Schizophrenia and obesity: May the gut microbiota serve as a link for the pathogenesis?

Longitudinal relationships between BMI and hs-CRP among people with schizophrenia

In people with schizophrenia (PwS), inflammation and metabolic issues significantly increase morbidity and mortality. However, our ability to understand inflammatory-metabolic mechanisms in this population has been limited to cross-sectional studies. This study involved 169 PwS and 156 non-psychiatric comparisons (NCs), aged 25-65, observed between 2012 and 2022 with 0 to 5 follow-ups post-baseline. High-sensitivity C-reactive protein (hs-CRP), a marker of inflammation, was measured via a particle-enhanced immuno-turbidimetric assay. Body mass index (BMI) was used as a proxy for metabolic function. The measurement intervals for hs-CRP and BMI ranged between 6 and 48 months. Linear mixed models (LMM) results revealed that at all time points, PwS has a higher hs-CRP (t (316) = 4.73, p < .001) and BMI (t (315) = 4.13, p < .001) than NCs; however, for BMI, this difference decreased over time (t (524) = -5.15, p < .001). To study interrelationships between hs-CRP and BMI, continuous time structural equational modeling (CTSEM) was used, accounting for uneven measurement intervals. CTSEM results showed that both hs-CRP predicted future BMI (Est. = 12.91, 95 % CI [7.70; 17.88]) and BMI predicted future hs-CRP (Est. = 1.54, 95 % CI [1.00; 2.04]), indicating a bidirectional relationship between inflammation and metabolic function. Notably, the influence of hs-CRP on future BMI was more robust than the other lagged relationship (p = .015), especially in PwS (Est. = 2.43, 95 % CI [0.39; 0.97]). Our study highlights the important role of inflammation in metabolic function and offers insights into potential interventions targeting inflammation in PwS.

Altered gut microbiota and systemic immunity in Chinese patients with schizophrenia comorbid with metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS) is highly prevalent in individuals with schizophrenia (SZ), leading to negative consequences like premature mortality. Gut dysbiosis, which refers to an imbalance of the microbiota, and chronic inflammation are associated with both SZ and MetS. However, the relationship between gut dysbiosis, host immunological dysfunction, and SZ comorbid with MetS (SZ-MetS) remains unclear. This study aims to explore alterations in gut microbiota and their correlation with immune dysfunction in SZ-MetS, offering new insights into its pathogenesis.

METHODS AND RESULTS

We enrolled 114 Chinese patients with SZ-MetS and 111 age-matched healthy controls from Zhejiang, China, to investigate fecal microbiota using Illumina MiSeq sequencing targeting 16 S rRNA gene V3-V4 hypervariable regions. Host immune responses were assessed using the Bio-Plex Pro Human Cytokine 27-Plex Assay to examine cytokine profiles. In SZ-MetS, we observed decreased bacterial α-diversity and significant differences in β-diversity. LEfSe analysis identified enriched acetate-producing genera (Megamonas and Lactobacillus), and decreased butyrate-producing bacteria (Subdoligranulum, and Faecalibacterium) in SZ-MetS. These altered genera correlated with body mass index, the severity of symptoms (as measured by the Scale for Assessment of Positive Symptoms and Scale for Assessment of Negative Symptoms), and triglyceride levels. Altered bacterial metabolic pathways related to lipopolysaccharide biosynthesis, lipid metabolism, and various amino acid metabolism were also found. Additionally, SZ-MetS exhibited immunological dysfunction with increased pro-inflammatory cytokines, which correlated with the differential genera.

CONCLUSION

These findings suggested that gut microbiota dysbiosis and immune dysfunction play a vital role in SZ-MetS development, highlighting potential therapeutic approaches targeting the gut microbiota. While these therapies show promise, further mechanistic studies are needed to fully understand their efficacy and safety before clinical implementation.

