Immune and metabolic alterations in first episode psychosis (FEP) patients

Interaction of serotonin/GLP-1 circuitry in a dual preclinical model for psychiatric disorders and metabolic dysfunction

Isolation of rodents throughout adolescence is known to induce many behavioral abnormalities which resemble neuropsychiatric disorders. Separately, this paradigm has also been shown to induce long-term metabolic changes consistent with a pre-diabetic state. Here, we investigate changes in central serotonin (5-HT) and glucagon-like peptide 1 (GLP-1) neurobiology that dually accompany behavioral and metabolic outcomes following social isolation stress throughout adolescence. We find that adolescent-isolation mice exhibit elevated blood glucose levels, impaired peripheral insulin signaling, altered pancreatic function, and fattier body composition without changes in bodyweight. These mice further exhibited disruptions in sleep and enhanced nociception. Using bulk and spatial transcriptomic techniques, we observe broad changes in neural 5-HT, GLP-1, and appetitive circuits. We find 5-HT neurons of adolescent-isolation mice to be more excitable, transcribe fewer copies of Glp1r (mRNA; GLP-1 receptor), and demonstrate resistance to the inhibitory effects of the GLP-1R agonist semaglutide on action potential thresholds. Surprisingly, we find that administration of semaglutide, commonly prescribed to treat metabolic syndrome, induced deficits in social interaction in group-housed mice and rescued social deficits in isolated mice. Overall, we find that central 5-HT circuitry may simultaneously influence mental well-being and metabolic health in this model, via interactions with GLP-1 and proopiomelanocortin circuitry.

Greater methylation of the IL-6 promoter region is associated with decreased integrity of the corpus callosum in schizophrenia

BACKGROUND

Schizophrenia is associated with chronic subclinical inflammation and decreased integrity of the corpus callosum (CC). Our previous study showed associations between peripheral IL-6 levels and the integrity of the CC. Epigenetic studies show associations between methylation of the genes related to immunological processes and integrity of the CC.

AIM

To investigate correlations between methylation status of IL-6 promotor and peripheral IL-6 levels and the integrity of the CC in schizophrenia.

MATERIAL AND METHODS

The participants were 29 chronic schizophrenia patients (SCH) and 29 controls. Decreased integrity of the CC was understood as increased mean diffusivity (MD) and/or decreased fractional anisotropy (FA) in diffusion tensor imaging. Peripheral IL-6 concentrations were measured in serum samples and IL-6 promoter methylation status of 6 CpG sites was analyzed in peripheral leukocytes by pyrosequencing.

RESULTS

Moderate positive correlations were found between CpG1 methylation and the MD of proximal regions of the CC (CCR1-CCR3) and between CpGmean and MD of CCR1 in SCH. Weaker positive correlations were found for CpGmean with CCR2 and CCR3 and negative correlations were found for CpG1 and FA of CCR3 in SCH. Multivariate regression showed that methylation of CpG1, type of antipsychotic treatment, and their interaction were significant independent predictors of MD of CCR1 in SCH. Methylation of CpG2 was negatively correlated with serum IL-6 in SCH.

CONCLUSIONS

The methylation level of the IL-6 promotor region in peripheral leukocytes is associated with the integrity of the CC in schizophrenia and this association may depend on the type of antipsychotic treatment. Further studies are necessary to explain the mechanisms of the observed associations.

Stress-induced red nucleus attenuation induces anxiety-like behavior and lymph node CCL5 secretion

Previous studies have speculated that brain activity directly controls immune responses in lymphoid organs. However, the upstream brain regions that control lymphoid organs and how they interface with lymphoid organs to produce stress-induced anxiety-like behavior remain elusive. Using stressed human participants and rat models, we show that CCL5 levels are increased in stressed individuals compared to controls. Stress-inducible CCL5 is mainly produced from cervical lymph nodes (CLN). Retrograde tracing from CLN identifies glutamatergic neurons in the red nucleus (RN), the activities of which are tightly correlated with CCL5 levels and anxiety-like behavior in male rats. Ablation or chemogenetic inhibition of RN glutamatergic neurons increases anxiety levels and CCL5 expression in the serum and CLNs, whereas pharmacogenetic activation of these neurons reduces anxiety levels and CCL5 synthesis after restraint stress exposure. Chemogenetic inhibition of the projection from primary motor cortex to RN elicits anxiety-like behavior and CCL5 synthesis. This brain-lymph node axis provides insights into lymph node tissue as a stress-responsive endocrine organ.

Vascular-related biomarkers in psychosis: a systematic review and meta-analysis

Background

While the molecular underpinnings of vascular dysfunction in psychosis are under active investigation, their implications remain unclear due to inconsistent and sometimes sparse observations. We conducted a comprehensive meta-analysis to critically assess the alterations of vascular-related molecules in the cerebrospinal fluid (CSF) and blood of patients with psychotic disorders compared with healthy individuals.

Methods

Databases were searched from inception to February 23, 2023. Meta-analyses were performed using a random-effects model. Meta-regression and subgroup analyses were conducted to assess the effects of clinical correlates.

Results

We identified 93 eligible studies with 30 biomarkers investigated in the CSF and/or blood. Among the biomarkers examined, psychotic disorders were associated with elevated CSF-to-serum albumin ratio (standardized mean difference [SMD], 0.69; 95% confidence interval [CI], 0.35-1.02); blood S100B (SMD, 0.88; 95% CI, 0.59-1.17), matrix metalloproteinase-9 (MMP-9; SMD, 0.66; 95% CI, 0.46-0.86), and zonulin (SMD, 1.17; 95% CI, 0.04-2.30). The blood levels of S100B, MMP-9, nerve growth factor (NGF), vascular endothelial growth factor (VEGF), intercellular adhesion molecule 1 (ICAM-1), and vascular adhesion molecule 1 (VCAM-1) were altered in patient subgroups differing in demographic and clinical characteristics. Blood S100B level was positively correlated with age and duration of illness. Substantial between-study heterogeneity was observed in most molecules.

