Asymmetric dimethylarginine in somatically healthy schizophrenia patients treated with atypical antipsychotics: a case-control study

A systematic review and meta-analysis of nitric oxide-associated arginine metabolites in schizophrenia

There is increasing interest in the pathophysiological role of arginine metabolism in schizophrenia, particularly in relation to the modulation of the endogenous messenger nitric oxide (NO). The assessment of specific arginine metabolites that, unlike NO, are stable can provide useful insights into NO regulatory enzymes such as isoform 1 of dimethylarginine dimethylaminohydrolase (DDAH1) and arginase. We investigated the role of arginine metabolomics in schizophrenia by conducting a systematic review and meta-analysis of the circulating concentrations of arginine metabolites associated with DDAH1, arginase, and NO synthesis [arginine, citrulline, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), dimethylamine, and ornithine] in this patient group. We searched PubMed, Scopus, and Web of Science from inception to the 31st of May 2023 for studies investigating arginine metabolites in patients with schizophrenia and healthy controls. The JBI Critical Appraisal Checklist for analytical studies and GRADE were used to assess the risk of bias and the certainty of evidence, respectively (PROSPERO registration number: CRD42023433000). Twenty-one studies were identified for analysis. There were no significant between-group differences in arginine, citrulline, and SDMA. By contrast, patients with schizophrenia had significantly higher ADMA (DDAH1 substrate, standard mean difference, SMD = 1.23, 95% CI 0.86-1.61, p < 0.001; moderate certainty of evidence), dimethylamine (DDAH1 product, SMD = 0.47, 95% CI 0.24-0.70, p < 0.001; very low certainty of evidence), and ornithine concentrations (arginase product, SMD = 0.32, 95% CI 0.16-0.49, p < 0.001; low certainty of evidence). In subgroup analysis, the pooled SMD for ornithine was significantly different in studies of untreated, but not treated, patients. Our study suggests that DDAH1 and arginase are dysregulated in schizophrenia. Further studies are warranted to investigate the expression/activity of these enzymes in the brain of patients with schizophrenia and the effects of targeted treatments.

COVID-19 and Antipsychotic Therapy: Unraveling the Thrombosis Risk

In the context of the COVID-19 pandemic, this study investigates the potential correlation between the increased use of antipsychotic medications and the rising incidence of venous thromboembolism (VTE). As psychiatric disorders surged, the consequential escalation in antipsychotic drug use raised concerns about thrombotic risks. We conducted a comprehensive literature review using PubMed, focusing on articles that intersected COVID-19, antipsychotic medication, and thrombosis. This approach allowed for a nuanced examination of the historical and recent data on antipsychotic drugs and their association with thrombotic events. Our findings reveal a notable link between the use of antipsychotic medications, particularly second-generation antipsychotics, and an increased risk of VTE, including pulmonary embolism and deep vein thrombosis. This association was evident, despite variations in study designs and populations. The study underscores the need for cautious medication management in psychiatric care, especially during pandemic conditions like COVID-19, to mitigate thrombotic risks. It advocates a personalized approach to prescribing antipsychotics, considering individual patient factors and comorbidities, to balance the benefits against potential thrombotic complications.

Evaluation of Asymmetric Dimethylarginine, Malondialdehyde, and Vitamin Levels of Borderline Personality Disorder Patients With and Without Self-Mutilation

OBJECTIVE

Believing that oxidative stress may be increased in borderline personality disorder (BPD) patients with self-mutilating behaviors (SMB), we aimed to measure serum asymmetric dimethylarginine (ADMA) and malondialdehyde (MDA) levels in these patients.

METHODS

The study included 60 patients diagnosed with BPD and 30 healthy controls. BPD patients were divided into two groups: 30 female patients with SMB and 30 female patients with no-self-mutilating behavior (NSMB). ADMA, MDA, vitamin A, and vitamin E levels were analyzed. Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI) were conducted with the participants.

RESULTS

Serum ADMA and MDA levels were higher in SMB and NSMB group compared to control group. Serum vitamin E levels were also lower in the SMB group compared to the control group. Positive correlations were determined between both ADMA and MDA, and between BDI and BAI scores. Also, BAI scores were statistically higher in SMB group compared to NSMB group.

CONCLUSION

It was discovered that levels of ADMA and MDA, which reflected oxidative stress, were elevated in patients with BPD who exhibited SMB. Accordingly, future studies should investigate the role of oxidative stress in a more comprehensive way in terms of the different mechanisms underlying and treatments involved in borderline personality disorder.

