Effectiveness of second-generation antipsychotics in patients with treatment-resistant schizophrenia: a review and meta-analysis of randomized trials

Three-dimensional AuNRs/MXene/NFs -based SERS platform for determination of quetiapine in urine

Determination of antipsychotic drugs in humans is meaningful for both individualized therapy and therapeutic drug monitoring. Quetiapine (QTP), as one of the newly developed antipsychotic drugs, may pose risks to human health if used improperly. In this work, we synthesized a three-dimensional (3D) Au nanorods/MXene (Ti3C2Tx)/nickel foams (named as AuNRs/MXene/NFs) composite material for detecting the antipsychotic drugs QTP. The prepared negatively charged MXene was first assembled on the surface of the NFs through electrostatic interaction to form MXene/NFs, and then the prepared AuNRs were anchored on the MXene/NFs to obtain the final 3D AuNRs/MXene/NFs. By integrating the porous structure and magnetic properties of NFs, large specific surface area of MXene, and the plasmonic hot spots of Au nanorods, the AuNRs/MXene/NFs-based SERS platform can easily and sensitively detect QTP in human urine with the limit of detection of 1.71 × 10-9 mol/L. The linearity was distinguished over the concentration range of QTP from 1 × 10-7 to 1 × 10-4 mol/L (calculated at 1030 cm-1), with correlation coefficients (R2) of 0.9955. The presented AuNRs/MXene/NFs-based SERS strategy realizes QTP detection using SERS technology and provides a novel protocol for the therapeutic drug monitoring.

Current perspectives on the recognition and management of treatment-resistant schizophrenia: challenges and opportunities

INTRODUCTION

Treatment-resistant schizophrenia (TRS) significantly impacts patients with schizophrenia, leading to a high disease burden, reduced quality of life, and functional impairment. Many patients fail to respond to standard antipsychotic treatments, requiring specialized therapeutic approaches. Clozapine remains the only approved treatment for patients with TRS, demonstrating effectiveness in reducing symptoms, hospitalizations, and risk of suicide. However, its use is often delayed due to concerns about adverse events, and the need for ongoing monitoring.

AREAS COVERED

This critical perspective incorporates insights from psychiatrists in Greece and a comprehensive literature analysis that includes clinical guidelines and systematic reviews. It highlights strategies for early diagnosis and timely initiation of clozapine, while emphasizing practical challenges in its use. Recommendations emphasize reducing treatment delays and overcoming barriers such as inadequate training and hesitancy among clinicians. A comprehensive literature search was conducted on PubMed, Google Scholar, and Cochrane Library without any date restrictions to ensure a thorough review of available evidence. The initial literature search was carried out in September 2024, with a subsequent search conducted in March 2025.

EXPERT OPINION

International guidelines consistently recommend clozapine as the first-line treatment for patients with TRS; nevertheless, the authors advocate enhanced awareness to optimize use. Most adverse events can be effectively managed with proper oversight, and early initiation is crucial to improving remission rates and the quality of life of patients with TRS. There is a need for systemic improvements in clinical practice, which requires evidence-based guidance to better address treatment efficacy in this challenging patient population.

Lights and shadows of clozapine on the immune system in schizophrenia: a narrative literature review

Schizophrenia is a chronic mental disorder and one of the main causes of disability in the world. Approximately 1% of the general population suffers from this disorder, and almost 30% of cases are unresponsive to antipsychotic therapies. Clozapine is a Food and Drug Administration (FDA)-approved antipsychotic drug for treatment-resistant schizophrenia (TRS). Clozapine is also approved for the prevention of suicide associated with schizophrenia. However, clozapine is not the preferred first-line medication because of its potential AEs, including agranulocytosis, metabolic syndromes, and myocarditis. Clozapine prescription requires weekly absolute neutrophil count (ANC) monitoring for the first six months, followed by biweekly monitoring until the patient has finished one year of treatment. Several psychiatric disorders have been reported to be associated with inflammatory biomarkers. Dysregulation of the immune system and the elevation of pro-inflammatory cytokines were also reported to be associated with schizophrenia, highlighting the necessity of further research into the etiology of the disease and the relationship between the immune system and clozapine-responsiveness to support better management of symptoms and potential AEs. In this framework, we searched PubMed using the medical subject headings (MeSH) terms "clozapine", "antipsychotics", "schizophrenia", "treatment-resistant schizophrenia", "immune system", "inflammation", "neuroinflammation", "biomarker", "cytokine", and "chemokine" with the aim of overview the impact of clozapine on the immune system in individuals with treatment-responsive and treatment-resistant schizophrenia.

Investigating DRD2 and HTR2A polymorphisms in treatment-resistant schizophrenia: a comparative analysis with other treatment-resistant mental disorders and the healthy state

This study investigates treatment-resistant schizophrenia (TRS) by analysing genetic markers in dopamine and serotonin receptors. Conducted on a cohort of 221 patients with treatment-resistant mental disorders, the research focused on DRD2 and HTR2A gene variants-specifically, rs1801028, rs6314, rs7997012, and rs6311. The findings suggest specific associations between certain genetic variants and TRS. Notably, the HTR2A rs6314 A|G genotype and rs7997012 G|G genotype were significantly more prevalent in TRS patients compared to healthy controls (HCs). Haplotype analyses revealed associations between specific haplotypes-such as A|G (rs6314-rs7997012)-and TRS, indicating their potential predictive value for TRS versus HCs. The study underscores the involvement of the serotonergic system in TRS. These findings offer valuable insights into the genetic factors contributing to TRS, paving the way for future research and the development of personalised prevention and treatment strategies in psychiatry.

Analysis of clinical studies on clozapine from 2012-2022

Clozapine has been considered the "gold standard" in the treatment of schizophrenia for many years. Clozapine has a superior effect, particularly in the treatment of negative symptoms and suicidal behaviour. However, due to its numerous adverse reactions, clozapine is mainly used for treatment-resistant schizophrenia. The aim of this paper is to analyze the results of clinical studies on clozapine from 2012-2022. PubMed was used as the database. Sixty-four studies were included and categorised by topic. The pharmacokinetic properties of clozapine tablets and a clozapine suspension solution did not differ markedly. Clozapine was superior to olanzapine and risperidone in reducing aggression and depression. A long-term study showed that metabolic parameters changed comparably with olanzapine and clozapine after 8 years. Risperidone and ziprasidone can be used as an alternative to clozapine. Scopolamine, atropine drops, and metoclopramide are effective in the treatment of clozapine-induced hypersalivation. Eight drugs, including liraglutide, exenatide, metformin, and orlistat, are potentially effective in the treatment of clozapine-induced weight gain. Ziprasidone, haloperidol, and aripiprazole showed a positive effect on symptoms when added to clozapine. No investigated drug was superior to clozapine for the treatment of schizophrenia. Ziprasidone and risperidone can also be used well for the treatment of schizophrenia. In the treatment of clozapine-induced hypersalivation and weight gain, some drugs proved to be effective.

Refining antipsychotic treatment strategies in schizophrenia: discovery of genetic biomarkers for enhanced drug response prediction

Schizophrenia (SCZ) is a severe mental disorder affecting around 1% of individuals worldwide. The variability in response to antipsychotic drugs (APDs) among SCZ patients presents a significant challenge for clinicians in determining the most effective medication. In this study, we investigated the biological markers and established a predictive model for APD response based on a large-scale genome-wide association study using 3269 Chinese schizophrenia patients. Each participant underwent an 8-week treatment regimen with one of five mono-APDs: olanzapine, risperidone, aripiprazole, quetiapine, or amisulpride. By dividing the response into ordinal groups of "high", "medium", and "low", we mitigated the bias of unclear treatment outcome and identified three novel significantly associated genetic loci in or near CDH12, WDR11, and ELAVL2. Additionally, we developed predictive models of response to each specific APDs, with accuracies ranging from 79.5% to 98.0%. In sum, we established an effective method to predict schizophrenia patients' response to APDs across three categories, integrating novel biomarkers to guide personalized medicine strategies.

