Pharmacogenetics of antipsychotic-induced weight gain: review and clinical implications

"I Haven't Told Anyone but You": Experiences and Biopsychosocial Support Needs of People With Type 2 Diabetes and Binge Eating

Up to 25% of people with type 2 diabetes (T2D) may binge eat which is almost 10 times as many as in the general population. Binge eating is associated with depression, anxiety, and social isolation. Moreover, binge eating may increase the risk of obesity and high blood glucose levels, both of which can accelerate the onset of complications to diabetes and death in people with T2D. Still, little is known about the experiences, needs, and preferences of people with T2D and binge eating that can inform and develop current and future treatment efforts. The aim of the study was therefore to gain in-depth insights into the experiences and biopsychosocial support needs of women and men with T2D and binge eating. Twenty semi-structured individual interviews (65% with females) were conducted and analyzed according to the methodology of Interpretive Description. Four themes were identified: (a) T2D and binge eating: Feeling trapped in a vicious circle; (b) Unwanted outcasts: Responding to continuous criticism; (c) Biomedical relief: Blaming and adjusting the body; and, (d) Silent struggles: Wanting to cease the secrecy. Pertinent to all themes were the guilt, shame, and worries about developing complications that the participants experienced when binge eating despite having T2D. Although binge eating triggered emotional distress, binge eating was at the same time a way of coping with such distress. Implications for treatment and future research are discussed, including the need to systematically assess and address binge eating in routine T2D care.

Genome-wide association study implicates lipid pathway dysfunction in antipsychotic-induced weight gain: multi-ancestry validation

Antipsychotic-induced weight gain (AIWG) is a common side effect of antipsychotic medication and may contribute to diabetes and coronary heart disease. To expand the unclear genetic mechanism underlying AIWG, we conducted a two-stage genome-wide association study in Han Chinese patients with schizophrenia. The study included a discovery cohort of 1936 patients and a validation cohort of 534 patients, with an additional 630 multi-ancestry patients from the CATIE study for external validation. We applied Mendelian randomization (MR) analysis to investigate the relationship between AIWG and antipsychotic-induced lipid changes. Our results identified two novel genome-wide significant loci associated with AIWG: rs10422861 in PEPD (P = 1.373 × 10-9) and rs3824417 in PTPRD (P = 3.348 × 10-9) in Chinese Han samples. The association of rs10422861 was validated in the European samples. Fine-mapping and functional annotation revealed that PEPD and PTPRD are potentially causal genes for AIWG, with their proteins being prospective therapeutic targets. Colocalization analysis suggested that AIWG and type 2 diabetes (T2D) shared a causal variant in PEPD. Polygenic risk scores (PRSs) for AIWG and T2D significantly predicted AIWG in multi-ancestry samples. Furthermore, MR revealed a risky causal effect of genetically predicted changes in low-density lipoprotein cholesterol (P = 7.58 × 10-4) and triglycerides (P = 2.06 × 10-3) caused by acute-phase of antipsychotic treatment on AIWG, which had not been previously reported. Our model, incorporating antipsychotic-induced lipid changes, PRSs, and clinical predictors, significantly predicted BMI percentage change after 6-month antipsychotic treatment (AUC = 0.79, R2 = 0.332). Our results highlight that the mechanism of AIWG involves lipid pathway dysfunction and may share a genetic basis with T2D through PEPD. Overall, this study provides new insights into the pathogenesis of AIWG and contributes to personalized treatment of schizophrenia.

Trajectories and Predictors for the Development of Clinically Significant Weight Gain in Children and Adolescents Prescribed Second-Generation Antipsychotics

Background: As many as 60% of pediatric patients taking second-generation antipsychotics (SGA) experience weight gain (antipsychotic-induced weight gain). However, the subgroup that experienced substantial weight increase was poorly understood. This study aimed to identify the development and predictors of clinically significant weight gain (CSWG) among pediatric SGA recipients. Methods: A retrospective analysis of the 2016 to 2021 IQVIA Ambulatory EMR-US database was conducted. The study cohort comprised SGA-naive patients ages 5 to 19, continuously prescribed SGA for ≥90 days. CSWG was defined as a weight gain in BMI z-score >0.5. The development of CSWG was described using the group-based trajectory model approach, and multinomial logistic regression analysis was conducted to examine the risk factors associated with the CSWG trajectories. Results: Of the 16,262 SGA recipients who met the inclusion criteria, 4 distinctive CSWG trajectories were identified: (1) Rapid (14.6%), (2) Gradual (12.6%), (3) Transit (7%), and (4) no CSWG (65.8%). Factors associated with a higher likelihood of having rapid or gradual CSWG versus nonsignificant weight gain were being younger (OR [95% CI] = 12-17 vs. 5-11, Rapid, 0.727 [0.655-0.806]; Gradual, 0.776 [0.668-0.903]), male (Rapid, 1.131 [1.021-1.253]), non-Hispanic White (Black vs. White: Rapid, 0.833 [0.709-0.98]), with lower baseline BMI z-score (Rapid, 0.376 [0.361-0.392]; Gradual, 0.449 [0.424-0.476]), and receiving olanzapine as the initial SGA (Rapid, 1.38 [1.093-1.74]). The Area under the Receiver operating characteristic (ROC) Curve for the comparison of rapid and gradual CSWG with no CSWG trajectory were 0.83 and 0.80, respectively. Conclusions: SGA recipients experienced four distinctive CSWG trajectories (Rapid, Gradual, Transient, and No CSWG). The risk of CSWG could be predicted using patient characteristics at the SGA initiation. This insight highlights the importance of personalized monitoring and timely intervention strategies for at-risk individuals who experienced persistent CSWG in real practice.

Relationship between functional connectivity and weight-gain risk of antipsychotics in schizophrenia

BACKGROUND

The mechanisms by which antipsychotic medications (APs) contribute to obesity in schizophrenia are not well understood. Because AP effects on functional brain connectivity may contribute to weight effects, the current study investigated how AP-associated weight-gain risk relates to functional connectivity in schizophrenia.

METHODS

Fifty-five individuals with schizophrenia (final N = 54) were divided into groups based on previously reported AP weight-gain risk (no APs/low risk [N = 19]; moderate risk [N = 17]; high risk [N = 18]). Resting-state functional magnetic resonance imaging (fMRI) was completed after an overnight fast ("fasted") and post-meal ("fed"). Correlations between AP weight-gain risk and functional connectivity were assessed at the whole-brain level and in reward- and eating-related brain regions (anterior insula, caudate, nucleus accumbens).

RESULTS

When fasted, greater AP weight-gain risk was associated with increased connectivity between thalamus and sensorimotor cortex (pFDR = 0.021). When fed, greater AP weight-gain risk was associated with increased connectivity between left caudate and left precentral/postcentral gyri (pFDR = 0.048) and between right caudate and multiple regions, including the left precentral/postcentral gyri (pFDR = 0.001), intracalcarine/precuneal/cuneal cortices (pFDR < 0.001), and fusiform gyrus (pFDR = 0.008). When fed, greater AP weight-gain risk was also associated with decreased connectivity between right anterior insula and ventromedial prefrontal cortex (pFDR = 0.002).

CONCLUSIONS

APs with higher weight-gain risk were associated with greater connectivity between reward-related regions and sensorimotor regions when fasted, perhaps relating to motor anticipation for consumption. Higher weight-gain risk APs were also associated with increased connectivity between reward, salience, and visual regions when fed, potentially reflecting greater desire for consumption following satiety.

Group-Based Trajectory Modeling to Identify Patterns of Antipsychotic-Associated Weight Gain Among Children and Adolescents

PURPOSE/BACKGROUND

Antipsychotic-associated weight gain (AAWG) is a common adverse effect of second-generation antipsychotic (SGA) medications among children and adolescents. This study applied group-based trajectory modeling to identify latent trajectories of AAWG among children and adolescents and associated risk factors.

PROCEDURES

This was a retrospective analysis of the IQVIA Ambulatory EMR-US database from 2016 to 2021. The cohort consisted of patients aged 6 to 19 years who were SGA naive and received at least 90 days of continuous SGA prescriptions. Group-based trajectory modeling was used to identify latent trajectories of AAWG development during a 24-month period since SGA initiation, and multinomial logistic regression analysis was conducted to examine the risk factors associated with the identified AAWG trajectories.

FINDINGS/RESULTS

A total of 16,262 patients were included. Group-based trajectory modeling identified the following 4 distinctive AAWG trajectories: persistent severe weight gain (4.2%), persistent moderate weight gain (20.1%), minor weight change (69.6%), and gradual weight loss (6.1%). Compared with the minor weight change group, younger age (12-17 vs 5-11: odds ratio [OR], 0.634; 95% confidence interval [CI], 0.521-0.771), lower baseline body mass index z -score (OR, 0.216; 95% CI, 0.198-0.236), and receiving olanzapine as the initial SGA (olanzapine vs aripiprazole: OR, 1.686; 95% CI, 1.673-1.699) were more likely to follow severe weight gain trajectories. The area under the receiver operating characteristic curves for comparing severe weight gain versus minor weight change groups and moderate weight vs minor weight change groups in the multinomial regression model were 0.91 and 0.8, respectively.

IMPLICATIONS/CONCLUSIONS

A quarter of pediatric SGA recipients experienced persistent weight gain during the SGA treatment. The risk of having persistent AAWG can be predicted using patient characteristics collected before SGA initiation and the initial SGA agent.

The Use of Phentermine for Obesity in Psychiatric Patients With Antipsychotics

OBJECTIVE

Phentermine is a commonly used weight-loss agent in the United States, but there is a little information about the use of phentermine for patients with obesity taking antipsychotic medications.

