Psychedelics and schizophrenia: a double-edged sword.

Psychedelics have shown promising effects in several psychiatric diseases as demonstrated by multiple clinical trials. However, no clinical experiments on patients with schizophrenia have been conducted up to date, except for some old semi-anecdotal studies mainly performed in the time-span '50s-'60s. Notably, these studies reported interesting findings, particularly on the improvement of negative symptoms and social cognition. With no doubts the lack of modern clinical studies is due to the psychomimetic properties of psychedelics, a noteworthy downside that could worsen positive symptoms. However, a rapidly increasing body of evidence has suggested that the mechanisms of action of such compounds partially overlaps with the pathogenic underpinnings of schizophrenia but in an opposite way. These findings suggest that, despite being a controversial issue, the use of psychedelics in the treatment of schizophrenia would be based on a strong biological rationale. Therefore, the aim of our perspective paper is to provide a background on the old experiments with psychedelics performed on patients with schizophrenia, interpreting them in the light of recent molecular findings on their ability to induce neuroplasticity and modulate connectivity, the immune and TAARs systems, neurotransmitters, and neurotropic factors. No systematic approach was adopted in reviewing the evidence given the difficulty to retrieve and interpret old findings. Interestingly, we identified a therapeutic potential of psychedelics in schizophrenia adopting a critical point of view, particularly on negative symptoms and social cognition, and we summarized all the relevant findings. We also identified an eligible subpopulation of chronic patients predominantly burdened by negative symptoms, outlining possible therapeutic strategies which encompass very low doses of psychedelics (microdosing), carefully considering safety and feasibility, to pave the way to future clinical trials.

Schizophrenia and psychedelic state: Dysconnection versus hyper-connection. A perspective on two different models of psychosis stemming from dysfunctional integration processes.

Psychotic symptoms are a cross-sectional dimension affecting multiple diagnostic categories, despite schizophrenia represents the prototype of psychoses. Initially, dopamine was considered the most involved molecule in the neurobiology of schizophrenia. Over the next years, several biological factors were added to the discussion helping to constitute the concept of schizophrenia as a disease marked by a deficit of functional integration, contributing to the formulation of the Dysconnection Hypothesis in 1995. Nowadays the notion of dysconnection persists in the conceptualization of schizophrenia enriched by neuroimaging findings which corroborate the hypothesis. At the same time, in recent years, psychedelics received a lot of attention by the scientific community and astonishing findings emerged about the rearrangement of brain networks under the effect of these compounds. Specifically, a global decrease in functional connectivity was found, highlighting the disintegration of preserved and functional circuits and an increase of overall connectivity in the brain. The aim of this paper is to compare the biological bases of dysconnection in schizophrenia with the alterations of neuronal cyto-architecture induced by psychedelics and the consequent state of cerebral hyper-connection. These two models of psychosis, despite diametrically opposed, imply a substantial deficit of integration of neural signaling reached through two opposite paths.

Improving outcome of treatment-resistant schizophrenia: effects of cognitive remediation therapy.

Treatment-Resistant Schizophrenia (TRS) represents a main clinical issue, associated with worse psychopathological outcomes, a more disrupted neurobiological substrate, and poorer neurocognitive performance across several domains, especially in verbal abilities. If cognitive impairment is a major determinant of patients' functional outcomes and quality of life, targeting cognitive dysfunction becomes even more crucial in TRS patients in order to minimize cognitive and functional deterioration. However, although Cognitive Remediation Therapy (CRT) represents the best available tool to treat cognitive dysfunction in schizophrenia, specific evidence of its efficacy in TRS is lacking. Based on these premises, our study aimed at investigating possible differences in CRT outcomes in a sample of 150 patients with schizophrenia, stratified according to antipsychotic response (TRS vs. non-TRS). Subjects were assessed for neurocognition through Brief Assessment of Cognition in Schizophrenia (BACS) and the Wisconsin Card Sorting Test (WCST) at baseline and after CRT. As expected, we observed greater baseline impairment among TRS patients in BACS-Verbal Memory and WCST-Executive Functions. Repeated measures ANCOVAs showed significant within-group pre-/post-CRT differences in the above-mentioned domains, both among non-TRS and TRS subjects. However, after CRT, no differences were observed between groups. This is the first study to indicate that CRT represents a highly valuable resource for TRS patients, since it may be able to fill the cognitive gap between treatment response groups. Our finding further highlights the importance of early implementation of CRT in addition to pharmacotherapy to reduce the cognitive and functional burden associated with the disease, especially for TRS patients.

