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Brain immune privilege for many years overshadowed investigation of interaction between the nervous and immune systems. Over time, however, evidence of their interdependence has emerged. In the 1970s, as antibody-mediated autoimmunity was being defined, the neurological disorder myasthenia gravis was shown to be due to autoantibodies that could be passively transferred to mice and removed from humans by plasma exchange. In the 1980s, Fink and Weihe showed that neurons innervate lymph nodes, and from the 1990s onwards, Rothwell and colleagues observed the impact of soluble inflammatory mediators on behaviour. For example, in a key experiment, her team showed that systemic and intraventricular injection of IL-1 led to fever and reduced food motivation in experimental animals, interpreted as “sickness behaviour”; this technique is now used as a model for inflammation-driven depression. Furthermore, IFN- α was unexpectedly found to cause depression when given as a treatment for hepatitis C. More recently, diseases have been identified in which autoantibodies interfere with neuronal function and cause severe psychiatric symptoms, such as N-Methyl D-Aspartate Receptor (NMDAR)-antibody encephalitis. There is now emerging interest in the patho-aetiological role of the immune system in various severe mental illnesses, and the use of immunotherapies in their treatment.
Antipsychotic treatment is associated with metabolic disturbance, with clear differences observed between drugs in the adult population. However, the degree to which metabolic alterations occur with different antipsychotics in children and adolescents is unclear. As such, we aimed to compare and rank antipsychotics based on their metabolic and endocrine side-effects when used in the treatment of schizophrenia in this age population.
Methods
We searched MEDLINE, EMBASE, and PsycINFO from inception until October 30, 2022. We included double blinded, randomised controlled trials comparing 12 antipsychotics and placebo in acute treatment of schizophrenia in individuals aged <18 years. We performed random-effects network meta-analyses to investigate treatment-induced changes in body weight, BMI, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, glucose, and prolactin concentrations. We performed meta-regressions to examine the relationship between metabolic/endocrine change and age, sex, and ethnicity
Results
Of 6697 citations, we included 15 randomised controlled trials, consisting of 2501 patients. Antipsychotics included in analyses were aripiprazole, asenapine, blonanserin, clozapine, haloperidol, lurasidone, molindone, olanzapine, paliperidone, quetiapine, risperidone, and ziprasidone. Median treatment duration was 6 weeks (IQR 6-12). Mean age was 15.13 (SD 0.94) years. Mean differences for weight gain compared with placebo ranged from -2.04 kg (95% CI -4.24 to 0.17) kg for molindone to 4.11 kg (-0.55 to 8.77) for clozapine; for BMI from -0.55 kg/m2 (-1.37 to 0.27) for molindone to 1.92 kg/m2 (0.16 to 3.68) for quetiapine; for total cholesterol from -0.14 mmol/L (-0.70 to 0.41) for risperidone/paliperidone to 0.46 mmol/L (0.00 to 0.90) for quetiapine; for LDL cholesterol from -0.32 mmol (-0.76 to 0.12) for aripiprazole to 0.24 mmol/L (-0.15 to 0.63) for olanzapine; for HDL cholesterol from 0.10 mmol/L (-0.05 to 0.26) for aripiprazole to -0.23 mmol/L (-0.52 to 0.06) for risperidone/paliperidone; for triglycerides from -0.01 mmol/L (-0.21 to 0.34) for molindone to 0.62 mmol/L (0.04 to 1.2) for clozapine; for glucose from -0.33 mmol/L (-0.64 to -0.02) for ziprasidone to 0.81 mmol/L (0.28 to 1.34) for clozapine; for prolactin from -1.92 ng/mL (-15.37 to 11.53) for aripiprazole to 28.10 ng/mL (16.23 to 39.96) for risperidone/paliperidone. Higher baseline age predicted by greater increases in body weight (p = 0.014).
Conclusion
We found significant differences between antipsychotics in terms of metabolic and endocrine side-effects when used in children and adolescents. Treatment guidelines should be updated to reflect our findings. However, the choice of antipsychotic should be made on an individual basis, considering the clinical circumstances and preferences of young people, carers, and clinicians.
Impaired brain metabolism may be central to schizophrenia pathophysiology, but the magnitude and consistency of metabolic dysfunction is unknown.