METHODS

We gathered 57 patients with obesity taking antipsychotic medications whose phentermine treatment was simultaneous with or after any type of antipsychotic exposure and collected data of clinical information, initial/follow-up anthropometric variables, and adverse events (AEs) for the 6-month study period.

RESULTS

In total, the mean body weight reduction (BWR) was 4.45 (7.04) kg, and the mean BWR percent (BWR%) was 3.92% (6.96%) at 6 months. Based on the response to phentermine, the patients were classified into two groups: the responder (n=25; BWR% ≥5%) and nonresponder (n=32; BWR% <5%) groups. The responder group's mean BWR and BWR% were 10.13 (4.43) kg and 9.35% (4.09%), respectively, at 6 months. The responders had higher rates of anticonvulsant combination therapy (ACT; responder, 72.0% vs. non-responder, 43.8%; p=0.033) and a shorter total antipsychotic exposure duration (responder, 23.9 [16.9] months vs. non-responder, 37.2 [27.6] months; p= 0.039). After adjusting age, sex, and initial body weight, ACT maintained a significant association with phentermine response (odds ratio=3.840; 95% confidence interval: 1.082-13.630; p=0.037). In the final cohort, there was no report of adverse or new-onset psychotic symptoms, and the common AEs were sleep disturbances, dry mouth, and dizziness.

CONCLUSION

Overall, phentermine was effective and tolerable for patients with obesity taking antipsychotic medications, and ACT (predominantly topiramate) augmented the weight-loss effect of phentermine.

Polygenic risk scores analyses of psychiatric and metabolic traits with antipsychotic-induced weight gain in schizophrenia: an exploratory study

Given the polygenic nature of antipsychotic-induced weight gain (AIWG), we investigated whether polygenic risk scores (PRS) for various psychiatric and metabolic traits were associated with AIWG. We included individuals with schizophrenia (SCZ) of European ancestry from two cohorts (N = 151, age = 40.3 ± 11.8 and N = 138, age = 36.5 ± 10.8). We investigated associations of AIWG defined as binary and continuous variables with PRS calculated from genome-wide association studies of body mass index (BMI), coronary artery disease (CAD), fasting glucose, fasting insulin, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C), triglycerides, type 1 and 2 diabetes mellitus, and SCZ, using regression models. We observed nominal associations (uncorrected p < 0.05) between PRSs for BMI, CAD, and LDL-C, type 1 diabetes, and SCZ with AIWG. While results became non-significant after correction for multiple testing, these preliminary results suggest that PRS analyses might contribute to identifying risk factors of AIWG and might help to elucidate mechanisms at play in AIWG.

Association between Empathy and Clinical Symptoms among Overweight and Non-Overweight Chinese Chronic Schizophrenia Patients

Patients with schizophrenia are afflicted by severe clinical symptoms and serious cognitive dysfunction. The aim of this study is to investigate the potential relationships between clinical symptoms and empathy and their variations between overweight and non-overweight schizophrenia patients. To address this problem, a group of 776 inpatients diagnosed with chronic schizophrenia (504 overweight patients and 272 non-overweight patients) was recruited. The Positive and Negative Syndrome Scale (PANSS) and its five-factor model were employed to assess clinical symptoms, while empathy levels were measured using the Interpersonal Reactivity Index (IRI). The overweight patients had lower education levels but higher positive symptoms than the non-overweight patients (all p < 0.05). In addition, the overweight patients performed significantly better with respect to empathy (FDR-corrected p < 0.05). Additional multiple regression analyses indicated significant associations between the total score of the IRI and PANSS negative symptoms, gender, and family history of psychiatric disorders among the overweight group; among non-overweight patients, there was a significant correlation between suicide and the total score of the IRI. This study provides evidence suggesting that chronic schizophrenia patients who are overweight may have distinct clinical characteristics, particularly with respect to their empathy, compared with non-overweight patients. Moreover, different variables are associated with empathy in different groups.

Increased Metabolic Potential, Efficacy, and Safety of Emerging Treatments in Schizophrenia

Patients with schizophrenia experience a broad range of detrimental health outcomes resulting from illness severity, heterogeneity of disease, lifestyle behaviors, and adverse effects of antipsychotics. Because of these various factors, patients with schizophrenia have a much higher risk of cardiometabolic abnormalities than people without psychiatric illness. Although exposure to many antipsychotics increases cardiometabolic risk factors, mortality is higher in patients who are not treated versus those who are treated with antipsychotics. This indicates both direct and indirect benefits of adequately treated illness, as well as the need for beneficial medications that result in fewer cardiometabolic risk factors and comorbidities. The aim of the current narrative review was to outline the association between cardiometabolic dysfunction and schizophrenia, as well as discuss the confluence of factors that increase cardiometabolic risk in this patient population. An increased understanding of the pathophysiology of schizophrenia has guided discovery of novel treatments that do not directly target dopamine and that not only do not add, but may potentially minimize relevant cardiometabolic burden for these patients. Key discoveries that have advanced the understanding of the neural circuitry and pathophysiology of schizophrenia now provide possible pathways toward the development of new and effective treatments that may mitigate the risk of metabolic dysfunction in these patients. Novel targets and preclinical and clinical data on emerging treatments, such as glycine transport inhibitors, nicotinic and muscarinic receptor agonists, and trace amine-associated receptor-1 agonists, offer promise toward relevant therapeutic advancements. Numerous areas of investigation currently exist with the potential to considerably progress our knowledge and treatment of schizophrenia.

Identification of four novel loci associated with psychotropic drug-induced weight gain in a Swiss psychiatric longitudinal study: A GWAS analysis

Patients suffering from mental disorders are at high risk of developing cardiovascular diseases, leading to a reduction in life expectancy. Genetic variants can display greater influence on cardiometabolic features in psychiatric cohorts compared to the general population. The difference is possibly due to an intricate interaction between the mental disorder or the medications used to treat it and metabolic regulations. Previous genome wide association studies (GWAS) on antipsychotic-induced weight gain included a low number of participants and/or were restricted to patients taking one specific antipsychotic. We conducted a GWAS of the evolution of body mass index (BMI) during early (i.e., ≤ 6) months of treatment with psychotropic medications inducing metabolic disturbances (i.e., antipsychotics, mood stabilizers and some antidepressants) in 1135 patients from the PsyMetab cohort. Six highly correlated BMI phenotypes (i.e., BMI change and BMI slope after distinct durations of psychotropic treatment) were considered in the analyses. Our results showed that four novel loci were associated with altered BMI upon treatment at genome-wide significance (p < 5 × 10-8): rs7736552 (near MAN2A1), rs11074029 (in SLCO3A1), rs117496040 (near DEFB1) and rs7647863 (in IQSEC1). Associations between the four loci and alternative BMI-change phenotypes showed consistent effects. Replication analyses in 1622 UK Biobank participants under psychotropic treatment showed a consistent association between rs7736552 and BMI slope (p = 0.017). These findings provide new insights into metabolic side effects induced by psychotropic drugs and underline the need for future studies to replicate these associations in larger cohorts.

Mechanism and treatments of antipsychotic-induced weight gain

The long-term use of antipsychotics (APs) may cause a variety of diseases, such as metabolic syndrome, antipsychotic-induced weight gain (AIWG), and even obesity. This paper reviews the various mechanisms of AIWG and obesity in detail, involving genetics, the central nervous system, the neuroendocrine system, and the gut microbiome. The common drug and non-drug therapies used in clinical practice are also introduced, providing the basis for research on the molecular mechanisms and the future selection of treatments.

Polygenic risk scores enhance prediction of body mass index increase in individuals with a first episode of psychosis

BACKGROUND

Individuals with a first episode of psychosis (FEP) show rapid weight gain during the first months of treatment, which is associated with a reduction in general physical health. Although genetics is assumed to be a significant contributor to weight gain, its exact role is unknown.

METHODS

We assembled a population-based FEP cohort of 381 individuals that was split into a Training (n = 224) set and a Validation (n = 157) set to calculate the polygenic risk score (PRS) in a two-step process. In parallel, we obtained reference genome-wide association studies for body mass index (BMI) and schizophrenia (SCZ) to examine the pleiotropic landscape between the two traits. BMI PRSs were added to linear models that included sociodemographic and clinical variables to predict BMI increase (∆BMI) in the Validation set.

RESULTS

The results confirmed considerable shared genetic susceptibility for the two traits involving 449 near-independent genomic loci. The inclusion of BMI PRSs significantly improved the prediction of ∆BMI at 12 months after the onset of antipsychotic treatment by 49.4% compared to a clinical model. In addition, we demonstrated that the PRS containing pleiotropic information between BMI and SCZ predicted ∆BMI better at 3 (12.2%) and 12 months (53.2%).

CONCLUSIONS

We prove for the first time that genetic factors play a key role in determining ∆BMI during the FEP. This finding has important clinical implications for the early identification of individuals most vulnerable to weight gain and highlights the importance of examining genetic pleiotropy in the context of medically important comorbidities for predicting future outcomes.

Pharmacological interventions for prevention of weight gain in people with schizophrenia

BACKGROUND

Antipsychotic-induced weight gain is an extremely common problem in people with schizophrenia and is associated with increased morbidity and mortality. Adjunctive pharmacological interventions may be necessary to help manage antipsychotic-induced weight gain. This review splits and updates a previous Cochrane Review that focused on both pharmacological and behavioural approaches to this problem.

OBJECTIVES

To determine the effectiveness of pharmacological interventions for preventing antipsychotic-induced weight gain in people with schizophrenia.

