Levels of cytokines in the cerebrospinal fluid of patients with psychotic disorders compared to individually matched healthy controls

BACKGROUND

Increased peripheral cytokine levels have been observed in patients with psychotic disorders; however, large high-quality studies with individually matched healthy controls have been lacking regarding cytokines in cerebrospinal fluid (CSF) of individuals with psychotic disorders.

METHODS

Patients diagnosed with a non-organic, non-affective psychotic disorder (ICD-10: F20/22-29) within a year prior to inclusion and individually age- and sex-matched healthy controls were included by identical in- and exclusion criteria's except for the psychiatric diagnoses. All participants were aged 18-50 years and individuals with neurological or immunological disorders were excluded. CSF cytokines were analyzed with MesoScale V-PLEX neuroinflammation panel. Co-primary outcomes were CSF interleukin-6 (IL-6) and IL-8.

RESULTS

We included 104 patients and 104 healthy controls, matching on age, sex and BMI. No significant differences were found for the primary outcomes IL-6 (relative mean difference (MD): 0.97, 95 %CI: 0.84-1.11, p = 0.637) or IL-8 (MD: 1.01, 95 %CI: 0.93-1.09, p = 0.895). Secondary analyses found patients to have higher IL-4 (MD: 1.30, 95 %CI: 1.04-1.61, p = 0.018), a trend towards higher IFN-γ (MD: 1.26, 95 %CI: 0.99-1.59, p = 0.056), and lower IL-16 (MD: 0.83, 95 %CI: 0.74-0.94, p = 0.004) than healthy controls, though not significant after correction for multiple testing. IL-8 and IL-16 were found positively associated with CSF white blood cells and CSF/serum albumin ratio. The study was limited by 77.9 % of the patients being on antipsychotic treatment at time of intervention, and that levels of nine of the 26 cytokines were below lower limit of detection (LLOD) in >50 % of samples; however, for the primary outcomes IL-6 and IL-8 more than 99.5 % of the samples were above LLOD and for IL-8 all samples exceeded the lower limit of quantification (LLOQ).

CONCLUSIONS

We found no evidence of increased IL-6 and IL-8 in patients with recent-onset psychotic disorders in contrary to previous findings in meta-analyses of CSF cytokines. Secondary analyses found indication of higher IL-4, decreased IL-16, and borderline increased IFN-γ in patients, neither of which have previously been reported on in CSF analyses of individuals with psychotic disorders.

Is reduced heart rate variability associated with functional somatic disorders? A cross-sectional population-based study; DanFunD

OBJECTIVES

It has been hypothesised that functional somatic disorders (FSD) could be initiated by sympathetic predominance in the autonomic nervous system as measured by low heart rate variability (HRV). Earlier studies on the association between HRV and FSD are small case-control studies hampered by selection bias and do not consider the great overlap between the various FSDs. The aim of the present study is to assess any associations between HRV and various FSDs and whether chronic stress confounds such an association.

DESIGN

A cross-sectional general population-based study.

SETTING

The Danish Study of Functional Somatic Disorders conducted 2013-2015 in 10 municipalities in the western part of Greater Copenhagen, Denmark.

PARTICIPANTS

A total of 6891 men and women aged 18-72 years were included in the analyses after exclusion of 602 persons with missing HRV data. Various delimitations of FSD (chronic fatigue, chronic widespread pain, irritable bowel and bodily distress syndrome) were identified by validated questionnaires and diagnostic interviews. HRV parameters in time and frequency domains were calculated from successive beat-to-beat heart rate (HR) data using the 'E-motion' HR monitor device during 7 min of supine rest. Chronic stress was assessed by Cohen's self-perceived stress scale.

OUTCOME MEASURES

Logistic regression analyses were used to calculate possible associations between the various delimitations of FSD and HRV adjusting for chronic stress.

RESULTS

Persons with FSD had a slightly higher mean HR and lower HRV as measured by time domain parameters, whereas associations with frequency domain parameters were not consistent. Adjusting for chronic stress attenuated associations slightly.

CONCLUSION

The study supports a sympathetic predominance in persons with FSD, which could not be entirely explained by chronic stress. However, it is not possible to conclude whether the association is a causal factor to or a consequence of FSD.

Lipid metabolism and functional somatic disorders in the general population. The DanFunD study

OBJECTIVES

Earlier studies on the association between plasma lipid profiles and functional somatic disorders (FSD) are mainly small case control studies hampered by selection bias and do not consider the great overlap between the various FSDs. The aim of the present study was to investigate the associations between various FSDs and plasma lipid profiles (total cholesterol, HDL cholesterol, non-HDL cholesterol and triglycerides) in a large, unselected population.

DESIGN

A cross-sectional general population-based study.

SETTING

The Danish Study of Functional Somatic Disorders (DanFunD) conducted in 2011-2015 in 10 municipalities in the western part of greater Copenhagen, Denmark.

PARTICIPANTS

A total of 8,608 men and women aged 18-76 years were included in the analyses. Various delimitations of FSD such as chronic fatigue, chronic widespread pain, irritable bowel, and bodily distress syndrome were measured using validated self-administrated questionnaires. Lipid parameters were measured from fasting plasma samples using colorimetric slide methods with Vitros 4600/5600 Ortho Clinical Diagnostics.

OUTCOME MEASURES

Logistic regression analyses were used to calculate possible associations between plasma lipids and the various delimitations of FSD. Associations are presented by OR (95% CI) and shown in boxplots.

RESULTS

We found a positive association between bodily distress syndrome and triglycerides and non-HDL cholesterol and a negative association with HDL-cholesterol, but no consistent association with total cholesterol. A similar pattern was observed for persons with chronic fatigue, and to some degree for persons with chronic widespread pain, whereas persons with irritable bowel did not show a clear association with the lipid profiles.

CONCLUSION

This is the first major study on plasma lipid profiles and FSD indicating an association between some delimitations of FSD and an unfavorable lipid profile. Due to the cross-sectional design, it cannot be determined whether the findings are consequences or determinants of FSD. Further studies-preferable prospective studies-are needed.

Brain Health After COVID-19, Pneumonia, Myocardial Infarction, or Critical Illness

Importance

Brain health is most likely compromised after hospitalization for COVID-19; however, long-term prospective investigations with matched control cohorts and face-to-face assessments are lacking.

Objective

To assess whether long-term cognitive, psychiatric, or neurological complications among patients hospitalized for COVID-19 differ from those among patients hospitalized for other medical conditions of similar severity and from healthy controls.

Design, Setting, and Participants

This prospective cohort study with matched controls was conducted at 2 academic hospitals in Copenhagen, Denmark. The case cohort comprised patients with COVID-19 hospitalized between March 1, 2020, and March 31, 2021. Control cohorts consisted of patients hospitalized for pneumonia, myocardial infarction, or non-COVID-19 intensive care-requiring illness between March 1, 2020, and June 30, 2021, and healthy age- and sex-matched individuals. The follow-up period was 18 months; participants were evaluated between November 1, 2021, and February 28, 2023.

Exposures

Hospitalization for COVID-19.

Main Outcomes and Measures

The primary outcome was overall cognition, assessed by the Screen for Cognitive Impairment in Psychiatry (SCIP) and the Montreal Cognitive Assessment (MoCA). Secondary outcomes were executive function, anxiety, depressive symptoms, and neurological deficits.

Results

The study included 345 participants, including 120 patients with COVID-19 (mean [SD] age, 60.8 [14.4] years; 70 men [58.3%]), 125 hospitalized controls (mean [SD] age, 66.0 [12.0] years; 73 men [58.4%]), and 100 healthy controls (mean [SD] age, 62.9 [15.3] years; 46 men [46.0%]). Patients with COVID-19 had worse cognitive status than healthy controls (estimated mean SCIP score, 59.0 [95% CI, 56.9-61.2] vs 68.8 [95% CI, 66.2-71.5]; estimated mean MoCA score, 26.5 [95% CI, 26.0-27.0] vs 28.2 [95% CI, 27.8-28.6]), but not hospitalized controls (mean SCIP score, 61.6 [95% CI, 59.1-64.1]; mean MoCA score, 27.2 [95% CI, 26.8-27.7]). Patients with COVID-19 also performed worse than healthy controls during all other psychiatric and neurological assessments. However, except for executive dysfunction (Trail Making Test Part B; relative mean difference, 1.15 [95% CI, 1.01-1.31]), the brain health of patients with COVID-19 was not more impaired than among hospitalized control patients. These results remained consistent across various sensitivity analyses.

Conclusions and Relevance

This prospective cohort study suggests that post-COVID-19 brain health was impaired but, overall, no more than the brain health of patients from 3 non-COVID-19 cohorts of comparable disease severity. Long-term associations with brain health might not be specific to COVID-19 but associated with overall illness severity and hospitalization. This information is important for putting understandable concerns about brain health after COVID-19 into perspective.

Antineuronal Autoantibodies in the Cerebrospinal Fluid and Serum From 106 Patients With Recent-Onset Depression Compared With 106 Individually Matched Healthy Control Subjects

No large studies have investigated the prevalence of cerebrospinal fluid antineuronal autoantibodies in isolated depression. In this case-control study comparing 106 patients with isolated depression (ICD-10 code F32) with 106 healthy control subjects, cerebrospinal fluid and serum samples were tested for 7 immunoglobulin G autoantibodies using commercial fixed cell-based assays. To explore validity of methods, positive samples were retested twice by cell-based assays and once by tissue-based assays (monkey cerebellum). The prevalence of any of the antineuronal autoantibodies in cerebrospinal fluid was 0.0% in both groups and the seroprevalence was 0.9% in both groups, based on consistent findings in cell-based assays. However, all samples were negative by the tissue-based assay. Evaluation of antineuronal autoantibodies in cerebrospinal fluid cannot be recommended routinely for patients with isolated depression of moderate severity. Future studies of isolated depression should consider much larger sample sizes and evaluation of antineuronal autoantibodies using modalities other than commercial kits.