Multi-omics analysis reveals the impact of gut microbiota on antipsychotic-induced weight gain in schizophrenia

Emerging evidence indicates that gut microbial dysbiosis is associated with the development of antipsychotic-induced weight gain in schizophrenia (SZ). However, the exact taxonomic composition and functionality that constitute the "obesogenic" microbial profile remain elusive. Our retrospective survey identified two groups of the SZ population separated by BMI, with 1/3 of patients developing overweight/obesity after chronic antipsychotic treatment. Based on multi-omics analysis, we observed altered gut microbiota in SZ patients with overweight/obesity, characterized by a reduction in several beneficial bacteria genera, including Bacteroides, Parabacteroides, Akkermansia, and Clostridium. This microbial dysbiosis was accompanied by disrupted energy expenditure and nutritional metabolism, worsened metabolic indices, and reduced levels of beneficial metabolites, e.g. indole-3-carboxylic acid and propionic acid. Moreover, leveraging data from first-episode drug-naïve schizophrenia (FSZ) patients at one-month and one-year follow-up, both artificial neural network and random forest classifier-based prediction models demonstrated a strong ability of microbial profiles to predict antipsychotic-induced weight gain. Importantly, FSZ patients with higher relative abundance of Parabacteria distasonis were less susceptible to antipsychotic-induced weight gain. Thus, gut microbiota could serve as a noninvasive approach to predict antipsychotic-induced weight gain, guiding clinical antipsychotics administration and developing novel therapeutic strategies for weight management in SZ.

Role of body mass index and weight change in the risk of cancer: A systematic review and meta-analysis of 66 cohort studies

Background

This study was designed to evaluate the effects of body mass index (BMI) and weight change on the risk of developing cancer overall and cancer at different sites.

Methods

We searched PubMed and other databases up to July 2023 using the keywords related to 'risk', 'cancer', 'weight', 'overweight', and 'obesity'. We identified eligible studies, and the inclusion criteria encompassed cohort studies in English that focused on cancer diagnosis and included BMI or weight change as an exposure factor. Multiple authors performed data extraction and quality assessment, and statistical analyses were carried out using RevMan and R software. We used random- or fixed-effects models to calculate the pooled relative risk (RR) or hazard ratio along with 95% confidence intervals (CIs). We used the Newcastle-Ottawa Scale to assess study quality.

Results

Analysis included 66 cohort studies. Compared to underweight or normal weight, overweight or obesity was associated with an increased risk of endometrial cancer, kidney cancer, and liver cancer but a decreased risk of prostate cancer and lung cancer. Being underweight was associated with an increased risk of gastric cancer and lung cancer but not that of postmenopausal breast cancer or female reproductive cancer. In addition, weight loss of more than five kg was protective against overall cancer risk.

Conclusions

Overweight and obesity increase the risk of most cancers, and weight loss of >5 kg reduces overall cancer risk. These findings provide insights for cancer prevention and help to elucidate the mechanisms underlying cancer development.

Registration

Reviewregistry1786.

Association between increased BMI and cognitive function in first-episode drug-naïve male schizophrenia

Objective

Although the adverse effects of obesity in schizophrenia are documented, there is limited research exists on the implications for untreated initial schizophrenia. Our investigation aimed to explore the connections between BMI and cognitive function in first-episode drug-naïve (FEDN)schizophrenia.

Methods

We enrolled 143 FEDN schizophrenia patients, and collected data on their body mass index, fasting blood glucose and lipid levels. Cognitive function was measured with the MATRICS Consensus Cognitive Battery (MCCB). Using correlation and regression analysis to assess the relationship between BMI and cognitive performance.

Results

The prevalence rate of overweight plus obesity in FEDN schizophrenia patients was 33.57%. Patients with FEDN schizophrenia exhibited extensive cognitive impairment, and those who were overweight/obesity demonstrated more severe impairments in working memory and visual learning when compared to normal/under weight counterparts. Correlation analysis indicated a negative association between working memory and BMI and TG, as well as a link between visual learning and BMI and LDL-C. Multiple linear regression analysis revealed that a higher BMI predicted a decrease in working memory in FEDN schizophrenia patients.