The effect of clozapine on immune-related biomarkers in schizophrenia patients

Globally, schizophrenia is one of the main causes of disability. Approximately 1 % of the general population suffers from schizophrenia, and 30 % of cases are unresponsive to therapy. Clozapine is the gold standard for therapy-resistant schizophrenia (TRS), yet it has limited effectiveness and serious adverse events in some patients. Because of the possibility of severe neutropenia, clozapine administration requires monthly hematological monitoring in the first four months. Previous investigations have demonstrated the immune system alteration after clozapine treatment in schizophrenia patients. Besides, it has been proposed that clozapine changes the cytokines profile in schizophrenia patients. These findings highlighted the need to learn more about the disease's etiology and investigate the relationship between peripheral immune system markers and clozapine response to support strategies for better treatment outcomes. The time decision-making to start clozapine could be significantly decreased if some biomarkers were developed to assist physicians in anticipating whether a particular patient will respond to the medication. Therefore, this study aimed to comprehensively review the effect of clozapine on immune-related biomarkers in schizophrenia patients.

Sex-dependent association study of complement C4 gene with treatment-resistant schizophrenia and hospitalization frequency

The complement component 4 (C4) gene, codes for two isotypes, C4A and C4B, and can exist in long or short forms (C4L and C4S). The C4AL variant has been associated with elevated schizophrenia (SCZ) risk. Here, we investigated the relationship between C4 variation and clinical outcomes in SCZ. N = 434 adults with SCZ or schizoaffective disorder were included in this retrospective study. A three-step genotyping workflow was performed to determine C4 copy number variants. These variants were tested for association with clinical outcome measures, including treatment-resistant SCZ (TRS), number of hospitalizations (NOH), and symptom severity (PANSS). Sex and ancestry stratified analyses were performed. We observed a marginally significant association between C4S and TRS in males only, and a negative association between C4S and NOH in the total sample. C4AS had negative association with NOH in males and non-Europeans. Lastly, C4A copy numbers and C4A predicted brain expression showed negative association with NOH in males only. Our study provides further support for sex-specific effect of C4 on SCZ clinical outcomes, and also suggests that C4S and C4AS might have a protective effect against increased severity. C4 could potentially serve as a genetic biomarker in the future, however, more research is required.

Dysfunction of the NMDA Receptor in the Pathophysiology of Schizophrenia and/or the Pathomechanisms of Treatment-Resistant Schizophrenia

For several decades, the dopamine hypothesis contributed to the discovery of numerous typical and atypical antipsychotics and was the sole hypothesis for the pathophysiology of schizophrenia. However, neither typical nor atypical antipsychotics, other than clozapine, have been effective in addressing negative symptoms and cognitive impairments, which are indices for the prognostic and disability outcomes of schizophrenia. Following the development of atypical antipsychotics, the therapeutic targets for antipsychotics expanded beyond the blockade of dopamine D2 and serotonin 5-HT2A receptors to explore the partial agonism of the D2 receptor and the modulation of new targets, such as D3, 5-HT1A, 5-HT7, and metabotropic glutamate receptors. Despite these efforts, to date, psychiatry has not successfully developed antipsychotics with antipsychotic properties proven to be superior to those of clozapine. The glutamate hypothesis, another hypothesis regarding the pathophysiology/pathomechanism of schizophrenia, was proposed based on clinical findings that N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists, such as phencyclidine and ketamine, induce schizophrenia-like psychotic episodes. Large-scale genome-wide association studies (GWASs) revealed that approximately 30% of the risk genes for schizophrenia (the total number was over one hundred) encode proteins associated with glutamatergic transmission. These findings supported the validation of the glutamate hypothesis, which was inspired by the clinical findings regarding NMDAR antagonists. Additionally, these clinical and genetic findings suggest that schizophrenia is possibly a syndrome with complicated pathomechanisms that are affected by multiple biological and genetic vulnerabilities. The glutamate hypothesis has been the most extensively investigated pathophysiology/pathomechanism hypothesis, other than the dopamine hypothesis. Studies have revealed the possibility that functional abnormalities of the NMDAR play important roles in the pathophysiology/pathomechanism of schizophrenia. However, no antipsychotics derived from the glutamatergic hypothesis have yet been approved for the treatment of schizophrenia or treatment-resistant schizophrenia. Considering the increasing evidence supporting the potential pro-cognitive effects of glutamatergic agents and the lack of sufficient medications to treat the cognitive impairments associated with schizophrenia, these previous setbacks cannot preclude research into potential novel glutamate modulators. Given this background, to emphasize the importance of the dysfunction of the NMDAR in the pathomechanism and/or pathophysiology of schizophrenia, this review introduces the increasing findings on the functional abnormalities in glutamatergic transmission associated with the NMDAR.

When, Why and How to Re-challenge Clozapine in Schizophrenia Following Myocarditis

Clozapine-induced myocarditis (CIM) is among the most important adverse events limiting the use of clozapine as the most effective treatment for schizophrenia. CIM necessitates the immediate termination of clozapine, often resulting in its permanent discontinuation with considerable detrimental effects on patients' psychopathology and long-term outcome. Consequently, a clozapine re-challenge after CIM is increasingly regarded as a viable alternative, with published reports indicating a success rate of approximately 60%. However, published cases of re-challenges after CIM remain limited. Here, we provide a narrative review of the current state of research regarding the epidemiology, pathophysiology, risk factors, diagnosis and clinical management of CIM as well as a synthesis of current recommendations for re-challenging patients after CIM. This includes a step-by-step guide for this crucial procedure based on the current evidence regarding the pathophysiology and risk factors for CIM. Slow dose titration regimes and addressing risk factors including concomitant valproate and olanzapine are crucial both to prevent CIM and to ensure a safe and successful re-challenge. Furthermore, we discuss the utility of C-reactive protein, troponin, N-terminal-pro hormone and brain natriuretic peptide, therapeutic drug-monitoring and cardiac magnetic resonance imaging for CIM screening and diagnosis as well as for post-CIM re-challenges.

The prevalence of constipation in adult psychiatric out-patients on clozapine treatment at a regional public hospital in Hong Kong

OBJECTIVE

To determine the occurrence of constipation in local patients on clozapine treatment, and to compare the demographical and clinical characteristics of patients on clozapine treatment with or without constipation.

METHODS

This is a cross-sectional, observational study. All adult psychiatric out-patients on clozapine treatment attending follow-up at a regional hospital were recruited for clinical interview and medical record review. The Enhanced Asian Rome III Questionnaire (EAR3Q) was used to define patients with constipation. The Bristol Stool Form Scale (BSFS) was used to assess stool form. The Brief Psychiatric Rating Scale-Anchored (BPRS-A) was used to measure psychiatric symptoms. The Brief Medication Adherence Scale (BMAS) was used to assess treatment adherence. Logistic regression was conducted to identify independent associating factors of constipation in patients on clozapine treatment.

RESULTS

The prevalence of constipation in patients on clozapine treatment was 26.3%, (95% CI [21.5%, 31.6%]). Independent associating factors included disorder of psychological development (aOR = 6.98, 95% CI [1.24, 39.18]), anxiety (very mild: aOR = 9.23, 95% CI [2.59, 32.87]; mild: aOR = 2.66, 95% CI [1.26, 5.62]), prescription with combination of laxatives (aOR = 0.40, 95% CI [0.17, 0.95]), and concomitant use of amisulpride (aOR = 2.52, 95% CI [1.09, 5.82]), quetiapine (aOR = 5.92, 95% CI [1.11, 31.56]) and metamucil (aOR = 9.30, 95% CI [1.53, 56.58]).

CONCLUSION

This study examined the prevalence of clozapine-associated constipation in Hong Kong using a validated questionnaire. The identification of independent factors associated with constipation could facilitate better risk stratification and risk modification in clinical practice.

A network meta-analysis of efficacy, acceptability, and tolerability of antipsychotics in treatment-resistant schizophrenia

OBJECTIVE

Clozapine is considered as the standard treatment for this subgroup, but the evidence is not unequivocal. There are several potential alternatives being used because of the possible adverse effects of clozapine. We aimed to examine the efficacy and adverse events of different antipsychotics in treatment-resistant schizophrenia by performing a network meta-analysis.

METHODS

We searched the Cochrane Schizophrenia Group register for randomized-controlled trials (up to March 06, 2022) and MEDLINE (up to January 20, 2023). We included blinded and open studies and participants with a broad definition of treatment resistance. The primary outcome was overall symptoms of schizophrenia; secondary outcomes were response to treatment, positive and negative symptoms of schizophrenia, discontinuation, side effects, quality of life, and functioning. The study was registered in Open Science Framework ( https://osf.io/9nf2y/ ).