Adjunctive agents to antipsychotics in schizophrenia: a systematic umbrella review and recommendations for amino acids, hormonal therapies and anti-inflammatory drugs

QUESTION

This umbrella review and guidelines aimed to provide evidence to support the rational choice of selected adjunctive therapies for schizophrenia.

STUDY SELECTION AND ANALYSIS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and World Federation of Societies of Biological Psychiatry (WFSBP)-grading recommendations, 63 randomised control trials (RCTs) (of which 4219 unique participants have completed the RCTs) and 29 meta-analyses were analysed.

FINDINGS

Provisional recommendations (WFSBP-grade 1) could be made for two molecules in augmentation to antipsychotics: (1) N-acetyl-cysteine (NAC, 1200-3600 mg/day, for >12 consecutive weeks) in improving negative symptoms, general psychopathology (positive and negative syndrome scale for schizophrenia (PANSS) general psychopathology factor (G)-G subscale), with the RCTs with the longer duration showing the most robust findings; (2) polyunsaturated fatty acids (3000 mg/day of eicosapentaenoic acid, for >12 weeks) in improving general psychopathology. Weaker recommendations (ie, WFSBP-grade 2) could be drawn for sarcosine (2 g/day) and minocycline (200-300 mg/day) for improving negative symptoms in chronic schizophrenia (not early schizophrenia), and NAC for improving positive symptoms and cognition. Weak recommendations are not ready for clinical practice. There is provisional evidence that oestrogens and raloxifene are effective in some patients, but further research is needed to determine their benefit/risk ratio.

CONCLUSIONS

The results of this umbrella review should be interpreted with caution as the number of RCTs included in the meta-analyses was generally small and the effect sizes were weak or medium. For NAC, two RCTs with low risk of bias have provided conflicting results and the WFSBP-grade recommendation included also the results of meta-analyses. These drugs could be provisionally prescribed for patients for whom no other treatments have been effective, but they should be discontinued if they prove ineffective.

Immunological Biomarkers as Predictors of Treatment Response in Psychotic Disorders

Psychotic disorders, notably schizophrenia, impose a detrimental burden on both an individual and a societal level. The mechanisms leading to psychotic disorders are multifaceted, with genetics and environmental factors playing major roles. Increasing evidence additionally implicates neuro-inflammatory processes within at least a subgroup of patients with psychosis. While numerous studies have investigated anti-inflammatory add-on treatments to current antipsychotics, the exploration of immunological biomarkers as a predictor of treatment response remains limited. This review outlines the current evidence from trials exploring the potential of baseline inflammatory biomarkers as predictors of the treatment effect of anti-inflammatory drugs as add-ons to antipsychotics and of antipsychotics alone. Several of the studies have found correlations between baseline immunological biomarkers and treatment response; however, only a few studies incorporated baseline biomarkers as a primary endpoint, and the findings thus need to be interpreted with caution. Our review emphasizes the need for additional research on the potential of repurposing anti-inflammatory drugs while utilizing baseline inflammatory biomarkers as a predictor of treatment response and to identify subgroups of individuals with psychotic disorders where add-on treatment with immunomodulating agents would be warranted. Future studies investigating the correlation between baseline inflammatory markers and treatment responses can pave the way for personalized medicine approaches in psychiatry centred around biomarkers such as specific baseline inflammatory biomarkers in psychotic disorders.

Biomarkers in the cerebrospinal fluid of patients with psychotic disorders compared to healthy controls: a systematic review and meta-analysis

Psychotic disorders are severe mental disorders with poorly understood etiology. Biomarkers in the cerebrospinal fluid (CSF) could provide etiological clues and diagnostic tools for psychosis; however, an unbiased overview of CSF alterations in individuals with psychotic disorders is lacking. The objective of this study was to summarize all quantifiable findings in CSF from individuals with psychotic disorders compared to healthy controls (HC). Studies published before January 25th, 2023 were identified searching PubMed, EMBASE, Cochrane Library, Web of Science, ClinicalTrials.gov, and PsycINFO. Screening, full-text review, data extraction, and risk of bias assessments were performed by two independent reviewers following PRISMA guidelines. Findings in patients and healthy controls were compared and summarized using random-effects analyses and assessment of publication bias, subgroup and sensitivity analyses were performed. 145 studies, covering 197 biomarkers, were included, of which 163 biomarkers have not previously been investigated in meta-analyses. All studies showed some degree of bias. 55 biomarkers measured in CSF were associated with psychosis and of these were 15 biomarkers measured in ≥2 studies. Patients showed increased levels of noradrenaline (standardized mean difference/SMD, 0.53; 95% confidence interval/CI, 0.16 to 0.90) and its metabolite 3-methoxy-4-hydroxyphenylglycol (SMD, 0.30; 95% CI: 0.05 to 0.55), the serotonin metabolite 5-hydroxyindoleacetic acid (SMD, 0.11; 95% CI: 0.01 to 0.21), the pro-inflammatory neurotransmitter kynurenic acid (SMD, 1.58; 95% CI: 0.34 to 2.81), its precursor kynurenine (SMD,0.99; 95% CI: 0.60 to 1.38), the cytokines interleukin-6 (SMD, 0.58; 95% CI: 0.39 to 0.77) and interleukin-8 (SMD, 0.43; 95% CI: 0.24 to 0.62), the endocannabinoid anandamide (SMD, 0.78; 95% CI: 0.53 to 1.02), albumin ratio (SMD, 0.40; 95% CI: 0.08 to 0.72), total protein (SMD, 0.29; 95% CI: 0.16 to 0.43), immunoglobulin ratio (SMD, 0.45; 95% CI: 0.06 to 0.85) and glucose (SMD, 0.48; 95% CI: 0.01 to 0.94). Neurotensin (SMD, -0.67; 95% CI: -0.89 to -0.46) and γ-aminobutyric acid (SMD, -0.29; 95% CI: -0.50 to -0.09) were decreased. Most biomarkers showed no significant differences, including the dopamine metabolites homovanillic acid and 3,4-dihydroxyphenylacetic acid. These findings suggest that dysregulation of the immune and adrenergic system as well as blood-brain barrier dysfunction are implicated in the pathophysiology of psychotic disorders.

Comparisons of 25 cerebrospinal fluid cytokines in a case-control study of 106 patients with recent-onset depression and 106 individually matched healthy subjects

BACKGROUND

Neuroinflammation has been suggested as a contributor to the pathophysiology of depression; however, large case-control studies investigating cytokine levels in the cerebrospinal fluid (CSF) from patients with recent-onset depression by multiplex analyses are missing.

METHODS

An individually matched (sex and age) prospective case-control study comparing patients with recent-onset depression to healthy controls. CSF was analyzed with the Mesoscale V-PLEX Neuroinflammation Panel 1.

OUTCOMES

comparisons of analyte levels in the CSF between groups with interleukin (IL)-6 and IL-8 as primary outcomes and 23 other cytokines as secondary outcomes.

RESULTS

We included 106 patients (84.0% outpatients) with recent-onset depression and 106 healthy controls. There were no significant differences in the primary outcomes IL-6 (relative mean difference (MD): 1.10; 95% confidence interval (CI) 0.93-1.30; p = 0.276) or IL-8 levels (MD: 1.05; 95% CI 0.96-1.16; p = 0.249) relative to healthy controls. IL-4 was 40% higher (MD: 1.40; 95% CI 1.14-1.72; p = 0.001), monocyte chemoattractant protein (MCP)-1 was 25% higher (MD: 1.25; 95% CI 1.06-1.47; p = 0.009) and macrophage inflammatory protein (MIP)-1β was 16% higher (MD: 1.16; 95% CI 1.02-1.33; p = 0.025) in patients with depression relative to healthy controls. However, only IL-4 was significantly elevated after correction for multiple testing of secondary outcomes (p = 0.025).

CONCLUSION

We found no significant differences in CSF levels of the co-primary outcomes IL-6 and IL-8, however, the higher CSF levels of IL-4, MCP-1 and MIP-1β among patients with recent-onset depression compared to healthy controls indicate a potential role of these cytokines in the neuroinflammatory response to depression.

Discovery of drug-omics associations in type 2 diabetes with generative deep-learning models

The application of multiple omics technologies in biomedical cohorts has the potential to reveal patient-level disease characteristics and individualized response to treatment. However, the scale and heterogeneous nature of multi-modal data makes integration and inference a non-trivial task. We developed a deep-learning-based framework, multi-omics variational autoencoders (MOVE), to integrate such data and applied it to a cohort of 789 people with newly diagnosed type 2 diabetes with deep multi-omics phenotyping from the DIRECT consortium. Using in silico perturbations, we identified drug-omics associations across the multi-modal datasets for the 20 most prevalent drugs given to people with type 2 diabetes with substantially higher sensitivity than univariate statistical tests. From these, we among others, identified novel associations between metformin and the gut microbiota as well as opposite molecular responses for the two statins, simvastatin and atorvastatin. We used the associations to quantify drug-drug similarities, assess the degree of polypharmacy and conclude that drug effects are distributed across the multi-omics modalities.