Conclusion

Our results indicate that the rate of overweight plus obesity is high in FEDN schizophrenia patients, and there is an association between BMI and cognitive function in schizophrenia, particularly in relation to working memory.

Integrated Analysis of Gut Microbiome, Inflammation, and Neuroimaging Features Supports the Role of Microbiome-Gut-Brain Crosstalk in Schizophrenia

Background and Hypothesis

Gut microbiota has been implicated in the pathogenesis of schizophrenia (SZ) and relevant changes in the brain, but the underlying mechanism remains elusive. This study aims to investigate the microbiota-gut-brain crosstalk centered on peripheral inflammation in SZ patients.

Study Design

We recruited a cohort of 182 SZ patients and 120 healthy controls (HC). Multi-omics data, including fecal 16S rRNA, cytokine data, and neuroimaging data, were collected and synthesized for analysis. Multi-omics correlations and mediation analyses were utilized to determine the associations of gut microbiome with inflammatory cytokines and neuroimaging characteristics. Additionally, machine learning models for effective SZ diagnosis were separately generated based on gut microbial and neuroimaging data.

Study Results

Gut microbial dysbiosis, characterized by a decrease in butyrate-producing bacteria and an increase in proinflammatory bacteria, has been identified in SZ patients. These key microbial taxa were associated with increased inflammatory cytokines, potentially through mediating lipid metabolic pathways such as steroid biosynthesis and linoleic acid metabolism. Further analysis revealed altered microbial genera to be correlated with disrupted gray matter volume and regional homogeneity in SZ patients. Importantly, certain inflammatory cytokines mediated the relationship between the SZ-enriched genus Succinivibrio and aberrant activity of anterior cingulate cortex and left inferior temporal gyrus in the SZ group. Moreover, the classification model based on gut microbial data showed comparable efficacy to the model based on brain functional signatures in SZ diagnosis.

Conclusions

This study presents evidence for the dysregulated microbiota-gut-brain axis in SZ and emphasizes the central role of peripheral inflammation.

Metabolic Syndrome Causing Cognitive Impairment in Patients With Schizophrenia: A Systematic Review

Schizophrenia often exhibits characteristics like cognitive deficits, and individuals with the condition are at a higher risk of developing metabolic syndrome. The effect of metabolic syndrome on schizophrenia-related cognitive impairment is still unknown, though. This systematic review aims to investigate the association between metabolic syndrome and cognitive impairment in patients with schizophrenia, specifically focusing on neurocognitive and social cognitive performance. Schizophrenia significantly strains the public healthcare system since it necessitates tremendous resources and care to support those suffering from the condition. Furthermore, patients with schizophrenia are more susceptible to developing obesity than the general population, leading to a higher possibility of developing metabolic syndrome. The gut microbiota has been recognized as a critical regulator of bidirectional interactions between the central nervous system and the gastrointestinal tract. Emerging evidence suggests that dysbiosis of the gut microbiota is closely linked to the development of both schizophrenia and obesity, sharing common pathophysiological mechanisms, particularly immune inflammation. In this systematic review, we examine the existing literature to explore the relationship between metabolic syndrome and cognitive impairment in individuals with schizophrenia. By synthesizing available evidence on neurocognitive and social cognitive performance, we aim to provide a comprehensive understanding of the association between metabolic syndrome and cognitive deficits in schizophrenia. The findings from this review will contribute to our knowledge of the complex interplay between metabolic abnormalities, gut microbiota dysbiosis, and cognitive impairments in patients with schizophrenia. This understanding may facilitate the development of novel interventions targeting metabolic syndrome as a potential avenue for improving cognitive outcomes in individuals with schizophrenia.