SEARCH METHODS

The Cochrane Schizophrenia Information Specialist searched Cochrane Schizophrenia's Register of Trials on 10 February 2021. There are no language, date, document type, or publication status limitations for inclusion of records in the register.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that examined any adjunctive pharmacological intervention for preventing weight gain in people with schizophrenia or schizophrenia-like illnesses who use antipsychotic medications.

DATA COLLECTION AND ANALYSIS

At least two review authors independently extracted data and assessed the quality of included studies. For continuous outcomes, we combined mean differences (MD) in endpoint and change data in the analysis. For dichotomous outcomes, we calculated risk ratios (RR). We assessed risk of bias for included studies and used GRADE to judge certainty of evidence and create summary of findings tables. The primary outcomes for this review were clinically important change in weight, clinically important change in body mass index (BMI), leaving the study early, compliance with treatment, and frequency of nausea. The included studies rarely reported these outcomes, so, post hoc, we added two new outcomes, average endpoint/change in weight and average endpoint/change in BMI.

MAIN RESULTS

Seventeen RCTs, with a total of 1388 participants, met the inclusion criteria for the review. Five studies investigated metformin, three topiramate, three H2 antagonists, three monoamine modulators, and one each investigated monoamine modulators plus betahistine, melatonin and samidorphan. The comparator in all studies was placebo or no treatment (i.e. standard care alone). We synthesised all studies in a quantitative meta-analysis. Most studies inadequately reported their methods of allocation concealment and blinding of participants and personnel. The resulting risk of bias and often small sample sizes limited the overall certainty of the evidence. Only one reboxetine study reported the primary outcome, number of participants with clinically important change in weight. Fewer people in the treatment condition experienced weight gains of more than 5% and more than 7% of their bodyweight than those in the placebo group (> 5% weight gain RR 0.27, 95% confidence interval (CI) 0.11 to 0.65; 1 study, 43 participants; > 7% weight gain RR 0.24, 95% CI 0.07 to 0.83; 1 study, 43 participants; very low-certainty evidence). No studies reported the primary outcomes, 'clinically important change in BMI', or 'compliance with treatment'. However, several studies reported 'average endpoint/change in body weight' or 'average endpoint/change in BMI'. Metformin may be effective in preventing weight gain (MD -4.03 kg, 95% CI -5.78 to -2.28; 4 studies, 131 participants; low-certainty evidence); and BMI increase (MD -1.63 kg/m2, 95% CI -2.96 to -0.29; 5 studies, 227 participants; low-certainty evidence). Other agents that may be slightly effective in preventing weight gain include H2 antagonists such as nizatidine, famotidine and ranitidine (MD -1.32 kg, 95% CI -2.09 to -0.56; 3 studies, 248 participants; low-certainty evidence) and monoamine modulators such as reboxetine and fluoxetine (weight: MD -1.89 kg, 95% CI -3.31 to -0.47; 3 studies, 103 participants; low-certainty evidence; BMI: MD -0.66 kg/m2, 95% CI -1.05 to -0.26; 3 studies, 103 participants; low-certainty evidence). Topiramate did not appear effective in preventing weight gain (MD -4.82 kg, 95% CI -9.99 to 0.35; 3 studies, 168 participants; very low-certainty evidence). For all agents, there was no difference between groups in terms of individuals leaving the study or reports of nausea. However, the results of these outcomes are uncertain given the very low-certainty evidence.

AUTHORS' CONCLUSIONS

There is low-certainty evidence to suggest that metformin may be effective in preventing weight gain. Interpretation of this result and those for other agents, is limited by the small number of studies, small sample size, and short study duration. In future, we need studies that are adequately powered and with longer treatment durations to further evaluate the efficacy and safety of interventions for managing weight gain.

Exploring Lead loci shared between schizophrenia and Cardiometabolic traits

Individuals with schizophrenia (SCZ) have, on average, a 10- to 20-year shorter expected life span than the rest of the population, primarily due to cardiovascular disease comorbidity. Genome-wide association studies (GWAS) have previously been used to separately identify common variants in SCZ and cardiometabolic traits. However, genetic variants jointly influencing both traits remain to be fully characterised. To assess overlaps (if any) between the genetic architecture of SCZ and cardiometabolic traits, we used conditional false discovery rate (FDR) and local genetic correlation statistical framework analyses. A conjunctional FDR was used to identify shared genetic traits between SCZ and cardiometabolic risk factors. We identified 144 genetic variants which were shared between SCZ and body mass index (BMI), and 15 variants shared between SCZ and triglycerides (TG). Furthermore, we discovered four novel single nucleotide polymorphisms (SNPs) (rs3865350, rs9860913, rs13307 and rs9614186) and four proximate genes (DERL2, SNX4, LY75 and EFCAB6) which were shared by SCZ and BMI. We observed that the novel genetic variant rs13307 and the most proximate gene LY75 exerted potential effects on SCZ and BMI comorbidity. Also, we observed a mixture of concordant and opposite direction associations with shared genetic variants. We demonstrated a moderate to high genetic overlap between SCZ and cardiometabolic traits associated with a pattern of bidirectional associations. Our data suggested a complex interplay between metabolism-related gene pathways in SCZ pathophysiology.

Antioxidant Enzymes and Weight Gain in Drug-naive First-episode Schizophrenia Patients Treated with Risperidone for 12 Weeks: A Prospective Longitudinal Study

BACKGROUND

Oxidative stress plays an important role in weight gain induced by antipsychotics in schizophrenia (SCZ). However, little is known about how antioxidant enzymes are involved in weight gain caused by risperidone monotherapy in antipsychotics-naïve first-episode (ANFE) patients with SCZ. Therefore, the main purpose of this study was to investigate the effects of risperidone on several antioxidant enzymes in patients with ANFE SCZ and the relationship between weight gain and changes in antioxidant enzyme activities.

OBJECTIVE

The activities of plasma superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as the levels of malondialdehyde (MDA) were measured in 225 ANFE patients and 125 healthy controls.

METHODS

Patients were treated with risperidone monotherapy for 12 weeks. Clinical symptoms, antioxidant enzyme activities, and MDA levels were measured at baseline and during follow-up.

RESULTS

Compared with healthy controls, the patients showed higher activities of SOD and CAT but lower MDA levels and GPx activity. At baseline, the CAT activity was associated with body weight or BMI. Further, based on a 7% weight increase from baseline to follow-up, we found 75 patients in the weight gain (WG) group and 150 patients in the non-WG group. Comparing SOD, CAT, GPx activities and MDA levels between the WG group and the non-WG group at baseline and during the 12-week follow-up, it was found that after treatment, the SOD activity in the WG group increased while the MDA level decreased in the non-WG group. Moreover, baseline SOD and GPx activities were predictors of weight gain at 12-week follow-up.

CONCLUSION

These results suggest that the antioxidant defense system may have predictive value for the weight gain of ANFE SCZ patients after risperidone treatment.

The Gender-Specific Association of DRD2 Polymorphism with Metabolic Syndrome in Patients with Schizophrenia

Background: Metabolic syndrome is widespread in patients with schizophrenia receiving long-term antipsychotic therapy. Dopamine D2 receptors play an important role in mediating both the therapeutic actions of antipsychotics and their side effects. The present study examined the association of two polymorphisms of the DRD2 gene with metabolic syndrome in patients with schizophrenia. Methods: We examined 517 patients from several regions of Siberia (Russia) with a clinical diagnosis of schizophrenia. Genotyping of two single nucleotide polymorphisms rs1799732 and rs4436578 of the dopamine D2 receptor gene (DRD2) was performed in a population of 471 patients. The results were analyzed using chi-square tests. Results: Functional polymorphism rs1799732 of the DRD2 gene is associated with drug-induced metabolic syndrome in women with schizophrenia. Conclusions: Our results show that the DRD2 gene may be involved in the pathogenesis of metabolic disorders in patients with schizophrenia. Further analysis of possible genetic markers will allow for personalized treatment with minimal side effects and optimal efficacy. This which seems relevant in light of the recent focus on improving the quality of life and ensuring a high level of social adaptation of patients with schizophrenia.

Doenças cardiovasculares e uso de antipsicóticos na esquizofrenia: uma revisão

RESUMO Objetivo Realizar uma revisão de escopo a respeito dos efeitos adversos cardiovasculares e metabólicos associados ao uso de antipsicóticos em pessoas com o diagnóstico de esquizofrenia. Métodos Foi realizada uma revisão de escopo utilizando-se da base de dados PubMed, com descritores MeSH relacionados às doenças cardiovasculares e antipsicóticos. Foram encontrados 976 artigos, os quais foram filtrados por títulos, seguidos dos resumos e, na sequência, lidos na íntegra. Ao final, foram selecionados 71 artigos para a análise. Resultados O uso de antipsicóticos típicos e atípicos para tratamento da esquizofrenia associa-se a alterações glicêmicas e lipídicas, síndrome metabólica, hipertensão, ganho de peso e morbidade cardiovascular. Os estudos evidenciaram a existência de subdiagnóstico e subtratamento de doenças crônicas nessa população. A mortalidade por doença cardiovascular demonstrou aumento considerável nos pacientes em tratamento com agentes antipsicóticos, em comparação com a população geral. Conclusão Alguns fatores dos antipsicóticos, ainda não completamente determinados na psicofarmacologia, vêm se mostrando relacionados a maior risco de distúrbios metabólicos, comportamentais e intrínsecos às pessoas diagnosticadas com esquizofrenia, os quais podem agravar o curso clínico de tais doenças. Reconhece-se a necessidade de aprimorar o acompanhamento e o diagnóstico de doenças cardiovasculares e metabólicas entre pessoas com diagnóstico de esquizofrenia em tratamento com antipsicóticos típicos e atípicos.