Conclusion

The alterations in certain vascular-related fluid markers in psychotic disorders suggest disturbances in normal vascular structures and functions. However, not all molecules examined displayed clear evidence of changes. While potential impacts of clinical factors, including the administered treatment, were identified, the exploration remained limited. Further studies are needed to investigate the diverse patterns of expression, and understand how these abnormalities reflect the pathophysiology of psychosis and the impact of clinical factors.

High blood levels of brain-derived neurotrophic factor (BDNF) mRNA in early psychosis are associated with inflammatory markers

The brain-derived neurotrophic factor (BDNF) single nucleotide polymorphism (SNP) rs6265C > T, Val66Met, affects BDNF secretion and has been related to inflammatory processes. Both the rs6265 and BDNF protein levels have been widely investigated in neuropsychiatric disorders with conflicting results. In the present study we examined BDNF mRNA expression in blood considering the SNP rs6265 and its relationship with inflammatory markers in the early stages of psychosis. The rs6265 genotype and blood BDNF mRNA levels were measured in 34 at-risk mental states (ARMS) individuals, 37 patients with first-episode psychosis (FEP) and 42 healthy controls (HCs) by quantitative PCR and reverse transcription (RT)-qPCR using validated TaqMan assays. We also obtained measures of interleukin-6 (IL6) mRNA levels, fibrinogen, neutrophil-to-lymphocyte ratio (NLR) and high-sensitivity C-reactive protein. We identified that BDNF mRNA levels were associated with the rs6265 genotype in an allele-dose-dependent manner, with low expression levels associated with the T allele (Met substitution). Thus, we controlled for the rs6265 genotype in all analyses. Blood BDNF mRNA levels differed between diagnostic groups: patients with FEP exhibited higher blood BDNF mRNA levels than ARMS individuals, and the lowest levels were observed in HC. In addition, we observed significant correlations between BDNF mRNA levels and inflammatory markers (IL6 mRNA levels and NLR), controlled by the rs6265 genotype, in ARMS and FEP groups. This exploratory study suggests that the rs6265 genotype is associated with differential blood mRNA expression of BDNF that increases with illness progression and correlated with inflammation in the early stages of psychosis.

Effect of Glucagon-like Peptide-1 Receptor Agonists on Cardio-Metabolic Risk Factors among Obese/Overweight Individuals Treated with Antipsychotic Drug Classes: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials

Introduction: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) constitute a drug class primarily developed for the treatment of subjects with type 2 diabetes, although they have also provided significant benefit for subjects with obesity without underlying diabetes. Individuals with psychotic disorders who are receiving antipsychotic treatment are a patient population at risk of developing obesity, which is linked to other metabolic disturbances. Methods: We searched PubMed and the Cochrane Library from inception to 1 December 2022, for randomized controlled trials (RCTs) enrolling obese or overweight adult subjects with an underlying psychotic disorder treated with antipsychotic drugs, randomized either to GLP-1RAs or a control. We set as the primary efficacy outcome the change in body weight and as secondary efficacy outcomes the change in body mass index (BMI) and in waist circumference, along with indices of glycemia, lipid profile, and blood pressure. Results: We pooled data from 4 trials (2 with liraglutide and 2 with exenatide) in a total of 199 enrolled subjects. GLP-1RA treatment, compared to control, resulted in a significant decrease in body weight by 3.8 kg [mean difference (MD) = −3.80, 95% CI; −6.35 to −1.24, I2 = 64%]. In addition, GLP-1RA treatment led to a significant decrease in BMI, compared to control, of 1.04 kg/m2 (MD = −1.04, 95% CI; −1.92 to −0.17, I2 = 35%). However, no significant effect on waist circumference was shown (MD = −3.2, 95% CI; −6.47 to 0.08, I2 = 88%). A significant improvement in glycemia and lipid profiles was also demonstrated with GLP-1RAs. No subgroup difference between liraglutide and exenatide was shown, and the use of GLP-1RAs did not increase the risk for treatment discontinuation compared to the control group. Conclusion: Treatment with GLP-1RAs can significantly improve weight loss and other cardiometabolic risk factors in obese people taking antipsychotic medications.

Depression recognition using a proposed speech chain model fusing speech production and perception features

BACKGROUND

Increasing depression patients puts great pressure on clinical diagnosis. Audio-based diagnosis is a helpful auxiliary tool for early mass screening. However, current methods consider only speech perception features, ignoring patients' vocal tract changes, which may partly result in the poor recognition.

METHODS

This work proposes a novel machine speech chain model for depression recognition (MSCDR) that can capture text-independent depressive speech representation from the speaker's mouth to the listener's ear to improve recognition performance. In the proposed MSCDR, linear predictive coding (LPC) and Mel-frequency cepstral coefficients (MFCC) features are extracted to describe the processes of speech generation and of speech perception, respectively. Then, a one-dimensional convolutional neural network and a long short-term memory network sequentially capture intra- and inter-segment dynamic depressive features for classification.

RESULTS

We tested the MSCDR on two public datasets with different languages and paradigms, namely, the Distress Analysis Interview Corpus-Wizard of Oz and the Multi-modal Open Dataset for Mental-disorder Analysis. The accuracy of the MSCDR on the two datasets was 0.77 and 0.86, and the average F1 score was 0.75 and 0.86, which were better than the other existing methods. This improvement reveals the complementarity of speech production and perception features in carrying depressive information.

