Cigarette Smoking and Schizophrenia: Etiology, Clinical, Pharmacological, and Treatment Implications

Heavy metal concentrations and clinical symptoms in patients diagnosed with schizophrenia related to cigarette smoking

In our study, blood concentrations of lead (Pb), arsenic (As), and cadmium (Cd) and urine concentrations of thallium (Tl) were measured together with related symptoms of heavy metal poisoning in cigarette smoking volunteers diagnosed with schizophrenia, in cigarette smokers not diagnosed with schizophrenia, and in the control group of non-smokers and not diagnosed with schizophrenia volunteers. Our study was performed on 171 volunteers divided into the following subgroups: patients diagnosed with schizophrenia with at least 1 year of continuous cigarette smoking experience (56 participants), cigarette smokers not diagnosed with schizophrenia with at least one year of continuous smoking experience (58), and control group (not diagnosed with schizophrenia and non-smoking volunteers) (57). Smoking durations of cigarette smokers diagnosed with schizophrenia and cigarette smokers not diagnosed with schizophrenia are not similar (p = 0.431). Blood Pb, As, and Cd concentrations and urine Tl concentrations were the highest in the subgroup of cigarette smokers not diagnosed with schizophrenia, followed by the subgroup of cigarette smokers diagnosed with schizophrenia, and the control group. Only blood Pb concentrations were significantly higher (probability value p < 0.05) in the group of cigarette smokers not diagnosed with schizophrenia (5.16 μg/dL), comparing to the group of cigarette smokers diagnosed with schizophrenia (3.83 μg/dL) and to the control group (3.43 μg/dL). Blood Cd and As concentrations and urine Tl concentrations were significantly higher (p < 0.05) in cigarette smokers not diagnosed with schizophrenia than in the control group. The results revealed a statistically significant positive correlation (p < 0.001) in the cigarette smokers in the schizophrenia diagnosed group between blood Pb, blood As, and urine Tl concentrations and the duration of cigarette smoking.

Efficacy of the combination of water aerobics and metacognitive training on psychological and physical health variables and their relationship with SP1 and SP4 biomarkers in people with psychosis: a study protocol

Background

Metacognitive Training (MCT) is widely used and effective in reducing positive symptoms in psychosis. Physical exercise, such as Water Aerobics (WA), improves general health, quality of life and symptoms as a low impact activity that allows social interactions. Preliminary results suggest a relationship between dopamine and psychotic symptoms, through SP transcription factors, SP1 and SP4 biomarkers. The aims of the project are to evaluate the efficacy of a combined intervention (WA and MCT) for psychosis to improve psychotic symptoms, physical health, and transcription levels of SP biomarkers.

Materials and methods

This is a unicentric randomized controlled trial of three parallel intervention groups: MCT, WA and combined intervention. The estimated sample will be 48 patients with a psychotic spectrum disorder diagnosis. The assessment will be performed at baseline and at 2-months' follow-up. Instruments used in the assessment will include clinical, cognitive, metacognitive, social cognitive and psychosocial variables.

Discussion

This will be the first study investigating the impact of the combination of MCT and WA in psychosis. Moreover, it will be the first study analyzing changes in the transcriptional biomarkers SP1 and SP4 after interventions. The results of this study may have clinical implications contributing to the improvement of treatment selection.

Clinical trial registration

https://clinicaltrials.gov/, identifier: NCT05455593.

Nicotine use disorder and Neuregulin 3: Opportunities for precision medicine

Nicotine use disorder remains a major public health emergency despite years of trumpeting the consequences of smoking. This is likely due to the complex interplay of genetics and nicotine exposure across the lifespan of these individuals. Genetics influence all aspects of life, including complex disorders such as nicotine use disorder. This review first highlights the critical neurocircuitry underlying nicotine dependence and withdrawal, and then describes the cellular signaling mechanisms involved. Finally, current genetic, genomic, and transcriptomic evidence for new drug development of smoking cessation aids is discussed, with a focus on the Neuregulin 3 Signaling Pathway.

Large-Scale Mendelian Randomization Study Reveals Circulating Blood-based Proteomic Biomarkers for Psychopathology and Cognitive Task Performance

Background

Research on peripheral (e.g., blood-based) biomarkers for psychiatric illness has typically been low-throughput in terms of both the number of subjects and the range of assays performed. Moreover, traditional case-control studies examining blood-based biomarkers are subject to potential confounds of treatment and other exposures common to patients with psychiatric illnesses. Our research addresses these challenges by leveraging large-scale, high-throughput proteomics data and Mendelian Randomization (MR) to examine the causal impact of circulating proteins on psychiatric phenotypes and cognitive task performance.