Deep Learning for Cross-Diagnostic Prediction of Mental Disorder Diagnosis and Prognosis Using Danish Nationwide Register and Genetic Data

Importance

Diagnoses and treatment of mental disorders are hampered by the current lack of objective markers needed to provide a more precise diagnosis and treatment strategy.

Objective

To develop deep learning models to predict mental disorder diagnosis and severity spanning multiple diagnoses using nationwide register data, family and patient-specific diagnostic history, birth-related measurement, and genetics.

Design, Setting, and Participants

This study was conducted from May 1, 1981, to December 31, 2016. For the analysis, which used a Danish population-based case-cohort sample of individuals born between 1981 and 2005, genotype data and matched longitudinal health register data were taken from the longitudinal Danish population-based Integrative Psychiatric Research Consortium 2012 case-cohort study. Included were individuals with mental disorders (attention-deficit/hyperactivity disorder [ADHD]), autism spectrum disorder (ASD), major depressive disorder (MDD), bipolar disorder (BD), schizophrenia spectrum disorders (SCZ), and population controls. Data were analyzed from February 1, 2021, to January 24, 2022.

Exposure

At least 1 hospital contact with diagnosis of ADHD, ASD, MDD, BD, or SCZ.

Main Outcomes and Measures

The predictability of (1) mental disorder diagnosis and (2) severity trajectories (measured by future outpatient hospital contacts, admissions, and suicide attempts) were investigated using both a cross-diagnostic and single-disorder setup. Predictive power was measured by AUC, accuracy, and Matthews correlation coefficient (MCC), including an estimate of feature importance.

Results

A total of 63 535 individuals (mean [SD] age, 23 [7] years; 34 944 male [55%]; 28 591 female [45%]) were included in the model. Based on data prior to diagnosis, the specific diagnosis was predicted in a multidiagnostic prediction model including the background population with an overall area under the curve (AUC) of 0.81 and MCC of 0.28, whereas the single-disorder models gave AUCs/MCCs of 0.84/0.54 for SCZ, 0.79/0.41 for BD, 0.77/0.39 for ASD, 0.74/0.38, for ADHD, and 0.74/0.38 for MDD. The most important data sets for multidiagnostic prediction were previous mental disorders and age (11%-23% reduction in prediction accuracy when removed) followed by family diagnoses, birth-related measurements, and genetic data (3%-5% reduction in prediction accuracy when removed). Furthermore, when predicting subsequent disease trajectories of the disorder, the most severe cases were the most easily predictable, with an AUC of 0.72.

Conclusions and Relevance

Results of this diagnostic study suggest the possibility of combining genetics and registry data to predict both mental disorder diagnosis and disorder progression in a clinically relevant, cross-diagnostic setting prior to clinical assessment.

Antineuronal antibodies in cerebrospinal fluid and serum of 104 patients with psychotic disorders compared to 104 individually matched healthy controls

BACKGROUND

Antineuronal antibodies can cause psychotic symptoms, particularly NMDAR antibodies; however, studies on the prevalence of antineuronal antibodies in cerebrospinal fluid (CSF) and serum of patients with psychotic disorders compared to matched healthy controls are sparse.

METHODS

We included 104 patients with a first-time diagnosis of a psychotic disorder within one year prior to inclusion (50 % outpatients) and 104 individually matched healthy controls, all without any known immunological conditions. CSF and serum were tested for IgG antibodies (Abs) against NMDAR NR1-subunit, GAD65, LGI1, CASPR2, AMPAR1, AMPAR2 and GABAb-receptor B1/B2 using commercial fixed cell-based assays (CBAs) (Euroimmun). Positive samples were retested with CBA twice, and tested with tissue-based assays (TBA). Primary outcomes were the presence of any of the seven anti-neuronal antibodies in CSF or serum. Secondarily, we analyzed the prevalence of each autoantibody.

RESULTS

No antineuronal IgG antibodies were consistently found in any CSF sample and NMDAR-antibodies were not consistently present in any of the 208 participants, neither in CSF nor serum. CASPR2-Abs were consistently found in the serum of one patient and one control, and one healthy control, without diabetes, was seropositive for GAD65-Abs. CASPR2 borderline seropositivity was additionally found in one patient and two controls. All samples positive on CBA were negative on TBA.

CONCLUSIONS

We found no significant differences between patients and controls. Antineuronal IgG antibodies are very rare when screening a broad group of individuals with recent-onset psychotic disorders without other indications of autoimmune encephalitis. Thus, much larger studies are needed to conclude on potential contrasts in prevalence compared to healthy controls.

The Immune System and Depression: From Epidemiological to Clinical Evidence

Depression is a frequent mental disorder with a substantial contribution to years lived with disability worldwide. In the search for new treatment targets, the immune system's contribution to the pathogenesis of depression has received increased attention as immune activation has been associated with depression in various epidemiological and case-control studies. Epidemiological studies have shown that immune exposures such as severe infections and autoimmune disorders increase the risk of depression. Furthermore, immune system activation has been indicated in case-control studies of depression revealing higher levels of key pro-inflammatory cytokines among patients with depression than healthy controls, particularly in blood and to some extent in the cerebrospinal fluid. Moreover, brain imaging studies indicate increased microglial activity during depression, and gut microbiota studies have documented alterations of gut microbiota composition to be associated with depression. Based on findings from animal and human studies, several immune-mediated molecular mechanisms have been suggested to underlie the association between increased immunological activity and depression. However, the research is challenged by the heterogeneity of the depression diagnosis and - to some extent - the precision of currently available technology for immune biomarker quantification, particularly regarding the assessment of low-grade neuroinflammation. Nonetheless, an enhanced understanding of the complex interactions between the immune system and the brain in the context of depression could pave the way for precision medicine approaches with immune-modulating treatment as a promising additional option in the treatment of depression.

11 The epidemiology of infections as a risk factor for psychiatric illness

Abstract

The immune system is linked to an increasing number of medical diseases, including lately also severe mental disorders. Utilizing the nationwide registers and biobanks in Denmark we have consistently displayed that infections and autoimmune diseases increases the risk of developing severe mental disorders in a dose-response relationship, where the risk of severe mental disorders particularly increases with the amount of infections exposed to. It is a broad range of infections and autoimmune diseases that are associated with an increased risk of severe mental disorders, with the more severe infections increasing the risk the most and the risk of severe mental disorders is particularly increased with the temporal proximity to the infection. Furthermore, we have shown a small immunogenetic contribution with moderate correlation between the genetic signals for the susceptibility for infections and mental disorders. Moreover, at diagnosis there are elevated levels of inflammatory markers in the blood and studies on the cerebrospinal fluid surrounding the brain have shown some evidence for elevated immune markers in the brain and signs of disrupted blood-brain barrier in some of the patients, making them more vulnerable to potential detrimental effects of immune components. Interestingly, our meta-analyses of randomized clinical trials have shown that anti-inflammatory treatment seems to be effective for depression and depressive symptoms and to some extent also for psychotic disorders. However, studies identifying subgroups that would be most likely to respond to immune modulating add-on treatment are still warranted to pave the field forward.

Cerebrospinal Fluid and Blood Biomarkers of Neuroinflammation and Blood-Brain Barrier in Psychotic Disorders and Individually Matched Healthy Controls

BACKGROUND AND HYPOTHESIS

Neuroinflammation and blood-brain barrier (BBB) dysfunction have been observed in patients with psychotic disorders. However, previous studies have mainly focused on selected patients and broad screenings of cerebrospinal fluid (CSF) of patients with recent onset psychosis compared to healthy controls are lacking.

STUDY DESIGN

We included 104 patients with recent onset psychotic disorder and 104 individually matched healthy controls. CSF and blood were analyzed for readily available markers assessing neuroinflammation and BBB dysfunction. Primary outcomes were CSF white blood cell count (WBC), total protein, IgG Index, and CSF/serum albumin ratio. Secondary outcomes included additional markers of inflammation and BBB, and analyses of association with clinical variables.

STUDY RESULTS

CSF/serum albumin ratio (Relative Mean Difference (MD): 1.11; 95%CI: 1.00-1.23; P = .044) and CSF/serum IgG ratio (MD: 1.17; 95%CI: 1.01-1.36; P = .036) was increased in patients compared to controls. A higher number of patients than controls had CSF WBC >3 cells/µl (seven vs. one, OR: 7.73, 95%CI: 1.33-146.49, P = .020), while WBC>5 cells/µl was found in two patients (1.9%) and no controls. Inpatients had higher serum WBC and neutrophil/lymphocyte ratio (all p-values for effect heterogeneity < .011). Mean CSF WBC (MD: 1.10; 95%CI: 0.97-1.26), protein (MD: 1.06; 95%CI: 0.98-1.15) and IgG index (MD: 1.05; 95%CI: 0.96-1.15) were not significantly elevated.

CONCLUSIONS

When comparing a broad group of patients with psychotic disorders with healthy controls, patients had increased BBB permeability, more patients had high CSF WBC levels, and inpatients had increased peripheral inflammation, consistent with the hypothesis of a subgroup of patients with increased activation of the immune system.

Association between infections and functional somatic disorders: a cross-sectional population-based cohort study

OBJECTIVES

It has been suggested that infections can trigger functional somatic disorders (FSD). However, current evidence is limited by inconsistent findings in smaller studies conducted in clinical settings within selected populations and short follow-up times. We aimed to test the hypothesis that former infections are associated with FSD using data from nationwide registries and a large population-based cohort study, the Danish Study of Functional Disorders study.