CB1R-stabilized NLRP3 inflammasome drives antipsychotics cardiotoxicity

Long-term use of antipsychotics is a common cause of myocardial injury and even sudden cardiac deaths that often lead to drug withdrawn or discontinuation. Mechanisms underlying antipsychotics cardiotoxicity remain largely unknown. Herein we performed RNA sequencing and found that NLRP3 inflammasome-mediated pyroptosis contributed predominantly to multiple antipsychotics cardiotoxicity. Pyroptosis-based small-molecule compound screen identified cannabinoid receptor 1 (CB1R) as an upstream regulator of the NLRP3 inflammasome. Mechanistically, antipsychotics competitively bond to the CB1R and led to CB1R translocation to the cytoplasm, where CB1R directly interacted with NLRP3 inflammasome via amino acid residues 177-209, rendering stabilization of the inflammasome. Knockout of Cb1r significantly alleviated antipsychotic-induced cardiomyocyte pyroptosis and cardiotoxicity. Multi-organ-based investigation revealed no additional toxicity of newer CB1R antagonists. In authentic human cases, the expression of CB1R and NLRP3 inflammasome positively correlated with antipsychotics-induced cardiotoxicity. These results suggest that CB1R is a potent regulator of the NLRP3 inflammsome-mediated pyroptosis and small-molecule inhibitors targeting the CB1R/NLRP3 signaling represent attractive approaches to rescue cardiac side effects of antipsychotics.

Metabolic syndrome following a first episode of psychosis: results of a 1-year longitudinal study conducted in metropolitan Lisbon, Portugal

Objective

We aimed to assess the prevalence and course of metabolic syndrome (MetS) and the associated metabolic parameters during the year following a first episode pf psychosis (FEP).

Methods

We performed a 1-year longitudinal observation of 60 patients who experienced FEP. MetS was defined using the modified definition of the National Cholesterol Education Program Adult Treatment Panel III. We assessed the metabolic parameters and socio-demographic and psychopathological data for the participants.

Results

The mean age of the participants was 27.1 years, and 33.3% of them were women. There was an increase in the prevalence of MetS from 6.7% to 11.7% during the year following the baseline assessment during the year following the baseline assessment (p = 0.250). There were also significant increases in the prevalences of abnormal triglyceride concentration, waist circumference, and high-density lipoprotein (HDL)-cholesterol concentration during this period. In addition, there was a considerable worsening of the metabolic profile of the participants. No baseline parameters were identified to be predictors of MetS over the 1-year follow-up period.

Conclusions

We can conclude that metabolic abnormalities are common in patients with FEP and that these rapidly worsen during the first year following the diagnosis of FEP. Studies on interventions are needed to reduce metabolic risk to cardiovascular diseases following the FEP.

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.

Bisphenol A Coupled with a High-Fat Diet Promotes Hepatosteatosis through Reactive-Oxygen-Species-Induced CD36 Overexpression

Bisphenol A (BPA) is an endocrine-disrupting chemical that affects lipid metabolism and contributes to non-alcoholic fatty liver disease (NAFLD). The mechanism of BPA exposure in hepatic lipid accumulation and its potential effect on NAFLD remain unclear. This study investigated the effect of BPA-exposure-induced hepatic lipid deposition on the pathology of NAFLD and its underlying mechanism in vitro and in vivo. BPA increased intracellular reactive oxygen species (ROS) levels, and promoted fatty acid uptake through upregulation of a free fatty acid uptake transporter, cluster of differentiation 36 (CD36), in HUH-7 cells. Additionally, C57BL/6 mice administered a high-fat/high-cholesterol/high-cholic acid diet (HFCCD) and BPA (50 mg/kg body weight) for 8 weeks developed a steatohepatitis-like phenotype, characterized by alpha-smooth muscle actin (α-SMA, an indicator of hepatic fibrosis) and cleaved caspase 3 (an indicator of apoptosis) in hepatic tissue; moreover, they had a higher oxidative stress index of 8-hydroxydeoxyguanosine (8-OHdG) in liver tissue compared to the control group. Treatment with ROS scavenger n-acetylcysteine (NAC) ameliorated BPA-mediated HFCCD-induced lipid accumulation and steatohepatitis in the livers of treated mice. Our study indicates that BPA acts synergistically to increase hepatic lipid uptake and promote NAFLD development by stimulating ROS-induced CD36 overexpression.

CYP2D6 Genetic Variation and Antipsychotic-Induced Weight Gain: A Systematic Review and Meta-Analysis

BACKGROUND

Antipsychotic-induced weight gain is a contributing factor in the reduced life expectancy reported amongst people with psychotic disorders. CYP2D6 is a liver enzyme involved in the metabolism of many commonly used antipsychotic medications. We investigated if CYP2D6 genetic variation influenced weight or BMI among people taking antipsychotic treatment.

METHODS

We conducted a systematic review and a random effects meta-analysis of publications in Pubmed, Embase, PsychInfo, and CENTRAAL that had BMI and/or weight measurements of patients on long-term antipsychotics by their CYP2D6-defined metabolic groups (poor, intermediate, normal/extensive, and ultra-rapid metabolizers, UMs).

RESULTS

Twelve studies were included in the systematic review. All cohort studies suggested that the presence of reduced-function or non-functional alleles for CYP2D6 was associated with greater antipsychotic-induced weight gain, whereas most cross-sectional studies did not find any significant associations. Seventeen studies were included in the meta-analysis with clinical data of 2,041 patients, including 93 poor metabolizers (PMs), 633 intermediate metabolizers (IMs), 1,272 normal metabolizers (NMs), and 30 UMs. Overall, we did not find associations in any of the comparisons made. The estimated pooled standardized differences for the following comparisons were (i) PM versus NM; weight = -0.07 (95%CI: -0.49 to 0.35, p = 0.74), BMI = 0.40 (95%CI: -0.19 to 0.99, p = 0.19). (ii) IM versus NM; weight = 0.09 (95% CI: -0.04 to 0.22, p = 0.16) and BMI = 0.09 (95% CI: -0.24 to 0.41, p = 0.60). (iii) UM versus EM; weight = 0.01 (95% CI: -0.37 to 0.40, p = 0.94) and BMI = -0.08 (95%CI: -0.57 to 0.42, p = 0.77).

CONCLUSION

Our systematic review of cohort studies suggested that CYP2D6 poor metabolizers have higher BMI than normal metabolizers, but the data of cross-sectional studies and the meta-analysis did not show this association. Although our review and meta-analysis constitutes one of the largest studies with comprehensively genotyped samples, the literature is still limited by small numbers of participants with genetic variants resulting in poor or UMs status. We need further studies with larger numbers of extreme metabolizers to establish its clinical utility in antipsychotic treatment. CYP2D6 is a key gene for personalized prescribing in mental health.

Association of a Single-Nucleotide Variant rs11100494 of the NPY5R Gene with Antipsychotic-Induced Metabolic Disorders

Background: The usage of antipsychotics (APs) is the most robust and scientifically based approach in the treatment of schizophrenia spectrum disorders (SSDs). The efficiency of APs is based on a range of target receptors of the central nervous system (CNS): serotoninergic, dopaminergic, adrenergic, histaminergic and cholinergic. Metabolic disorders are the most severe adverse drug reactions (ADRs) and lead to cardiovascular diseases with a high rate of mortality in patients with SSDs. Neuropeptide Y receptor Y5 (NPY5R) is known in the chain of interaction to target receptors for APs, agouti-related peptide receptors and proopiomelanocortin receptors. We studied the association of the single-nucleotide variants (SNVs) rs11100494 and rs6837793 of the NPY5R gene, and rs16147, rs5573, rs5574 of the NPY gene, with metabolic disorders in Russian patients with SSDs. Methods: We examined 99 patients with SSDs (mean age—24.56 years old). The mean duration of APs monotherapy was 8 weeks. The biochemical blood test included levels of glucose, cholesterol, lipoproteins, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein and albumin. Anthropometry included weight, height, waist circumference and hip circumference. We used real-time PCR to study the carriage of major and minor alleles of the SNV rs11100494 (1164C>A) of the NPY5R gene (chromosome localization—4q32.2). Group 1 comprised 25 patients with SSDs taking APs with a change in body weight of more than 6% since the start of APs therapy. Group 2 comprised 74 patients with SSDs taking APs with a change in body weight of less than 6% since the start of APs therapy. Results: We show the significance of genetic risk factors (carriage of major allele C of SNV rs11100494 of the NPY5R gene) for the development of AP-induced weight gain in Russian patients with SSDs. The allele C predisposes to AP-induced weight gain (OR = 33.48 [95% CI: 12.62; 88.82], p-value < 0.001). Additionally, the results of our study demonstrate that first-generation APs (FGAs) are more likely to cause an increase in serum transaminase levels but are less likely to increase body weight. Second-generation APs (SGAs) are more likely to cause weight gain and changes in serum glucose levels. Conclusion: Our study shows the predictive role of the allele C of SNV rs11100494 of the NPY5R gene in the development of AP-induced weight gain. However, we did not find a significant association between biochemical markers and this SNV in Russian patients with SSDs.