Methods

We utilized plasma proteomics data from the UK Biobank (3,072 proteins assayed in 34,557 European-ancestry individuals) and deCODE Genetics (4,719 proteins measured across 35,559 Icelandic individuals). Significant proteomic quantitative trait loci (both cis-pQTLs and trans-pQTLs) served as MR instruments, with the most recent GWAS for schizophrenia, bipolar disorder, major depressive disorder, and cognitive task performance (all excluding overlapping UK Biobank participants) as phenotypic outcomes.

Results

MR revealed 109 Bonferroni-corrected causal associations (44 novel) involving 88 proteins across the four phenotypes. Several immune-related proteins, including interleukins and complement factors, stood out as pleiotropic across multiple outcome phenotypes. Drug target enrichment analysis identified several novel potential pharmacologic repurposing opportunities, including anti-inflammatory agents for schizophrenia and bipolar disorder and duloxetine for cognitive performance.

Conclusions

Identification of causal effects for these circulating proteins suggests potential biomarkers for these conditions and offers insights for developing innovative therapeutic strategies. The findings also indicate substantial evidence for the pleiotropic effects of many proteins across different phenotypes, shedding light on the shared etiology among psychiatric conditions and cognitive ability.

Smoking, Symptoms Improvement, and Total Antioxidant Capacity in Patients with Drug-naive First-episode Schizophrenia: A Prospective Cohort Study

BACKGROUND

It has been hypothesized that smoking is associated with the severity of negative symptoms. Until now, no studies have investigated whether the impact of smoking on negative symptoms is dependent on antioxidants. This study was designed to evaluate the effect of smoking on therapeutic response and total antioxidants capacity (TAOC) in antipsychotic-naïve first-episode (ANFE) patients.

METHODS

The severity of the patient's symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). A total of 237 ANFE patients were recruited and treated with risperidone (oral tablets, 4-6 mg/day twice a day) for 12 weeks. PANSS was assessed at baseline and a 12-week follow-up. Plasma TAOC levels were also assayed at baseline and week 12.

RESULTS

Relative to nonsmokers with ANFE SZ, smokers had higher PANSS negative subscores. There was no significant difference in TAOC changes after 12 weeks of treatment with risperidone between smokers and non-smokers. However, we found greater improvement in negative symptoms in smokers compared to non-smokers. Further analysis in smokers with SZ demonstrated that improvements in negative symptoms were not associated with changes in TAOC.

CONCLUSION

Our study suggested that smoking affected the severity of baseline negative symptoms and further contributed to their reduction after risperidone treatment. However, improvement in negative symptoms was not dependent on the changes in TAOC.

Association of smoking cigarettes, age, and sex with serum concentrations of olanzapine in patients with schizophrenia

Introduction

Olanzapine is an atypical antipsychotic drug which is effective in the treatment of schizophrenia. Cigarette smoking, age, and sex could be related to the pharmacokinetics and serum concentrations of olanzapine in patients with schizophrenia. The aim of the study was to examine whether there was a significant difference in the serum olanzapine concentrations with regard to the mentioned factors.

Materials and methods

A total of 58 outpatients with schizophrenia (37 smokers, 42 men, 35 older than 40 years) participated in the study. Blood was sampled in serum tubes just before taking the next dose of olanzapine. Olanzapine was extracted by liquid-liquid extraction and was measured by an in-house high-performance liquid chromatography method on Shimadzu Prominence HPLC System with diode array detector SPD-M20A (Shimadzu, Kyoto, Japan). The results were expressed as the ratio of concentration to the daily dose of olanzapine (C/D). Non-parametric statistical tests were used to analyse differences between variables.

Results

The median C/D of olanzapine (interquartile range) in smokers was 6.0 (3.4-10.2) nmol/L/mg and in non-smokers 10.1 (5.9-17.6) nmol/L/mg; P = 0.007. The median C/D of olanzapine in patients younger than 40 years was 5.6 (4.5-10.2) nmol/L/mg and in patients older than 40 years 8.4 (5.6-13.0) nmol/L/mg; P = 0.105. The median C/D of olanzapine in male patients was 6.6 (4.6-10.4) nmol/L/mg and in female patients 9.0 (5.9-15.3) nmol/L/mg; P = 0.064.

Conclusions

The serum olanzapine concentration was significantly lower in smoking than in non-smoking patients with schizophrenia. No significant difference was demonstrated with regard to age and sex.