DESIGN

FSD cases were identified in a cross-sectional population-based cohort and linked retrospectively to former hospital contacts with infections identified in the Danish National Patient Registry. The associations between FSD and former infections within 17 years were analysed using logistic regressions to calculate ORs and 95% CIs adjusted for age, sex and subjective social status.

SETTING

A population-based cohort in Denmark examined between 2011 and 2015.

PARTICIPANTS

A total of 9656 men and women aged 18-76 years.

MAIN OUTCOME MEASURES

FSD measured by various delimitations, including bodily distress syndrome (BDS), irritable bowel (IB), chronic fatigue (CF), chronic widespread pain (CWP), and multiple chemical sensitivity (MCS).

RESULTS

Overall, infections were associated with increased risk of all delimitations of FSD. The associations were more pronounced for multisystemic FSD. The number of prior infections increased the risk in a dose-response manner (p<0.0001). Bacterial but not viral infections were significantly associated with BDS (OR 1.69 (95% CI 1.46 to 1.96)), IB (OR 1.41 (95% CI 1.06 to 1.88)), CWP (OR 1.47 (95% CI 1.13 to 1.90)) and CF (OR 1.62 (95% CI 1.34 to 1.96)), but not MCS.

CONCLUSION

Former infections leading to hospital contacts were associated with a higher risk of having FSD. These associations were more pronounced for bacterial than viral infections, and more infections increased the risk in a dose-response manner. These results tend to support the idea that severe infections could play a role in FSD.

Examine the public health impacts of functional somatic disorders using the DanFunD study

Background: Persistent physical symptoms (e.g. pain, fatigue) are prevalent in the population and some persons may develop a functional somatic disorder (FSD). We still need to explore the limits between general bodily sensations and FSD, and great controversies exist as regard delimitation, occurrence, risk factors, prognosis, and costs of FSD in the general population. This is mainly due to the lack of focused, sufficient powered, population-based epidemiological studies. Material and Methods: The DanFunD study is the largest focused population-based study on FSD and has the potential to answer these crucial questions regarding the FSD disorders. DanFunD has its origin in the Copenhagen area of Denmark and was initiated in 2009 by an interdisciplinary team of researchers including basic scientists, clinical researchers, epidemiologists, and public health researchers. A population-based cohort of nearly 10,000 people have filled in detailed questionnaires, gone through a thorough health examination, and a biobank is established. The cohort was re-examined after five years. Results:The prevalence of FSD in the Danish population is about 10-15% and is twice as common in women as in men. Persons with FSD report impaired daily activities and low self-perceived health, which qualifies FSD as a major public health problem. The research plan to unravel the risk factors for FSD employs a bio-psycho-social approach according to a detailed plan. Preliminary results are presented, and work is in progress. Likewise, plans for assessing prognosis and health care costs are provided. Conclusion: We invite researchers in the field to collaborate on this unique data material.

Genetic and psychosocial influence on the association between early childhood infections and later psychiatric disorders

To evaluate the influence of extensive genetic and psychosocial confounding on the association between early childhood infection and five major psychiatric disorders METHODS: A case-cohort study including participants from the Danish iPSYCH2012 sample, a case-cohort sample where all cases born between May 1, 1981, and December 31, 2005, diagnosed with attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), bipolar affective disorder (BIP), Major Depressive Disorder (MDD) or schizophrenia (SCZ), were identified and pooled with a representative sample (subcohort) of the Danish population. We used Cox proportional hazards regression customized to the case-cohort setup to calculate hazard ratios of outcome with 95% confidence intervals (CIs), following exposure to early childhood infection before the age of 5 years for ADHD and ASD, and before the age of 10 years for BIP, MDD, and SCZ. To evaluate psychosocial confounding we included sex, calendar period, sibling infections, urbanicity, parental socio-economic status, parental mental health information, and polygenic risk scores for all five disorders, as covariates. To estimate how liability for psychiatric disorders measured through the PRS influenced the risk of early childhood infection, we calculated odds ratios (ORs) with 95% CIs, using logistic regression RESULTS: Early childhood infection was associated with ADHD, ASD, MDD, and SCZ with number of childhood infections increasing the hazard. The HR was still significant in the model with full adjustments after 1 infection for ADHD (HR 1.29, 95% CI: 1.19-1.41), ASD (HR 1.28, 95% CI: 1.18-1.40), MDD (HR 1.23, 95% CI: 1.14-1.33), and SCZ (HR 1.21, 95% CI: 1.07-1.36), but not for BIP (HR1.17, 95% CI: 0.96-1.42). Probands exposed to sibling infections, but not own infection had an absolute risk of ADHD, BIP, MDD, and SCZ that closely approached the absolute risk for individuals exposed to own infections. We found evidence of gene-environment correlation with higher PRS of MDD and to some extent SCZ increasing the risk of infections and higher PRS of BIP associated with significantly decreased risk CONCLUSION: Early childhood infection is significantly associated with ADHD, ASD, MDD, and SCZ and not explained by genetic or psychosocial confounding. Although we found evidence of gene-environment correlation, it had minor impact on the results.

Deep learning-based integration of genetics with registry data for stratification of schizophrenia and depression

Currently, psychiatric diagnoses are, in contrast to most other medical fields, based on subjective symptoms and observable signs and call for new and improved diagnostics to provide the most optimal care. On the basis of a deep learning approach, we performed unsupervised patient stratification of 19,636 patients with depression [major depressive disorder (MDD)] and/or schizophrenia (SCZ) and 22,467 population controls from the iPSYCH2012 case cohort. We integrated data of disorder severity, history of mental disorders and disease comorbidities, genetics, and medical birth data. From this, we stratified the individuals in six and seven unique clusters for MDD and SCZ, respectively. When censoring data until diagnosis, we could predict MDD clusters with areas under the curve (AUCs) of 0.54 to 0.80 and SCZ clusters with AUCs of 0.71 to 0.86. Overall cases and controls could be predicted with an AUC of 0.81, illustrating the utility of data-driven subgrouping in psychiatry.

Cerebrospinal Fluid Biomarkers in Patients With Unipolar Depression Compared With Healthy Control Individuals: A Systematic Review and Meta-analysis

IMPORTANCE

Depression has been associated with alterations in neurotransmitters, hormones, and inflammatory and neurodegenerative biomarkers, and biomarkers quantified in the cerebrospinal fluid (CSF) are more likely to reflect ongoing biochemical changes within the brain. However, a comprehensive overview of CSF biomarkers is lacking and could contribute to the pathophysiological understanding of depression.

OBJECTIVE

To investigate differences in quantified CSF biomarkers in patients with unipolar depression compared with healthy control individuals.

DATA SOURCES

PubMed, EMBASE, PsycINFO, Cochrane Library, Web of Science, and ClinicalTrials.gov were searched for eligible trials from database inception to August 25, 2021.

STUDY SELECTION

All studies investigating CSF biomarkers in individuals 18 years and older with unipolar depression and healthy control individuals were included. One author screened titles and abstracts, and 2 independent reviewers examined full-text reports. Studies that did not include healthy control individuals or included control individuals with recent hospital contacts or admissions that might affect CSF biomarker concentrations were excluded.

DATA EXTRACTION AND SYNTHESIS

Data extraction and quality assessment were performed by 2 reviewers following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines. Meta-analyses were performed using standardized mean differences (SMDs) calculated with random-effects models. A third investigator was consulted if the 2 reviewers reached different decisions or when in doubt.

MAIN OUTCOMES AND MEASURES

Quantifiable CSF biomarkers.

RESULTS

A total of 167 studies met eligibility criteria, and 97 had available data and were included in the meta-analysis. These 97 studies comprised 165 biomarkers, 42 of which were quantified in 2 or more studies. CSF levels of interleukin 6 (7 studies; SMD, 0.35; 95% CI, 0.12 to 0.59; I2 = 16%), total protein (5 studies; SMD, 0.53; 95% CI, 0.35 to 0.72; I2 = 0%), and cortisol (2 studies; SMD, 1.23; 95% CI, 0.89 to 1.57; I2 = 0%) were higher in patients with unipolar depression compared with healthy control individuals, whereas homovanillic acid (17 studies; SMD, -0.26; 95% CI, -0.39 to -0.14; I2 = 11%), γ-aminobutyric acid (4 studies; SMD, -0.50; 95% CI, -0.92 to -0.08; I2 = 55%), somatostatin (5 studies; SMD, -1.49; 95% CI, -2.53 to -0.45; I2 = 91%), brain-derived neurotrophic factor (3 studies; SMD, -0.58; 95% CI, -0.97 to -0.19; I2 = 0%), amyloid-β 40 (3 studies; SMD, -0.80; 95% CI, -1.14 to -0.46; I2 = 0%), and transthyretin (2 studies; SMD, -0.82; 95% CI, -1.37 to -0.27; I2 = 0%) were lower. The remaining 33 biomarkers had nonsignificant results.

CONCLUSIONS AND RELEVANCE

The findings of this systematic review and meta-analysis point toward a dysregulated dopaminergic system, a compromised inhibitory system, hypothalamic-pituitary-adrenal axis hyperactivity, increased neuroinflammation and blood-brain barrier permeability, and impaired neuroplasticity as important factors in depression pathophysiology.

Association between hospital-diagnosed sleep disorders and suicide: a nationwide cohort study

STUDY OBJECTIVES

Sleep disorders are related to mental disorders. Yet few studies have examined their association with suicide. We examined whether males and females diagnosed with sleep disorders had higher rates of suicide than individuals not diagnosed with sleep disorders.