Theory of mind and stereotypic behavior promote daily functioning in patients with schizophrenia.

OBJECTIVES: Functional disruption is a main feature of schizophrenia and still represents a major treatment challenge. A more in-depth identification of functional predictors is crucial for the creation of individualized rehabilitation treatments, which can translate into better functional outcomes. In this study, we aimed at pinpointing specific domains that affect different functional profiles, using a data-driven approach. METHODS: We included a comprehensive evaluation of functional predictors, namely demographic, cognitive, sociocognitive and clinical variables, with a focus on constituent subdomains of autistic symptoms that have been associated with functioning in the recent literature. RESULTS: In 123 schizophrenia patients, a two-step cluster analysis identified two groups of patients with different functional profiles (low vs high functioning). A backward stepwise logistic regression analysis showed that the odds of being a member of the high functioning group are significantly higher for individuals with (1) more years of education, (2) better Theory of Mind abilities, (3) higher levels of stereotypies/narrowed interests, (4) lower difficulties in social interaction, (5) lower communication difficulties and with (6) being male. CONCLUSION: Findings raise the intriguing possibility that stereotypic behaviors may have a beneficial effect on functioning in schizophrenia. While the underlying mechanism is currently unknown, we hypothesize that patients may benefit from contexts in which more predictive relationships between environmental entities can systematically be established. This study underscores the potential utility of routinely assessing autistic symptomatology in schizophrenia, which can be instrumental in identifying novel therapeutic targets that can be utilized to improve daily functioning.

Cognition in Schizophrenia: Modeling the Interplay between Interleukin-1ß C-511T Polymorphism, Metabolic Syndrome, and Sex.

INTRODUCTION: Cognitive deficits and metabolic disturbances are among the main determinants of functional impairment and reduced life expectancy in patients with schizophrenia, and they may share underlying biological mechanisms. Among these, interleukin-1ß (IL-1ß), a key mediator of inflammatory response, is of particular interest. IL-1ß C-511T polymorphism has been associated with neuropsychiatric conditions and, in the general population, with cognitive and metabolic alterations. This study aims to evaluate the effects of the IL-1ß C-511T polymorphism on both cognition and metabolic syndrome in a sample of patients affected by schizophrenia, with a focus on sex differences. METHODS: 138 patients with schizophrenia were assessed for metabolic parameters and neurocognitive measures by means of the Brief Assessment of Cognition Scale. The effects of IL-1ß C-511T polymorphism on cognition and metabolic syndrome were evaluated in the context of general linear models. RESULTS: The analysis showed a significant interaction between IL-1ß genotype and sex on 2 core cognitive domains. In detail, among CC homozygous, females outperformed males on processing speed, while among T carriers, males outperformed females on executive functions. A significant interaction also emerged between metabolic syndrome, sex, and IL-1ß genotype for executive functions, with worse performance for T carrier females with metabolic syndrome. No significant direct effect was observed for metabolic syndrome on cognition. CONCLUSION: These findings support the hypothesis that IL-1ß polymorphism could play a key role in mediating the complex and refined relationship between metabolic syndrome and cognitive performance.

Hemophagocytic syndrome secondary to SARS-Cov-2 infection: a case report.

BACKGROUND: Hemophagocytic syndrome (HPS) is a severe hyperinflammatory disease, whose diagnosis is based on the HLH-2004 criteria. In secondary forms of HLH (sHLH), the primary goal is treating the triggering factors such as COVID-19 (Coronavirus disease 2019). The link between the cytokine storm related to COVID-19 and development of sHLH has already been reported since the onset of pandemic, but little is known about clinical manifestations of HLH which develop after the patient's recovery from mild symptomatic or asymptomatic Sars-CoV-2 infection. CASE PRESENTATION: We describe the case of a woman diagnosed with sHLH related to previous Sars-CoV-2 infection and successfully treated with steroids, colchicine, etoposide and ruxolitinib. CONCLUSIONS: Our report suggests that HLH-like syndrome might be secondary to Sars-CoV-2 infection, even if the patient utterly recovered from the mildly symptomatic viral infection. In addition, we underline the treatment with low dose ruxolitinib plus etoposide as a potential choice for Sars-CoV-2 infection related HLH.

Structural Refinement of Carbimazole by NMR Crystallography.

