Treatment-resistant schizophrenia - A RCT on the effectiveness of repeated-dose sodium nitroprusside.

OBJECTIVES: Sodium nitroprusside (SNP) has shown efficacy in schizophrenia in early stages of the disease in a previous study, but in more recent studies it has not shown efficacy in patients with longer disease duration. In present study, we evaluated the efficacy of repeated-dose SNP in treatment-resistant schizophrenia. METHODS: This was a double-blind, randomized, placebo-controlled trial. Twenty DSM-IV schizophrenia subjects, aged 18-60 years, with a history of nonresponse to ≥2 trials of antipsychotics of adequate dose and duration (≥6 weeks) were enrolled. Participants received SNP or placebo 4-hour infusions at 0.5 µg/kg/min. A total of 4 infusions and 4 follow-up evaluations, with an interval of 2 weeks, were performed. Severity of symptoms were assessed by using Positive and Negative Syndrome Scale (PANSS), Brief Psychiatric Rating Scale (BPRS-18) and Clinical Global Impression (CGI) scales. RESULTS: SNP and placebo groups did not differ at baseline or in change from baseline for PANSS-total (F = 0.525; p = 0.841), PANSS-positive (F = 0.32; p = 0.958), PANSS-negative (F = 1.05; p = 0.483), BPRS (F = 0.615; p = 0.734), or CGI-S (F = 1.11; p = 0.416) scores. SNP was well tolerated and showed a good safety profile. CONCLUSION: Although preliminary, the present findings suggest that SNP is not efficacious in TRS, reinforcing previous studies that have not demonstrated symptom improvement in chronic schizophrenia subjects. At this time, it is conceivable to speculate that efficacy of SNP might be restricted to early stages of disease.

Peripheral biomarkers allow differential diagnosis between schizophrenia and bipolar disorder.

Schizophrenia (SCZ) and bipolar disorder (BD) are severe mental disorders that pose important challenges for diagnosis by sharing common symptoms, such as delusions and hallucinations. The underlying pathophysiology of both disorders remains largely unknown, and the identification of biomarkers with potential to support diagnosis is highly desirable. In a previous study, we successfully discriminated SCZ and BD patients from healthy control (HC) individuals by employing proton magnetic resonance spectroscopy (1H-NMR). In this study, 1H-NMR data treated by chemometrics, principal component analysis (PCA) and supervised partial least-squares discriminant analysis (PLS-DA), provided the identification of metabolites present only in BD (as for instance the 2,3-diphospho-D-glyceric acid, N-acetyl aspartyl-glutamic acid, monoethyl malonate) or only in SCZ (as isovaleryl carnitine, pantothenate, mannitol, glycine, GABA). This may represent a set of potential biomarkers to support the diagnosis of these mental disorders, enabling the discrimination between SCZ and BD, and among these psychiatric patients and HC (as 6-hydroxydopamine was present in BD and SCZ but not in HC). The presence or absence of these metabolites in blood allowed the categorization of 182 independent subjects into one of these three groups. In addition, the presented data suggest disturbances in metabolic pathways in SCZ and BD, which may provide new and important information to support the elucidation and/or new insights into the neurobiology underlying these mental disorders.