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Elevated cerebrospinal fluid (CSF) levels of the glia-derived N -methyl- D -aspartic acid receptor antagonist kynurenic acid (KYNA) have consistently been implicated in schizophrenia and bipolar disorder. Here, we conducted a genome-wide association study based on CSF KYNA in bipolar disorder and found support for an association with a common variant within 1p21.3. After replication in an independent cohort, we linked this genetic variant—associated with reduced SNX7 expression—to positive psychotic symptoms and executive function deficits in bipolar disorder. A series of post-mortem brain tissue and in vitro experiments suggested SNX7 downregulation to result in a caspase-8-driven activation of interleukin-1β and a subsequent induction of the brain kynurenine pathway. The current study demonstrates the potential of using biomarkers in genetic studies of psychiatric disorders, and may help to identify novel drug targets in bipolar disorder.

Essential thrombocythemia (ET) is currently diagnosed either by the British Committee of Standards in Haematology (BCSH) criteria that are predominantly based on exclusion and not necessarily on bone marrow (BM) morphology, or the World Health Organization (WHO) criteria that require BM examination as essential criterion. We studied the morphological and clinical features in patients diagnosed according either to the BCSH ( n =238) or the WHO guidelines ( n =232). The BCSH-defined ET cohort was re-evaluated by applying the WHO classification. At presentation, patients of the BCSH group showed significantly higher values of serum lactate dehydrogenase and had palpable splenomegaly more frequently. Following the WHO criteria, the re-evaluation of the BCSH-diagnosed ET cohort displayed a heterogeneous population with 141 (59.2%) ET, 77 (32.4%) prefibrotic primary myelofibrosis (prePMF), 16 (6.7%) polycythemia vera and 4 (1.7%) primary myelofibrosis. Contrasting WHO-confirmed ET, the BCSH cohort revealed a significant worsening of fibrosis-free survival and prognosis. As demonstrated by the clinical data and different outcomes between WHO-diagnosed ET and prePMF, these adverse features were generated by the inadvertent inclusion of prePMF to the BCSH group. Taken together, the diagnosis of ET without a scrutinized examination of BM biopsy specimens will generate a heterogeneous cohort of patients impairing an appropriate clinical management.

The kynurenine pathway metabolite kynurenic acid (KYNA), modulating glutamatergic and cholinergic neurotransmission, is increased in cerebrospinal fluid (CSF) of patients with schizophrenia or bipolar disorder type 1 with psychotic features. KYNA production is critically dependent on kynurenine 3-monooxygenase (KMO). KMO mRNA levels and activity in prefrontal cortex (PFC) are reduced in schizophrenia. We hypothesized that KMO expression in PFC would be reduced in bipolar disorder with psychotic features and that a functional genetic variant of KMO would associate with this disease, CSF KYNA level and KMO expression. KMO mRNA levels were reduced in PFC of bipolar disorder patients with lifetime psychotic features ( P =0.005, n =19) or schizophrenia ( P =0.02, n =36) compared with nonpsychotic patients and controls. KMO genetic association to psychotic features in bipolar disorder type 1 was studied in 493 patients and 1044 controls from Sweden. The KMO Arg 452 allele was associated with psychotic features during manic episodes ( P =0.003). KMO Arg 452 was studied for association to CSF KYNA levels in an independent sample of 55 Swedish patients, and to KMO expression in 717 lymphoblastoid cell lines and 138 hippocampal biopsies. KMO Arg 452 associated with increased levels of CSF KYNA ( P =0.03) and reduced lymphoblastoid and hippocampal KMO expression ( P ⩽0.05). Thus, findings from five independent cohorts suggest that genetic variation in KMO influences the risk for psychotic features in mania of bipolar disorder patients. This provides a possible mechanism for the previous findings of elevated CSF KYNA levels in those bipolar patients with lifetime psychotic features and positive association between KYNA levels and number of manic episodes.