Methods
We searched MEDLINE, PsychINFO and EMBASE between 01/01/1980 and 13/05/2021 for studies comparing regional brain glucose metabolism using 18FDG-PET, in schizophrenia/first-episode psychosis v. controls. Effect sizes (Hedges g) were pooled using a random-effects model. Primary measures were regional absolute and relative CMRGlu in frontal, temporal, parietal and occipital lobes, basal ganglia and thalamus.
Results
Thirty-six studies (1335 subjects) were included. Frontal absolute glucose metabolism (Hedge's g = −0.74 ± 0.54, p = 0.01; I2 = 67%) and metabolism relative to whole brain (g = −0.44 ± 0.34, p = 0.01; I2 = 55%) were lower in schizophrenia v. controls with moderate heterogeneity. Absolute frontal metabolism was lower in chronic (g = −1.18 ± 0.73) v. first-episode patients (g = −0.09 ± 0.88) and controls. Medicated patients showed frontal hypometabolism relative to controls (−1.04 ± 0.26) while metabolism in drug-free patients did not differ significantly from controls. There were no differences in parietal, temporal or occipital lobe or thalamic metabolism in schizophrenia v. controls. Excluding outliers, absolute basal ganglia metabolism was lower in schizophrenia v. controls (−0.25 ± 0.24, p = 0.049; I2 = 5%). Studies identified reporting voxel-based morphometry measures of absolute 18FDG uptake (eight studies) were also analysed using signed differential mapping analysis, finding lower 18FDG uptake in the left anterior cingulate gyrus (Z = −4.143; p = 0.007) and the left inferior orbital frontal gyrus (Z = −4.239; p = 0.02) in schizophrenia.
Conclusions
We report evidence for hypometabolism with large effect sizes in the frontal cortex in schizophrenia without consistent evidence for alterations in other brain regions. Our findings support the hypothesis of hypofrontality in schizophrenia.
Clozapine is the only drug licensed for treatment-resistant schizophrenia (TRS) but the real-world clinical and cost-effectiveness of community initiation of clozapine is unclear.
Aims
The aim was to assess the feasibility and cost-effectiveness of community initiation of clozapine.
Method
This was a naturalistic study of community patients recommended for clozapine treatment.
Results
Of 158 patients recommended for clozapine treatment, 88 (56%) patients agreed to clozapine initiation and, of these, 58 (66%) were successfully established on clozapine. The success rate for community initiation was 65.4%; which was not significantly different from that for in-patient initiation (58.82%, χ2(1,88) = 0.47, P = 0.49). Following clozapine initiation, there was a significant reduction in median out-patient visits over 1 year (from 24.00 (interquartile range (IQR) = 14.00–41.00) to 13.00 visits (IQR = 5.00–24.00), P < 0.001), and 2 years (from 47.50 visits (IQR = 24.75–71.00) to 22.00 (IQR = 11.00–42.00), P < 0.001), and a 74.71% decrease in psychiatric hospital bed days (z = −2.50, P = 0.01). Service-use costs decreased (1 year: –£963/patient (P < 0.001); 2 years: –£1598.10/patient (P < 0.001). Subanalyses for community-only initiation also showed significant cost reductions (1 year: –£827.40/patient (P < 0.001); 2 year: –£1668.50/patient (P < 0.001) relative to costs prior to starting clozapine. Relative to before initiation, symptom severity was improved in patients taking clozapine at discharge (median Positive and Negative Syndrome Scale total score: initial visit: 80 (IQR = 71.00–104.00); discharge visit 50.5 (IQR = 44.75–75.00), P < 0.001) and at 2 year follow-up (Health of Nation Outcome Scales total score median initial visit: 13.00 (IQR = 9.00–15.00); 2 year follow-up: 8.00 (IQR = 3.00–13.00), P = 0.023).
Conclusions
These findings indicate that community initiation of clozapine is feasible and is associated with significant reductions in costs, service use and symptom severity.
First-episode psychosis (FEP) is associated with metabolic alterations. However, it is not known if there is heterogeneity in these alterations beyond what might be expected due to normal individual differences, indicative of subgroups of patients at greater vulnerability to metabolic dysregulation.