LIMITATIONS

The sample size was relatively small, which may limit the application in clinical translation to some extent.

CONCLUSION

This experiment proves the good generalization ability and superiority of the proposed MSCDR and suggests that the vocal tract changes in patients with depression deserve attention for audio-based depression diagnosis.

Serum Inflammatory Markers and Integrity of the Superior Longitudinal Fasciculus and the Inferior Longitudinal Fasciculus in Schizophrenia, from Prodromal Stages to Chronic Psychosis-A Cross-Sectional Study

Chronic subclinical inflammation is believed to be an important factor in the pathogenesis of schizophrenia. Meta-analyses confirm the presence of increased levels of peripheral inflammatory markers (IM) in schizophrenia and its prodromal stages. Peripheral cytokines may affect the brain microstructure through chronic activation of microglia. Disruptions in the integrity of the superior longitudinal fasciculus (SLF) and inferior longitudinal fasciculus (ILF) are commonly seen in patients with schizophrenia spectrum disorders. We therefore attempted to verify in a cross-sectional study whether there is a correlation between levels of peripheral IM and the integrity of these brain regions in healthy controls, from prodromal states and first episode psychosis to long-term schizophrenia. The integrity of white matter was measured using diffusion tensor imaging. Despite a broad analysis of six IM (CRP, IL-6, IL-8, IL-10, TNF-α, and IFN-γ), we did not find any correlations with the integrity of the SLF or ILF in any of the analyzed groups (after correction for multiple comparisons). In conclusion, our study does not support the existence of a link between disrupted levels of peripheral IM and reduced integrity of ILF and SLF in schizophrenia spectrum disorders. However, prospective studies are needed to verify this over a long period of time.

Crosstalk between Schizophrenia and Metabolic Syndrome: The Role of Oxytocinergic Dysfunction

The high prevalence of metabolic syndrome in persons with schizophrenia has spurred investigational efforts to study the mechanism beneath its pathophysiology. Early psychosis dysfunction is present across multiple organ systems. On this account, schizophrenia may be a multisystem disorder in which one organ system is predominantly affected and where other organ systems are also concurrently involved. Growing evidence of the overlapping neurobiological profiles of metabolic risk factors and psychiatric symptoms, such as an association with cognitive dysfunction, altered autonomic nervous system regulation, desynchrony in the resting-state default mode network, and shared genetic liability, suggest that metabolic syndrome and schizophrenia are connected via common pathways that are central to schizophrenia pathogenesis, which may be underpinned by oxytocin system dysfunction. Oxytocin, a hormone that involves in the mechanisms of food intake and metabolic homeostasis, may partly explain this piece of the puzzle in the mechanism underlying this association. Given its prosocial and anorexigenic properties, oxytocin has been administered intranasally to investigate its therapeutic potential in schizophrenia and obesity. Although the pathophysiology and mechanisms of oxytocinergic dysfunction in metabolic syndrome and schizophrenia are both complex and it is still too early to draw a conclusion upon, oxytocinergic dysfunction may yield a new mechanistic insight into schizophrenia pathogenesis and treatment.

Serum inflammatory markers and their associations with white matter integrity of the corpus callosum in schizophrenia patients and healthy controls

Schizophrenia is associated with disrupted integrity of white matter microstructure of a variety of brain regions, especially the corpus callosum (CC). Chronic subclinical inflammation is considered to be one of the factors involved in the pathogenesis of this disease, and increased levels of peripheral inflammatory markers are often observed in schizophrenia patients. Therefore, we decided to investigate whether the integrity of the corpus callosum is correlated with levels of these markers. A total of 50 patients with stable chronic schizophrenia (SCH) and 30 controls (CON) were enrolled in the study. All participants underwent psychiatric evaluation, neuroimaging, and blood sampling including the measurement of serum concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL - 10), tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), and C-reactive protein (CRP). Additional potentially related factors, such as age, gender, BMI, smoking, disease duration, and treatment were included in the analysis. Significantly higher IL-6 and IFN-γ levels were observed in SCH compared to CON. In SCH, IFN-γ was positively correlated with mean diffusivity of region 2 of the CC. In CON, IL-6 was inversely correlated with fractional anisotropy of region 1 of the CC. These results support the potential influence of peripheral inflammatory markers on the integrity of the CC in schizophrenia, but require verification in longitudinal studies.

Adiponectin, leptin and resistin levels in first-episode, drug-naïve patients with psychosis before and after short-term antipsychotic treatment

OBJECTIVE

There is increasing evidence that adiponectin, resistin and leptin may be implicated in the pathophysiology of neuropsychiatric disorders, including schizophrenia. The results of the studies so far remain controversial. Our aim was to compare serum adiponectin, leptin and resistin levels between drug-naïve, first -episode patients with psychosis and healthy controls and in the same group of patients after six weeks of antipsychotic treatment.

METHODS

Forty first-episode patients with psychosis and 40 matched controls were included in the study. Serum levels of adiponectin, resistin and leptin were measured by enzyme linked immunosorbent assay (ELISA) in both groups. In the patient group, the same adipokines were also measured six weeks after the initiation of antipsychotic treatment.

RESULTS

Log-transformed serum levels of adiponectin (mean difference = 1.68, 95% confidence interval [CI] = 1.30 to 2.06, U = 157, p < 0.0001), resistin (0.48, 95% CI = 0.36 to 0.59, t = 8.00, p < 0.0001) and leptin (0.66, 95% CI = 0.52 to 0.80, U = 160, p < 0.0001) were significantly higher to the patient group compared to controls. Leptin levels were significantly decreased in the patient group six weeks after the initiation of antipsychotic treatment (mean change = -0.40, 95% CI = -0.59 to -0.21, W = 666; p < 0.0001) while those of adiponectin and resistin levels did not change significantly.