RESULTS

We included 60 studies involving 6838 participants in the network meta-analysis. In the primary outcome, clozapine and olanzapine were more efficacious than risperidone, haloperidol, fluphenazine, sertindole, chlorpromazine, and quetiapine (range of mean SMDs, - 0.11 to - 0.48). The difference between clozapine and olanzapine was trivial and uncertain (SMD - 0.05, 95% CI, - 0.21 to 0.11). The result of other efficacy outcomes as well as subgroup and sensitivity analyses were consistent with the primary analysis. Clozapine and olanzapine were associated with more weight gain, and clozapine was associated with more sedation events compared to many other antipsychotics.

CONCLUSIONS

Clozapine remains the gold standard for patients with treatment-resistant schizophrenia. Olanzapine seems to be second-best and could be tried before switching to clozapine.

Efficacy of pharmacological agents for the management of treatment-resistant schizophrenia: a network meta-analysis

OBJECTIVE

The present network meta-analysis (NMA) was conducted to compare and generate evidence for the most efficacious treatment among available pharmacological interventions for treatment-resistant schizophrenia (TRS).

METHODS

Reviewers extracted data from 47 studies screened from PubMed/MEDLINE, Embase, Cochrane databases and clinical trial registries fulfilling the eligibility criteria. Random effects Bayesian NMA was done with non-informative priors. Network geometry was visualized, and node splitting was done for the closed triangles. Standardized mean difference and 95% credible interval(95%CrI) were reported for the reduction in symptom severity scores. The probability of each intervention for each rank was plotted. Meta-regression was done for the duration of the therapy.

RESULTS

Augmentation of antipsychotics with escitalopram (SMD: -1.7[95%CrI: -2.8, -0.70]), glycine (SMD: -1.2 [95%CrI: -2.2, -0.28]) and Yokukansan (SMD: -1.3 [95%CrI: -2.4, -0.24]) shows a statistically significant reduction in symptom severity when compared to clozapine. As per surface under cumulative ranking curve analysis, escitalopram in combination with antipsychotics appeared to be the best intervention with moderate certainty of evidence. There was no significant effect of the duration of therapy on the treatment effects.

CONCLUSION

Escitalopram augmentation of antipsychotics appears to be the most efficacious treatment with moderate certainty of evidence among the available pharmacological interventions.

PROSPERO REGISTRATION

CRD42022380292.

Precision psychiatry and Research Domain Criteria: Implications for clinical trials and future practice

Psychiatric disorders are associated with significant social and economic burdens, many of which are related to issues with current diagnosis and treatments. The coronavirus (COVID-19) pandemic is estimated to have increased the prevalence and burden of major depressive and anxiety disorders, indicating an urgent need to strengthen mental health systems globally. To date, current approaches adopted in drug discovery and development for psychiatric disorders have been relatively unsuccessful. Precision psychiatry aims to tailor healthcare more closely to the needs of individual patients and, when informed by neuroscience, can offer the opportunity to improve the accuracy of disease classification, treatment decisions, and prevention efforts. In this review, we highlight the growing global interest in precision psychiatry and the potential for the National Institute of Health-devised Research Domain Criteria (RDoC) to facilitate the implementation of transdiagnostic and improved treatment approaches. The need for current psychiatric nosology to evolve with recent scientific advancements and increase awareness in emerging investigators/clinicians of the value of this approach is essential. Finally, we examine current challenges and future opportunities of adopting the RDoC-associated translational and transdiagnostic approaches in clinical studies, acknowledging that the strength of RDoC is that they form a dynamic framework of guiding principles that is intended to evolve continuously with scientific developments into the future. A collaborative approach that recruits expertise from multiple disciplines, while also considering the patient perspective, is needed to pave the way for precision psychiatry that can improve the prognosis and quality of life of psychiatric patients.

Effectiveness and safety of second-generation antipsychotics for psychiatric disorders apart from schizophrenia: A systematic review and meta-analysis

Second-generation antipsychotics (SGAs) are widely used in treating schizophrenia and related disorders, also other mental disorders. However, the efficacy and safety of SGAs for treating other mental disorders is unclear. A systematic literature search for randomized, placebo-controlled trials of 11 SGAs for treating 18 mental disorders apart from schizophrenia were carried out from database inception to April 3, 2022. The primary outcome was the mean change in the total score for different mental disorders. The secondary outcome was the odds ratio (OR) of response, remission rates and risk ratio (RR) of adverse events (AEs). A total of 181 studies (N = 65,480) were included. All SGAs showed significant effects in treating other mental disorders compared with placebo, except autistic disorder and dementia. Aripiprazole is the most effective treatment for bipolar mania [effect size = -0.90, 95% CI: -1.59, -0.21] and Tourette's disorder [effect size = -0.80, 95% CI: -1.14, -0.45], olanzapine for bipolar depression [effect size = -0.86, 95% CI: -1.32, -0.39] and post-traumatic stress disorder [effect size = -0.98, 95% CI: -1.55, -0.41], lurasidone for depression [effect size = -0.66, 95% CI: -0.82, -0.50], quetiapine for anxiety [effect size = -1.20, 95% CI: -1.96, -0.43], sleep disorders [effect size = -1.2, 95% CI: -1.97, -0.58], and delirium [effect size = -0.36, 95% CI: -0.70, -0.03], and risperidone for obsessive-compulsive disorder [effect size = -2.37, 95% CI: -3.25, -1.49], respectively. For safety, AE items for each SGAs was different. Interestingly, we found that some AEs of OLZ, QTP, RIS and PALI have significant palliative effects on some symptoms. Significant differences in the efficacy and safety of different SGAs for treatment of other mental disorders should be considered for choosing the drug and for the balance between efficacy and tolerability for the specific patient.

Cariprazine augmentation of clozapine in schizophrenia-a retrospective chart review

The aim of our study was to evaluate the efficacy of cariprazine augmentation of clozapine in treatment-resistant schizophrenia in a retrospective chart review. Among 916 medical records of schizophrenia patients, we identified 12 individuals treated with a combination of those drugs for a duration of 3-60 weeks [median 32 (10-40)]. Clinical Global Impression-Improvement (CGI-I) scores were used to measure the treatment response between the introduction of cariprazine augmentation of clozapine and the last point of observation. The majority of the patients presented treatment response (9/12 patients, 75%) after 4-16 weeks of therapy [median 6 (4-12)]. Treatment was associated with the decrease in positive, negative, affective, and anxiety symptom severity, as well as improvement of patient global functioning. One patient discontinued the treatment due to side effects (akathisia), and two patients halted the therapy due to the exacerbation of psychotic symptoms. Our study presents a thorough clinical description of the largest number of treatment-resistant schizophrenia patients medicated using cariprazine augmentation of clozapine in a "real-world" setting. Our results suggest that the use of this combination may lead to the improvement in a broad range of symptoms of patients with this condition.

Global Neuropsychopharmacological Prescription Trends in Adults with Schizophrenia, Clinical Correlates and Implications for Practice: A Scoping Review

It is important to examine the psychotropic prescription practices in schizophrenia, as it can inform regarding changing treatment choices and related patient profiles. No recent reviews have evaluated the global neuropsychopharmacological prescription patterns in adults with schizophrenia. A systematic search of the literature published from 2002 to 2023 found 88 empirical papers pertinent to the utilization of psychotropic agents. Globally, there were wide inter-country and inter-regional variations in the prescription of psychotropic agents. Overall, over time there was an absolute increase in the prescription rate of second-generation antipsychotics (up to 50%), mood stabilizers (up to 15%), and antidepressants (up to 17%), with an observed absolute decrease in the rate of antipsychotic polypharmacy (up to 15%), use of high dose antipsychotic (up to 12% in Asia), clozapine (up to 9%) and antipsychotic long-acting injectables (up to 10%). Prescription patterns were mainly associated with specific socio-demographic (such as age), illness (such as illness duration), and treatment factors (such as adherence). Further work, including more evidence in adjunctive neuropsychopharmacological treatments, pharmaco-economic considerations, and examination of cohorts in prospective studies, can proffer insights into changing prescription trends relevant to different treatment settings and predictors of such trends for enhancement of clinical management in schizophrenia.