Anorexia nervosa (AN) is a severe psychiatric disorder with high mortality and, to a large extent, unknown pathophysiology. Structural brain differences, such as global or focal reductions in grey or white matter volumes, as well as enlargement of the sulci and the ventricles, have repeatedly been observed in individuals with AN. However, many of the documented aberrances normalize with weight recovery, even though some studies show enduring changes. To further explore whether AN is associated with neuronal damage, we analysed the levels of neurofilament light chain (NfL), a marker reflecting ongoing neuronal injury, in plasma samples from females with AN, females recovered from AN (AN-REC) and normal-weight age-matched female controls (CTRLS). We detected significantly increased plasma levels of NfL in AN vs CTRLS (medianAN = 15.6 pg/ml, IQRAN = 12.1–21.3, medianCTRL = 9.3 pg/ml, IQRCTRL = 6.4–12.9, and p < 0.0001), AN vs AN-REC (medianAN-REC = 11.1 pg/ml, IQRAN-REC = 8.6–15.5, and p < 0.0001), and AN-REC vs CTRLS (p = 0.004). The plasma levels of NfL are negatively associated with BMI overall samples (β (±se) = −0.62 ± 0.087 and p = 6.9‧10−12). This indicates that AN is associated with neuronal damage that partially normalizes with weight recovery. Further studies are needed to determine which brain areas are affected, and potential long-term sequelae.

Telomere shortening is a hallmark of aging and has been associated with oxidative stress, inflammation and chronic somatic, as well as psychiatric disorders, including schizophrenia and depression. Additionally, antidepressants have been found to protect against telomere shortening. However, pharmacological telomere studies are lacking in bipolar disorder (BD). Therefore, the objective of this study was to explore telomere length (TL) in patients with BD in the context of lithium treatment. We determined TL by quantitative real-time PCR using peripheral blood leukocytes. Participants were outpatients diagnosed with BD type 1 or 2 ( n =256) and healthy controls ( n =139). Retrospective case–control and case–case study designs were applied. Lithium response (LiR) was scored using the Alda-Scale. Lithium-treated BD patients overall, as well as those on lithium monotherapy, had 35% longer telomeres compared with controls ( P <0.0005, partial η 2 =0.13). TL correlated positively with lithium treatment duration of >30 months ( P =0.031, R 2 =0.13) and was negatively associated with increasing number of depressive episodes ( P <0.007). BD patients responding well to lithium treatment had longer telomeres than those not responding well. This is the first study to report a positive effect of long-term lithium treatment on TL. Importantly, longer TL was also associated with a better LiR in BD patients. These data suggest that lithium exerts a protective effect against telomere shortening especially when therapeutically efficacious. We hypothesize that induction of telomerase activity may be involved in LiR in BD.

The role of genetics for predicting the response to cognitive behavior therapy (CBT) for social anxiety disorder (SAD) has only been studied in one previous investigation. The serotonin transporter (5-HTTLPR), the catechol-o-methyltransferase (COMT) val158met, and the tryptophan hydroxylase-2 (TPH2) G-703T polymorphisms are implicated in the regulation of amygdala reactivity and fear extinction and therefore might be of relevance for CBT outcome. The aim of the present study was to investigate if these three gene variants predicted response to CBT in a large sample of SAD patients. Participants were recruited from two separate randomized controlled CBT trials (trial 1: n = 112, trial 2: n = 202). Genotyping were performed on DNA extracted from blood or saliva samples. Effects were analyzed at follow-up (6 or 12 months after treatment) for both groups and for each group separately at post-treatment. The main outcome measure was the Liebowitz Social Anxiety Scale Self-Report. At long-term follow-up, there was no effect of any genotype, or gene × gene interactions, on treatment response. In the subsamples, there was time by genotype interaction effects indicating an influence of the TPH2 G-703T-polymorphism on CBT short-term response, however the direction of the effect was not consistent across trials. None of the three gene variants, 5-HTTLPR, COMTval158met and TPH2 G-703T, was associated with long-term response to CBT for SAD. ClinicalTrials.gov (ID-NCT0056496).