CONCLUSION

In our study we found higher levels of adiponectin, leptin and resistin in drug-naïve, first-episode patients with normal Body Mass Index (BMI) compared to controls. After six weeks of antipsychotic treatment, there was no change in adiponectin and resistin levels, while leptin levels were reduced compared to baseline.

Social isolation triggers oxidative status and impairs systemic and hepatic insulin sensitivity in normoglycemic rats

Drug-naïve psychotic patients show metabolic and hepatic dysfunctions. The rat social isolation model of psychosis allows to investigate mechanisms leading to these disturbances to which oxidative stress crucially contributes. Here, we investigated isolation-induced central and peripheral dysfunctions in glucose homeostasis and insulin sensitivity, along with redox dysregulation. Social isolation did not affect basal glycemic levels and the response to glucose and insulin loads in the glucose and insulin tolerance tests. However, HOMA-Index value were increased in isolated (ISO) rats. A hypothalamic reduction of AKT phosphorylation and a trend toward an increase in AMPK phosphorylation were observed following social isolation, accompanied by reduced GLUT-4 levels. Social isolation also induced a reduction of phosphorylation of the insulin receptor, of AKT and GLUT-2, and a decreased phosphorylation of AMPK in the liver. Furthermore, a significant reduction in hepatic CPT1 and PPAR-α levels was detected. ISO rats also showed significant elevations in hepatic ROS amount, lipid peroxidation and NOX4 expression, whereas no differences were detected in NOX2 and NOX1 levels. Expression of SOD2 in the mitochondrial fraction and SOD1 in the cytosolic fraction was not altered following social isolation, whereas SOD activity was increased. Furthermore, a decrease of hepatic CAT and GSH amount was observed in ISO rats compared to GRP animals. Our data suggest that the increased oxidant status and antioxidant capacity modifications may trigger hepatic and systemic insulin resistance, by altering signal hormone pathway and sustaining subsequent alteration of glucose homeostasis and metabolic impairment observed in the social isolation model of psychosis.

The role of BDNF and NGF plasma levels in first-episode schizophrenia: A longitudinal study

Neurotrophins have been proposed to be involved in biological mechanisms which might underlie different clinical outcomes in schizophrenia. The aims of the present study were to examine the BDNF/NGF plasma levels in a cohort of first-episode schizophrenia (FES) patients in remission as potential biological predictors of relapse; to study the associations between these neurotrophins and the symptomatology severity through different stages after a FES in two independent cohorts. 2EPs-Cohort: 69 first-episode in clinical remission were included. BDNF/NGF plasma levels and symptom severity were measured at enrollment and at 3-year or at the time of the second episode/relapse. FLAMM-PEPs-Cohort: 65 first-episodes were also included. BDNF/NGF and symptom severity were obtained at enrollment and 2-year follow-up. Symptomatology was assessed with the Marder-PANSS-Factor scores. Plasma neurotrophins did not differ significantly over time and neither BDNF/NGF were predictors of relapse. Besides, in remission stages, baseline BDNF levels showed significant correlations with both positive and negative symptoms (p<0.05); NGF, with negative symptomatology (p<0.01). Similarly, in the FLAMM-PEPs-Cohort, baseline BDNF/NGF levels showed significant correlations with negative symptoms (and not positive symptomatology) at follow-up (p<0.05). In both cohorts, lower levels correlated with higher symptom severity. Findings did not support a role for BDNF/NGF plasma levels as biomarkers of relapse in FES patients. Nevertheless, baseline BDNF/NGF may lead to be considered potentially useful biomarkers of long-term severity in schizophrenia and of the underlying illness traits, specially of negative symptomatology severity. More longitudinal studies in FES samples and adding a control group are warranted to replicate these findings.

Peripheral Blood Levels of Brain-Derived Neurotrophic Factor in Patients with First Episode Psychosis: A Systematic Review and Meta-Analysis

Background: Peripheral blood level of brain-derived neurotrophic factor (BDNF) may be used as a diagnostic and/or prognostic marker for schizophrenia. Previous studies were inconsistent. A systematic review was conducted to examine whether BDNF level is different in patients with first episode psychosis (FEP) compared to health controls (HC) and whether it changes after treatment. Methods: Literature search was done in PubMed, Web of Science, and Google Scholar following standard procedures. Hedges’ g was used as the measure of effect size (ES), which was pooled with random effects model. Publication bias and moderator effects were examined. Results: Search yielded 29 studies with a total sample size of 2912. First meta-analysis included 27 studies with FEP vs. HC comparison. Pooled ES was −0.63, p < 0.001, indicating that BDNF level was lower in FEP than in HC. Studies were heterogeneous, and moderator analysis showed that studies of younger patient, higher symptom severity, and more drug naïve had larger ES. Second meta-analysis examined change in BDNF levels before and after antipsychotic treatment in eight studies. A pooled ES of −0.003 (p = 0.96) showed no change in peripheral BDNF level after treatment. Conclusion: Peripheral BDNF level was decreased in FEP compared to HC, but it did not change after treatment.