The Many Faces of Histidine Triad Nucleotide Binding Protein 1 (HINT1)

The histidine triad nucleotide binding protein 1 (HINT1) is a nucleoside phosphoramidase that has garnered interest due to its widespread expression and participation in a broad range of biological processes. Herein, we discuss the role of HINT1 as a regulator of several CNS functions, tumor suppressor, and mast cell activator via its interactions with multiple G-protein-coupled receptors and transcription factors. Importantly, altered HINT1 expression and mutation are connected to the progression of multiple disease states, including several neuropsychiatric disorders, peripheral neuropathy, and tumorigenesis. Additionally, due to its involvement in the activation of several clinically used phosphoramidate prodrugs, tremendous efforts have been made to better understand the interactions behind nucleoside binding and phosphoramidate hydrolysis by HINT1. We detail the substrate specificity and catalytic mechanism of HINT1 hydrolysis, while highlighting the structural biology behind these efforts. The aim of this review is to summarize the multitude of biological and pharmacological functions in which HINT1 participates while addressing the areas of need for future research.

Infections associated with clozapine: a pharmacovigilance study using VigiBase®

Introduction: Clozapine is primarily reserved for treatment-resistant schizophrenia due to safety concerns associated with its use. Infections have been reported with clozapine, which may lead to elevated serum levels of the drug. However, the existing literature on this topic is limited. Therefore, we conducted a study using VigiBase® to investigate the potential over-reporting of infections associated with clozapine, to explore the presence of dose-dependency, and to investigate the underlying mechanism. Methods: Disproportionality analyses were performed using VigiBase to assess the association between clozapine and all types of infections, the association between clozapine-associated infections and neutropenia, the association between clozapine-associated infections and agranulocytosis, the dose-effect relationship between clozapine and infections, and the interaction between clozapine and the main strong CYP450 inhibitors using reports carried out until 11 April 2023. Results: A statistically significant signal of infections was observed with clozapine, as indicated by an information component of 0.43 [95% CI: (0.41-0.45)]. The most commonly reported infections were respiratory and gastrointestinal in nature. Neutropenia showed weaker association with clozapine-associated reports of infections compared to other clozapine-associated reports [X2 (1, N = 204,073) = 454; p < 0.005], while agranulocytosis demonstrated a stronger association with clozapine-associated reports of infections [X2 (1, N = 204,073) = 56; p < 0.005]. No evidence of dose-dependency was observed. Among the 17 tested CYP inhibitors, significant drug-drug interactions were found with clarithromycin, metronidazole, valproic acid, lansoprazole, omeprazole, amiodarone, and esomeprazole. Discussion: Our study revealed a significant safety signal between clozapine use and infections, predominantly respiratory and gastrointestinal infections. The co-administration of clozapine with valproic acid or proton pump inhibitors may potentially contribute to an increased risk of infection. Further vigilance is warranted in clinical practice, and consideration of therapeutic drug monitoring of clozapine in cases involving concomitant use of these drugs or in the presence of infections may be beneficial.

Smoke, GPx activity and symptoms improvement in patients with drug-naive first-episode schizophrenia: A large-scale 12-week follow-up study

The relationship between tobacco smoke and schizophrenia (SZ) is well established. Smoking is hypothesized to alleviate symptoms and reduce the adverse effects of antipsychotic medications in patients with SZ. However, the underlying biological mechanisms by which smoke improves symptoms in SZ remain unclear. The aim of this study was to investigate the effect of smoking on clinical symptoms and antioxidant enzyme activity after risperidone treatment in a 12-week prospective cohort study of drug-naïve first-episode (DNFE) SZ patients. Two hundred and fifteen DNFE patients were recruited and received 12 weeks of risperidone monotherapy. The Positive and Negative Syndrome Scale (PANSS) was used to assess the severity of patient's symptoms at baseline and post-treatment. Plasma GPx activity was also measured at baseline and at the end of 12 weeks. Smokers showed greater improvement in negative symptoms relative to nonsmokers with DNFE SZ. In addition, repeated ANCOVA analysis showed no significant interaction of time and group on GPx activity. Improvement in negative symptoms was not associated with changes in GPx activity. However, in nonsmokers, increased GPx activity was correlated with improvement in positive symptoms.

Child abuse and aggressiveness in individuals diagnosed with schizophrenia in Lebanon

OBJECTIVES

To identify individual and clinical risk factors of aggressiveness, including exposure to different forms of childhood trauma, in a sample of Lebanese patients with schizophrenia.

METHODS

A total of 131 patients diagnosed with schizophrenia participated in this cross-sectional study.

RESULTS

Higher physical (Beta = 0.24, p < 0.001) and sexual (Beta = 0.29, p = 0.003) abuse, alcohol drinking (Beta = 1.46, p = 0.008), having a history of head trauma (Beta = 1.10, p = 0.041), and male gender (Beta = -1.59, p = 0.009) were significantly associated with higher mean aggression scores.

PRACTICAL IMPLICATIONS

Our investigation of the factors linked to aggressiveness in patients with schizophrenia complement those of earlier findings, showing that the relationship between interacting individual and environmental risk factors and later aggressiveness is quite complex, and needs further longitudinal and prospective studies.