Pharmacogenetics of Antipsychotic Treatment in Schizophrenia

Antipsychotics are the mainstay treatment for schizophrenia. There is large variability between individuals in their response to antipsychotics, both in efficacy and adverse effects of treatment. While the source of interindividual variability in antipsychotic response is not completely understood, genetics is a major contributing factor. The identification of pharmacogenetic markers that predict antipsychotic efficacy and adverse reactions is a growing area of research and holds the potential to replace the current trial-and-error approach to treatment selection in schizophrenia with a personalized medicine approach.In this chapter, we provide an overview of the current state of pharmacogenetics in schizophrenia treatment. The most promising pharmacogenetic findings are presented for both antipsychotic response and commonly studied adverse reactions. The application of pharmacogenetics to schizophrenia treatment is discussed, with an emphasis on the clinical utility of pharmacogenetic testing and directions for future research.

Clinical pearls for the monitoring and treatment of antipsychotic induced metabolic syndrome

Antipsychotic medications increase the risk of metabolic syndrome, which then increases the risk of atherosclerotic cardiovascular disease and premature death. Routinely monitoring for signs of metabolic syndrome in patients taking antipsychotics allows for early detection and intervention. Psychiatric pharmacists can improve patient care through metabolic syndrome monitoring and recommendation of appropriate interventions. Monitoring for the metabolic adverse effects of antipsychotics, management of weight gain, and management of lipids and blood pressure are explored through 2 patient cases.

Associations of Genetic Variants of Methylenetetrahydrofolate Reductase and Serum Folate Levels with Metabolic Parameters in Patients with Schizophrenia

The one-carbon metabolism pathway is a suitable candidate for studying the genetic and epigenetic factors contributing to metabolic abnormalities in patients with schizophrenia. We recruited 232 patients with schizophrenia and analyzed their serum folate, vitamin B12, and homocysteine levels and metabolic parameters to investigate the associations of genetic variants of methylenetetrahydrofolate reductase (MTHFR) and folate levels with metabolic parameters. MTHFR C677T and MTHFR A1298C were genotyped. Results showed that MTHFR 677T allele carriers had lower levels of total cholesterol and low-density lipoprotein cholesterol than those with the 677CC genotype. Metabolic parameters did not differ between MTHFR 1298C and 1298AA carriers. Patients with a low folate level had a lower high-density lipoprotein cholesterol level than those with a normal folate level, but the effect disappeared after adjustment for age, sex, and types of antipsychotics used. We found significant interactions between MTHFR A1298C and the folate level status (low vs. normal) in terms of body mass index and waist circumference. In conclusion, genetic variants in one-carbon metabolism might play a role in antipsychotic-induced metabolic abnormalities. Prospective studies on drug-naïve, first-episode patients with schizophrenia are warranted to identify key regions of DNA methylation changes accounting for antipsychotic-induced metabolic abnormalities.

Metabolic disturbances associated with antipsychotic drug treatment in patients with schizophrenia: State-of-the-art and future perspectives

Metabolic disturbances and obesity are major cardiovascular risk factors in patients with schizophrenia, resulting in a higher mortality rate and shorter life expectancy compared with those in the general population. Although schizophrenia and metabolic disturbances may share certain genetic or pathobiological risks, antipsychotics, particularly those of second generation, may further increase the risk of weight gain and metabolic disturbances in patients with schizophrenia. This review included articles on weight gain and metabolic disturbances related to antipsychotics and their mechanisms, monitoring guidelines, and interventions. Nearly all antipsychotics are associated with weight gain, but the degree of the weight gain varies considerably. Although certain neurotransmitter receptor-binding affinities and hormones are correlated with weight gain and specific metabolic abnormalities, the precise mechanisms underlying antipsychotic-induced weight gain and metabolic disturbances remain unclear. Emerging evidence indicates the role of genetic polymorphisms associated with antipsychotic-induced weight gain and antipsychotic-induced metabolic disturbances. Although many guidelines for screening and monitoring antipsychotic-induced metabolic disturbances have been developed, they are not routinely implemented in clinical care. Numerous studies have also investigated strategies for managing antipsychotic-induced metabolic disturbances. Thus, patients and their caregivers must be educated and motivated to pursue a healthier life through smoking cessation and dietary and physical activity programs. If lifestyle intervention fails, switching to another antipsychotic drug with a lower metabolic risk or adding adjunctive medication to mitigate weight gain should be considered. Antipsychotic medications are essential for schizophrenia treatment, hence clinicians should monitor and manage the resulting weight gain and metabolic disturbances.

Identification of EP300 as a Key Gene Involved in Antipsychotic-Induced Metabolic Dysregulation Based on Integrative Bioinformatics Analysis of Multi-Tissue Gene Expression Data

Antipsychotics (APs) are associated with weight gain and other metabolic abnormalities such as hyperglycemia, dyslipidemia and metabolic syndrome. This translational study aimed to uncover the underlying molecular mechanisms and identify the key genes involved in AP-induced metabolic effects. An integrative gene expression analysis was performed in four different mouse tissues (striatum, liver, pancreas and adipose) after risperidone or olanzapine treatment. The analytical approach combined the identification of the gene co-expression modules related to AP treatment, gene set enrichment analysis and protein-protein interaction network construction. We found several co-expression modules of genes involved in glucose and lipid homeostasis, hormone regulation and other processes related to metabolic impairment. Among these genes, EP300, which encodes an acetyltransferase involved in transcriptional regulation, was identified as the most important hub gene overlapping the networks of both APs. Then, we explored the genetically predicted EP300 expression levels in a cohort of 226 patients with first-episode psychosis who were being treated with APs to further assess the association of this gene with metabolic alterations. The EP300 expression levels were significantly associated with increases in body weight, body mass index, total cholesterol levels, low-density lipoprotein cholesterol levels and triglyceride concentrations after 6 months of AP treatment. Taken together, our analysis identified EP300 as a key gene in AP-induced metabolic abnormalities, indicating that the dysregulation of EP300 function could be important in the development of these side effects. However, more studies are needed to disentangle the role of this gene in the mechanism of action of APs.

The atypical antipsychotic risperidone targets hypothalamic melanocortin 4 receptors to cause weight gain

Atypical antipsychotics such as risperidone cause drug-induced metabolic syndrome. However, the underlying mechanisms remain largely unknown. Here, we report a new mouse model that reliably reproduces risperidone-induced weight gain, adiposity, and glucose intolerance. We found that risperidone treatment acutely altered energy balance in C57BL/6 mice and that hyperphagia accounted for most of the weight gain. Transcriptomic analyses in the hypothalamus of risperidone-fed mice revealed that risperidone treatment reduced the expression of Mc4r. Furthermore, Mc4r in Sim1 neurons was necessary for risperidone-induced hyperphagia and weight gain. Moreover, we found that the same pathway underlies the obesogenic effect of olanzapine-another commonly prescribed antipsychotic drug. Remarkably, whole-cell patch-clamp recording demonstrated that risperidone acutely inhibited the activity of hypothalamic Mc4r neurons via the opening of a postsynaptic potassium conductance. Finally, we showed that treatment with setmelanotide, an MC4R-specific agonist, mitigated hyperphagia and obesity in both risperidone- and olanzapine-fed mice.

Effect of 5-HT2C receptor gene polymorphism (HTR2C-759C/T) on metabolic adverse effects in Thai psychiatric patients treated with risperidone

BACKGROUND

The use of Atypical antipsychotics (AAPs) is related to metabolic disturbances, which put psychiatric patients at risk for cardiovascular morbidity and mortality. Evidence is emerging of genetic risk factors. The HTR2C gene is an essential candidate in pharmacogenetic studies of antipsychotic-induced metabolic effects. Nevertheless, there were inconsistent results among studies.

OBJECTIVE

To investigate the relationship between -759C/T, functional polymorphism of the HTR2C gene and metabolic adverse effects in Thai psychiatric patients treated with risperidone monotherapy.

METHOD

In this cross-sectional study, 108 psychiatric patients treated with risperidone monotherapy for ≥3 months were recruited. Anthropometric measurements and laboratory tests were obtained upon enrollment and history of treatment was reviewed from medical records. Weight gain was defined as an increase ≥7% of baseline weight. Metabolic syndrome was evaluated according to the 2005 International Diabetes Federation (IDF) Asia criteria. The -759C/T, polymorphism was genotyped. The associations between -759C/T polymorphism and metabolic side effects were analyzed. Multiple logistic regression was used for determining potential confounders.

RESULTS

Neither weight gain nor metabolic syndrome was significantly associated with -759C/T allelic and genotype variants of HTR2C. However, T allele of -759C/T polymorphism significantly associated with the hypertension. This association was not affected by possible confounding factors such as gender, risperidone dose, duration of treatment and family history of hypertension.

CONCLUSION

Our findings suggest that psychiatric patients with T allele of -759C/T polymorphism may be at higher risk for hypertension. Further study with prospective design with larger patient groups are needed.

The Burden of Antipsychotic-Induced Weight Gain and Metabolic Syndrome in Children

Antipsychotic medications are critical to child and adolescent psychiatry, from the stabilization of psychotic disorders like schizophrenia, bipolar disorder, and psychotic depression to behavioral treatment of autism spectrum disorder, tic disorders, and pediatric aggression. While effective, these medications carry serious risk of adverse events-most commonly, weight gain and cardiometabolic abnormalities. Negative metabolic consequences affect up to 60% of patients and present a major obstacle to long-term treatment. Since antipsychotics are often chronically prescribed beginning in childhood, cardiometabolic risk accumulates. An increased susceptibility to antipsychotic-induced weight gain (AIWG) has been repeatedly documented in children, particularly rapid weight gain. Associated cardiometabolic abnormalities include central obesity, insulin resistance, dyslipidemia, and systemic inflammation. Lifestyle interventions and medications such as metformin have been proposed to reduce risk but remain limited in efficacy. Furthermore, antipsychotic medications touted to be weight-neutral in adults can cause substantial weight gain in children. A better understanding of the biological underpinnings of AIWG could inform targeted and potentially more fruitful treatments; however, little is known about the underlying mechanism. As yet, modest genetic studies have nominated a few risk genes that explain only a small percentage of the risk. Recent investigations have begun to explore novel potential mechanisms of AIWG, including a role for gut microbiota and microbial metabolites. This article reviews the problem of AIWG and AP metabolic side effects in pediatric populations, proposed mechanisms underlying this serious side effect, and strategies to mitigate adverse impact. We suggest future directions for research efforts that may advance the field and lead to improved clinical interventions.