Schizophrenia patients discharged on antipsychotic polypharmacy from a public psychiatric hospital in Taiwan, 2006-2021

The aim of this study was to identify the factors associated with antipsychotic polypharmacy (APP), investigate whether APP could affect the risk of rehospitalization, and explore temporal trends in APP use. Schizophrenia patients discharged from the study hospital between 2006 and 2021 (n = 16,722) were included in the analysis. The logistic regression model was employed to determine the predictors significantly associated with APP use. Survival analysis was used to compare time to rehospitalization between APP and antipsychotic monotherapy (AMT). The temporal trend of APP use was analyzed using the Cochran-Armitage Trend test. In comparison with the patients (n = 10,909) who were discharged on AMT, those (n = 5,813) on APP were significantly more likely to be male gender, to receive LAIs, to take clozapine, to take anticholinergic agents, to have a greater number of previous hospitalizations, and to have a higher CPZ equivalent dose of antipsychotic prescription. The prescription rate of APP significantly increased from 18.4 % in 2006 to 44.9 % in 2021. Compared with AMT, APP was associated with more clozapine use, more LAI use, higher doses of antipsychotics, and an increased risk of rehospitalization. In addition, the prescription of APP continued to increase during the study period.

The potential role of por*28 and cyp1a2*f genetic variations and lifestyle factors on clozapine and n-desmethyl clozapine plasma levels in schizophrenia patients

BACKGROUND

Despite its advantages over other antipsychotics, for treatment-resistant schizophrenia, clinical use of Clozapine (CLZ) is challenging by its narrow therapeutic index and potentially life-threatening dose-related adverse effects.

RESEARCH DESIGN AND METHODS

As the potential role in CLZ metabolism is assigned to CYP1A2 enzyme and consequently Cytochrome P450 oxidoreductase (POR) their genetic variations might help to determine CLZ levels in schizophrenia patients. For this purpose, 112 schizophrenia patients receiving CLZ were included in the current study. Plasma CLZ and N-desmethylclozapine (DCLZ) levels were analyzed by using HPLC and genetic variations were identified with the PCR-RFLP method.

RESULTS

The patients' CYP1A2 and POR genotypes seemed to not affect plasma CLZ and DCLZ levels whereas in the subgroup analysis, POR × 28 genotype significantly influenced simple and adjusted plasma CLZ and DLCZ levels concerning smoking habit and caffeine consumption.

CONCLUSIONS

The findings of the present study highlight the importance of both genetic and non-genetic factors (smoking and caffeine consumption) for the individualization of the CLZ treatment. In addition to that, it suggests that the added utility of not only the CLZ metabolizing enzymes but also POR, which is crucial for proper CYP activity, to guide CLZ dosing might be useful for clinical decision-making.

Association Between Clozapine Plasma Concentrations and Treatment Response: A Systematic Review, Meta-analysis and Individual Participant Data Meta-analysis

BACKGROUND AND OBJECTIVES

Although therapeutic drug monitoring of clozapine is recommended, its optimisation is often adjusted only on the basis of dosage. The aim of this study was to assess the link between clozapine plasma concentrations and clinical response by a meta-analysis of published studies and by an individual participant data meta-analysis.

METHODS

We conducted a computerised search of bibliographic databases (EMBASE, PubMed, Clinical Trials, and Web of Science) to identify studies that assessed the relationship between clozapine serum or plasma concentrations and clinical efficacy. Using pooled data, we investigated the association between improvement of clinical outcome and clozapine or norclozapine plasma concentrations, the sum of clozapine and norclozapine plasma concentrations, and the coefficient of variation of clozapine plasma concentrations. Using available individual data, we assessed the relationship between clozapine plasma concentrations and clinical response (changes in the Brief Psychiatric Rating Scale score) and identified a threshold level for a favourable clinical response.

RESULTS

Fifteen studies satisfied inclusion criteria. Our meta-analysis showed that responders had clozapine plasma concentrations that were, on average, 117 ng/mL higher than non-responders. The patients with plasma clozapine concentrations above the thresholds identified in each study had a higher likelihood of responding (odds ratio = 2.94, p < 0.001). Norclozapine plasma concentrations were not associated with a clinical response. The meta-analysis of individual data supported this result and confirmed the link between clozapine concentrations and a change in the Brief Psychiatric Rating Scale score and/or the probability of clinical response. Finally, with the analysis of the coefficient of variation of clozapine plasma concentrations, we found that a greater inter-individual fluctuation in plasma concentrations was associated with a loss of clinical response.

CONCLUSIONS

Our work confirmed that, in contrast to clozapine doses, clozapine plasma concentrations were related to a favourable clinical response, with a mean difference between responders and non-responders of 117 ng/mL. A threshold for a treatment response of 407 ng/mL was determined, with a high discriminatory capacity, and a sensitivity and specificity of 71% and 89.1%, respectively.

Second to none: rationale, timing, and clinical management of clozapine use in schizophrenia

Despite its enduring relevance as the single most effective and important evidence-based treatment for schizophrenia, underutilization of clozapine remains considerable. To a substantial degree, this is attributable to a reluctance of psychiatrists to offer clozapine due to its relatively large side-effect burden and the complexity of its use. This underscores the necessity for continued education regarding both the vital nature and the intricacies of clozapine treatment. This narrative review summarizes all clinically relevant areas of evidence, which support clozapine's wide-ranging superior efficacy - for treatment-resistant schizophrenia (TRS) and beyond - and make its safe use eminently feasible. Converging evidence indicates that TRS constitutes a distinct albeit heterogeneous subgroup of schizophrenias primarily responsive to clozapine. Most importantly, the predominantly early onset of treatment resistance and the considerable decline in response rates associated with its delayed initiation make clozapine an essential treatment option throughout the course of illness, beginning with the first psychotic episode. To maximize patients' benefits, systematic early recognition efforts based on stringent use of TRS criteria, a timely offer of clozapine, thorough side-effect screening and management as well as consistent use of therapeutic drug monitoring and established augmentation strategies for suboptimal responders are crucial. To minimize permanent all-cause discontinuation, re-challenges after neutropenia or myocarditis should be considered. Owing to clozapine's unique efficacy, comorbid conditions including substance use and most somatic disorders should not dissuade but rather encourage clinicians to consider clozapine. Moreover, treatment decisions need to be informed by the late onset of clozapine's full effects, which for reduced suicidality and mortality rates may not even be readily apparent. Overall, the singular extent of its efficacy combined with the high level of patient satisfaction continues to distinguish clozapine from all other available antipsychotics.

Treatment-Resistant Schizophrenia, Clozapine Resistance, Genetic Associations, and Implications for Precision Psychiatry: A Scoping Review

Treatment-resistant schizophrenia (TRS) is often associated with severe burden of disease, poor quality of life and functional impairment. Clozapine is the gold standard for the treatment of TRS, although it is also known to cause significant side effects in some patients. In view of the burgeoning interest in the role of genetic factors in precision psychiatry, we conducted a scoping review to narratively summarize the current genetic factors associated with TRS, clozapine resistance and side effects to clozapine treatment. We searched PubMed from inception to December 2022 and included 104 relevant studies in this review. Extant evidence comprised associations between TRS and clozapine resistance with genetic factors related to mainly dopaminergic and serotoninergic neurotransmitter systems, specifically, TRS and rs4680, rs4818 within COMT, and rs1799978 within DRD2; clozapine resistance and DRD3 polymorphisms, CYP1A2 polymorphisms; weight gain with LEP and SNAP-25 genes; and agranulocytosis risk with HLA-related polymorphisms. Future studies, including replication in larger multi-site samples, are still needed to elucidate putative risk genes and the interactions between different genes and their correlations with relevant clinical factors such as psychopathology, psychosocial functioning, cognition and progressive changes with treatment over time in TRS and clozapine resistance.