The characterization of the three-dimensional structure of solids is of major importance, especially in the pharmaceutical field. In the present work, NMR crystallography methods are applied with the aim to refine the crystal structure of carbimazole, an active pharmaceutical ingredient used for the treatment of hyperthyroidism and Grave's disease. Starting from previously reported X-ray diffraction data, two refined structures were obtained by geometry optimization methods. Experimental 1H and 13C isotropic chemical shift measured by the suitable 1H and 13C high-resolution solid state NMR techniques were compared with DFT-GIPAW calculated values, allowing the quality of the obtained structure to be experimentally checked. The refined structure was further validated through the analysis of 1H-1H and 1H-13C 2D NMR correlation experiments. The final structure differs from that previously obtained from X-ray diffraction data mostly for the position of hydrogen atoms.

Proteasome inhibition in multiple myeloma: lessons for other cancers.

Cellular protein homeostasis (proteostasis) depends on the controlled degradation of proteins that are damaged or no longer required by the ubiquitin-proteasome system (UPS). The 26S proteasome is the principal executer of substrate-specific proteolysis in eukaryotic cells and regulates a myriad of cellular functions. Proteasome inhibitors were initially developed as chemical tools to study proteasomal function but rapidly became widely used anticancer drugs that are now used at all stages of treatment for the bone marrow cancer multiple myeloma (MM). Here, we review the mechanisms of action of proteasome inhibitors that underlie their preferential toxicity to MM cells, focusing on endoplasmic reticulum stress, depletion of amino acids, and effects on glucose and lipid metabolism. We also discuss mechanisms of resistance to proteasome inhibition such as autophagy and metabolic rewiring and what lessons we may learn from the success and failure of proteasome inhibition in MM for treating other cancers with proteostasis-targeting drugs.

Autologous stem cell transplantation is safe in selected elderly multiple myeloma patients.

OBJECTIVES: ASCT is currently the "gold standard" first-line treatment for multiple myeloma patients younger than 65 years old, and limited data on efficacy and safety in older patients are available. METHODS: We retrospectively analyzed a cohort of 83 newly diagnosed multiple myeloma patients aged 65 or older. All patients were evaluated for fitness at diagnosis and after bortezomib-based induction treatment. RESULTS AND CONCLUSIONS: All patients collected an adequate PBSC graft, mainly after G-CSF plus cyclophosphamide; a median of 6.47 × 106 /kg CD34 + cells was collected. The conditioning regimen consisted of melphalan 100, 140 and 200 mg/m2 in 40, 15 and 28 patients, respectively. Median time to neutrophils' and platelets' recovery was 11 and 12 days, respectively. Adverse events of any grade were referred by 40% of patients. The overall response rate was 93%, CR/sCR were 39%. Median PFS was 35 months; median OS was not reached. In our study cohort, the achievement of at least VGPR after induction therapy and the obtainment of CR/sCR after ASCT are the only parameters that were associated with an improved PFS. ASCT is an effective and safe first-line treatment approach, a careful patients selection reduce the toxicity of the procedure.

The Complete Protist Symbiont Communities of Coptotermes formosanus and Coptotermes gestroi: Morphological and Molecular Characterization of Five New Species.

Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) (Blattoidea: Rhinotermitidae) are invasive subterranean termite pest species with a major global economic impact. However, the descriptions of the mutualistic protist communities harbored in their respective hindguts remain fragmentary. The C. formosanus hindgut has long been considered to harbor three protist species, Pseudotrichonympha grassii (Trichonymphida), Holomastigotoides hartmanni, and Cononympha (Spirotrichonympha) leidyi (Spirotrichonymphida), but molecular data have suggested that the diversity may be higher. Meanwhile, the C. gestroi community remains undescribed except for Pseudotrichonympha leei. To complete the characterization of these communities, hindguts of workers from both termite species were investigated using single-cell PCR, microscopy, cell counts, and 18S rRNA amplicon sequencing. The two hosts were found to harbor intriguingly parallel protist communities, each consisting of one Pseudotrichonympha species, two Holomastigotoides species, and two Cononympha species. All protist species were unique to their respective hosts, which last shared a common ancestor ~18 MYA. The relative abundances of protist species in each hindgut differed remarkably between cell count data and 18S rRNA profiles, calling for caution in interpreting species abundances from amplicon data. This study will enable future research in C. formosanus and C. gestroi hybrids, which provide a unique opportunity to study protist community inheritance, compatibility, and potential contribution to hybrid vigor.