Glucagon-like peptide-1 serum levels are associated with weight gain in patients treated with clozapine

Metabolic syndrome and related cardiovascular risk factors are well-known comorbidities among patients with schizophrenia. Biomarkers of these antipsychotic-associated metabolic adverse effects and antipsychotic-induced weight gain are needed. Glucagon-like peptide-1 (GLP-1) is involved in insulin secretion, regulation of satiety, inhibition of food intake, and inhibition of gastric emptying. GLP-1 also induces reduction in body weight. Visfatin/ NAMPT/ PBEF is an adipocytokine secreted by several cells and tissues. Increased plasma visfatin levels have been associated with overweight/obesity, type 2 diabetes mellitus, insulin resistance, metabolic syndrome and cardiovascular diseases, low grade inflammation, and proinflammatory markers. Associations between antipsychotic-induced weight gain and serum visfatin and GLP-1 levels have been little studied in patients with schizophrenia. The aim of the present study was to test the possible role of serum GLP-1 and visfatin level alterations as markers of weight gain in association with metabolic and inflammatory markers in 190 patients (109 male, 81 female) with schizophrenia on clozapine treatment. High serum levels of GLP-1 correlated significantly with higher levels of visfatin, leptin, insulin, HOMA-IR, higher BMI, and weight change among men. Associations between serum visfatin levels and BMI or weight change were not found in the present patients. Serum GLP-1 level seems to be a marker of metabolic risk factors among men with schizophrenia on clozapine treatment. Female patients may be more sensitive to suppressive effects of clozapine on GLP-1 secretion. Patients on clozapine would benefit from GLP-1 agonists as preventive treatment.

A longitudinal study of gene expression in first-episode schizophrenia; exploring relapse mechanisms by co-expression analysis in peripheral blood

Little is known about the pathophysiological mechanisms of relapse in first-episode schizophrenia, which limits the study of potential biomarkers. To explore relapse mechanisms and identify potential biomarkers for relapse prediction, we analyzed gene expression in peripheral blood in a cohort of first-episode schizophrenia patients with less than 5 years of evolution who had been evaluated over a 3-year follow-up period. A total of 91 participants of the 2EPs project formed the sample for baseline gene expression analysis. Of these, 67 provided biological samples at follow-up (36 after 3 years and 31 at relapse). Gene expression was assessed using the Clariom S Human Array. Weighted gene co-expression network analysis was applied to identify modules of co-expressed genes and to analyze their preservation after 3 years of follow-up or at relapse. Among the 25 modules identified, one module was semi-conserved at relapse (DarkTurquoise) and was enriched with risk genes for schizophrenia, showing a dysregulation of the TCF4 gene network in the module. Two modules were semi-conserved both at relapse and after 3 years of follow-up (DarkRed and DarkGrey) and were found to be biologically associated with protein modification and protein location processes. Higher expression of DarkRed genes was associated with higher risk of suffering a relapse and early appearance of relapse (p = 0.045). Our findings suggest that a dysregulation of the TCF4 network could be an important step in the biological process that leads to relapse and suggest that genes related to the ubiquitin proteosome system could be potential biomarkers of relapse.

Treating cognitive impairment in schizophrenia with GLP-1RAs: an overview of their therapeutic potential

INTRODUCTION

Schizophrenia is a neuropsychiatric disorder that affects approximately 1% of individuals worldwide. There are no available medications to treat cognitive impairment in this patient population currently. Preclinical evidence suggests that glucagon-like peptide-1 receptor agonists (GLP-1 RAs) improve cognitive function. There is a need to evaluate how GLP-1 RAs alter specific domains of cognition and whether they will be of therapeutic benefit in individuals with schizophrenia.

AREAS COVERED

This paper summarizes the effects of GLP-1 RAs on metabolic processes in the brain and how these mechanisms relate to improved cognitive function. We provide an overview of preclinical studies that demonstrate GLP-1 RAs improve cognition and comment on their potential therapeutic benefit in individuals with schizophrenia.

EXPERT OPINION

To understand the benefits of GLP-1 RAs in individuals with schizophrenia, further preclinical research with rodent models relevant to schizophrenia symptomology are needed. Moreover, preclinical studies must focus on using a wider range of behavioral assays to understand whether important aspects of cognition such as executive function, attention, and goal-directed behavior are improved using GLP-1 RAs. Further research into the specific mechanisms of how GLP-1 RAs affect cognitive function and their interactions with antipsychotic medication commonly prescribed is necessary.

Adipose tissue dysregulation at the onset of psychosis: Adipokines and social determinants of health

Recent evidence suggests that patients with psychotic disorders have metabolic disturbances (e.g., insulin resistance, dyslipidemia) at the onset of the disease and before antipsychotic exposure. Such disturbances are strongly associated with adipose tissue dysregulation. Measuring adipokines, the molecular mediators of adipose function, could provide a picture of the state of metabolic regulation at the onset of psychosis. The present study explores adipokine changes in a population of first-episode psychosis (FEP) patients with minimal prior exposure to antipsychotics. The effects of social determinants of health (childhood trauma and minority status) associated with both metabolic and psychotic disorders were studied as potential determinants of this phenomenon. Data was collected through the Signature project, a biobank of clinical, socio-demographic, and biological markers. Adipokines (leptin, adiponectin, resistin and chemerin) were measured in serum of FEP patients with minimal exposure to antipsychotics (N = 48) and controls (N = 39). Data were analyzed with univariate (t-tests) and multivariate (linear regression) statistical methods. Patients, compared to controls, had significantly higher levels of adiponectin and resistin, and significantly lower levels of leptin and chemerin. These results persisted after controlling for sex, waist-to-height ratio, childhood trauma, and visible minority status. Adiponectin and chemerin retained their effects after further controlling for tobacco and depression. Resistin increased with childhood trauma scores; chemerin was higher in visible minority patients. Adipose tissue dysfunction is present in FEP patients, before exposure to antipsychotics. Social determinants of health contribute to adipose (and metabolic) dysregulation in FEP, but may not be the main determinants of this relationship.