METHODS

In a cohort study, nationwide data on all males and females aged over 15 years living in Denmark during 1980-2016 were analyzed. Sleep disorders were identified through diagnoses recorded during contacts to somatic hospitals. Incidence rate ratios (IRR) were estimated using Poisson regression models and adjusted for covariates.

RESULTS

In all, 3 674 563 males and 3 688 164 females were included, of whom 82 223 (2.2%, mean age: 50.2 years, SD: 17.5) males and 40 003 (1.1%, mean age: 50.6 years, SD: 19.9) females had sleep disorder diagnoses. Compared with those with no sleep disorders, the adjusted IRR for suicide were 1.6 (95% CI, 1.4 to 1.7) and 2.2 (95% CI, 1.8 to 2.6) for males and females with sleep disorders, respectively. Excess rates for narcolepsy were found for males (IRR: 1.2, 95% CI, 1.0 to 1.5) and females (IRR: 3.3, 95% CI, 3.0 to 4.1), and for sleep apnea in males (IRR: 1.8, 95% CI, 1.5 to 2.2). A difference with respect to age and sex was observed (p < 0.001) between males and females. Males and females had IRR of 4.1 (95% CI, 3.1 to 5.5) and 7.0 (95% CI, 4.8 to 10.1), during the first 6 months after being diagnosed with a sleep disorder.

CONCLUSIONS

Sleep disorders were associated with higher suicide rates even after adjusting for preexisting mental disorders. Our findings suggest attention toward suicidality in patients with sleep disorders is warranted.

Preclinical animal models of mental illnesses to translate findings from the bench to the bedside: Molecular brain mechanisms and peripheral biomarkers associated to early life stress or immune challenges

Animal models are useful preclinical tools for studying the pathogenesis of mental disorders and the effectiveness of their treatment. While it is not possible to mimic all symptoms occurring in humans, it is however possible to investigate the behavioral, physiological and neuroanatomical alterations relevant for these complex disorders in controlled conditions and in genetically homogeneous populations. Stressful and infection-related exposures represent the most employed environmental risk factors able to trigger or to unmask a psychopathological phenotype in animals. Indeed, when occurring during sensitive periods of brain maturation, including pre, postnatal life and adolescence, they can affect the offspring's neurodevelopmental trajectories, increasing the risk for mental disorders. Not all stressed or immune challenged animals, however, develop behavioral alterations and preclinical animal models can explain differences between vulnerable or resilient phenotypes. Our review focuses on different paradigms of stress (prenatal stress, maternal separation, social isolation and social defeat stress) and immune challenges (immune activation in pregnancy) and investigates the subsequent alterations in several biological and behavioral domains at different time points of animals' life. It also discusses the "double-hit" hypothesis where an initial early adverse event can prime the response to a second negative challenge. Interestingly, stress and infections early in life induce the activation of the hypothalamic-pituitary-adrenal (HPA) axis, alter the levels of neurotransmitters, neurotrophins and pro-inflammatory cytokines and affect the functions of microglia and oxidative stress. In conclusion, animal models allow shedding light on the pathophysiology of human mental illnesses and discovering novel molecular drug targets for personalized treatments.

Effectiveness of medical treatment for bipolar disorder regarding suicide, self-harm and psychiatric hospital admission: between- and within-individual study on Danish national data

BACKGROUND

Mood stabilisers are the main treatment for bipolar disorder. However, it is uncertain which drugs have the best outcomes.

AIMS

To investigate whether rates of suicide, self-harm and psychiatric hospital admission in individuals with bipolar disorder differ between mood stabilisers.

METHOD

A cohort design was applied to people aged ≥15 years who were diagnosed with bipolar disorder and living in Denmark during 1995-2016. Treatment with lithium, valproate, other mood stabilisers and antipsychotics were compared in between- and within-individual analyses, and adjusted for sociodemographic characteristics and previous self-harm.

RESULTS

A total of 33 337 individuals with bipolar disorder were included (266 900 person-years). When compared with individuals not receiving treatment, those receiving lithium had a lower rate of suicide (hazard ratio 0.40, 95% CI 0.31-0.51). When comparing treatment and non-treatment periods in the same individuals, lower rates of self-harm were found for lithium (hazard ratio 0.74, 95% CI 0.61-0.91). Lower rates of psychiatric hospital admission were found for all drug categories compared with non-treatment periods in within-individual analyses (P<0.001). The low rates of self-harm and hospital admission for lithium in within-individual analyses were supported by results of between-individual analyses.

CONCLUSIONS

Lithium was associated with lower rates of suicide, self-harm and psychiatric hospital readmission in all analyses. With respect to suicide, lithium was superior to no treatment. Although confounding by indication cannot be excluded, lithium seems to have better outcomes in the treatment of bipolar disorder than other mood stabilisers.

[Digital innovation provides new perspectives in psychiatry]

Digital health technology is promising for improving mental healthcare by enabling continuous monitoring of behaviour by smartphones and wearables, new paradigms for testing in virtual reality, and analysis of big data through machine learning for prediction models. This might advance prevention efforts, and contribute to diagnostics and treatment; however, high quality studies of clinical effects and applicability are needed before implementation. In this review, we summarize the current status of the field relevant for a Danish mental healthcare setting, and comment on challenges.

Neuroimmunological investigations of cerebrospinal fluid in patients with recent onset depression - a study protocol

BACKGROUND

A proinflammatory response has been suggested to be involved in the pathophysiology of depression in a subgroup of patients. However, comprehensive largescale studies on neuroimmunological investigations of the cerebrospinal fluid (CSF) are lacking and no largescale longitudinal CSF studies comparing patients with depression to healthy controls currently exist.

METHODS

A longitudinal case-control study including at least 100 patients with first time depression (ICD-10: F32) within the past year with ongoing symptoms and at least 100 sex and age matched healthy controls with collection of CSF, blood, and fecal samples. All individuals will be evaluated by neurological examination including neurological soft signs, interviewed for psychopathology assessment and have symptomatology evaluated by relevant rating scales. Level of functioning and quality of life will be evaluated by a panel of interview questions and rating scales, and cognitive function assessed by a relevant test battery. In addition, a large number of potential confounders will be registered (BMI, smoking status, current medication etc.). Primary outcomes: CSF white cell count, CSF/serum albumin ratio, CSF total protein levels, IgG index, CSF levels of IL-6 and IL-8, and the prevalence of any CNS-reactive autoantibody in CSF and/or blood.

SECONDARY OUTCOMES

exploratory analyses of a wide range of neuroimmunological markers and specific autoantibodies. Power calculations are computed for all primary outcomes based on previous CSF studies including patients with depression and healthy controls.

DISCUSSION

This study will represent the hitherto largest investigation of CSF in patients with recent onset depression compared to healthy controls. We expect to elucidate neuroimmunological alterations in individuals with depression and characterize an immunological profile paving the way for the development of effective treatments based on biomarkers.

TRIAL REGISTRATION

The study is approved by The Regional Committee on Health Research Ethics (Capital Region, j.no: H-16030985) and The Danish Data Protection Agency (j.no: RHP-2016-020, I-Suite no.: 04945).

Need for improved diabetes support among people with psychiatric disorders and diabetes treated in psychiatric outpatient clinics: results from a Danish cross-sectional study

INTRODUCTION

People with psychiatric disorders have increased risk of premature death partly due to diabetes. This study aims to explore the quality of diabetes care, diabetes management, diabetes support and well-being of people with psychiatric disorders and diabetes.

RESEARCH DESIGN AND METHODS

A total of 107 participants aged ≥18 years with diabetes and psychiatric disorders treated at psychiatric outpatient clinics in Denmark were recruited from August 2018 to June 2019. This descriptive cross-sectional study includes data from medical records on quality of diabetes care (eg, level and annual examination of hemoglobin A1c (HbA_1c)) and questionnaires on diabetes management (measured on items from the Summary of Diabetes Self-Care Activities Scale and diabetes distress based on Problem Areas in Diabetes Scale (PAID-5)), diabetes support (no, some or high support from eight potential support persons and experience of care actions measured on items from Patient Assessment of Chronic Illness Care) and well-being (WHO 5-Item Scale and self-rated general health).

RESULTS

The mean age was 52 years, 56% were men, the mean body mass index was 31.9 kg/m², the median HbA_1c was 53 mmol/mol (7.0%) and the mean blood pressure was 131/83 mm Hg. The proportion with annual measurements of HbA_1c was 93%, blood pressure 80%, cholesterol 93%, foot examination 77% and eye examination 75%. Fifty-one per cent had high diabetes distress (PAID-5 score ≥8). Diabetologists and general practitioners (39% and 37%) were the health professionals most frequently reported to provide high diabetes support.

CONCLUSIONS

This study highlights a need for improved diabetes support in people with psychiatric disorders and diabetes. Although a high proportion received appropriate diabetes care, we found high levels of diabetes distress, moderate levels of optimal self-management behaviors, low well-being and low diabetes support from psychiatric health professionals, while one-third of the population found it relevant to receive diabetes support from psychiatric health professionals.

Psychiatric Admissions, Referrals, and Suicidal Behavior Before and During the COVID-19 Pandemic in Denmark: A Time-Trend Study

OBJECTIVE

To assess the patterns in psychiatric admissions, referrals, and suicidal behavior before and during the COVID-19 pandemic.

METHODS

This study utilized health records from hospitals and Emergency Medical Services (EMS) covering 46% of the Danish population (n = 2,693,924). In a time-trend study, we compared the number of psychiatric in-patients, referrals to mental health services and suicidal behavior in years prior to the COVID-19 pandemic to levels during the first lockdown (March 11 - May 17, 2020), inter-lockdown period (May 18 - December 15, 2020), and second lockdown (December 16, 2020 - February 28, 2021).