Lurasidone Augmentation of Clozapine in Schizophrenia—Retrospective Chart Review

The aim of our study was to evaluate the effectiveness of lurasidone augmentation of clozapine in treatment-resistant schizophrenia (SZ) in a retrospective chart review. From the medical records of 916 SZ patients, we identified 16 individuals treated with a combination of clozapine and lurasidone. The detailed clinical data are described separately for each patient. We compared the Clinical Global Impression—Severity (CGI-S) scores between three points of observation: before the treatment and one month and two months after its initiation. CGI Improvement (CGI-I) scores were used to evaluate the treatment response between the first and last points of observation. The vast majority of patients (14/16, 87.5%) responded to lurasidone augmentation of clozapine (CGI-I scores 1 or 2). Therapeutic effects were observable after 3–12 weeks of treatment (median 6 (4–6)). A reduction in CGI-S scores was observed after the first month of observation. There was an observable reduction in positive, depressive and anxiety symptoms, as well as an improvement in psychosocial functioning. Two patients discontinued treatment due to side effects. Our study suggests that lurasidone augmentation of clozapine may lead to improvements in a broad range of SZ symptom dimensions.

Efficacy of clozapine compared with other second-generation antipsychotic drugs in patients with treatment-resistant schizophrenia: protocol for a systematic review and individual patient data meta-analysis of randomised controlled trials

INTRODUCTION

Guidelines recommend clozapine for treatment-resistant schizophrenia. However, meta-analysis of aggregate data (AD) did not demonstrate higher efficacy of clozapine compared with other second-generation antipsychotics but found substantial heterogeneity between trials and variation between participants in treatment effects. Therefore, we will conduct an individual participant data (IPD) meta-analysis to estimate the efficacy of clozapine compared with other second-generation antipsychotics while accounting for potentially important effect modifiers.

METHODS AND ANALYSIS

In a systematic review, two reviewers will independently search Cochrane Schizophrenia Group's trial register (without restrictions in date, language or state of publication) and related reviews. We will include randomised controlled trials (RCTs) in participants with treatment-resistant schizophrenia comparing clozapine with other second-generation antipsychotics for at least 6 weeks. We will apply no restrictions in age, gender, origin, ethnicity or setting, but exclude open-label studies, studies from China, experimental studies and phase II of cross-over trials. IPD will be requested from trial authors and cross-check against published results. AD will be extracted in duplicate. Risk of bias will be assessed using Cochrane's Risk of Bias 2 tool.The primary outcome will be overall symptoms of schizophrenia.We will synthesise results using random-effects meta-analysis and meta-regression methods in a 3-level Bayesian model. The model combines IPD with AD when IPD is not available for all studies, and include participant, intervention and study design characteristics as potential effect modifiers. The effect size measures will be mean difference (or standardised mean difference when different scales were used). Confidence in the evidence will be assessed using GRADE.

ETHICS AND DISSEMINATION

This project has been approved by the ethics commission of the Technical University of Munich (#612/21 S-NP). The results will be published open-access in a peer-review journal and a plain-language version of the results will be disseminated.If we need to amend this protocol, we will describe the change and give the rationale in a specific section in the resulting publication 'Changes with respect to the protocol'.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (#CRD42021254986).

Antipsychotic prescribing practices for outpatients with schizophrenia and reasons for non-clozapine treatment - Data from a Danish quality assessment audit

BACKGROUND

Clozapine is the gold standard for treating treatment-resistant schizophrenia (TRS) although widely underutilised. Both organisational, patient- and clinician related reasons for the underutilisation have been reported, however, the clinical impact of either in real-world settings is not fully elucidated.

AIM

This audit aimed to evaluate the local antipsychotic (AP) prescribing practices for outpatients with schizophrenia and to assess the spectrum and prevalence of journalised reasons for non-clozapine treatment amongst eligible outpatients.

METHODS

Data on demographics, current and former AP treatments, as well as documented reasons for non-clozapine treatment, was extracted through chart audit.

RESULTS

Of the 668 affiliated outpatients with schizophrenia, 43% were treated with AP polytherapy (APP) and 19.6% with clozapine. The most prevalent reason for clozapine discontinuation was related to side effects whereas the most prevalent reason for refusal or omission of clozapine treatment was related to the associated monitoring regimen.

CONCLUSIONS

This audit showed that APP prescribing is a highly prevalent practice in our services when treating outpatients with schizophrenia and that clozapine is underutilised in a 'last resort' manner. The blood-monitoring regimen associated with clozapine treatment was found to be an important factor in the underutilisation. It seemed, however, that the monitoring constituted a barrier for different reasons, requiring different approaches to remedy. Future studies, directly involving both patients and clinicians in the identification and management of the most clinically relevant barriers and their corresponding facilitators, are warranted.

Clozapine-induced Myocarditis: Pathophysiologic Mechanisms and Implications for Therapeutic Approaches

Clozapine, a superior treatment for treatment-resistant schizophrenia can cause potentially life-threatening myocarditis and dilated cardiomyopathy. While the occurrence of this condition is well known, its molecular mechanisms are unclear and may be multifactorial. Putative mechanisms warrant an in-depth review not only from the perspective of toxicity but also for understanding the molecular mechanisms of the adverse cardiac effects of clozapine and the development of novel therapeutic approaches. Clozapine-induced cardiac toxicity encompasses a diverse set of pathways, including (i) immune modulation and proinflammatory processes encompassing an IgEmediated (type I hypersensitivity) response and perhaps a cytokine release syndrome (ii) catecholaminergic activation (iii) induction of free radicals and oxidative stress (iv) activation of cardiomyocyte cell death pathways, including apoptosis, ischemia through impairment in coronary blood flow via changes in endothelial production of NO and vasoconstriction induced by norepinephrine as well as other factors released from cardiac mast cells. (v) In addition, an extensive examination of the effects of clozapine on non-cardiac cellular proteins demonstrates that clozapine can impair enzymes involved in cellular metabolism, such as pyruvate kinase, mitochondrial malate dehydrogenase, and other proteins, including α-enolase, triosephosphate isomerase and cofilin, which might explain clozapine-induced reductions in myocardial energy generation for cell viability as well as contractile function. Pharmacologic antagonism of these cellular protein effects may lead to the development of strategies to antagonize the cardiac damage induced by clozapine.

Ethnic disparities in clozapine prescription for service-users with schizophrenia-spectrum disorders: a systematic review

Clozapine is the only licenced medication for treating treatment-resistant schizophrenia. Previous studies have suggested unequal rates of clozapine treatment by ethnicity among individuals with schizophrenia-spectrum disorders. One previous review has investigated this topic but was restricted to studies from the USA. This current review aims to synthesise the international literature regarding ethnic disparities in clozapine prescription amongst individuals with schizophrenia-spectrum disorders. We searched CINAHL, PubMed, Medline, Embase, APA PsycINFO and Open Grey and reviewed studies reporting on the proportion of service-users prescribed clozapine separately for different ethnic groups, in individuals with a primary diagnosis of schizophrenia or any schizophrenia-spectrum disorders. A narrative synthesis was conducted to integrate information from included studies. The review was registered in PROSPERO (Number: CRD42020221731). From 24 studies, there is strong, consistent evidence that Black and Hispanic service-users in the UK and the USA are significantly less likely to receive clozapine than White/Caucasian service-users after controlling for multiple demographic and clinical potential confounders. In New Zealand, Māori service-users were reported to be more likely to receive clozapine than those of White/European ethnicity. There is mixed evidence regarding Asian service-users in the UK. The mentioned disparities were observed in studies with TRS and non-TRS cohorts. The results imply that access to clozapine treatment varies among ethnic groups. These findings raise an ethical concern as they suggest a compromise of the standards of care in schizophrenia treatment practices. Interventions are needed to reduce clozapine prescribing disparities among ethnic communities.

Treatment-resistant schizophrenia: How far have we traveled?

Treatment-resistant schizophrenia is a lack of adequate response to antipsychotic medications resulting in incomplete functional and social recovery from the illness. Different definitions have been proposed for clinical practice and research work. Antipsychotics that are used in the management of schizophrenia mainly act on multiple dopaminergic pathways which are implicated in the development of symptoms of schizophrenia. Newer antipsychotics also are implicated to affect the serotonergic pathways. Clozapine is the only evidence-based treatment available for the management of treatment-resistant cases. Neurobiologically, there is a considerable overlap between treatment-resistant and treatment-responsive cases. The factors that are implicated in the evolution of treatment resistance are still not conclusive. These make the management of such patients a challenge. However, certain peculiarities of treatment-resistant schizophrenia have been identified which can guide us in the early identification and precise treatment of the treatment-resistant cases.

