatory and anti-oxidant effects. These are thought to be responsible for the potential effects of statins on various psychiatric disorders. In this study, we comprehensively review the literature to investigate the effects of statins on various psychiatric disorders including depression, schizophrenia, and dementia. In addition, we review adverse effects and drug interactions of statins to give clinically useful information guiding statin use in the psychiatric field. Statins seem useful in reducing depression, particularly in patients with physical disorders such as cardiovascular disease. In patients with schizophrenia, negative symptoms may be reduced by adjuvant statin therapy. Studies on cohorts at risk for dementia have generally shown protective effects of statins, while those on treatment for dementia show inconsistent results. In conclusion, statins used in combination with conventional psychotropic medications may be effective for various psychiatric disorders including depression, schizophrenia, and dementia. Further study is required to determine optimal doses and duration of statin use for the treatment of psychiatric disorders.

Ondansetron - a promising adjunctive treatment for persistent schizophrenia

BACKGROUND

Ondansetron is a serotonin 3 receptor antagonist widely used to prevent nausea and vomiting in pregnancy and in patients receiving chemotherapy. There is growing evidence that adjunctive ondansetron treatment improves symptomatology associated with schizophrenia, particularly with respect to the positive, negative and cognitive symptoms. Further studies that are applicable to real world practice are required to assess the efficacy and effectiveness of this treatment, which could be readily and rapidly translated into clinical practice.

AIMS

This randomized control trial compared adjunctive (8 mg/daily) ondansetron or placebo to commonly prescribed atypical antipsychotics for people suffering with chronic schizophrenia ( ClinicalTrials.gov NCT01121042).

METHODS

The study involved 85 outpatients aged 18-65 years with a diagnosis of schizophrenia or schizoaffective disorder who participated in a two-arm randomized control trial.

RESULTS

Longitudinal analyses revealed adjunctive ondansetron provided significant improvement in the cognitive domain ( p<0.05) as measured by the Positive and Negative Syndrome Scale between baseline and week 12. The analysis of "Combination" showed ondansetron effect on Total Positive and Negative Syndrome Scale, approaching significance by week 12 ( p=0.06). No group differences were obtained in the Montgomery-Asberg Depression Rating Scale or Positive and Negative Syndrome Scale subscales.

CONCLUSION

This treatment trial provides some support for adjunctive ondansetron medication as a treatment for the cognitive disorganization symptoms of schizophrenia.

Autoimmune phenotypes in schizophrenia reveal novel treatment targets

Typical and atypical antipsychotics are the first-line treatments for schizophrenia, but these classes of drugs are not universally effective, and they can have serious side effects that impact compliance. Antipsychotic drugs generally target the dopamine pathways with some variation. As research of schizophrenia pathophysiology has shifted away from a strictly dopamine-centric focus, the development of new pharmacotherapies has waned. A field of inquiry with centuries-old roots is gaining traction in psychiatric research circles and may represent a new frontier for drug discovery in schizophrenia. At the forefront of this investigative effort is the immune system and its many components, pathways and phenotypes, which are now known to actively engage the brain. Studies in schizophrenia reveal an intricate association of environmentally-driven immune activation in concert with a disrupted genetic template. A consistent conduit through this gene-environmental milieu is the gut-brain axis, which when dysregulated can generate pathological autoimmunity. In this review, we present epidemiological and biochemical evidence in support of an autoimmune component in schizophrenia and depict gut processes and a dysbiotic microbiome as a source and perpetuator of autoimmune dysfunction in the brain. Within this framework, we review the role of infectious agents, inflammation, gut dysbioses and autoantibody propagation on CNS pathologies such as neurotransmitter receptor hypofunction and complement pathway-mediated synaptic pruning. We then review the new pharmacotherapeutic horizon and novel agents directed to impact these pathological conditions. At the core of this discourse is the understanding that schizophrenia is etiologically and pathophysiologically heterogeneous and thus its treatment requires individualized attention with disease state variants diagnosed with objective biomarkers.

Relation of inflammatory markers with symptoms of psychotic disorders: a large cohort study

AIMS

Immunological mechanisms may play a role in symptomatology of patients with a psychotic disorder. Besides metabolic problems and medication use, inflammatory processes that may occur due to the disorder may cause increased inflammatory markers and concurrent psychiatric symptoms. The aim of this study is to investigate whether levels of C-reactive protein (CRP) and white blood cell count (WBC) are related to positive and negative symptoms of psychotic disorders, and whether age, gender, duration of illness, smoking behavior, haloperidol equivalents, mediation use, body mass, and metabolic syndrome affect this relation.