Vascular endothelial growth factor in major depressive disorder, schizophrenia, and bipolar disorder: A network meta-analysis

The peripheral levels of vascular endothelial growth factor (VEGF) have been studied in major psychiatric diseases compared with healthy controls (HCs), but the results were inconsistent. Moreover, few studies have compared VEGF levels between these psychiatric diseases. The aim of the present study was to compare blood VEGF levels in major depressive disorder (MDD), schizophrenia (SCZ), bipolar disorder either in a manic episode, a depressive episode, or a euthymic state, and HC. We supposed that VEGF levels may be elevated in some of these diseases as a potential biomarker. In this study, forty-four studies with 6343 participants were included, and network meta-analysis was used to synthesize evidence from both direct and indirect comparisons. The main analysis showed that no significant differences were found between these groups. Subgroup analysis found that patients with MDD may have higher blood VEGF levels than patients with SCZ when the levels were measured through ELISA, and VEGF levels were increased in medication-treated MDD patients compared with HCs. Taken together, blood VEGF levels may be unaltered in these psychiatric disorders, while detection of VEGF in blood by ELISA may a feasible way to distinguish MDD and SCZ. Further replicated studies with larger samples are needed.

Impaired hormonal regulation of appetite in schizophrenia: A narrative review dissecting intrinsic mechanisms and the effects of antipsychotics

Cardiometabolic diseases are the main contributor of reduced life expectancy in patients with schizophrenia. It is now widely accepted that antipsychotic treatment plays an important role in the development of obesity and its consequences. However, some intrinsic mechanisms need to be taken into consideration. One of these mechanisms might be related to impaired hormonal regulation of appetite in this group of patients. In this narrative review, we aimed to dissect impairments of appetite-regulating hormones attributable to intrinsic mechanisms and those related to medication effects. Early hormonal alterations that might be associated with intrinsic mechanisms include low levels of leptin and glucagon-like peptide-1 (GLP-1) together with elevated insulin levels in first-episode psychosis (FEP) patients. However, evidence regarding low GLP-1 levels in FEP patients is based on one large study. In turn, multiple-episode schizophrenia patients show elevated levels of insulin, leptin and orexin A together with decreased levels of adiponectin. In addition, patients receiving olanzapine may present with low ghrelin levels. Post mortem studies have also demonstrated reduced number of neuropeptide Y neurons in the prefrontal cortex of patients with schizophrenia. Treatment with certain second-generation antipsychotics may also point to these alterations. Although our understanding of hormonal regulation of appetite in schizophrenia has largely been improved, several limitations and directions for future studies need to be addressed. This is of particular importance since several novel pharmacological interventions for obesity and diabetes have already been developed and translation of these developments to the treatment of cardiometabolic comorbidities in schizophrenia patients is needed.

Metabolic profile of methylazoxymethanol model of schizophrenia in rats and effects of three antipsychotics in long-acting formulation

Mortality in psychiatric patients with severe mental illnesses reaches a 2-3 times higher mortality rate compared to the general population, primarily due to somatic comorbidities. A high prevalence of cardiovascular morbidity can be attributed to the adverse metabolic effects of atypical antipsychotics (atypical APs), but also to metabolic dysregulation present in drug-naïve patients. The metabolic aspects of neurodevelopmental schizophrenia-like models are understudied. This study evaluated the metabolic phenotype of a methylazoxymethanol (MAM) schizophrenia-like model together with the metabolic effects of three APs [olanzapine (OLA), risperidone (RIS) and haloperidol (HAL)] administered via long-acting formulations for 8 weeks in female rats. Body weight, feed efficiency, serum lipid profile, gastrointestinal and adipose tissue-derived hormones (leptin, ghrelin, glucagon and glucagon-like peptide 1) were determined. The lipid profile was assessed in APs-naïve MAM and control cohorts of both sexes. Body weight was not altered by the MAM model, though cumulative food intake and feed efficiency was lowered in the MAM compared to CTR animals. The effect of the APs was also present; body weight gain was increased by OLA and RIS, while OLA induced lower weight gain in the MAM rats. Further, the MAM model showed lower abdominal adiposity, while OLA increased it. Serum lipid profile revealed MAM model-induced alterations in both sexes; total, HDL and LDL cholesterol levels were increased. The MAM model did not exert significant alterations in hormonal parameters except for elevation in leptin level. The results support intrinsic metabolic dysregulation in the MAM model in both sexes, but the MAM model did not manifest higher sensitivity to metabolic effects induced by antipsychotic treatment.

Correlations between immune and metabolic serum markers and schizophrenia/bipolar disorder polygenic risk score in first-episode psychosis

AIMS

There is a strong interest in identifying the biological mechanisms involved in the genetic risk for psychotic disorders. In this study, we evaluated the correlation between serum concentrations of specific molecular markers and the genetic component for schizophrenia and bipolar disorder.

METHODS

We analysed the association between the polygenic risk score (PRS) and the serum levels of different inflammatory/metabolic markers in a sample of 81 first-episode psychosis patients (FEP) with a diagnosis of schizophrenia or bipolar disorder and 33 controls.

RESULTS

A positive correlation of schizophrenia and bipolar disorder PRS with the inflammatory marker C-C Motif Chemokine Ligand 4 serum concentration (ρ = 0.42, P = 1.56 × 10^-04 and ρ = 0.40, P = 1.65 × 10^-03 , respectively) and a negative correlation with the serum ghrelin content (ρ = - 0.35, P = 4.27 × 10^-03 and ρ = - 0.45, P = 6.05 × 10^-04 , respectively) were observed.

CONCLUSION

These findings provide new insight into the biological underpinnings of the PRS component, thus supporting a role of the genetic liability on the inflammatory and metabolic alterations that characterize psychosis onset.