RESULTS

During the pandemic, the rate of psychiatric in-patients declined compared to pre-pandemic levels (RR = 0.95, 95% CI = 0.94 - 0.96, p < 0.01), with the largest decrease of 19% observed three weeks into the first lockdown. Referrals to mental health services were not significantly different (RR = 1.01, 95% CI = 0.92 - 1.10, p = 0.91) during the pandemic; neither was suicidal behavior among hospital contacts (RR = 1.04, 95% CI = 0.94 - 1.14, p = 0.48) nor EMS contacts (RR = 1.08, 95% CI = 1.00 - 1.18, p = 0.06). Similar trends were observed across nearly all age groups, sexes, and types of mental disorders examined. In the age group <18, an increase in the rate of psychiatric in-patients (RR = 1.11, 95% CI = 1.07 - 1.15, p < 0.01) was observed during the pandemic; however, this did not exceed the pre-pandemic, upwards trend in psychiatric hospitalizations in the age group <18 (p = 0.78).

CONCLUSION

The COVID-19 pandemic has been associated with a decrease in psychiatric hospitalizations, while no significant change was observed in referrals to mental health services and suicidal behavior. Psychiatric hospitalizations among children and adolescents increased during the pandemic; however, this appears to be a continuation of a pre-pandemic trend.

Associations between patterns in comorbid diagnostic trajectories of individuals with schizophrenia and etiological factors

Schizophrenia is a heterogeneous disorder, exhibiting variability in presentation and outcomes that complicate treatment and recovery. To explore this heterogeneity, we leverage the comprehensive Danish health registries to conduct a prospective, longitudinal study from birth of 5432 individuals who would ultimately be diagnosed with schizophrenia, building individual trajectories that represent sequences of comorbid diagnoses, and describing patterns in the individual-level variability. We show that psychiatric comorbidity is prevalent among individuals with schizophrenia (82%) and multi-morbidity occur more frequently in specific, time-ordered pairs. Three latent factors capture 79% of variation in longitudinal comorbidity and broadly relate to the number of co-occurring diagnoses, the presence of child versus adult comorbidities and substance abuse. Clustering of the factor scores revealed five stable clusters of individuals, associated with specific risk factors and outcomes. The presentation and course of schizophrenia may be associated with heterogeneity in etiological factors including family history of mental disorders.

Cerebrospinal fluid test results and associations with subsequent mental disorders, neurological diseases, and CNS infections: A population-based cohort study

BACKGROUND

Cerebrospinal fluid (CSF) immune alterations have been associated with mental disorders, neurological disease, and CNS infections; however, comprehensive large-scale longitudinal CSF studies are lacking.

METHODS

By using the Clinical Laboratory Information System (LABKA) Research Database in the Central Denmark Region (1994-2012), we included 15,030 individuals tested for CSF WBC, CSF/serum albumin ratio, IgG index, total protein, albumin, or IgG with follow-up for the risk of mental disorders, psychotropic prescriptions, neurological diseases, or CNS infections, estimated by Cox regression.

RESULTS

Among individuals receiving a mental disorder diagnosis (N = 1,147) after a CSF test, 30·0% had an abnormal CSF test result, while for those with a neurological disease (N = 3,201), 39·9% had abnormal test results, and among individuals with CNS infections (N = 1,276), 73·0% had abnormal test results. Individuals with abnormal CSF test results had an increased risk of mental disorders (HR = 3·20; 95%CI = 2·86-3·59), neurological diseases (HR = 12·40; 95%CI = 11·65-13·20), and CNS infections (HR = 338·59; 95%CI = 299·06-383·35) compared to individuals not registered with a CSF test. However, the risk of mental disorders was higher (P < 0·001) after CSF test results within the normal range (HR = 4·45; 95%CI = 4·08-4·86), whereas for neurological diseases (HR = 9·72; 95%CI = 9·19-10·29) and CNS infections (HR = 55·17; 95%CI = 47·12-64·60), the risk was highest after abnormal CSF test results (all P < 0·001). The risk of organic mental disorders tended to be highest in individuals with abnormal CSF test results (HR = 19·30; 95%CI = 13·44-27·71) even though not significantly different from the risk in the group of individuals with CSF test results in the normal range (HR = 13·55; 95%CI = 9·36-19·60) (P ≥ 0·05). Abnormal CSF test results were associated with an elevated risk of psychotropic prescriptions (HR = 3·91; 95%CI = 3·66-4·18), as were CSF test results within the normal range (HR = 4·26; 95%CI = 4·03-4·51) (P < 0·05).

CONCLUSIONS

Immunological CSF abnormalities are associated with an increased risk of mental disorders, neurological disease, and particularly CNS infections; however, the included CSF parameters were not specific for mental disorders and the relevant CSF biomarkers in psychiatry are yet to be discovered.

Number of traumatic brain injuries and temporal associations with depression: A register-based cohort study

OBJECTIVE

To explore the association of the number of traumatic brain injuries (TBIs) and temporal associations with the subsequent risk of depression in the population.

METHODS

National register-based cohort study on all individuals registered with TBI (ICD-10: S06, ICD-8: 85.0-85.5) from 1977 to 2015 in Denmark (n = 494,216) and a sex- and age-matched reference population (n = 499,505). The associations with the number of TBIs and time to depression (0-6, 7-12 and more than 12 months following TBI) were analyzed using Cox proportional hazard regression.

RESULTS

During a follow-up of mean 14.5 (SD 11.3) years, a total of 27,873 (5.6%) individuals who had at least one TBI and 15,195 (3.0%) in the reference population were diagnosed with a depression. First-time TBI was associated with a higher risk of depression in both men (HR = 1.73 [95% CI:1.67-1.79]) and women (HR = 1.66 [95% CI:1.61-1.70]) after multiple adjustments for educational status and comorbidities including previous depression, and the association became stronger in a dose-response association with the number of TBIs (test for trend p < 0.01). The HRs for depression were highest the first 6 months after the TBI in both men (HR = 5.69 [95% CI:4.66-6.94]) and women (HR = 4.55 [95% CI:3.93-5.26]) and decreased gradually the following year but remained elevated from one year after TBI until end of follow-up independent of the number of TBIs (p < 0.01). The associations did not vary with age or calendar time.

CONCLUSION

Traumatic brain injury is associated with a higher risk of depression, especially in the first months after TBI and the risk increases with the number of TBIs.

Immunological investigations of the cerebrospinal fluid in patients with recent onset psychotic disorders: A study protocol

BACKGROUND

Though many previous studies have indicated immunological alterations in psychotic disorders, the role and prevalence of neuroinflammation is still unknown. Studies previously investigating immune related biomarkers in the cerebrospinal fluid (CSF) of these patients are mainly small studies on few markers, and many have not compared patients to healthy controls.

METHODS

We will conduct a large case-control study including at least 100 patients with recent onset psychotic disorders and 100 sex- and age matched healthy controls. The cases will include patients diagnosed with a psychotic disorder according to ICD-10 (F20/F22-29) within a year prior to inclusion. We will collect both CSF, blood and fecal samples, to gain insight into possible immunological alterations. The psychopathology of all participants will thoroughly be evaluated using the SCAN interview, and multiple rating scales covering different symptom groups. All participants will partake in a detailed neurological examination, including the Neurological Evaluation Scale assessing neurological soft signs. Additionally, we will assess cognitive functioning, evaluate quality of life and level of functioning, and collect data on a broad array of possible confounders. Our primary outcomes will include CSF leucocytes, CSF/serum albumin ratio, CSF total protein, IgG index, CSF levels of IL-6 and IL-8, and presence of antineuronal autoantibodies in CSF and blood. For our secondary outcomes, exploratory analyses will be performed on a broader panel of neuroimmunological markers. All participants will be invited for a follow-up visit to assess longitudinal changes. The current study is part of a larger CSF biobank build-up for severe mental disorders (PSYCH-FLAME).

DISCUSSION

This study will represent the largest investigation of CSF in patients with psychotic disorders compared to healthy controls to date. We expect the study to contribute with new, important knowledge on pathophysiological mechanisms, and to help pave the way for future investigations of individualized treatment options.

TRIAL REGISTRATION

The study is approved by The Regional Committee on Health Research Ethics (Capital Region, j.no: H-16030985) and The Danish Data Protection Agency (j.no: RHP-2016-020, I-Suite no.: 04945).

Conditioned pain modulation and pain sensitivity in functional somatic disorders: The DanFunD study

Background

Disrupted pain regulation has been proposed as a component in functional somatic disorders (FSD). The objective of this study was to examine a general population sample, encompassing three delimitations of FSD while assessing pain sensitivity and conditioning pain modulation (CPM).

Methods

Pressure pain thresholds (PPTs) at the tibialis and trapezius muscles were recorded at baseline. During cold pressor stimulation of the hand, the tibialis PPTs were re‐assessed and the difference from baseline measures defined the CPM effect. Participants (n = 2,198, 53% females) were randomly selected from the adult Danish population. FSD was established by self‐reported symptom questionnaires.

Results

With a few exceptions, only weak associations were seen between PPTs and CPM in cases with FSD (p > .1). A high PPT was associated with lower odds of having multi‐organ bodily distress syndrome (OR^{PPT trapezius}: 0.66, 95% CI: 0.49–0.88, p = .005), with the symptom profile characterized by all symptoms (OR^{PPT trapezius}: 0.72, 95% CI: 0.58–0.90, p = .003 and OR^{PPT tibialis}: 0.75, 95% CI: 0.62–0.91, p = .004), and with multiple chemical sensitivity (OR^{PPT trapezius}: 0.81, 95% CI: 0.67–0.97, p = .022). High CPM was associated with high odds of having irritable bowel (OR^{CPM relative}: 1.22, 95% CI: 1.04–1.43, p = .013 and OR^{CPM absolute} = 2.66, 95% CI: 1.07–6.45, p = .033).