Brain stimulation and other biological non-pharmacological interventions in mental disorders: An umbrella review

BACKGROUND

The degree of efficacy, safety, quality, and certainty of meta-analytic evidence of biological non-pharmacological treatments in mental disorders is unclear.

METHODS

We conducted an umbrella review (PubMed/Cochrane Library/PsycINFO-04-Jul-2021, PROSPERO/CRD42020158827) for meta-analyses of randomized controlled trials (RCTs) on deep brain stimulation (DBS), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), electro-convulsive therapy (ECT), and others. Co-primary outcomes were standardized mean differences (SMD) of disease-specific symptoms, and acceptability (for all-cause discontinuation). Evidence was assessed with AMSTAR/AMSTAR-Content/GRADE.

RESULTS

We selected 102 meta-analyses. Effective interventions compared to sham were in depressive disorders: ECT (SMD=0.91/GRADE=moderate), TMS (SMD=0.51/GRADE=moderate), tDCS (SMD=0.46/GRADE=low), DBS (SMD=0.42/GRADE=very low), light therapy (SMD=0.41/GRADE=low); schizophrenia: ECT (SMD=0.88/GRADE=moderate), tDCS (SMD=0.45/GRADE=very low), TMS (prefrontal theta-burst, SMD=0.58/GRADE=low; left-temporoparietal, SMD=0.42/GRADE=low); substance use disorder: TMS (high frequency-dorsolateral-prefrontal-deep (SMD=1.16/GRADE=moderate), high frequency-left dorsolateral-prefrontal (SMD=0.77/GRADE=very low); OCD: DBS (SMD=0.89/GRADE=moderate), TMS (SMD=0.64/GRADE=very low); PTSD: TMS (SMD=0.46/GRADE=moderate); generalized anxiety disorder: TMS (SMD=0.68/GRADE=low); ADHD: tDCS (SMD=0.23/GRADE=moderate); autism: tDCS (SMD=0.97/GRADE=very low). No significant differences for acceptability emerged. Median AMSTAR/AMSTAR-Content was 8/2 (suggesting high-quality meta-analyses/low-quality RCTs), GRADE low.

DISCUSSION

Despite limited certainty, biological non-pharmacological interventions are effective and safe for numerous mental conditions. Results inform future research, and guidelines.

FUNDING

None.

Emerging Roles of FTO in Neuropsychiatric Disorders

FTO (fat mass and obesity associated) is a recently discovered gene related to obesity and expressed in various tissues of the human body, especially with high expression in the brain. Earlier studies have found that FTO is involved in several biological processes, including brain development and function. In particular, recent studies have found that FTO is a demethylase of N6-methyladenosine (m6A) and it can affect neurological function through the m6A modification of mRNA. At present, a number of studies have shown that FTO is associated with many neuropsychiatric disorders. This paper reviews the discovery, structure, function, and tissue expression of FTO followed by discussing the relationship between FTO and neuropsychiatric diseases. In addition, the potential roles of FTO gene in drug addiction, major depression (MDD), and schizophrenia (SCZ) through regulating m6A modification of dopamine related genes were also highlighted.

The role of alcohol intake in the pharmacogenetics of treatment with clozapine

Clozapine (CLZ) is an atypical antipsychotic reserved for patients with refractory psychosis, but it is associated with a significant risk of severe adverse reactions (ADRs) that are potentiated with the concomitant use of alcohol. Additionally, pharmacogenetic studies have explored the influence of several genetic variants in CYP450, receptors and transporters involved in the interindividual response to CLZ. Herein, we systematically review the current multiomics knowledge behind the interaction between CLZ and alcohol intake, and how its concomitant use might modulate the pharmacogenetics. CYP1A2*1F, *1C and other alleles not yet discovered could support a precision medicine approach for better therapeutic effects and fewer CLZ ADRs. CLZ monitoring systems should be amended and include alcohol intake to protect patients from severe CLZ ADRs.

Complete blood count inflammatory markers in treatment-resistant schizophrenia: Evidence of association between treatment responsiveness and levels of inflammation

Accumulating evidence suggests that the variable response to antipsychotic treatment in schizophrenia reflects distinct biological subtypes. The pathophysiology of schizophrenia is associated with alteration in the immune system which can be measured with complete blood count (CBC) markers of systemic inflammation, including the neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR). While previous research suggested a decrease in CBC inflammatory markers following treatment, it is unknown if treatment or response to treatment is associated with CBC markers in treatment-resistant schizophrenia. Here, we retrospectively analyzed the CBC at admission and discharge in schizophrenia inpatients classified as treatment-responsive, treatment-resistant, and ultra-treatment-resistant. Despite similar NLR at admission, the subtypes manifested different changes in NLR during treatment resulting in significant differences at discharge. Only the treatment-responsive group presented a significant decrease in inflammatory markers after treatment. Additionally, we found that the responsive group had a higher PLR at admission and was the only subgroup to demonstrate a significant reduction following treatment. In sum, our results support the idea that persistent inflammation is a biological trait marker of treatment resistance in schizophrenia.

The short and long-term effects of aerobic, strength, or mixed exercise programs on schizophrenia symptomatology

The purpose of this study was to compare the effects of three different physical exercise programs on the symptomatology, body composition, physical activity, physical fitness, and quality of life of individuals with schizophrenia. A total of 432 patients were assessed for eligibility and 86 were randomized into the aerobic (n = 28), strength (n = 29) or mixed (n = 29) groups. Positive, negative, and general symptoms of psychosis, body mass index (BMI), physical activity (IPAQ-SF), physical fitness (6-min walk test [6MWT] and hand-grip strength [HGS]), and quality of life (WHOQUOL-BREF) were assessed at baseline, post-intervention (16 weeks), and at 10-months. Our results at 16 weeks showed significant improvements in all three groups in the negative, general, and total symptoms with moderate to large effect sizes (P < 0.01, η_p² > 0.11), no change in the BMI, 6MWT or IPAQ-SF, and a significant improvement in the HGS test in the strength and mixed groups (P ≤ 0.05, η_p² > 0.08). Nonetheless, all the improvements had disappeared at 10 months. We concluded that 3 weekly sessions of a moderate to vigorous progressive exercise program for 16 weeks improved the symptomatology of individuals with schizophrenia in all three groups, with no differences between them. However, the effects had declined to baseline levels by the 10-month follow-up, suggesting that exercise interventions should be maintained over time.

Progress in mechanistically novel treatments for schizophrenia

Currently available pharmacological treatments for schizophrenia derive their activity mainly by directly modulating the D2 receptor. This mode of action can alleviate the positive symptoms of schizophrenia but do not address the negative or cognitive symptoms of the disease and carry a heavy side effect burden that leads to high levels of patient non-compliance. Novel mechanisms to treat the positive symptoms of schizophrenia with improved tolerability, as well as medicines to treat negative and cognitive symptoms are urgently required. Recent efforts to identify small molecules for schizophrenia with non-D2 mechanisms will be highlighted, with a focus on those that have reached clinical development. Finally, the potential for disease modifying treatments for schizophrenia will also be discussed.

Efficacy and safety of clozapine in psychotic disorders-a systematic quantitative meta-review

A recent increase in the literature regarding the evidence base for clozapine has made it increasingly difficult for clinicians to judge "best evidence" for clozapine use. As such, we aimed at elucidating the state-of-the-art for clozapine with regard to efficacy, effectiveness, tolerability, and management of clozapine and clozapine-related adverse events in neuropsychiatric disorders. We conducted a systematic PRISMA-conforming quantitative meta-review of available meta-analytic evidence regarding clozapine use. Primary outcome effect sizes were extracted and transformed into relative risk ratios (RR) and standardized mean differences (SMD). The methodological quality of meta-analyses was assessed using the AMSTAR-2 checklist. Of the 112 meta-analyses included in our review, 61 (54.5%) had an overall high methodological quality according to AMSTAR-2. Clozapine appears to have superior effects on positive, negative, and overall symptoms and relapse rates in schizophrenia (treatment-resistant and non-treatment-resistant subpopulations) compared to first-generation antipsychotics (FGAs) and to pooled FGAs/second-generation antipsychotics (SGAs) in treatment-resistant schizophrenia (TRS). Despite an unfavorable metabolic and hematological adverse-event profile compared to other antipsychotics, hospitalization, mortality and all-cause discontinuation (ACD) rates of clozapine surprisingly show a pattern of superiority. Our meta-review outlines the superior overall efficacy of clozapine compared to FGAs and most other SGAs in schizophrenia and suggests beneficial efficacy outcomes in bipolar disorder and Parkinson's disease psychosis (PDP). More clinical studies and subsequent meta-analyses are needed beyond the application of clozapine in schizophrenia-spectrum disorders and future studies should be directed into multidimensional clozapine side-effect management to foster evidence and to inform future guidelines.