Prevalence of obesity and clinical and metabolic correlates in first-episode schizophrenia relative to healthy controls

OBJECTIVE

People with schizophrenia exhibit a high obesity rate. However, little is known about the prevalence of obesity and its relationship with clinical symptoms and metabolic indicators in first-episode drug-naïve (FEDN) schizophrenia.

METHODS

Demographic and lipid parameters were gathered from 297 FEDN schizophrenia and 325 healthy controls. The patients' symptomatology was evaluated by the Positive and Negative Syndrome Scale (PANSS).

RESULTS

The obesity rate of FEDN patients was 10.77%, similar to that of controls (10.5%). The prevalence of overweight plus obesity of patients was 44.8%, significantly higher than that of controls (36.6%). Compared with non-obese patients, obese patients had higher levels of cholesterol (4.81 ± 0.93 vs 4.22 ± 1.00 mmol/L), triglyceride (0.27 ± 0.21 vs 0.14 ± 0.24 mg/dL), low-density lipoprotein (0.48 ± 0.12 vs 0.40 ± 0.12 mg/dL), greater ratio of triglyceride/high-density lipoprotein (2.01 ± 1.23 vs 1.44 ± 1.26), and higher PANSS positive symptom subscale score (29.81 ± 6.29 vs 27.05 ± 6.15), general psychopathology subscale score (70.75 ± 11.74 vs 66.87 ± 11.37), and total score (149.81 ± 21.08 vs 140.64 ± 21.58), but lower high-density lipoprotein level (1.09 ± 0.21 vs 1.27 ± 0.34 mg/dL) (all p < 0.05). Correlation analysis revealed that body mass index (BMI) was positively correlated with triglyceride, cholesterol, high-density lipoprotein, low-density lipoprotein, triglyceride/high-density lipoprotein ratio, PANSS positive symptoms, general psychopathology, and total scores (all p < 0.05, r = 0.124 ~ 0.335). Multiple regression analysis confirmed that PANSS positive symptoms, total score, and cholesterol level were significantly associated with BMI (all p < 0.05, β: 0.126-0.162).

CONCLUSION

There was no significant difference in the prevalence of obesity between FEDN patients and the control group. Moreover, BMI was positively associated with positive symptom severity in FEDN patients.

Associations between plasma clozapine/N-desmethylclozapine ratio, insulin resistance and cognitive performance in patients with co-morbid obesity and ultra-treatment resistant schizophrenia

Clozapine (CLZ), the sole antipsychotic with superior efficacy for ultra-treatment resistant schizophrenia (TRS), is limited by adverse effects, including metabolic dysregulation. Clozapine's main metabolite, N-desmethylclozapine (NDMC), has potent 5-HT2C antagonist properties which may explain this metabolic dysfunction, thus the CLZ:NDMC ratio is of particular interest. High insulin resistance states could be associated with CYP1A2 induction and lower CLZ:NDMC ratios. Additionally, lower CLZ:NDMC ratios have been associated with better cognitive, but worse metabolic functioning. This study investigated associations between metabolic and cognitive parameters with the CLZ/NDMC ratio. Primary outcomes included relationships between the CLZ:NDMC ratio to the homeostatic model assessment for insulin resistance (HOMA-IR) and Brief Assessment of Cognition in Schizophrenia (BACS) composite z-scores. Secondary outcomes assessed relationships between CLZ:NDMC ratios to fasting insulin, BMI, weight, fasting glucose, and BACS digit sequencing z-scores. 38 patients who were overweight or obese with schizophrenia or schizoaffective disorder completed fasting bloodwork, anthropometric, psychopathological, and cognitive assessments. Multivariate regressions found a statistically significant inverse association between the CLZ/NDMC ratio and HOMA-IR (B = - 1.028, SE B = .473, β = - 0.348 p = 0.037), which may have been driven by fasting insulin levels (B = - 27.124, SE B = 12.081, β = - 0.351 p = 0.031). The CLZ/NDMC ratio may predict insulin resistance/metabolic comorbidity among patients with TRS receiving clozapine.

Association of MTHFR C677T Polymorphism With Antipsychotic-Induced Change of Weight and Metabolism Index

Although antipsychotic medication contributed to the improvement of psychotic symptoms and reduced relapse, it induced weight gain and metabolic syndrome during antipsychotic medication treatment, which was seriously concerning. To investigate the association of methylenetetrahydrofolate reductase (MTHFR) gene C677T (rs1801133) polymorphism with antipsychotic-induced weight gain and metabolism parameter change, we employed 1,868 patients with schizophrenia in this study and randomly allocated them to seven antipsychotic medication treatment groups. All patients received antipsychotics monotherapy and were followed up for 6 weeks. Height, body weight, and metabolic parameters of the patients were measured at baseline and at 2, 4, and 6 weeks after antipsychotic treatment. We genotyped blood DNA from patients for MTHFR C677T polymorphisms and performed quantitative analyses using analysis of variance (ANOVA) and the analysis of covariance (ANCOVA) among three genotype groups. We found a predominant association between MTHFR C677T and body weight mass index (BMI) change after 6-week risperidone treatment. After 6-week treatment of risperidone, the BMI change rate (%) of MTHFR C677 carriers was significantly higher than that of MTHFR TT genotype carriers [CC (2.81 ± 6.77)%, CT (3.79 ± 5.22)%, TT (1.42 ± 3.53)%, F = 4.749, P = 0.009]. Some of the abnormal metabolic parameters were found to be associated with the MTHFR 677T, including higher levels of low-density lipoprotein and waist circumference. Validation was performed in an independent cohort, consisting of 252 patients with schizophrenia treated with three atypical antipsychotic drugs. Overall, the MTHFR C677 was associated with high risk of antipsychotic-induced weight gain and metabolism abnormalities.

Biopsychosocial factors associated with disordered eating behaviors in schizophrenia

BACKGROUND

Recent hypotheses have suggested that schizophrenic patients are more likely to consume unhealthy foods, causing increased rates of mortality and morbidity associated with metabolic syndrome. This raises the need for more in-depth research on disordered eating behaviors (DEBs) in schizophrenic patients. This study, therefore, aimed to investigate biopsychosocial factors associated with DEBs in schizophrenia.

METHODS

In this cross-sectional study, a total of 308 participants (including 83 subjects in the active phase of schizophrenia, 71 subjects in the remission phase of schizophrenia, and 154 control subjects) were recruited through convenience sampling among patients who referred to the Baharan Psychiatric hospital in Zahedan, Iran. Patients were assessed through Eating Attitudes Test (EAT-26), Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI-II), and Positive and Negative Syndrome Scale (PANSS). Data were analyzed using SPSS v25 software. Further, the statistical significance level was set at p < 0.05.

RESULTS

The prevalence of DEBs was 41.5% in schizophrenic patients (vs. 10.3% in the control group, p = 0.012). No significant difference was observed in the EAT-26 scores based on gender and phases of schizophrenia. According to multiple linear regression analysis, lack of psychosocial rehabilitation, use of atypical antipsychotics, early stages of psychosis, high level of anxiety and depression, expression of more active psychotic symptoms, tobacco smoking, and suffering from type 2 diabetes were all associated with increased development of DEBs among schizophrenic patients.

CONCLUSIONS

Since the occurrence of DEBs is independent of different phases of schizophrenia, the risk of DEBs is required to be evaluated during the entire course of schizophrenia especially at earlier stages of schizophrenia. Moreover, the use of psychosocial interventions, treatment of affective disorders (i.e., anxiety and depression), antipsychotic medication switching, treatment of tobacco smoking and type 2 diabetes may reduce the risk of DEBs among schizophrenic patients. However, further investigations are required to prove the actual roles of the above factors in developing DEBs among schizophrenic patients.

Risperidone-Induced Obesity in Children and Adolescents With Autism Spectrum Disorder: Genetic and Clinical Risk Factors

Aims: Obesity is a significant problem for patients taking atypical antipsychotics. There were two aims of our study. The first aim was to compare the prevalence of overweight and obesity between children and adolescents with autism spectrum disorder (ASD) treated with risperidone with the general pediatric population. The second aim was to investigate the association of the HTR2C -759C>T, ABCB1 1236C>T, ABCB1 2677G>T/A, and ABCB1 3435C>T polymorphisms with risperidone-induced overweight and obesity in children and adolescents with ASD. Methods: Body weight and height were measured in 134 subjects. Overweight and obesity in children and adolescents were classified using the International Obesity Task Force (IOTF) criteria. Genotyping was performed by TaqMan real-time polymerase chain reaction (PCR). Results: Our study found that the prevalence of overweight and obesity was significantly higher in children and adolescents with ASD treated with risperidone compared with healthy individuals (p = 0.01 and p = 0.002). The genetic polymorphisms of HTR2C -759C>T, ABCB1 1236C>T, ABCB1 2677G>T/A, and ABCB1 3435C>T were not associated with overweight/obesity in children and adolescents with ASD treated with risperidone after adjustment for multiple comparisons by the method of Bonferroni. Additionally, haplotype analysis revealed that there was no significant association between ABCB1 3435T-2677T/A-1236T haplotype and overweight/obesity. In multivariate logistic regression, after adjustment by the Bonferroni correction, there was only the duration of risperidone treatment that was significantly associated with overweight/obesity in children and adolescents with ASD. Conclusions: The findings suggest that children and adolescents with ASD treated with risperidone are at a higher risk of obesity, especially patients with extended treatment with risperidone. For the pharmacogenetic factors, -759C>T polymorphism of HTR2C gene and 1236C>T, 2677G>T/A, and 3435C>T polymorphisms of ABCB1 gene were not likely to be associated with the susceptibility to overweight/obesity in children and adolescents treated with risperidone. Due to the small sample size, further studies with a larger independent group are needed to confirm these findings.