Asymmetric dimethylarginine in psychiatric disorders

Serum concentrations of asymmetric dimethylarginine (ADMA) in patients with schizophrenia, schizoaffective disorder, bipolar disorder, and depression were determined and compared to serum concentrations in healthy individuals. In all psychiatric diseases investigated, the ADMA concentration was elevated compared to the control group. Patients with recurrent depressive disorder had higher ADMA levels than patients with only one depressive episode. No differences between women and men were found. The elevated ADMA levels suggest that ADMA is involved in the pathophysiology of psychiatric diseases.

Comparison of serum levels of asymmetric dimethylarginine between patients who take two types of atypical anti psychotics

Background: Schizophrenia is associated with increased cardiovascular morbidity. Asymmetric dimethylarginine (ADMA) has been suggested as a cardiovascular biomarker. Treatment with atypical antipsychotics can increase some traditional risk factors of coronary artery disease. In addition to traditional risk factors, this study is carried out as a comparison of serum levels of ADMA and non-traditional factors among patients who take two types of atypical antipsychotics. Methods: In this clinical study, 57 schizophrenic patients with multiple episodes and 20 healthy voluntaries that fulfilled inclusion and exclusion criteria were entered into the study. The patients were divided into 3 groups (18 patients received risperidone alone, 20 patients received clozapine alone and 19 patients did not receive any drug). Plasma concentrations of ADMA, high-sensitivity Creactive protein (hs-CRP) and homocysteine were measured through enzyme-linked immunosorbent assay (ELISA), and traditional risk factors of metabolic syndrome were measured. Results: Mean age of participants was 46.08±12.54 years. Moreover, the traditional (High-density lipoprotein (HDL), total cholesterol, waistline, and Body Mass Index (BMI)) and non-traditional factors (Homocysteine, hs-CRP) and ADMA were higher in patients with schizophrenia compared to healthy group (p≤ 0.05). Also, in the clozapine group, all mentioned non-traditional factors and ADMA were significantly higher than other groups (p≤ 0.05). Conclusion: In the clozapine group, levels of non-traditional factors and ADMA were significantly higher which indicates these patients are at risk of cardiovascular disease.

Increased plasma asymmetric dimethylarginine is associated with cognitive deficits in patients with schizophrenia

Cognitive deficits are a core feature of schizophrenia. Previous studies have shown that plasma asymmetric dimethylarginine (ADMA), an endogenous inhibitor of the nitric oxide synthase, was increased in patients with schizophrenia. This study aimed to investigate the association of ADMA with cognitive deficits in schizophrenia. Forty-seven patients with schizophrenia and 45 healthy control subjects were recruited in present study. Cognitive function was assessed with a neuropsychological battery including 7 neurocognitive tests. Schizophrenic symptoms were assessed using the Positive and Negative Syndrome Scale and plasma ADMA concentration was measured by HPLC. We found that patients with schizophrenia exhibited poorer performances in nearly all of the cognitive tests except for the visual memory index compared with healthy controls. Plasma ADMA levels were significantly increased in patients with schizophrenia when compared to normal controls, and the mean ADMA concentration in patients with multiple episode schizophrenia was much higher than that of patients with first episode schizophrenia. For the patients, ADMA was negatively associated with attention, working memory and executive function in schizophrenia. These results suggest that ADMA may be involved in the pathophysiology of schizophrenia-associated cognitive impairments, and plasma ADMA could be a peripheral biomarker for evaluation of cognitive function in schizophrenia.

Plasma concentrations of three methylated arginines, endogenous nitric oxide synthase inhibitors, in schizophrenic patients undergoing antipsychotic drug treatment

Plasma concentration of three methylated arginines, endogenous nitric oxide synthase inhibitors, is not studied in schizophrenic patients. The purpose of this study was to determine plasma concentrations of N(G)-monomethyl-L-arginine (l-NMMA), N(G),N(G)-dimethyl-L-arginine (ADMA), N(G),N(G')-dimethyl-L-arginine (SDMA), and l-arginine in 56 male and 45 female schizophrenic patients undergoing antipsychotic drug treatment versus those of 39 male and 24 female healthy controls. Plasma concentrations of methylated arginines and l-arginine were measured using newly developed high performance liquid chromatography with fluorescence detection which we previously reported. Methylated arginine levels were slightly but significantly higher in schizophrenic patients. L-Arginine levels and the l-arginine/(ADMA+l-NMMA) ratio were higher in schizophrenic patients than in healthy controls. It is considered that pharmacological treatment of schizophrenic patients may lower methylated arginine levels that are increased by the disease, and increase L-arginine levels, eliciting an improvement in nitric oxide (NO) bioavailability.