Conclusion

However, only PPT measured over the trapezius muscle were still significant after correction for multiple testing for the symptom profile characterized by all symptoms. Findings from this study do not support altered pain regulation in questionnaire‐based FSD which is in contrast with the existing presumption. Further epidemiological studies in this field are needed.

Significance

Disrupted pain regulation as measured by abnormal pain thresholds has been hypothesized as a central mechanism in Functional Somatic Disorders (FSD). The hypothesis has been raised in clinical setting where patients presented subjective and objective features of hypersensitivity. The present population‐based study does not support this notion. This points to the importance of further studies into the underlying pathophysiology mechanisms of FSD.

The impact of the Covid-19 pandemic on mental and physical health in Denmark - a longitudinal population-based study before and during the first wave

BACKGROUND

In the continuation of the first wave of the Covid-19 outbreak in Denmark, unprecedented restrictions with great impact on the citizen's everyday life were implemented. The objectives of this study were to investigate the influence of the Covid-19 pandemic on mental and physical health in the Danish population during the spring 2020 first wave outbreak and lockdown.

METHODS

A sample from the adult Danish population (n = 2190) were included. Self-reported measures of illness worry (Whiteley-6-R), emotional distress (SCL-90), and physical symptom load (SLC-90) were obtained before and during the first wave of the pandemic and compared with Wilcoxon signed-rank tests. Impact of covariates on physical and mental health was evaluated with ordinal regression analyses. Results from a tailored questionnaire regarding the Covid-19 pandemic were presented to explore the direct impact of the pandemic.

RESULTS

We only found minor increases in illness worry, emotional distress and physical symptom load (0-1 points difference, p ≤ 0.007) during the Covid-19 pandemic compared to before the pandemic. Sex, age, education, and physical disease were not associated with illness worry, emotional distress, or physical symptom load. Overall, the participants were trustful in the authorities' recommendations and felt that they managed the pandemic and the restrictions to a great extent despite that some expected great/major future consequences of the pandemic.

CONCLUSIONS

This study suggested that the first wave of the Covid-19 pandemic only had minor impact on mental and physical health in the Danish general population. Future studies should address the impact of the second wave of the pandemic and the renewed implementation of the concomitant restrictions.

Detection of illness worry in the general population: A specific item on illness rumination improves the Whiteley Index

OBJECTIVE

The Whiteley Index (WI) is the most widely used screening tool for health anxiety/illness worry. Diverse versions (different number of items and factors) have been used. We aimed to examine psychometric properties of 7 items of the WI besides adding a new item on obsessive illness rumination for better future detection of health anxiety.

METHODS

Data from a large population-based study in Denmark (N = 9656). Construct validity was examined by exploratory (EFA) and confirmatory factor analysis (CFA) plus hypothesis testing. Criterion validity was evaluated via Receiver Operating Characteristic curves and area under the curve (AUC) using a diagnostic criterion as gold standard.

RESULTS

Factor loadings of EFA revealed viable one-factor models (6, 7, or 8 items) and two-factor models (7 or 8 items). Factor one indicated a dimension of illness worry. Factor two indicated a somatic symptoms dimension. The new item on obsessive illness rumination merged well with the existing items. EFA of two-factor models and one-factor 6-item model showed good fit. CFA resembles these findings. A one-factor 6-item model (including the item on obsessive illness rumination and excluding two items concerning somatic symptoms) was chosen as the optimal model and presented good criterion validity: AUC 0.88 (95%CI(0.84;0.92)). Main hypotheses concerning associations with somatic symptoms, anxiety, and depression were met.

CONCLUSIONS

We found good psychometric properties for a new one-factor 6-item version of the WI. Through elimination of items concerning somatic symptoms and inclusion of obsessive illness rumination, we propose a clear, unidimensional and improved measure of illness worry: Whiteley-6-R.

COVID-19 pandemic and mental health consequences: Systematic review of the current evidence

BACKGROUND

During the COVID-19 pandemic general medical complications have received the most attention, whereas only few studies address the potential direct effect on mental health of SARS-CoV-2 and the neurotropic potential. Furthermore, the indirect effects of the pandemic on general mental health are of increasing concern, particularly since the SARS-CoV-1 epidemic (2002-2003) was associated with psychiatric complications.

METHODS

We systematically searched the database Pubmed including studies measuring psychiatric symptoms or morbidities associated with COVID-19 among infected patients and among none infected groups the latter divided in psychiatric patients, health care workers and non-health care workers.

RESULTS

A total of 43 studies were included. Out of these, only two studies evaluated patients with confirmed COVID-19 infection, whereas 41 evaluated the indirect effect of the pandemic (2 on patients with preexisting psychiatric disorders, 20 on medical health care workers, and 19 on the general public). 18 of the studies were case-control studies/compared to norm, while 25 of the studies had no control groups. The two studies investigating COVID-19 patients found a high level of post-traumatic stress symptoms (PTSS) (96.2%) and significantly higher level of depressive symptoms (p = 0.016). Patients with preexisting psychiatric disorders reported worsening of psychiatric symptoms. Studies investigating health care workers found increased depression/depressive symptoms, anxiety, psychological distress and poor sleep quality. Studies of the general public revealed lower psychological well-being and higher scores of anxiety and depression compared to before COVID-19, while no difference when comparing these symptoms in the initial phase of the outbreak to four weeks later. A variety of factors were associated with higher risk of psychiatric symptoms and/or low psychological well-being including female gender, poor-self-related health and relatives with COVID-19.

CONCLUSION

Research evaluating the direct neuropsychiatric consequences and the indirect effects on mental health is highly needed to improve treatment, mental health care planning and for preventive measures during potential subsequent pandemics.

Correction to: Psychiatric comorbidity in individuals with bullous pemphigoid and all bullous disorders in the Danish national registers

An amendment to this paper has been published and can be accessed via the original article.

Blood-brain barrier pathology in patients with severe mental disorders: a systematic review and meta-analysis of biomarkers in case-control studies

Background

Blood-brain barrier (BBB) pathology may be associated with mental disorders. The aim of this systematic review and meta-analysis is to identify, evaluate and summarize available evidence on whether potential biomarkers of BBB pathology are altered in patients with schizophrenia spectrum disorders, major depression and bipolar disorder compared to healthy controls.

Methods

The primary outcome is blood S100B, while secondary outcomes include biomarkers in blood and/or cerebrospinal fluid, i.e. albumin ratio, fibrinogen, immunoglobulin G, glial fibrillary acidic protein, amyloid beta (Aβ), matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases, endothelial glycocalyx constituents, and cell adhesion molecules (CAMs). A systematic search in PubMed, Embase and PsycINFO resulted in 131 eligible studies, of which 93 were included in the meta-analysis. Meta- and subgroup analyses were undertaken using random-effects modelling. The protocol was a priori registered on PROSPERO (CRD42020152721).

Results

S100B was increased in schizophrenia spectrum disorders (24 studies; 1107 patients; standardized mean difference (SMD) ​= ​0.82; 95% confidence interval (CI) ​= ​0.51 to 1.13; I² ​= ​90%), major depression (13 studies; 584 patients; SMD ​= ​0.57; 95% CI ​= ​0.31 to 0.83; I² ​= ​73%) and bipolar disorder (4 studies; 142 patients; SMD ​= ​0.55; 95% CI ​= ​0.16 to 0.94; I² ​= ​48%). Similarly, numerous secondary outcomes, including albumin ratio, fibrinogen, Aβ, MMPs and CAMs, were altered. Results of the included studies varied considerably, and important confounders were often not accounted for.

Conclusions

The findings implicate occurrence of BBB pathology in patients with schizophrenia spectrum disorders, major depression and bipolar disorder compared to healthy controls. However, definite conclusions cannot be drawn, mainly because the investigated biomarkers are indirect measures of BBB pathology.

•

The blood-brain barrier (BBB) can be studied indirectly through markers in blood and CSF.

•

Markers of BBB pathology were altered in schizophrenia, depression and bipolar disorder.

•

The findings implicate occurrence of BBB pathology in patients compared to controls.

•

BBB pathology is expected to contribute to the pathogenesis of severe mental disorders.

Infections as a Risk Factor for and Prognostic Factor After Substance-Induced Psychoses

OBJECTIVE

Previous studies have suggested that infections increase the risk of schizophrenia. In this study, the authors aimed to investigate 1) whether infections increase the risk of substance-induced psychosis, and 2) whether infections increase the risk of converting from substance-induced psychosis to schizophrenia.

METHODS

The study data were drawn from the combined nationwide Danish registers and included all people born in Denmark since 1981. The authors used Cox proportional hazards regression with infections as time-varying covariates, estimating hazard ratios and 95% confidence intervals. Infections were operationalized both as any infection and by the site of infection.

RESULTS

The study included 2,256,779 individuals, for whom 3,618 cases of incident substance-induced psychosis were recorded. Any infection increased the risk of substance-induced psychosis (hazard ratio=1.30, 95% CI=1.22-1.39). For the first 2 years, the risk was doubled. Hepatitis was the infection most strongly associated with substance-induced psychosis (hazard ratio=3.42, 95% CI=2.47-4.74). Different types of infections were linked with different types of substance-induced psychosis. Most associations remained significant after controlling for potential confounders, such as substance use disorders. Only hepatitis predicted conversion to schizophrenia after substance-induced psychosis (hazard ratio=1.87, 95% CI=1.07- 3.26).