Association between the -2548G/A polymorphism of the leptin gene and antipsychotic-induced weight gain: Analysis of the CATIE sample and meta-analysis

BACKGROUND

Antipsychotics, especially most of the second-generation antipsychotics, have a high risk for metabolic syndrome and antipsychotic-induced weight gain (AIWG). A promoter variant of the leptin (LEP) gene, -2548G/A (rs7799039), has been associated with AIWG in several studies. The aim of this study was to evaluate this association in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) sample, followed by meta-analysis.

METHODS

We investigated the association between rs7799039 and AIWG in a sub-sample of European (N = 164) individuals from the CATIE study. Body mass index (BMI) change and weight gain (presence or absence) was analyzed using ANCOVA and logistic regression, respectively. For the meta-analysis, a literature search was conducted using MEDLINE, Embase, and PsycINFO up to October 2019. The pooled odds ratio was calculated for presence or absence of weight gain (≥7% weight change) using a random effects model.

RESULTS

We did not detect an association between rs7799039 and BMI change or weight gain (presence or absence) in the CATIE sample. As for the meta-analysis, we included 12 studies. No significant associations between the LEP rs7799039 polymorphism and AIWG were observed under the allelic genetic model (allele A vs. allele G) (OR = 1.10 [0.71, 1.70], p = .68). In the subgroup analyses of first-episode schizophrenia patients, a significant association between the A-allele and weight gain was observed, respectively (OR = 2.32 [1.41, 3.82], p = .0009).

CONCLUSIONS

The present meta-analysis showed no significant effect of rs7799039 on AIWG. However, this variant may influence AIWG in first-episode schizophrenia patients. Further investigation of a larger and more homogenous sample is required to elucidate the role of the LEP gene in AIWG.

Comparative Tolerability of Dopamine D2/3 Receptor Partial Agonists for Schizophrenia

Aripiprazole, brexpiprazole and cariprazine differ from all other second-generation antipsychotics due to partial agonism at the dopamine D2 and D3 receptors. In contrast to aripiprazole, brexpiprazole has lower intrinsic dopamine D2 activity and higher affinity for the serotonin 5-HT1A and 5-HT2A receptors, while cariprazine has the highest affinity for the dopamine D3 receptor, and the longest half-life. The main adverse effect of dopamine receptor partial agonists (DRPAs) is akathisia of low-to-moderate severity, which occurs in a small proportion of patients, usually in the first few weeks of treatment. While definitive conclusions concerning differences between the DRPAs require head-to-head comparison studies, on the available evidence, akathisia is probably least likely to occur with brexpiprazole and most likely with cariprazine; the risk of akathisia with aripiprazole lies in between. Weight-gain risk is low with aripiprazole and cariprazine, but moderate with brexpiprazole. Risk of sedation is low with DRPAs, as is risk of insomnia and nausea. Partial dopamine agonism leads to a low risk for hyperprolactinaemia (and probably a low risk of sexual dysfunction). Prolactin concentrations fall in some patients (particularly those with elevated levels prior to initiating the drugs). Rates of discontinuation due to adverse effects in pivotal studies were low, and on the whole, DRPAs are well tolerated. Aripiprazole has been implicated in pathological gambling and other impulse control behaviours, likely due to partial dopamine agonist activity (there have been no reports with brexpiprazole and cariprazine). The risks for diabetes and tardive dyskinesia with DRPAs are unknown, but are likely to be low. On the basis of tolerability, DRPAs should be considered as first-line treatment options, particularly in patients with early schizophrenia.

Efficacy and Safety of Paliperidone Palmitate Treatment in Patients With Schizophrenia: A Real-World Multicenter, Retrospective, Mirror-Image Study

PURPOSE

The aim of the study was to assess efficacy and safety of paliperidone palmitate (PP) in schizophrenic patients using real-life data.

METHODS

This national, multicenter, retrospective, and mirror-image study was performed reviewing the medical records of patients in 18 centers. Adult schizophrenic patients receiving PP treatment (n = 205) were enrolled. Patients' data covering the last 12 months before the initial PP injection and the period until the end of study with at least 12 months after the initial PP injection were evaluated. Patients' characteristics, scale scores, and adverse events were recorded.

RESULTS

Nonadherence to prior medication was the most frequent reason for switching to PP treatment. Comparing with the period before PP treatment, the rate of patients visiting the hospital for relapse (79.5% vs 28.9%, P < 0.001) and the median number of hospitalizations (2 vs 0, P < 0.001) were lower during PP treatment. During PP treatment, the Positive and Negative Syndrome Scale score decreased by 20% or more (response to treatment) in 75.7% of the patients. The frequency of adverse events did not differ between the period before and during PP treatment. Improvement in functionality was higher in those with disease duration of 5 years or less.

CONCLUSIONS

Paliperidone palmitate is effective and safe in treatment of schizophrenic patients and in switching to PP treatment in patients with schizophrenia, which reduced the percentage of patients admitted to the hospital for relapse and the median number hospitalization, and has positive effects on functionality.

Pharmacogenetics of Antipsychotic Drug Treatment: Update and Clinical Implications

Numerous genetic variants have been shown to be associated with antipsychotic response and adverse effects of schizophrenia treatment. However, the clinical application of these findings is limited. The aim of this narrative review is to summarize the most recent publications and recommendations related to the genetics of antipsychotic treatment and shed light on the clinical utility of pharmacogenetics/pharmacogenomics (PGx). We reviewed the literature on PGx studies with antipsychotic drugs (i.e., antipsychotic response and adverse effects) and commonly used commercial PGx tools for clinical practice. Publications and reviews were included with emphasis on articles published between January 2015 and April 2018. We found 44 studies focusing on antipsychotic response and 45 studies on adverse effects (e.g., antipsychotic-induced weight gain, movement disorders, hormonal abnormality, and clozapine-induced agranulocytosis/granulocytopenia), albeit with mixed results. Overall, several gene variants related to antipsychotic response and adverse effects in the treatment of patients with schizophrenia have been reported, and several commercial pharmacogenomic tests have become available. However, further well-designed investigations and replication studies in large and well-characterized samples are needed to facilitate the application of PGx findings to clinical practice.

Molecular pathway analysis associates alterations in obesity-related genes and antipsychotic-induced weight gain

OBJECTIVE

Antipsychotics often induce excessive weight gain. We hypothesised that individuals with genetic variations related to known obesity-risk genes have an increased risk of excessive antipsychotic-induced weight gain (AIWG). This hypothesis was tested in a subset of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trial data set.

METHODS

The CATIE trial compared effects and side effects of five different antipsychotics through an 18-month period. Based on the maximum weight gain recorded, excessive weight gain was defined as >7% weight gain. Cytoscape and GeneMANIA were instrumental in composing a molecular pathway from eight selected genes linked to obesity. Genetic information on a total of 495.172 single-nucleotide polymorphisms (SNPs) were available from 765 (556 males) individuals. Enrichment test was conducted through ReactomePA and Bioconductor. A permutation test was performed, testing the generated pathway against 105 permutated pathways (p ≤ 0.05). In addition, a standard genome-wide association study (GWAS) analysis was performed.

RESULT

GWAS analysis did not detect significant differences related to excessive weight gain. The pathway generated contained 28 genes. A total of 2067 SNPs were significantly expressed (p < 0.01) within this pathway when comparing excessive weight gainers to the rest of the sample. Affected genes including PPARG and PCSK1 were not previously related to treatment-induced weight gain.

CONCLUSIONS

The molecular pathway composed from high-risk obesity genes was shown to overlap with genetics of patients who gained >7% weight gain during the CATIE trial. This suggests that genes related to obesity compose a pathway of increased risk of excessive AIWG. Further independent analyses are warranted that may confirm or clarify the possible reasoning behind.

Psychiatric drugs impact mitochondrial function in brain and other tissues

Mitochondria have been linked to the etiology of schizophrenia (SZ). However, studies of mitochondria in SZ might be confounded by the effects of pharmacological treatment with antipsychotic drugs (APDs) and other common medications. This review summarizes findings on relevant mitochondria mechanisms underlying SZ, and the potential impact of psychoactive drugs including primarily APDs, but also antidepressants and anxiolytics. The summarized data suggest that APDs impair mitochondria function by decreasing Complex I activity and ATP production and dissipation of the mitochondria membrane potential. At the same time, in the brains of patients with SZ, antipsychotic drug treatment normalizes gene expression modules enriched in mitochondrial genes that are decreased in SZ. This indicates that APDs may have both positive and negative effects on mitochondria. The available evidence suggests three conclusions i) alterations in mitochondria functions in SZ exist prior to APD treatment, ii) mitochondria alterations in SZ can be reversed by APD treatment, and iii) APDs directly cause impairment of mitochondria function. Overall, the mechanisms of action of psychiatric drugs on mitochondria are both direct and indirect; we conclude the effects of APDs on mitochondria may contribute to both their therapeutic and metabolic side effects. These studies support the hypothesis that neuronal mitochondria are an etiological factor in SZ. Moreover, APDs and other drugs must be considered in the evaluation of this pathophysiological role of mitochondria in SZ. Considering these effects, pharmacological actions on mitochondria may be a worthwhile target for further APD development.