METHODS

CRP and WBC values of 2123 patients with a psychotic disorder were related to positive and negative symptoms measured with a psychiatric interview. CRP was analyzed by survival analysis accounting for detection limit and WBC by linear mixed model analysis. In case of a significant association, the confounding factors were added to the model.

RESULTS

Both WBC and CRP were related to both positive and negative symptoms, even after correction for age, gender, smoking, use of medication and metabolic problems. Of the covariates, gender, metabolic problems, smoking and statins also showed a strong association with inflammatory markers.

CONCLUSIONS

This study in a large patient-group confirmed that inflammatory markers are related to psychotic disorders, particularly negative symptoms. Future studies could use more precise measures of inflammatory markers and measure symptomatic state at specific moments in illness progression.

Adjunctive therapy with statins in schizophrenia patients: A meta-analysis and implications

There are some conflicting results regarding the benefit of adjunctive therapy with statins for severity of negative symptoms in schizophrenia. This study aimed to verify whether statins use for adjunctive therapy was indeed beneficial to improve psychiatric symptoms in schizophrenia. The data were from CENTRAL, PubMed, Embase and MEDLINE. The Boolean search term used for the electronic database search was (statin OR simvastatin OR atorvastatin OR fluvastatin OR lovastatin OR mevastatin OR pitavastatin OR pravastatin OR rosuvastatin OR cerivastatin) and (schizophrenia OR schizoaffective disorder OR psychosis). Inclusion criteria were the following: RCTs, the adult schizophrenia patients, received antipsychotics plus statins or placebo, and the PANSS or SANS scores. Exclusion criteria were as follows: no data reported and multiple reports of the same study. A meta-analysis was used to compare psychiatric symptoms in schizophrenia patients with or without statins adjunctive therapy. The 6 RCTs included in the analysis represented 339 participants (169 in treatment group versus 170 in placebo group). A test for overall effect demonstrated that the PANSS positive scale and negative scale significantly reduced in participants receiving compliant with statins. Our meta-analyses first clarified that adjunctive therapy with statins could improve psychiatric symptoms, either negative symptoms or positive symptoms.

Statin add-on therapy in the antipsychotic treatment of schizophrenia: A meta-analysis

A comprehensive meta-analysis of statin add-on therapy in the antipsychotic treatment of schizophrenia was conducted. Data from previous studies, prior to 8/21/2017, was obtained from Scopus, PubMed, PsycINFO, and Cochrane Library. Both a systematic review and meta-analysis were conducted with patient data from randomized placebo-controlled trials (RCTs) to compare statins with placebo in order to calculate effect size. Across the five RCTs (mean duration: 9.2 weeks), 236 adult patients with schizophrenia were randomly selected to receive either placebo (n=117) or statins (n=119). Pooled statin add-on therapy showed significant superiority over placebo in the improvement of Positive and Negative Syndrome Scale (PANSS) total scores (mean difference=-1.96; 95% confidence interval, -2.94 to -0.98; p<0.0001; I²=0%; N=4, n=174). However, there were no statistically significant differences in other efficacy outcomes between the two treatment groups. Statin did not have a significant difference in its incidence of discontinuation or have individual adverse events compared to placebo. Our results suggest that statins may have considerable potential as an add-on therapy for schizophrenia. However, determining the effectiveness of this treatment in clinical practice requires future investigation due to limitations of the current evidence-base including small sample, potential for publication and selection biases and short duration of follow-up.

New Targets for Schizophrenia Treatment beyond the Dopamine Hypothesis

Schizophrenia has been primarily associated with dopamine dysfunction, and treatments have been developed that target the dopamine pathway in the central nervous system. However, accumulating evidence has shown that the core pathophysiology of schizophrenia might involve dysfunction in dopaminergic, glutamatergic, serotonergic, and gamma-aminobutyric acid (GABA) signaling, which may lead to aberrant functioning of interneurons that manifest as cognitive, behavioral, and social dysfunction through altered functioning of a broad range of macro- and microcircuits. The interactions between neurotransmitters can be modeled as nodes and edges by using graph theory, and oxidative balance, immune, and glutamatergic systems may represent multiple nodes interlocking at a central hub; imbalance within any of these nodes might affect the entire system. Therefore, this review attempts to address novel treatment targets beyond the dopamine hypothesis, including glutamate, serotonin, acetylcholine, GABA, and inflammatory cytokines. Furthermore, we outline that these treatment targets can be possibly integrated with novel treatment strategies aimed at different symptoms or phases of the illness. We anticipate that reversing anomalous activity in these novel treatment targets or combinations between these strategies might be beneficial in the treatment of schizophrenia.