Clozapine in patients with schizoaffective disorder: A systematic review

Schizoaffective disorder is defined by the appearance of positive psychotic symptomatology as well as affective features, even when it is considered a controversial nosologic entity, proving difficult to accord on its definition or diagnostic criteria. Due to these conceptual differences, it has been a challenge to study effective therapeutic measures and, consequently, the availability of data in the current literature, resulting in the extrapolation of clinical guidelines and recommendations initially established for patients with schizophrenia or bipolar disorder. The current study aimed to systematically search and summarize the published evidence to date about the use of clozapine in patients with schizoaffective disorder. Seven studies were identified, that are heterogeneous on their designs and methodology, including samples of patients mixed with bipolar or schizophrenic disorders. The evidence was summarized both in a table and a narrative fashion, suggesting that clozapine may be an effective treatment for both psychotic and affective symptoms, indistinctively of an acute or maintenance phase.

Risk factors for clozapine-induced central nervous system abnormalities in Japanese patients with treatment-resistant schizophrenia

The purpose of this study was to assess the risk factors for clozapine-induced central nervous system (CNS) abnormalities (i.e., electroencephalogram [EEG] abnormalities, myoclonus, and seizures). We retrospectively analyzed data from 106 patients with schizophrenia who received clozapine treatment through our hospital. A review of the EEG recordings showed that 71 of these patients (67.0 %) developed CNS abnormalities after initiating clozapine treatment. EEG abnormalities, myoclonus, and seizures occurred in 53.8 %, 38.7 %, and 8.5 % of the patients, respectively. Multivariate logistic regression analysis showed that the risk factors for clozapine-induced CNS abnormalities were concomitant lithium usage (odds ratio, 4.560; 95 % confidence interval, 1.750-11.900) and shorter illness durations before clozapine initiation (odds ratio, 0.796; 95 % confidence interval, 0.649-0.976). However, plasma clozapine levels and the usage of antiepileptics did not exhibit associations with the risks of CNS abnormalities. Clinicians should monitor their patients for incident CNS abnormalities when administering lithium in combination with clozapine regardless of plasma clozapine levels or the usage of antiepileptics. This is especially true for patients with short illness durations.

A Chart Audit Study of Clozapine Utilization in Early Psychosis

PURPOSE

This study aimed to document the treatment trajectories and clozapine use in first-episode psychosis patients and to document the underlying reasons for using or not using clozapine in patients not achieving psychosis remission.

METHODS

We conducted a retrospective chart audit of patients aged 18 to 30 years having DSM-5 diagnoses of schizophrenia spectrum psychotic disorders treated in 3 Canadian early intervention programs for psychosis. The severity of the patient's illness (using the Clinical Global Impression Severity [CGI-S] scale) and remission of psychosis were rated before and after each antipsychotic trial.

RESULTS

One hundred and forty-seven patients were included in the study. There were 19.7% patients exposed to clozapine after an average of 2.4 antipsychotic trials and a mean delay of 470.8 days. There were 75.9% patients who improved their CGI-S score (mean improvement, 2.5) after the clozapine trial and 62.1% achieved a CGI-S score ≤3. Full remission of psychosis on clozapine was achieved in 69.0% of the patients. Clozapine was successfully used for some patients with a nonadherent profile in our sample (eg, personality disorder, substance use disorder). Although the mean duration of clozapine trials during the observation period was 688.6 days, no patient discontinued clozapine because of adherence issues.

CONCLUSIONS

Clozapine use in these early intervention programs were at a rate consistent to what is expected from the literature and allowed a majority of patients to achieve remission of psychosis and to experience a robust improvement of severity of illness.

White matter microstructure and structural networks in treatment-resistant schizophrenia patients after commencing clozapine treatment: A longitudinal diffusion imaging study

This study investigates changes on white matter microstructure and neural networks after 6 months of switching to clozapine in schizophrenia patients compared to controls, and whether any changes are related to clinical variables. T1 and diffusion-weighted MRI images were acquired at baseline before commencing clozapine and after 6 months of treatment for 22 patients with treatment-resistant schizophrenia and 23 controls. The Tract-based spatial statistics approach was used to compare changes over time between groups in fractional anisotropy (FA). Changes in structural network organisation weighted by FA and number of streamlines were assessed using graph theory. Patients displayed a significant reduction of FA over time (p<0.05) compared to controls in the genu and body of the corpus callosum and bilaterally in the anterior and superior corona radiata. There was no correlation between FA change in patients and changes in clinical variables or serum level of clozapine. There was no changes in structural network organisation between groups (F(7,280)=2.80;p = 0.187). This longitudinal study demonstrated progressive focal FA abnormalities in key anterior tracts, but preserved brain structural network organisation in patients. The FA reduction was independent of any clinical measures and may reflect progression of the underlying pathophysiology of this malignant form of schizophrenia illness.

A descriptive study of 10-year clozapine use from the nationwide database in Japan

This survey was conducted to identify the actual usage of clozapine and changes required to increase the number of patients with schizophrenia who would benefit from clozapine. We obtained Clozaril® Patient Monitoring Service (CPMS) data for 8,263 patients that received clozapine between July 2009 and January 2020. Patients were divided into the early (n=3,696 cases, which have been analyzed previously) and late groups (n=4,567 cases) according to the date of the treatment initiation. In total, 417 facilities offered the drug, with a surge in cases in the late group (40.0 hospitals/year, 568.6 cases/year vs. 39.3 hospitals/year, 1,141.8 cases/year). We found a significant between-group difference in the mean dosage during treatment (early group: 309.1 mg/day; late group: 247.9 mg/day). The treatment continuation rates at 1 and 4 years in all study participants were 77.2% and 65.1%, respectively. The incidences of granulocytopenia and agranulocytosis were 5.5% and 1.0%, respectively. The discontinuation rate because of granulocytopenia was significantly lower in the late group. There were no differences in the discontinuation rate because of glucose intolerance between the groups. An assessment of the current CPMS regulations may be required to further examine the clozapine use effectiveness.

Tardive Dyskinesia: Spotlight on Current Approaches to Treatment

Tardive dyskinesia (TD) is a debilitating, iatrogenic, and potentially severe movement disorder characterized by involuntary, repetitive, purposeless movements that are present throughout the body. The authors present a review of studies of past, current, and possible future treatment approaches to the management of TD; consider the phenomenology, assessment, and putative pathophysiological mechanisms of TD, early pharmacological trials, a focus on the newer vesicular monoamine transporter 2 inhibitors, and other evidence-based approaches, such as clozapine; and present preliminary evidence for newer approaches, such as deep brain stimulation and repetitive transcranial magnetic stimulation. On the basis of the evidence presented here, the authors highlight the importance of early recognition and assessment of TD, as well as how to best approach management of these often incapacitating symptoms.

Evaluation of the effectiveness and acceptability of intramuscular clozapine injection: illustrative case series

AIMS AND METHOD

A series of eleven patients prescribed intramuscular clozapine at five UK sites is presented. Using routinely collected clinical data, we describe the use, efficacy and safety of this treatment modality.

RESULTS

We administered 188 doses of intramuscular clozapine to eight patients. The remaining three patients accepted oral medication. With the exception of minor injection site pain and nodules, side-effects were as expected with oral clozapine, and there were no serious untoward events. Nine patients were successfully established on oral clozapine with significant improvement in their clinical presentations.

CLINICAL IMPLICATIONS

Although a novel formulation in the UK, we have shown that intramuscular clozapine can be used safely and effectively when the oral route is initially refused.

A Synthetic Literature Review on the Management of Emerging Treatment Resistance in First Episode Psychosis: Can We Move towards Precision Intervention and Individualised Care?