Progress in Genetic Polymorphisms Related to Lipid Disturbances Induced by Atypical Antipsychotic Drugs

Metabolic side effects such as weight gain and disturbed lipid metabolism are often observed in the treatment of atypical antipsychotic drugs (AAPDs), which contribute to an excessive prevalence of metabolic syndrome among schizophrenic patients. Great individual differences are observed but the underlying mechanisms are still uncertain. Research on pharmacogenomics indicates that gene polymorphisms involved in the pathways controlling food intake and lipid metabolism may play a significant role. In this review, relevant genes (HTR2C, DRD2, LEP, NPY, MC4R, BDNF, MC4R, CNR1, INSIG2, ADRA2A) and genetic polymorphisms related to metabolic side effects of AAPDs especially dyslipidemia were summarized. Apart from clinical studies, in vitro and in vivo evidence is also analyzed to support related theories. The association of central and peripheral mechanisms is emphasized, enabling the possibility of using peripheral gene expression to predict the central status. Novel methodological development of pharmacogenomics is in urgent need, so as to provide references for individualized medication and further to shed some light on the mechanisms underlying AAPD-induced lipid disturbances.

Non-Coding RNAs in Psychiatric Disorders and Suicidal Behavior

It is well known that only a small proportion of the human genome code for proteins; the rest belong to the family of RNAs that do not code for protein and are known as non-coding RNAs (ncRNAs). ncRNAs are further divided into two subclasses based on size: 1) long non-coding RNAs (lncRNAs; >200 nucleotides) and 2) small RNAs (<200 nucleotides). Small RNAs contain various family members that include microRNAs (miRNAs), small interfering RNAs (siRNAs), piwi-interacting RNAs (piRNAs), small nucleolar RNAs (snoRNAs), and small nuclear RNAs (snRNAs). The roles of ncRNAs, especially lncRNAs and miRNAs, are well documented in brain development, homeostasis, stress responses, and neural plasticity. It has also been reported that ncRNAs can influence the development of psychiatric disorders including schizophrenia, major depressive disorder, and bipolar disorder. More recently, their roles are being investigated in suicidal behavior. In this article, we have comprehensively reviewed the findings of lncRNA and miRNA expression changes and their functions in various psychiatric disorders including suicidal behavior. We primarily focused on studies that have been done in postmortem human brain. In addition, we have briefly reviewed the role of other small RNAs (e.g. piwiRNA, siRNA, snRNA, and snoRNAs) and their expression changes in psychiatric illnesses.

C677T Polymorphism in the MTHFR Gene Is Associated With Risperidone-Induced Weight Gain in Schizophrenia

OBJECTIVE

To explore the association of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism with risperidone-induced weight gain.

METHODS

We analyzed the association between MTHFR C677T polymorphism and risperidone-induced weight gain in 356 schizophrenia patients. The patients were treated with risperidone for 8 weeks. The height and body weight of the patients were measured before and 8 weeks after risperidone treatment. Blood DNA was genotyped for MTHFR C677T polymorphisms.

RESULTS

We found a significant association between MTHFR C677T polymorphism and body mass index (BMI) change after 8-week risperidone treatment. The BMI of carriers with different genotypes of MTHFR gene increased over 2-8 weeks. After 8 weeks of risperidone treatment, BMI added value (kg/m²) of CC or CT genotype carriers was significantly higher than that of TT genotype carriers [CC (4.47 ± 1.09), CT (4.54 ± 1.27), TT (2.31 ± 0.75), F = 5.634, P = 0.001]. Based on whether the rate of weight gain from baseline at 8 weeks of treatment exceeded 7%, it was divided into a weight gain group (n = 61) and a non-weight gain group (n = 295). The C allele frequency was significantly different between the two groups (48.4% vs 32.4%, χ² = 11.342, P = 0.001).

CONCLUSION

MTHFR C677T polymorphism was associated with risperidone-induced weight gain in Chinese Han population.

Relationship of SNAP25 variants with schizophrenia and antipsychotic-induced weight change in large-scale schizophrenia patients

The SNAP25 gene is involved in the development of antipsychotic-induced weight gain (AIWG) or metabolic syndrome during antipsychotics use in Americans and Europeans, but its role in Asians remains unknown. To identify common variants in SNAP25 associated with schizophrenia and evaluate their effects on AIWG and antipsychotic responses in Han Chinese individuals with schizophrenia, we conducted a two-stage case-control study of 3,243 patients and 6,154 healthy controls. 2128 inpatients in the replication stage have received conventional treatment with an antipsychotic monotherapy (Haloperidol, Olanzapine or Risperidone) for 10 weeks at least. Weight change, antipsychotic responses and metabolic indices change were assessed during treatments. Three SNPs were significantly associated with schizophrenia in samples (rs6039769, P = 6.64 × 10^-7; rs3787283, P = 0.004283; rs3746544, P = 2.51 × 10^-6). Of these, rs6039769 is a novel schizophrenia-associated SNP and is uncorrelated with the other two variants, which have previously been associated with schizophrenia in European-ancestry samples. Rs6039769 was significantly associated with AIWG (P < 0.001), but not with antipsychotic responses or metabolic indices. Another two SNPs were not associated with AIWG or antipsychotic responses or metabolic indices. Overall, there were significant differences in antipsychotic responses and metabolic indices among the three treatment groups. Our findings suggest that SNAP25 gene may contribute to the susceptibility of AIWG and even metabolic disturbances. A prior identification of high-risk of patients with rs6039769 would contribute to a better precision of the pharmacological treatment.

Psychotropic drug-induced genetic-epigenetic modulation of CRTC1 gene is associated with early weight gain in a prospective study of psychiatric patients

BACKGROUND

Metabolic side effects induced by psychotropic drugs represent a major health issue in psychiatry. CREB-regulated transcription coactivator 1 (CRTC1) gene plays a major role in the regulation of energy homeostasis and epigenetic mechanisms may explain its association with obesity features previously described in psychiatric patients. This prospective study included 78 patients receiving psychotropic drugs that induce metabolic disturbances, with weight and other metabolic parameters monitored regularly. Methylation levels in 76 CRTC1 probes were assessed before and after 1 month of psychotropic treatment in blood samples.

RESULTS

Significant methylation changes were observed in three CRTC1 CpG sites (i.e., cg07015183, cg12034943, and cg 17006757) in patients with early and important weight gain (i.e., equal or higher than 5% after 1 month; FDR p value = 0.02). Multivariable models showed that methylation decrease in cg12034943 was more important in patients with early weight gain (≥ 5%) than in those who did not gain weight (p = 0.01). Further analyses combining genetic and methylation data showed that cg12034943 was significantly associated with early weight gain in patients carrying the G allele of rs4808844A>G (p = 0.03), a SNP associated with this methylation site (p = 0.03).

CONCLUSIONS

These findings give new insights on psychotropic-induced weight gain and underline the need of future larger prospective epigenetic studies to better understand the complex pathways involved in psychotropic-induced metabolic side effects.

The clozapine to norclozapine ratio: a narrative review of the clinical utility to minimize metabolic risk and enhance clozapine efficacy

Introduction: Clozapine remains the most effective antipsychotic for treatment-refractory schizophrenia. However, ~40% of the patients respond insufficiently to clozapine. Clozapine's effects, both beneficial and adverse, have been proposed to be partially attributable to its main metabolite, N-desmethylclozapine (NDMC). However, the relation of the clozapine to norclozapine ratio (CLZ:NDMC; optimally defined as ~2) to clinical response and metabolic outcomes is not clear.Areas covered: This narrative review comprehensively examines the clinical utility of the CLZ:NDMC ratio to reduce metabolic risk and increase treatment efficacy. The association of the CLZ:NDMC ratio with changes in psychopathology, cognitive functioning, and cardiometabolic burden will be explored, as well as adjunctive treatments and their effects.Expert opinion: The literature suggests a positive association between the CLZ:NDMC ratio and better cardiometabolic outcomes. Conversely, the CLZ:NDMC ratio appears inversely associated with better cognitive functioning but less consistently with other psychiatric domains. The CLZ:NDMC ratio may be useful for predicting and monitoring cardiometabolic adverse effects and optimizing potential cognitive benefits of clozapine. Future studies are required to replicate these findings, which if substantiated, would encourage examination of adjunctive treatments aiming to alter the CLZ:NDMC ratio to best meet the needs of the individual patient, thereby broadening clozapine's clinical utility.

Treatment resistant schizophrenia: Clinical, biological, and therapeutic perspectives

Treatment resistant schizophrenia (TRS) refers to the significant proportion of schizophrenia patients who continue to have symptoms and poor outcomes despite treatment. While many definitions of TRS include failure of two different antipsychotics as a minimum criterion, the wide variability in inclusion criteria has challenged the consistency and reproducibility of results from studies of TRS. We begin by reviewing the clinical, neuroimaging, and neurobiological characteristics of TRS. We further review the current treatment strategies available, addressing clozapine, the first-line pharmacological agent for TRS, as well as pharmacological and non-pharmacological augmentation of clozapine including medication combinations, electroconvulsive therapy, repetitive transcranial magnetic stimulation, deep brain stimulation, and psychotherapies. We conclude by highlighting the most recent consensus for defining TRS proposed by the Treatment Response and Resistance in Psychosis Working Group, and provide our overview of future perspectives and directions that could help advance the field of TRS research, including the concept of TRS as a potential subtype of schizophrenia.