CONCLUSIONS

The study results support the hypothesis of an immunological component to psychosis.

Association Between Neurological Disorders and Death by Suicide in Denmark

IMPORTANCE

Neurological disorders have been linked to suicide, but the risk across a broad spectrum of neurological disorders remains to be assessed.

OBJECTIVES

To examine whether people with neurological disorders die by suicide more often than other people and to assess for temporal associations.

DESIGN, SETTING, AND PARTICIPANTS

Nationwide, retrospective cohort study on all persons 15 years or older living in Denmark, from 1980 through 2016 (N = 7 300 395).

EXPOSURES

Medical contact for head injury, stroke, epilepsy, polyneuropathy, diseases of myoneural junction, Parkinson disease, multiple sclerosis, central nervous system infections, meningitis, encephalitis, amyotrophic lateral sclerosis, Huntington disease, dementia, intellectual disability, and other brain diseases from 1977 through 2016 (n = 1 248 252).

MAIN OUTCOMES AND MEASURES

Death by suicide during 1980-2016. Adjusted incidence rate ratio (IRRs) were estimated using Poisson regressions, adjusted for sociodemographics, comorbidity, psychiatric diagnoses, and self-harm.

RESULTS

Of the more than 7.3 million individuals observed over 161 935 233 person-years (49.1% males), 35 483 died by suicide (median duration of follow-up, 23.6 years; interquartile range, 10.0-37.0 years; mean age, 51.9 years; SD, 17.9 years). Of those, 77.4% were males, and 14.7% (n = 5141) were diagnosed with a neurological disorder, equivalent to a suicide rate of 44.0 per 100 000 person-years compared with 20.1 per 100 000 person-years among individuals not diagnosed with a neurological disorder. People diagnosed with a neurological disorder had an adjusted IRR of 1.8 (95% CI, 1.7-1.8) compared with those not diagnosed. The excess adjusted IRRs were 4.9 (95% CI, 3.5-6.9) for amyotrophic lateral sclerosis, 4.9 (95% CI, 3.1-7.7) for Huntington disease, 2.2 (95% CI, 1.9-2.6) for multiple sclerosis, 1.7 (95% CI, 1.6-1.7) for head injury, 1.3 (95% CI, 1.2-1.3) for stroke, and 1.7 (95% CI, 1.6-1.8) for epilepsy. The association varied according to time since diagnosis with an adjusted IRR for 1 to 3 months of 3.1 (95% CI, 2.7-3.6) and for 10 or more years, 1.5 (95% CI, 1.4 to 1.6, P < .001). Compared with those who were not diagnosed with a neurological disorder, those with dementia had a lower overall adjusted IRR of 0.8 (95% CI, 0.7-0.9), which was elevated during the first month after diagnosis to 3.0 (95% CI, 1.9-4.6; P < .001). The absolute risk of suicide for people with Huntington disease was 1.6% (95% CI, 1.0%-2.5%).

CONCLUSIONS AND RELEVANCE

In Denmark from 1980 through 2016, there was a significantly higher rate of suicide among those with a diagnosed neurological disorder than persons not diagnosed with a neurological disorder. However, the absolute risk difference was small.

Efficacy of anti-inflammatory treatment on major depressive disorder or depressive symptoms: meta-analysis of clinical trials

BACKGROUND

No study has gathered evidence from all randomized clinical trials (RCTs) with anti-inflammatory drugs measuring antidepressant effects including a detailed assessment of side-effects and bias.

METHODS

We performed a systematic review identifying RCTs published prior to January 1, 2018, studying antidepressant treatment effects and side-effects of pharmacological anti-inflammatory intervention in adults with major depressive disorder (MDD) or depressive symptoms. Outcomes were depression scores after treatment, remission, response, and side-effects. Pooled standard mean differences (SMD) and risk ratios (RR) including 95% confidence intervals (95%-CI) were calculated.

RESULTS

We identified 36 RCTs, whereof 13 investigated NSAIDs (N = 4214), 9 cytokine inhibitors (N = 3345), seven statins (N = 1576), 3 minocycline (N = 151), 2 pioglitazone (N = 77), and 2 glucocorticoids (N = 59). Anti-inflammatory agents improved depressive symptoms compared to placebo as add-on in patients with MDD (SMD = -0.64; 95%-CI = -0.88, -0.40; I²  = 51%; N = 597) and as monotherapy (SMD = -0.41; 95%-CI = -0.60, -0.22; I²  = 93%, N = 8825). Anti-inflammatory add-on improved response (RR = 1.76; 95%-CI = 1.44-2.16; I²  = 16%; N = 341) and remission (RR = 2.14; 95%-CI = 1.03-4.48; I²  = 57%; N = 270). We found a trend toward an increased risk for infections, and all studies showed high risk of bias.

CONCLUSION

Anti-inflammatory agents improved antidepressant treatment effects. Future RCTs need to include longer follow-up, identify optimal doses and subgroups of patients that can benefit from anti-inflammatory intervention.

Autoimmune Diseases and Psychotic Disorders

The notion of immunological pathways playing a role in the etiology of a subset of psychotic disorders has received increased interest in the last decades. One of the findings that has spiked interest herein, is an apparent link between autoimmune diseases and psychotic disorders. This is supported by genetic findings associating immune-related genetic markers with schizophrenia and clinical studies finding increased levels of inflammatory markers in patients with psychosis. Several large-scale epidemiologic studies have found positive associations between autoimmune diseases and psychosis. Particularly, autoimmune diseases as multiple sclerosis and lupus are known to have higher frequencies of neuropsychiatric symptoms, including psychosis, compared to healthy controls. Cross sectional studies have found higher prevalence of psychiatric diagnoses among those with autoimmune diseases, and longitudinal studies have shown bidirectional associations between several autoimmune diseases and increased risks associated with schizophrenia. Moreover, a family history of autoimmune diseases has been shown to be associated with an increased risk of psychotic disorders and vice versa. In this review we will summarize the epidemiologic evidence on associations between autoimmune diseases and psychosis. Possible mechanisms accountable for the association will be discussed, amongst others the probable role of shared genetic risk factors, the impact of infections on both autoimmunity and the development of psychotic disorders, and the potential role of the microbiome. We discuss the findings on and influence of autoantibodies and dysregulation of T- and B-cells in both disease categories, and why further research hereon is needed. In addition to the potential importance of autoimmunity in etiological mechanisms of psychotic disorders, the association also brings important attention to somatic comorbidity in patients with psychotic disorders.

Cerebrospinal fluid markers of inflammation and infections in schizophrenia and affective disorders: a systematic review and meta-analysis

Infections and inflammatory processes have been associated with the development of schizophrenia and affective disorders; however, no study has yet systematically reviewed all available studies on cerebrospinal fluid (CSF) immune alterations. We aimed to systematically review the CSF immunological findings in schizophrenia spectrum and affective disorders. We identified all studies investigating CSF inflammatory markers in persons with schizophrenia or affective disorders published prior to March 23, 2017 searching PubMed, CENTRAL, EMBASE, Psychinfo, and LILACS. Literature search, data extraction and bias assessment were performed by two independent reviewers. Meta-analyses with standardized mean difference (SMD) including 95% confidence intervals (CI) were performed on case-healthy control studies. We identified 112 CSF studies published between 1942-2016, and 32 case-healthy control studies could be included in meta-analyses. Studies varied regarding gender distribution, age, disease duration, treatment, investigated biomarkers, and whether recruitment happened consecutively or based on clinical indication. The CSF/serum albumin ratio was increased in schizophrenia (1 study [54 patients]; SMD = 0.71; 95% CI 0.33-1.09) and affective disorders (4 studies [298 patients]; SMD = 0.41; 95% CI 0.23-0.60, I² = 0%), compared to healthy controls. Total CSF protein was elevated in both schizophrenia (3 studies [97 patients]; SMD = 0.41; 95% CI 0.15-0.67, I² = 0%) and affective disorders (2 studies [53 patients]; SMD = 0.80; 95% CI 0.39-1.21, I² = 0%). The IgG ratio was increased in schizophrenia (1 study [54 patients]; SMD = 0.68; 95% CI 0.30-1.06), whereas the IgG Albumin ratio was decreased (1 study [32 patients]; SMD = -0.62; 95% CI -1.13 to -0.12). Interleukin-6 (IL-6) levels (7 studies [230 patients]; SMD = 0.55; 95% CI 0.35-0.76; I² = 1%) and IL-8 levels (3 studies [95 patients]; SMD = 0.46; 95% CI 0.17-0.75, I² = 0%) were increased in schizophrenia but not significantly increased in affective disorders. Most of the remaining inflammatory markers were not significantly different compared to healthy controls in the meta-analyses. However, in the studies which did not include healthy controls, CSF abnormalities were more common, and two studies found CSF dependent re-diagnosis in 3.2-6%. Current findings suggest that schizophrenia and affective disorders may have CSF abnormalities including signs of blood-brain barrier impairment and inflammation. However, the available evidence does not allow any firm conclusion since all studies showed at least some degree of bias and vastly lacked inclusion of confounding factors. Moreover, only few studies investigated the same parameters with healthy controls and high-quality longitudinal CSF studies are lacking, including impact of psychotropic medications, lifestyle factors and potential benefits of anti-inflammatory treatment in subgroups with CSF inflammation.