Treatment resistance is prevalent in early intervention in psychosis services, and causes a significant burden for the individual. A wide range of variables are shown to contribute to treatment resistance in first episode psychosis (FEP). Heterogeneity in illness course and the complex, multidimensional nature of the concept of recovery calls for an evidence base to better inform practice at an individual level. Current gold standard treatments, adopting a ‘one-size fits all’ approach, may not be addressing the needs of many individuals. This following review will provide an update and critical appraisal of current clinical practices and methodological approaches for understanding, identifying, and managing early treatment resistance in early psychosis. Potential new treatments along with new avenues for research will be discussed. Finally, we will discuss and critique the application and translation of machine learning approaches to aid progression in this area. The move towards ‘big data’ and machine learning holds some prospect for stratifying intervention-based subgroups of individuals. Moving forward, better recognition of early treatment resistance is needed, along with greater sophistication and precision in predicting outcomes, so that effective evidence-based treatments can be appropriately tailored to the individual. Understanding the antecedents and the early trajectory of one’s illness may also be key to understanding the factors that drive illness course.

Relationship of Change in Plasma Clozapine/N-desmethylclozapine Ratio with Cognitive Performance in Patients with Schizophrenia

OBJECTIVE

The clozapine/N-desmethylclozapine (NDMC) ratio is proposed to be used as a predictor of cognitive performance in clozapine-treated patients, as its principal metabolite, NDMC, has an opposite action with clozapine on the cholinergic system. The aim of this study is to determine whether clozapine has influence on cognitive performance in accordance with changes in the clozapine/NDMC in patients with schizophrenia.

METHODS

The data of fifteen patients with schizophrenia, who had initial and follow-up assessments after starting clozapine treatment, were retrospectively collected. The assessments included clinical scale, cognitive battery, and pharmacological data including plasma concentrations of clozapine and NDMC. The data were analyzed with Pearson correlation and stepwise multiple regression analyses.

RESULTS

ΔAttention/vigilance, Δsocial cognition, and Δcomposite score had a significant correlation with Δclozapine/NDMC ratio, while ΔWorking memory had correlation with Δclozapine concentration and ΔNDMC concentration, and Δsocial cognition had association with Δclozapine concentration. Multiple regression analysis showed that Δattention/vigilance had negative association with Δclozapine/NDMC ratio, Δworking memory had negative relation with Δclozapine concentration, and that Δsocial cognition had negative association with Δclozapine concentration.

CONCLUSION

This finding implicates that lowering the clozapine/NDMC ratio could enhance cognition in patients with schizophrenia treated with clozapine.

Molecular mechanisms of psychiatric diseases

For most psychiatric diseases, pathogenetic concepts as well as paradigms underlying neuropsychopharmacologic approaches currently revolve around neurotransmitters such as dopamine, serotonin, and norepinephrine. However, despite the fact that several generations of neurotransmitter-based psychotropics including atypical antipsychotics, selective serotonin reuptake inhibitors, and serotonin-norepinephrine reuptake inhibitors are available, the effectiveness of these medications is limited, and relapse rates in psychiatric diseases are relatively high, indicating potential involvement of other pathogenetic pathways. Indeed, recent high-throughput studies in genetics and molecular biology have shown that pathogenesis of major psychiatric illnesses involves hundreds of genes and numerous pathways via such fundamental processes as DNA methylation, transcription, and splicing. Current review summarizes these and other molecular mechanisms of such psychiatric illnesses as schizophrenia, major depressive disorder, and alcohol use disorder and suggests a conceptual framework for future studies.

Investigating aberrantly expressed microRNAs in peripheral blood mononuclear cells from patients with treatment‑resistant schizophrenia using miRNA sequencing and integrated bioinformatics

Treatment-resistant schizophrenia (TRS) is a common phenotype of schizophrenia that places a considerable burden on patients as well as on society. TRS is known for its tendency to relapse and uncontrollable nature, with a poor response to antipsychotics other than clozapine. Therefore, it is urgent to identify objective biological markers, so as to guide its treatment and associated clinical work. In the present study, the peripheral blood mononuclear cells (PBMCs) of patients with TRS and a healthy control group, which were gender-, age- and ethnicity-matched, were subjected to microRNA (miRNA/miR) sequencing to screen out the top three miRNAs with the highest fold change values. These were then validated in the TRS (n=34) and healthy control (n=31) groups by reverse transcription-quantitative PCR. For two of the top three miRNAs, the PCR results were in accordance with the sequencing result (P<0.01), while the third miRNA exhibited the opposite trend (P<0.01). To elucidate the functions of these two miRNAs, Homo sapiens (hsa)-miR-218-5p and hsa-miR-1262 and their regulatory network, target gene prediction was first performed using online TargetScan and Diana-micro T software. Bioinformatics analysis was then performed using functional enrichment analysis to determine the Gene Ontology terms in the category biological process and the Kyoto Encyclopedia of Genes and Genomes pathways. It was revealed that these target genes were markedly associated with the nervous system and brain function, and it was obvious that the differentially expressed miRNAs most likely participated in the pathogenesis of TRS. A receiver operating characteristic curve was generated to confirm the distinct diagnostic value of these two miRNAs. It was concluded that aberrantly expressed miRNAs in PMBCs may be implicated in the pathogenesis of TRS and may serve as specific peripheral blood-based biomarkers for the early diagnosis of TRS.

The relationship between plasma levels of clozapine and N-desmethyclozapine as well as M1 receptor polymorphism with cognitive functioning and associated cortical activity in schizophrenia

Studies that examined the effect of clozapine on cognitive functions in schizophrenia provided contradictory results. N-desmethylclozapine (NDMC) is the major metabolite of clozapine and have procognitive effects via agonistic activity in the M1 cholinergic receptors. The rs2067477 polymorphism in the M1 receptors may play role in cognitive profile in schizophrenia. We investigated the association of plasma clozapine (PClz), NDMC (PNdmc) levels and the rs2067477 polymorphism with cognitive functions and cortical activity measured by functional near infrared spectroscopy during the N-Back task in subjects with schizophrenia (N = 50) who are under antipsychotic monotherapy with clozapine. We found that PClz and PNdmc levels were negatively, PNdmc/PClz ratio was positively correlated with immediate recall score in the Rey Auditory Verbal Learning Test. PNdmc/PClz ratio was positively correlated with cortical activity during the N-back task. M1 wild-type group (CC: wild-type) produced higher cortical activity than M1 non wild-type group (CA: heterozygote / AA: mutant) in cortical regions associated with working memory (WM). These results suggest that individual differences in clozapine's effect on short term episodic memory may be associated with PClz and PNdmc. Higher activity in the M1 wild-type group may indicate inefficient use of cortical resources and/or excessive use of certain cognitive strategies during WM performance.

Treating schizophrenia: the quality of evidence behind treatment recommendations and how it can improve

OBJECTIVE

To assess the methodological and reporting quality of systematic reviews that comprise the American Psychiatric Association (APA) Practice Guideline for the Treatment of Patients with Schizophrenia and to determine the extent to which results from Cochrane systematic reviews published after guideline development would alter or confirm current recommendations.

PARTICIPANTS

Systematic reviews that underpinned recommendations in the APA guidelines and Cochrane systematic reviews.

MAIN OUTCOME

Three independent reviewers scored all systematic reviews referenced in the guideline for quality and reporting using AMSTAR and PRISMA checklist, respectively. Items in both tools were individually graded and compared to identify consistently low-performing areas within the systematic reviews. Post hoc analysis of the Cochrane systematic reviews since the latest revision of APA's guidelines were performed to determine whether their findings were congruent with recent recommendations.

RESULTS

The mean score of the 57 reviews on the PRISMA checklist was 70%. The mean AMSTAR score was 6.8, correlating with a moderate quality score. Post hoc analysis revealed that 171 Cochrane reviews had been published since the APA guideline release. Only half of the reviews of pharmacological interventions confirmed current recommendations.

CONCLUSIONS AND RELEVANCE

The methodological quality of the systematic reviews included in the APA guideline was deficient in key areas. Our study brings to light the importance of using high-quality evidence in the development of clinical practice guidelines. An updated APA guideline (last updated in 2009) is necessary to provide the highest quality treatment recommendations for clinicians in the management of schizophrenia.

TRIAL REGISTRATION NUMBER

UMIN-CTR, UMIN000023099.