The kynurenine pathway of tryptophan metabolism has been implicated in the pathophysiology of psychiatric disorders, including schizophrenia. We report here that the kynurenine metabolite, xanturenic acid (XA), interacts with, and activates mGlu2 and mGlu3 metabotropic glutamate receptors in heterologous expression systems. However, the molecular nature of this interaction is unknown, and our data cannot exclude that XA acts primarily on other targets, such as the vesicular glutamate transporter, in the CNS. Systemic administration of XA in mice produced antipsychotic-like effects in the MK-801-induced model of hyperactivity. This effect required the presence of mGlu2 receptors and was abrogated by the preferential mGlu2/3 receptor antagonist, LY341495. Because the mGlu2 receptor is a potential drug target in the treatment of schizophrenia, we decided to measure serum levels of XA and other kynurenine metabolites in patients affected by schizophrenia. Serum XA levels were largely reduced in a large cohort of patients affected by schizophrenia, and, in patients with first-episode schizophrenia, levels remained low after 12 months of antipsychotic medication. As opposed to other kynurenine metabolites, XA levels were also significantly reduced in first-degree relatives of patients affected by schizophrenia. We suggest that lowered serum XA levels might represent a novel trait marker for schizophrenia.

Background The present paper provides an updated review of both the large number of new/novel/emerging psychoactive substances (NPS) and their associated psychopathological consequences. Focus was here given on identification of those NPS being commented in specialised online sources and the related short-/long-term psychopathological and medical ill-health effects. Methods NPS have been identified through an innovative crawling/navigating software, called the ‘NPS.Finder®’, created in order to facilitate the process of early recognition of NPS online. A range of information regarding NPS, including chemical and street names; chemical formula; three-dimensional image and anecdotally reported clinical/psychoactive effects, were here made available. Results Using the ‘NPS.Finder®’ approach, a few thousand NPS were here preliminarily identified, a number which is about 4-fold higher than those figures suggested by European and international drug agencies. NPS most commonly associated with the onset of psychopathological consequences included here synthetic cannabinoids/cannabimimetics; new synthetic opioids; ketamine-like dissociatives; novel stimulants; novel psychedelics and several prescription and over-the-counter medicines. Conclusions The ever-increasing changes in terms of recreational psychotropics' availability represent a relatively new challenge for psychiatry, as the pharmacodynamics and pharmacokinetics of many NPS have not been thoroughly understood. Health/mental health professionals should be informed about the range of NPS; their intake modalities; their psychoactive sought-after effects; the idiosyncratic psychotropics' combinations and finally, their medical and psychopathological risks.

Background: Mixed depression (MxD) is narrowly defined in the DSM-IV and somewhat broader in the DSM-5, although both exclude psychomotor agitation as a diagnostic criterion. This article proposes a clinical description for defining MxD, which emphasizes psychomotor excitation. Methods: Two hundred and nineteen consecutive outpatients were diagnosed with an MxD episode using criteria proposed by Koukopoulos et al. [Acta Psychiatr Scand 2007;115(suppl 433):50-57]; we here report their clinical features and antidepressant-related effects. Results: The most frequent MxD symptoms were: psychic agitation or inner tension (97%), absence of retardation (82%), dramatic description of suffering or weeping spells (53%), talkativeness (49%), and racing or crowded thoughts (48%). MxD was associated with antidepressants in 50.7% of patients, with similar frequency for tricyclic antidepressants (45%) versus selective serotonin reuptake inhibitors (38.5%). Positive predictors of antidepressant-associated MxD were bipolar disorder type II diagnosis, higher index depression severity, and higher age at index episode. Antipsychotic or no treatment was protective against antidepressant-associated MxD. Conclusions: MxD, defined as depression with excitatory symptoms, can be clinically identified, is common, occurs in both unipolar depression and bipolar disorder, and is frequently associated with antidepressant use. If replicated, this view of MxD could be considered a valid alternative to the DSM-5 criteria for depression with mixed features.

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Aims Within the new psychoactive substances (NPS) scenario, several hundred different molecules, mostly including synthetic cannabinoids and cathinones, have been identified so far. The aims of the paper were to: (i) identify the number of synthetic cathinones mentioned in a range of psychonaut, NPS‐related, online sources; and (ii) describe the associated acute/long term clinical scenario and the related treatment/management plan. Methods After about 18 months of operation and exclusion of false positives/duplicates, some 4204 unique NPS molecules were included in the NPSfinder® crawling/navigating software database. Most popular NPS included: 1265 psychedelic phenethylamines (30.1%; confidence interval [CI] 95%: 28.7–31.5%); 1253 synthetic cannabinoids (29.8%; CI 95%: 28.4–31.2%); 429 synthetic opioids (10.2%; CI 95%: 9.3–10.2%); and 171 synthetic cathinones (4.1%; CI 95% 3.5–4.7%). Conversely, the United Nations Office on Drugs and Crime and the European Monitoring Centre for Drugs and Drug Addiction databases respectively included 169 and 140 cathinones. Overall, the 3 databases reported some 222 synthetic cathinones, and 41 were uniquely identified by the NPSfinder®. Results In terms of clinical scenarios, synthetic cathinone ingestion is initially associated with stimulant effects; however, psychopathological disturbances, violence, suicidal behaviour, hyperthermia, coma and death have also been described. Conclusion The proportion of cathinones commented on by psychonaut fora appeared to be relatively small, and similar to those reported by both the United Nations Office on Drugs and Crime and European Monitoring Centre for Drugs and Drug Addiction. This may be associated with a recent significant decline in both cathinone‐related consumption and acute medical presentation. Due to their complex behavioural and medical toxicity issues, healthcare professionals should be, however, be educated to recognise the signs and symptoms of NPS, including synthetic cathinone, ingestion.