The assessment of minimal residual disease versus that of somatic mutations for predicting the outcome of acute myeloid leukemia patients.

BACKGROUND: In addition to morphological and cytogenetic features, acute myeloid leukemias are characterized by mutations that can be used for target-therapy; also the minimal/measurable residual disease (MRD) could be an important prognostic factor. The purpose of this retrospective study was to investigate if somatic mutations could represent an additional prognostic value in respect of MRD alone. METHOD: At baseline, 98 patients were tested for NPM1, FLT3, and for WT1 expression; 31 for ASXL1, TET2, IDH1, IDH2, N-RAS, WT1, c-KIT, RUNX1, and DNMT3A. The same genes have been also tested after induction and consolidation. RESULTS: Overall, 60.2% of our patients resulted mutated: 24.5% carried mutations of FLT3-ITD, 38.7% of NPM1, 48.4% of c-KIT, 25.8% of N-RAS and 19.3% of IDH2. The probability of achieving a complete response (CR) was higher for younger patients, with low ELN risk score, NPM1-mutated, with low WT1 levels, and without FLT3. The presence of additional mutations represented a poor predictive factor: only 19% of these cases achieved CR in comparison to 43% of subjects without any of it. Concerning survival, it was conditioned by a lower ELN risk score, younger age, reduction > 1 log of the NPM1 mutational burden, disappearance of FLT3 mutations and lower WT1 expression. Regarding the role of the additional mutations, they impaired the outcome of 20% of the already MRD-negative patients. Concerning the possibility of predicting relapse, we observed an increase of the NPM1 mutational burden at the time-point immediately preceding the relapse (about 2 months earlier) in 50% of subjects. Similarly concerning WT1, an increase of its expression anticipated disease recurrence in 64% of cases. CONCLUSIONS: We demonstrated that additional somatic mutations are able to impair outcome of the already MRD-negative subjects. About MRD, we suggest a prognostic role also for the WT1 expression. Finally, we considered as relevant the assessment of NPM1 quantity clearance instead of the presence/absence of mutations alone. Still remains in doubt the utility in terms of long-term prognosis of a baseline more complex mutational screening; we could hypothesize that it would be useful for those patients where other markers are not available or who reached the MRD negativity.

Sedimentary basins investigation using teleseismic P-wave time delays.

Passive seismic methods have been proven successful in recent years at retrieving information about the large-scale structure of a sedimentary basin. These methods are based on ambient noise recordings, and local and distant (teleseismic) earthquake data. In particular, it has been previously observed that the arrival time of teleseismic P-waves recorded inside a sedimentary basin shows time delays and polarization that both strongly depend on the basin properties and structure. In this paper, we present a new methodology for determining seismic P-wave velocity in a sedimentary basin, based on the time delay of a teleseismic P-wave travelling through the low-velocity basin infill, with respect to a teleseismic wave recorded outside the basin. The new methodology is developed in a Bayesian framework and, thus, it includes estimates of the uncertainties of the P-wave velocities. For this study, we exploit synchronous recordings of teleseismic P-wave arrivals at a dense linear array of broadband seismic stations, using data from two teleseismic events coming from two different incoming angles. The results obtained by the new proposed methodology are successfully compared to classical cross-correlation measurements, and are used to infer properties of a sedimentary basin, such as the basin bounding fault's geometry and the average P-wave velocity of the sedimentary basin fill.

Modulation of Cox-1, 5-, 12- and 15-Lox by popular herbal remedies used in southern Italy against psoriasis and other skin diseases.

Acanthus mollis (Acanthaceae), Achillea ligustica, Artemisia arborescens and Inula viscosa (Asteraceae) are used in Southern Italy against psoriasis and other skin diseases that occur with an imbalanced production of eicosanoids. We here assessed their in vitro effects upon 5-, 12-, 15-LOX and COX-1 enzymes as well as NFκB activation in intact cells as their possible therapeutic targets. All methanol crude extracts inhibited both 5-LOX and COX-1 activities under 200 µg/mL, without significant effects on the 12-LOX pathway or any relevant in vitro free radical scavenging activity. NFκB activation was prevented by all extracts but A. mollis. Interestingly, A. ligustica, A. arborescens and A. mollis increased the biosynthesis of 15(S)-HETE, an anti-inflammatory eicosanoid. A. ligustica (IC50 =49.5 µg/mL) was superior to Silybum marianum (IC50 =147.8 µg/mL), which we used as antipsoriatic herbal medicine of reference. Its n-hexane, dichloromethane and ethyl acetate fractions had also inhibitory effects on the LTB4 biosynthesis (IC50 s=9.6, 20.3 and 68 µg/mL, respectively) evidencing that the apolar extracts of A. ligustica are promising active herbal ingredients for future phytotherapeutical products targeting psoriasis.