A Longitudinal Study of Serum Brain-Derived Neurotrophic Factor Levels in First-Episode Schizophrenia

BACKGROUND

Biomarkers identified for psychosis might allow for early diagnosis, more accurate prognosis, and tailored individualized interventions. Brain-derived neurotrophic factor (BDNF) is suggested to be a likely candidate biomarker for the diagnosis and treatment evaluation in psychosis. The aims of present study were to examine the levels of serum BDNF in both patients with first-episode psychosis (FEP) and in healthy controls for a year, and to investigate the association between BDNF with symptom severity and remission status.

METHODS

A sample of 31 healthy controls and 29 patients with FEP were included in this study. Diagnoses were ascertained on the Structured Clinical Interview for DSM-IV-TR. Symptom severity was assessed on the Positive and Negative Syndrome Scale. Serum levels of BDNF were measured using enzyme-linked immunosorbent assay method at recruitment and at 3-, 6-, and 12-month time points.

RESULTS

Serum BDNF levels in both groups did not differ significantly over time. Baseline BDNF levels in patients with FEP did not correlate with symptom severity and neither baseline BDNF level nor its relative change at 3-month predicted remission status at 6- and 12-month follow-up visits. Of note, we observe similar fluctuations in serum BDNF levels in both patients and healthy controls over the 12-month period.

CONCLUSIONS

Findings from our study did not support a role for serum BDNF as a biomarker for patients with FEP. Because of the polygenic nature of psychosis, we recommend a comprehensive multimarker profile consisting of markers from representative components of mediated neuronal nutrition, neuroimmunology, and neurologic functional deficit to allow for better predictive power.

Elevated serum chemokine CCL22 levels in first-episode psychosis: associations with symptoms, peripheral immune state and in vivo brain glial cell function

Several lines of research support immune system dysregulation in psychotic disorders. However, it remains unclear whether the immunological marker alterations are stable and how they associate with brain glial cell function. This longitudinal study aimed at investigating whether peripheral immune functions are altered in the early phases of psychotic disorders, whether the changes are associated with core symptoms, remission, brain glial cell function, and whether they persist in a one-year follow-up. Two independent cohorts comprising in total of 129 first-episode psychosis (FEP) patients and 130 controls were assessed at baseline and at the one-year follow-up. Serum cyto-/chemokines were measured using a 38-plex Luminex assay. The FEP patients showed a marked increase in chemokine CCL22 levels both at baseline (p < 0.0001; Cohen's d = 0.70) and at the 12-month follow-up (p = 0.0007) compared to controls. The group difference remained significant (p = 0.0019) after accounting for relevant covariates including BMI, smoking, and antipsychotic medication. Elevated serum CCL22 levels were significantly associated with hallucinations (ρ = 0.20) and disorganization (ρ = 0.23), and with worse verbal performance (ρ = -0.23). Brain glial cell activity was indexed with positron emission tomography and the translocator protein radiotracer [¹¹C]PBR28 in subgroups of 15 healthy controls and 14 FEP patients with serum CCL22/CCL17 measurements. The distribution volume (V_T) of [¹¹C]PBR28 was lower in patients compared to controls (p = 0.026; Cohen's d = 0.94) without regionally specific effects, and was inversely associated with serum CCL22 and CCL17 levels (p = 0.036). Our results do not support the over-active microglia hypothesis of psychosis, but indicate altered CCR4 immune signaling in early psychosis with behavioral correlates possibly mediated through cross-talk between chemokine networks and dysfunctional or a decreased number of glial cells.

Childhood trauma and glucose metabolism in patients with first-episode psychosis

Although the associations between first-episode psychosis (FEP) and metabolic abnormalities on one side, and childhood trauma (CT) and risk of developing psychosis on the other are both well established, evidence on the relationship between CT and metabolic dysregulation in terms of abnormal glucose metabolism is very limited. We tested whether, already at illness onset, FEP patients with a history of CT show dysregulation of a broad range of glucose metabolism markers. In particular, in 148 FEP patients we evaluated serum concentrations of c-peptide, insulin, plasminogen-activator-inhibitor-1 (PAI-1), resistin, visfatin, glucagon, glucagon-like peptide-1 (GLP-1), gastric-inhibitor-peptide (GIP), leptin, and ghrelin. We also assessed CT with the Childhood Experience of Care and Abuse Questionnaire, and stressful life events (SLEs) with a semi-structured interview. Psychopathology, cannabis and tobacco habits, Body Mass Index (BMI) were recorded. Serum concentrations of markers were analyzed from peripheral blood. Ninety-five patients (56 % males, mean age 29.5) reported CT. Multivariate models showed that CT is associated only with the concentrations of c-peptide and insulin after adjusting for age, sex, BMI and SLEs. FEP patients who had experienced CT showed higher c-peptide and insulin serum concentrations. Our study reports that CT might be associated with the metabolic abnormalities in the first stage of psychosis, suggesting that a thorough anamnestic evaluation at psychosis onset that would include the history of CT could be helpful for clinicians in order to implement early programmes of healthy lifestyle education and to guide choice of therapeutic interventions for trauma.

Appetite regulating hormones in first-episode psychosis: A systematic review and meta-analysis

We aimed to perform a systematic review and meta-analysis of appetite regulating hormones in patients with first-episode psychosis (FEP). Meta-analyses were conducted using random-effects models with Hedges' g as the effect size estimate. We identified 31 eligible studies, investigating the levels of 7 appetite regulating hormones (adiponectin, insulin, leptin, ghrelin, orexin, resistin and visfatin) in 1792 FEP patients and 1364 controls. The insulin levels in FEP patients were higher than in controls (g = 0.34, 95%CI: 0.19 - 0.49, p < 0.001), even considering only antipsychotic-naïve patients (g = 0.39, 95%CI: 0.12 - 0.66, p = 0.005). The severity of negative symptoms was positively associated with the effect size estimates (β = 0.08, 95%CI: 0.01 - 0.16, p = 0.030). Moreover, we found lower levels of leptin in antipsychotic-naïve FEP patients (g = -0.62, 95%CI: -1.11 - 0.12, p = 0.015). Impaired appetite regulation, in terms of elevated insulin levels and decreased leptin levels, occurs in early psychosis, before antipsychotic treatment. Hyperinsulinemia might be related to negative symptoms.