Methods
We employed meta-analysis of variance, indexed using the coefficient of variation ratio (CVR), to compare variability of the following metabolic parameters in antipsychotic naïve FEP and controls: fasting glucose, glucose post-oral glucose tolerance test (OGTT), fasting insulin, insulin resistance, haemoglobin A1c (HbA1c), total-cholesterol, low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, and triglycerides. Standardised mean difference in metabolic parameters between groups was also calculated; meta-regression analyses examined physiological/demographic/psychopathological moderators of metabolic change.
Results
Twenty-eight studies were analysed (1716 patients, 1893 controls). Variability of fasting glucose [CVR = 1.32; 95% confidence interval (CI) 1.12–1.55; p = 0.001], glucose post-OGTT (CVR = 1.43; 95% CI 1.10–1.87; p = 0.008), fasting insulin (CVR = 1.31; 95% CI 1.09–1.58; p = 0.01), insulin resistance (CVR = 1.34; 95% CI 1.12–1.60; p = 0.001), HbA1c (CVR = 1.18; 95% CI 1.06–1.27; p < 0.0001), total-cholesterol (CVR = 1.15; 95% CI 1.01–1.31; p = 0.03), LDL-cholesterol (CVR = 1.28; 95% CI 1.09–1.50; p = 0.002), and HDL-cholesterol (CVR = 1.15; 95% CI 1.00–1.31; p < 0.05), but not triglycerides, was greater in patients than controls. Mean glucose, glucose post-OGTT, fasting insulin, insulin resistance, and triglycerides were greater in patients; mean total-cholesterol and HDL-cholesterol were reduced in patients. Increased symptom severity and female sex were associated with worse metabolic outcomes.
Conclusions
Patients with FEP present with greater variability in metabolic parameters relative to controls, consistent with a subgroup of patients with more severe metabolic changes compared to others. Understanding determinants of metabolic variability could help identify patients at-risk of developing metabolic syndrome. Female sex and severe psychopathology are associated with poorer metabolic outcomes, with implications for metabolic monitoring in clinical practice.
Evidence from genetics, post mortem and animal studies suggest that N-Methyl-D-Aspartate Receptor (NMDAR) hypofunction has an important role in the pathophysiology of psychosis. However, it is not known if NMDAR activity is altered in the early stages of psychosis or if this links to symptom severity. Our aim was to investigate NMDAR availability in first-episode psychosis (FEP) and determine if it links to symptom severity. The NMDAR hypofunction hypothesis of schizophrenia was initially proposed in the 1990s on the basis of observations that ketamine and phencyclidine (PCP) induced the full range of schizophrenia-like symptoms (positive, negative and cognitive) when given to healthy participants and also that they worsen symptoms in patients with schizophrenia.
Method
We recruited 40 volunteers, including 21 patients with schizophrenia from early intervention services in London (12 antipsychotic-free and 9 receiving antipsychotic medication) and 19 matched healthy controls. The uptake of an NMDAR selective ligand, [18F]GE179, was measured using positron emission tomography (PET) and indexed using the distribution volume ratio (DVR) and volume of distribution (VT, in millilitres per cubic centimetre) of [18F]GE179 in the hippocampus and additional exploratory regions (anterior cingulate cortex (ACC), thalamus, striatum and temporal lobe). Symptom severity was measured using the Positive and Negative Syndrome Scale (PANSS).
Result
A total of 37 individuals were included in the analyses (mean [SD] age of controls, 26.7 [4.5] years; mean [SD] age of patients, 25.3 [4.9] years). There was a significant reduction in hippocampal DVR in the patients with schizophrenia relative to healthy controls (p = 0.02, Cohen's d = 0.81). Although the VT of [18F]GE179 was lower in absolute terms in patients, there was no significant effect of group on VT in the hippocampus (p = 0.15, Cohen's d = 0.49) or the exploratory brain regions. There was a negative association between hippocampal DVR and total PANSS symptoms (rho = –0.47, p = 0.04), depressive symptoms (rho = –0.67, p = 0.002), and general PANSS symptoms (rho = –0.74, p = 0.001).
Conclusion
These results indicate lower hippocampal NMDAR levels in schizophrenia relative to controls with a large effect size, and that lower NMDAR levels are associated with greater levels of symptom severity. These findings are consistent with the role of NMDAR hypofunction in the pathophysiology of schizophrenia; however, further work is required to test specificity and causal relationships.
Heart disease is the leading cause of death in schizophrenia. However, there has been little research directly examining cardiac function in schizophrenia.