Exploring the Effect of Resins of Different Origin on the Structure, Dynamics and Curing Characteristics of SBR Compounds.

The replacement of synthetic and petroleum-based ingredients with greener alternatives of natural origin is an imperative issue in rubber technology for the tire industry. In this study, a glycerin-esterified maleated rosin resin, derived from natural resources, is examined as a potential tackifier in styrene-butadiene rubber (SBR) formulations. A comparison is made with two synthetic resins commonly used as tackifiers in tire manufacturing: a petroleum-derived aromatic resin and a phenolic resin. Specifically, this research investigates how these resins affect the structure, dynamics, and curing characteristics of SBR compounds, which are strictly related to the mechanical and technological properties of the final products. Moving die rheometer and equilibrium swelling experiments are employed to analyze vulcanization kinetics and crosslink density, which are differently influenced by the different resins. Information on the polymer-resin compatibility is gained by differential scanning calorimetry and dynamo-mechanical analysis, while solid-state NMR methods offer insights into the structure and dynamics of both cured and uncured SBR compounds at the molecular level. Overall, our analysis shows that the resin of vegetal origin has a comparable impact on the SBR compound to that observed for the synthetic resins and could be further tested for industrial applications.

Direct Determination of Carrier Parameters in Indium Tin Oxide Nanocrystals.

We develop here a comprehensive experimental approach to independently determine charge carrier parameters, namely, carrier density and mass, in plasmonic indium tin oxide nanocrystals. Typically, in plasmonic nanocrystals, only the ratio between these two parameters is accessible through optical absorption experiments. The multitechnique methodology proposed here combines single particle and ensemble optical and magneto-optical spectroscopies, also using 119Sn solid-state nuclear magnetic resonance spectroscopy to probe the surface depletion layer. Our methodology overcomes the limitations of standard fitting approaches based on absorption spectroscopy and ultimately gives access to carrier effective mass directly on the NCs, discarding the use of literature value based on bulk or thin film materials. We found that mass values depart appreciably from those measured on thin films; consequently, we found carrier density values that are different from reported literature values for similar systems. The effective mass was found to deviate from the parabolic approximation at a high carrier density. Finally, the dopant activation and defect diagram for ITO NCs for tin doping between 2.5 and 15% are determined. This approach can be generalized to other plasmonic heavily doped semiconductor nanostructures and represents, to the best of our knowledge, the only method to date to characterize the full Drude parameter space of 0-D nanosystems.

Neuroinflammation and kynurenines in schizophrenia: Impact on cognition depending on cognitive functioning and modulatory properties in relation to cognitive remediation and aerobic exercise.

Background: In the last decade, the kynurenine pathway (KP) has gained attention in the pathogenesis of cognitive impairment in schizophrenia being at the croassroad between neuroinflammation and glutamatergic and cholinergic neurotransmission. However, clinical findings are scarse and conflicting, and the specific contributions of these two systems to the neurobiology of cognitive symptoms are far from being elucidated. Furthermore, little is known about the molecular underpinnings of non-pharmacological interventions for cognitive improvement, including rehabilitation strategies. Methods: The current study examined 72 patients with schizophrenia, divided in two clusters depending on the severity of the cognitive impairment, with the aim to evaluate the impact of inflammatory biomarkers and KP metabolites depending on cognitive functioning. Moreover, we studied their possible link to the cognitive outcome in relation to sessions of cognitive remediation therapy (CRT) and aerobic exercise (AE) in a longitudinal arm of 42 patients. Results: Neuroinflammation appeared to exert a more pronounced influence on cognition in patients exhibiting a higher cognitive functioning, contrasting with the activation of the KP, which had a greater impact on individuals with a lower cognitive profile. Cognitive improvements after the treatments were negatively predicted by levels of TNF-α and positively predicted by the 3-hydroxykynurenine (3-HK)/kynurenine (KYN) ratio, an index of the kynurenine-3-monooxygenase (KMO) enzyme activity. Conclusion: Overall, these findings add novel evidence on the biological underpinnings of cognitive impairment in schizophrenia pointing at a differential role of neuroinflammation and KP metabolites in inducing cognitive deficits depending on the cognitive reserve and predicting outcomes after rehabilitation.