Symptomatic thinking: the current state of Phase III and IV clinical trials for cognition in schizophrenia

Research indicates that relieving the cognitive and negative symptoms of schizophrenia is crucial for improving patient quality of life. However effective pharmacotherapies for cognitive and negative symptoms do not currently exist. A review of ongoing Phase III clinical trials indicates that, despite numerous compounds being investigated for cognition in schizophrenia, few are actually novel and most are not backed by empirically driven preclinical research efforts. Based on these trials, and a general disinvestment in development of novel therapies for schizophrenia, the likelihood of a major advancement in treating cognitive differences in schizophrenia does not look promising. Possible ways in which the remaining resources for development of novel treatment for schizophrenia can best be leveraged are discussed.

Modified Mediterranean Diet for Enrichment of Short Chain Fatty Acids: Potential Adjunctive Therapeutic to Target Immune and Metabolic Dysfunction in Schizophrenia?

Growing interest in gut and digestive processes and their potential link to brain and peripheral based inflammation or biobehavioral phenotypes has led to an increasing number of basic and translational scientific reports focused on the role of gut microbiota within the context of neuropsychiatric disorders. However, the effect of dietary modification on specific gut metabolites, in association with immune, metabolic, and psychopathological functioning in schizophrenia spectrum disorders has not been well characterized. The short chain fatty acids (SCFA) acetate, butyrate, and propionate, major metabolites derived from fermentation of dietary fibers by gut microbes, interact with multiple immune and metabolic pathways. The specific pathways that SCFA are thought to target, are dysregulated in cardiovascular disease, type II diabetes, and systemic inflammation. Most notably, these disorders are consistently linked to an attenuated lifespan in schizophrenia. Although, unhealthy dietary intake patterns and increased prevalence of immune and metabolic dysfunction has been observed in people with schizophrenia; dietary interventions have not been well utilized to target immune or metabolic illness. Prior schizophrenia patient trials primarily focused on the effects of gluten free diets. Findings from these studies indicate that a diet avoiding gluten benefits a limited subset of patients, individuals with celiac disease or non-celiac gluten sensitivity. Therefore, alternative dietary and nutritional modifications such as high-fiber, Mediterranean style, diets that enrich the production of SCFA, while being associated with a minimal likelihood of adverse events, may improve immune and cardiovascular outcomes linked to premature mortality in schizophrenia. With a growing literature demonstrating that SCFA can cross the blood brain barrier and target key inflammatory and metabolic pathways, this article highlights enriching dietary intake for SCFA as a potential adjunctive therapy for people with schizophrenia.

Simvastatin adjunct therapy for negative symptoms of schizophrenia: a randomized double-blind placebo-controlled trial

We investigated the effects of simvastatin adjunctive therapy on the negative symptoms of schizophrenia. In this double-blind trial, inpatients with chronic schizophrenia were clinically stabilized on a constant dose of risperidone for at least 4 weeks before the study and were then randomized to receive risperidone (4-6 mg/day) plus either simvastatin (40 mg/day) (n=33) or placebo (n=33) for 8 weeks. The Positive and Negative Syndrome Scale was used to measure the negative, positive, and general symptoms of schizophrenia at baseline and every 2 weeks. The Hamilton Depression Rating Scale and the Extrapyramidal Symptom Rating Scale were used to measure depression and extrapyramidal symptoms at baseline and week 8. Difference in change in negative symptoms score from the baseline to week 8 was considered the single primary outcome. At baseline, negative symptoms scores were higher than positive symptoms scores in both simvastatin and placebo groups. There was no baseline difference between the two groups in terms of any of the measured variables. Compared with the placebo group, the simvastatin group showed a significantly higher reduction in negative symptoms scores from baseline to week 8 [mean difference: 95% confidence interval=-1.42 (-2.32 to -0.52), P=0.003]. Similar findings were observed for total scores [mean difference: 95% confidence interval=-1.85 (-2.87 to -0.83), P=0.001]. The results were not significant for positive symptoms or general psychopathology scores. We found a favorable effect of simvastatin on negative symptoms of patients with schizophrenia; however, future studies are warranted to confirm these results.

Efficacy of Risperidone Augmentation with Ondansetron in the Treatment of Negative and Depressive Symptoms in Schizophrenia: A Randomized Clinical Trial

BACKGROUND

Given the potential role of the 5-hydroxytryptamine-3 receptor in the pathogenesis of schizophrenia, this study was performed to determine whether ondansetron plus risperidone could reduce the negative and depressive symptoms in patients with treatment-resistant schizophrenia.