Aims
To investigate cardiac structure and function in individuals with schizophrenia using cardiac magnetic resonance imaging (CMR) after excluding medical and metabolic comorbidity.
Method
In total, 80 participants underwent CMR to determine biventricular volumes and function and measures of blood pressure, physical activity and glycated haemoglobin levels. Individuals with schizophrenia (‘patients’) and controls were matched for age, gender, ethnicity and body surface area.
Results
Patients had significantly smaller indexed left ventricular (LV) end-diastolic volume (effect size d = −0.82, P = 0.001), LV end-systolic volume (d = −0.58, P = 0.02), LV stroke volume (d = −0.85, P = 0.001), right ventricular (RV) end-diastolic volume (d = −0.79, P = 0.002), RV end-systolic volume (d = −0.58, P = 0.02), and RV stroke volume (d = −0.87, P = 0.001) but unaltered ejection fractions relative to controls. LV concentricity (d = 0.73, P = 0.003) and septal thickness (d = 1.13, P < 0.001) were significantly larger in the patients. Mean concentricity in patients was above the reference range. The findings were largely unchanged after adjusting for smoking and/or exercise levels and were independent of medication dose and duration.
Conclusions
Individuals with schizophrenia show evidence of concentric cardiac remodelling compared with healthy controls of a similar age, gender, ethnicity, body surface area and blood pressure, and independent of smoking and activity levels. This could be contributing to the excess cardiovascular mortality observed in schizophrenia. Future studies should investigate the contribution of antipsychotic medication to these changes.
Converging lines of evidence implicate an important role for the immune system in schizophrenia. Microglia are the resident immune cells of the central nervous system and have many functions including neuroinflammation, axonal guidance and neurotrophic support. We aimed to provide a quantitative review of in vivo PET imaging studies of microglia activation in patients with schizophrenia compared with healthy controls.
Methods
Demographic, clinical and imaging measures were extracted from each study and meta-analysis was conducted using a random-effects model (Hedge's g). The difference in 18-kDa translocator protein (TSPO) binding between patients with schizophrenia and healthy controls, as quantified by either binding potential (BP) or volume of distribution (VT), was used as the main outcome. Sub-analysis and sensitivity analysis were carried out to investigate the effects of genotype, ligand and illness stage.
Results
In total, 12 studies comprising 190 patients with schizophrenia and 200 healthy controls met inclusion criteria. There was a significant elevation in tracer binding in schizophrenia patients relative to controls when BP was used as an outcome measure, (Hedge's g = 0.31; p = 0.03) but no significant differences when VT was used (Hedge's g = −0.22; p = 0.29).
Conclusions
In conclusion, there is evidence for moderate elevations in TSPO tracer binding in grey matter relative to other brain tissue in schizophrenia when using BP as an outcome measure, but no difference when VT is the outcome measure. We discuss the relevance of these findings as well as the methodological issues that may underlie the contrasting difference between these outcomes.
The extent of metabolic and lipid changes in first-episode psychosis (FEP) is unclear.
Aims
To investigate whether individuals with FEP and no or minimal antipsychotic exposure show lipid and adipocytokine abnormalities compared with healthy controls.
Method
We conducted a meta-analysis of studies examining lipid and adipocytokine parameters in individuals with FEP and no or minimal antipsychotic exposure v. a healthy control group. Studies reported fasting total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides and leptin levels.
Results
Of 2070 citations retrieved, 20 case–control studies met inclusion criteria including 1167 patients and 1184 controls. Total cholesterol and LDL cholesterol levels were significantly decreased in patients v. controls, corresponding to an absolute reduction of 0.26mmol/L and 0.15mmol/L respectively. Triglyceride levels were significantly increased in the patient group, corresponding to an absolute increase of 0.08 mmol/L However, HDL cholesterol and leptin levels were not altered in patients v. controls.
Conclusions
Total and LDL cholesterol levels are reduced in FEP, indicating that hypercholesterolaemia in patients with chronic disorder is secondary and potentially modifiable. In contrast, triglycerides are elevated in FEP. Hypertriglyceridaemia is a feature of type 2 diabetes mellitus, therefore this finding adds to the evidence for glucose dysregulation in this cohort. These findings support early intervention targeting nutrition, physical activity and appropriate antipsychotic prescription.
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