Increased levels of serum leptin in the early stages of psychosis

BACKGROUND

Studies evaluating leptin levels in patients with first-episode psychoses (FEP) have been inconclusive, and apparently, the high levels of leptin reported in patients with schizophrenia may be associated with weight gain. The aim of this study was to evaluate leptin levels at the early stages of the disease and the relationship between leptin and lifestyle habits, stress-related variables and metabolic parameters.

METHODS

In total, 14 at-risk mental state (ARMS) patients, 39 FEP patients, 32 psychotic patients in the critical period (CP) and 21 healthy controls (HCs) were assessed. Anthropometric and biochemical parameters, as well as dietary intake, physical activity, stress-related variables and symptomatology, were collected.

RESULTS

Leptin levels were higher in the ARMS, FEP and CP patients than in the HCs. After controlling for age, sex, BMI, physical exercise, tobacco use and dietary intake, the highest differences in leptin levels were observed between the ARMS patients and HCs (p = 0.025). In the whole sample, leptin levels were positively correlated with BMI (p < 0.001), waist circumference (p < 0.001), insulin levels (p = 0.020), levels of the inflammatory marker IL-6 (p = 0.007) and energy intake (p = 0.043) and negatively correlated with HDL cholesterol (p = 0.018). Interestingly, energy intake and food craving scores were positively correlated with levels of leptin only in females (p = 0.022 and p = 0.036, respectively).

DISCUSSION

The present study detected increased leptin levels in the early stages of psychosis and significant correlations between leptin levels and anthropometric, lipid, hormone, and cytokine parameters. We found higher leptin levels in women, and we identified dietary intake habits associated with leptin exclusively in females that advocate considering sex in future studies.

Psychotic symptoms in youth with Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) may reflect syndrome severity and heterogeneity

OBJECTIVE

In the clinical syndrome Pediatric Acute-onset Neuropsychiatric Syndrome (PANS), obsessive compulsive disorder (OCD) and/or food refusal symptoms have an abrupt-onset (over 48 h) coupled with at least two other specified neuropsychiatric symptoms. We aimed to characterize in detail for the first time, psychotic symptoms experienced by children with PANS as well as the impact of psychotic symptoms on disease severity and course of illness. We inform about the diagnosis of the clinical description: PANS and hope to improve evaluation, treatment, diagnostic validity and future investigation.

METHODS

Retrospective review of 143 consecutive PANS clinic patient charts meeting inclusion criteria. The Caregiver Burden Inventory, Global Impairment Score, and Children's Global Assessment Scale were used to assess impairment.

RESULTS

Visual and auditory hallucinations were each experienced by 36%, of which most (83%) were transient and complex (non-threatening voices or figures). 6.3% and 5.5% of patients experienced delusions and thought disorganization respectively. Those with psychotic symptoms showed statistically significant differences in disease impairment and caregiver burden. There were no differences in time to treatment access or length of illness.

CONCLUSIONS

Over 1/3 of children with PANS experienced transient hallucinations. They were more impaired than those without psychotic symptoms, but showed no differences in disease progression. This difference may point toward heterogeneity in PANS. When evaluating children with acute psychotic symptoms, clinicians should screen for abrupt-onset of a symptom cluster including OCD and/or food refusal, with neuropsychiatric symptoms (enuresis, handwriting changes, tics, hyperactivity, sleep disorder) before initiating treatment.

Vascular endothelial growth factor in patients with schizophrenia: A systematic review and meta-analysis

BACKGROUND

Accumulating evidence indicates that schizophrenia might be accompanied by abnormal vascularization. Vascular endothelial growth factor (VEGF) is one of key molecules involved in the development of vessels with vasodilatory activities.

OBJECTIVES

We aimed to perform a systematic review and meta-analysis of studies investigating serum or plasma levels of VEGF in patients with schizophrenia and first-episode psychosis (FEP).

METHODS

Electronic databases were searched from their inception until 18th Apr 2018. Meta-analysis was performed using random-effects models with Hedges' g as the effect size estimate. Quality assessment was performed using the Newcastle-Ottawa Scale.

RESULTS

We included 15 eligible studies, representing 982 patients and 791 healthy controls. Main analysis revealed no significant differences in VEGF levels between patients and controls (g = 0.10, 95%CI = -0.24-0.45, p = .553). Subgroup analysis demonstrated unaltered levels of VEGF in FEP patients (g = 0.03, 95%CI = -0.53-0.59, p = .911), including antipsychotic-naïve individuals (g = 0.34, 95%CI = -0.07-0.74, p = .103). However, the levels of VEGF were significantly higher in medicated multiple-episode schizophrenia (MES) patients (g = 0.45, 95%CI = 0.03-0.87, p = .036) compared to controls. Heterogeneity across studies was significant in the majority of analyses, except for the analysis of antipsychotic-naïve FEP patients. Tests of asymmetry were insignificant, indicating a lack of publication bias.

LIMITATIONS

Main limitations of our meta-analysis include inability to address medication effects exhaustively and relatively low number of studies in subgroup analyses.

CONCLUSIONS

Our results indicate elevated levels of VEGF in MES patients that are unaltered in FEP individuals. Longitudinal studies are required to disentangle whether elevated levels of VEGF in MES patients reflect illness progression, comorbid physical health impairments or appear due to medication effects.