METHODS

In a double-blinded, placebo-controlled, randomized trial (IRCT registration # 201112125280N7), in 2012-2013 in Mashhad, Iran, 38 patients with treatment-resistant schizophrenia received risperidone either combined with a fixed dose (4-8 mg/d) of ondansetron (n=18) or with a placebo (n=20) for 12 weeks. The patients were evaluated using the Positive and Negative Syndrome Scale (PANSS), Wechsler's Adult Intelligence Scale-Revised (WAIS-R), and Hamilton's Rating Scale for Depression (HRSD) at baseline and 12 weeks later. Changes in the inventories were used to evaluate the efficacy of the treatment. The t test, Chi-square test, and SPSS (version 16) were used to analyze the data. The statistical significance was set atP<0.05.

RESULTS

Ondansetron plus risperidone was associated with a significantly larger improvement in the PANSS overall scale and subscales for negative symptoms and cognition than was risperidone plus placebo (P<0.001). The WAIS-R scale results indicated significant differences between the 2 groups before and after administrating the medicine and the placebo. The administration of ondansetron significantly improved visual memory based on the subtests of the WAIS (P<0.05). Ondansetron had no positive effects on depressive symptoms (effect size=0.13).

CONCLUSION

This study confirmed that ondansetron, as an adjunct treatment, reduces negative symptoms in patients with schizophrenia and can be used as a potential adjunctive strategy particularly for negative symptoms and cognitive impairments. Trial Registration Number: IRCT201112125280N7.

Functional Implications of the IL-23/IL-17 Immune Axis in Schizophrenia

The aetiology of schizophrenia seems to stem from complex interactions amongst environmental, genetic, metabolic, immunologic and oxidative components. Chronic low-grade inflammation has been persistently linked to schizophrenia, and this has primarily been based on the findings derived from Th1/Th2 cytokine balance. While the IL-23/IL-17 axis plays crucial role in the pathogenesis of several immune-mediated disorders, it has remained relatively unexplored in neuropsychiatric disorders. Altered levels of cytokines related to IL-23/IL-17 axis have been observed in schizophrenia patients in a few studies. In addition, other indirect factors known to confer schizophrenia risk like complement activation and altered gut microbiota are shown to modulate the IL-23/IL-17 axis. These preliminary observations provide crucial clues about the functional implications of IL-23/IL-17 axis in schizophrenia. In this review, an attempt has been made to highlight the biology of IL-23/IL-17 axis and its relevance to schizophrenia risk and pathogenesis. Given the pathogenic potential of the IL-23/IL-17 axis, therapeutic targeting of this axis may be a promising approach to benefit patients suffering from this devastating disorder.

5HT3 receptors: Target for new antidepressant drugs

5HT3 receptors (5HT3Rs) have long been identified as a potential target for antidepressants. Several studies have reported that antagonism of 5HT3Rs produces antidepressant-like effects. However, the exact role of 5HT3Rs and the mode of antidepressant action of 5HT3R antagonists still remain a mystery. Here, we provide a comprehensive overview of 5HT3Rs: (a) regional and subcellular distribution of 5HT3Rs in discrete brain regions, (b) preclinical and clinical evidence supporting the antidepressant effect of 5HT3R antagonists, and (c) neurochemical, biological and neurocellular signaling pathways associated with the antidepressant action of 5HT3R antagonists. 5HT3Rs located on the serotonergic and other neurotransmitter interneuronal projections control their release and affect mood and emotional behavior; however, new evidence suggests that apart from modulating the neurotransmitter functions, 5HT3R antagonists have protective effects in the pathogenic events including hypothalamic-pituitary-adrenal-axis hyperactivity, brain oxidative stress and impaired neuronal plasticity, pointing to hereby unknown and novel mechanisms of their antidepressant action. Nonetheless, further investigations are warranted to establish the exact role of 5HT3Rs in depression and antidepressant action of 5HT3R antagonists.

Emerging Treatments in Schizophrenia: Highlights from Recent Supplementation and Prevention Trials

In this column we examine the recent literature regarding adjunctive antipsychotic treatment of schizophrenia. We provide a brief introduction outlining the urgent need for new therapeutics, particularly for the treatment of negative and cognitive symptoms of schizophrenia. We then address (by mechanism of action) the most extensively studied adjunctive antipsychotic treatments. We conclude that adjunctive treatments targeting glutamatergic modulation, as well as supplementation with certain vitamins, have the strongest evidence for use in the treatment of schizophrenia. Further, larger randomized, controlled trials are needed, focusing on certain subgroups of patients and specific antipsychotic medications.