Background Cognitive behavioral therapy (CBT) represents a learning process leading to symptom relief and resulting in long-term changes in behavior. CBT for panic disorder is based on exposure and exposure-based processes can be studied in the laboratory as extinction of experimentally acquired fear responses. We have recently demonstrated that the ability to extinguish learned fear responses is associated with a functional genetic polymorphism (COMTval158met) in the COMT gene and this study was aimed at transferring the experimental results on the COMTval158met polymorphism on extinction into a clinical setting. Methods We tested a possible effect of the COMTval158met polymorphism on the efficacy of CBT, in particular exposure-based treatment modules, in a sample of 69 panic disorder patients. Results We present evidence that panic patients with the COMTval158met met/met genotype may profit less from (exposure-based) CBT treatment methods as compared to patients carrying at least one val-allele. No association was found with the 5-HTTLPR/rs25531 genotypes which is presented as additional material. Conclusions We were thus able to transfer findings on the effect of the COMTval158met polymorphism from an experimental extinction study obtained using healthy subjects to a clinical setting. Furthermore patients carrying a COMT val-allele tend to report more anxiety and more depression symptoms as compared to those with the met/met genotype. Limitations of the study as well as possible clinical implications are discussed. Trial registration Clinical Trial Registry name: Internet-Versus Group-Administered Cognitive Behavior Therapy for Panic Disorder (IP2). Registration Identification number: NCT00845260, http://www.clinicaltrials.gov/ct2/show/NCT00845260

Neuropsychiatric manifestations are common in both the acute and post-acute phase of SARS-CoV-2 infection, but the mechanisms of these effects are unknown. In a newly established brain organoid model with innately developing microglia, we demonstrate that SARS-CoV-2 infection initiate neuronal cell death and cause a loss of post-synaptic termini. Despite limited neurotropism and a decelerating viral replication, we observe a threefold increase in microglial engulfment of postsynaptic termini after SARS-CoV-2 exposure. We define the microglial responses to SARS-CoV-2 infection by single cell transcriptomic profiling and observe an upregulation of interferon-responsive genes as well as genes promoting migration and synapse engulfment. To a large extent, SARS-CoV-2 exposed microglia adopt a transcriptomic profile overlapping with neurodegenerative disorders that display an early synapse loss as well as an increased incident risk after a SARS-CoV-2 infection. Our results reveal that brain organoids infected with SARS-CoV-2 display disruption in circuit integrity via microglia-mediated synapse elimination and identifies a potential novel mechanism contributing to cognitive impairments in patients recovering from COVID-19.

Fibromyalgia (FM) patients have dysfunctional endogenous pain modulation, where opioid and serotonergic signaling is implicated. The aim of this study was to investigate whether genetic variants in the genes coding for major structures in the opioid and serotonergic systems can affect pain modulation in FM patients and healthy controls (HC). Conditioned pain modulation (CPM), evaluating the effects of ischemic pain on pressure pain sensitivity, was performed in 82 FM patients and 43 HC. All subjects were genotyped for relevant functional polymorphisms in the genes coding for the μ-opioid receptor (OPRM1, rs1799971 ), the serotonin transporter (5-HTT, 5-HTTLPR / rs25531 ) and the serotonin 1a receptor (5-HT1a, rs6295) . Results showed the OPRM1 G-allele was associated with decreased CPM. A significant gene-to-gene interaction was found between the OPRM1 and the 5-HT1a gene. Reduced CPM scores were seen particularly in individuals with the OPRM1 G*/5-HT1a CC genotype, indicating that the 5-HT1a CC genotype seems to have an inhibiting effect on CPM if an individual has the OPRM1 G-genotype. Thus, regardless of pain phenotype, the OPRM1 G-allele independently as well as with an interaction with the 5-HT1a gene influenced pain modulation. FM patients had lower CPM than HC but no group differences were found regarding the genetic effects on CPM, indicating that the results reflect more general mechanisms influencing pain modulatory processes rather than underlying the dysfunction of CPM in FM. In conclusion, a genetic variant known to alter the expression of, and binding to, the my-opioid receptor reduced a subject’s ability to activate descending pain inhibition. Also, the results suggest a genetically inferred gene-to-gene interaction between the main opioid receptor and a serotonergic structure essential for 5-HT transmission to modulate pain inhibition. The results in this study highlight the importance of studying joint synergistic and antagonistic effects of neurotransmittor systems in regard to pain modulation.