Transdermal Fentanyl in Patients with Cachexia-A Scoping Review.

Cachectic patients frequently require transdermal fentanyl (TDF) for pain management, but data on its efficacy and safety are scarce and inconsistent. This scoping review aims to analyze the evidence concerning TDF administration in patients with cachexia irrespective of the underlying pathology. The primary objective is to assess the analgesic efficacy and tolerability of TDF in cachectic patients. The secondary objective is to identify cachexia characteristics that may influence fentanyl pharmacokinetics (PK). A comprehensive search of PubMed, Embase, and Web of Science databases was conducted up to March 2024. The review included observational and clinical studies on cachectic patients with moderate to severe pain treated with TDF patches at any dosage or frequency. Phase 1 trials, animal studies, case reports, preclinical studies and conference abstracts were excluded. Nine studies were included: four studies reported that cachexia negatively impacted TDF efficacy, increasing required doses and lowering plasma concentrations; three studies found minimal or no impact of cachexia on TDF efficacy and PK; two studies suggested that cachexia might improve TDF outcomes. Study quality ranged from moderate to high, according to the National Institutes of Health (NIH) Quality Assessment Tool. The current evidence is insufficient to provide any definitive recommendations for TDF prescribing in cachectic patients.

FGF2 promotes the expansion of parietal mesothelial progenitor pools and inhibits BMP4-mediated smooth muscle cell differentiation.

Mesothelial cells, in the outermost layer of internal organs, are essential for both organ development and homeostasis. Although the parietal mesothelial cell is the primary origin of mesothelioma that may highjack developmental signaling, the signaling pathways that orchestrate developing parietal mesothelial progenitor cell (MPC) behaviors, such as MPC pool expansion, maturation, and differentiation, are poorly understood. To address it, we established a robust protocol for culturing WT1+ MPCs isolated from developing pig and mouse parietal thorax. Quantitative qPCR and immunostaining analyses revealed that BMP4 facilitated MPC differentiation into smooth muscle cells (SMCs). In contrast, FGF2 significantly promoted MPC progenitor pool expansion but blocked the SMC differentiation. BMP4 and FGF2 counterbalanced these effects, but FGF2 had the dominant impact in the long-term culture. A Wnt activator, CHIR99021, was pivotal in MPC maturation to CALB2+ mesothelial cells, while BMP4 or FGF2 was limited. Our results demonstrated central pathways critical for mesothelial cell behaviors.

The kynurenine pathway in treatment-resistant schizophrenia at the crossroads between pathophysiology and pharmacotherapy.

Two cardinal elements in the complex and multifaceted pathophysiology of schizophrenia (SCZ) are neuroinflammation and dysregulation of glutamatergic neurotransmission, with the latter being especially involved in treatment-resistant schizophrenia (TRS). Interestingly, the Kynurenine (KYN) pathway (KP) is at the crossroad between them, constituting a potential causal link and a therapeutic target. Although there is preclinical and clinical evidence indicating a dysregulation of KP associated with the clinical phenotype of SCZ, clinical studies investigating the possible relationship between changes in biomarkers of the KP and response to pharmacotherapy are still limited. Therefore, we have studied possible differences in the circulating levels of biomarkers of the metabolism of tryptophan along the KP in 43 responders to first-line treatments (FLR) and 32 TRS patients treated with clozapine, and their possible associations with psychopathology in the two subgroups. Plasma levels of KYN were significantly higher in TRS patients than in FLR patients, indicating a greater activation of KP. Furthermore, the levels of quinolinic (NMDA receptor agonist) and kynurenic acid (NMDA negative allosteric modulator) showed a negative and a positive correlation with several dimensions and the overall symptomatology in the whole sample and in FLR, but not in TRS, suggesting a putative modulating effect of clozapine elicited through the NMDA receptors. Despite the cross-sectional design of the study that prevents us from demonstrating causation, these findings show a significant relationship among circulating KP biomarkers, psychopathology, and response to pharmacotherapy in SCZ. Therefore, plasma KP biomarkers should be further investigated for developing personalized medicine approaches in SCZ.