Deterioration in cognitive control related mPFC function underlying development of treatment resistance in early psychosis.

One third of people with psychosis become antipsychotic treatment-resistant and the underlying mechanisms remain unclear. We investigated whether altered cognitive control function is a factor underlying development of treatment resistance. We studied 50 people with early psychosis at a baseline visit (mean < 2 years illness duration) and follow-up visit (1 year later), when 35 were categorized at treatment-responsive and 15 as treatment-resistant. Participants completed an emotion-yoked reward learning task that requires cognitive control whilst undergoing fMRI and MR spectroscopy to measure glutamate levels from Anterior Cingulate Cortex (ACC). Changes in cognitive control related activity (in prefrontal cortex and ACC) over time were compared between treatment-resistant and treatment-responsive groups and related to glutamate. Compared to treatment-responsive, treatment-resistant participants showed blunted activity in right amygdala (decision phase) and left pallidum (feedback phase) at baseline which increased over time and was accompanied by a decrease in medial Prefrontal Cortex (mPFC) activity (feedback phase) over time. Treatment-responsive participants showed a negative relationship between mPFC activity and glutamate levels at follow-up, no such relationship existed in treatment-resistant participants. Reduced activity in right amygdala and left pallidum at baseline was predictive of treatment resistance at follow-up (67% sensitivity, 94% specificity). The findings suggest that deterioration in mPFC function over time, a key cognitive control region needed to compensate for an initial dysfunction within a social-emotional network, is a factor underlying development of treatment resistance in early psychosis. An uncoupling between glutamate and cognitive control related mPFC function requires further investigation that may present a future target for interventions.

Adherence, health care utilization, and costs between long-acting injectable and oral antipsychotic medications in South Carolina Medicaid beneficiaries with schizophrenia.

BACKGROUND: Schizophrenia and schizoaffective disorder require long-term antipsychotic treatment with antipsychotic medications, but poor medication adherence can lead to increased health care utilization and costs. Long-acting injectable antipsychotics (LAIs) offer potential therapeutic advantages in that they require less frequent dosing and improved medication adherence. South Carolina has the highest adoption of LAIs among US states, making it an ideal population for comparing the effectiveness of LAIs vs oral antipsychotics (OAPs) in treating schizophrenia or schizoaffective disorder. OBJECTIVE: To evaluate the effect of LAIs compared with OAPs on medication adherence, health care resource utilization, and costs among South Carolina Medicaid beneficiaries with schizophrenia or schizoaffective disorder. METHODS: South Carolina Medicaid beneficiaries with at least 1 claim for an LAI or OAP between January 1, 2015, and December 31, 2018, aged 18 to 65, with at least 2 claims with diagnoses of schizophrenia or schizoaffective disorder were included. Propensity scores (PSs) were calculated using logistic regression adjusting for confounders and predictors of the outcome. We estimated the "average treatment effect on the treated" by employing PS-weighted t-tests and chi-square tests. RESULTS: A total of 3,531 patients met the inclusion criteria, with 1,537 (44.5%) treated with LAIs and 1,994 (56.5%) treated with OAPs. In PS-weighted analyses, the LAI cohort had a greater proportion of days covered than the OAP cohort with a 365-day fixed denominator (69% vs 64%; P < 0.0001), higher medication possession ratio with a variable denominator while on therapy (85% vs 80%; P < 0.0001), and higher persistence (82% vs 64%; P < 0.0001). The average number of inpatient visits and emergency department visits did not significantly differ between cohorts (0.28 hospitalizations, P = 0.90; 3.68 vs 2.96 emergency department visits, P = 0.19). The number of outpatient visits, including visits for medication administration, were greater in the LAI cohort (23.1 [SD 24.2]) vs OAP (16.9 [SD 21.2]; P < 0.0001); however, including the costs for medication administration visits, outpatient costs (per member) were approximately $2,500 lower in the LAI cohort (P < 0.0001). The number of pharmacy visits was greater in the OAP cohort (LAI 21.0 [SD 17.0] vs OAP 23.0 [SD 15.0]; P = 0.006). All-cause total costs were greater in the LAI cohort ($26,025 [SD $29,909]) vs the OAP cohort ($17,291 [SD $25,261]; P < 0.0001) and were driven by the difference in pharmaceutical costs (LAI $15,273 [SD $16,183] vs OAP $4,696 [SD $10,371]; P < 0.0001). CONCLUSIONS: Among South Carolina Medicaid beneficiaries, treatment with LAIs for schizophrenia or schizoaffective disorder was associated with greater medication adherence rates. Patients using LAIs had higher drug costs and total costs, but lower outpatient and total nondrug costs compared with those using OAPs.

Cognitive Impairments in Drug-Naive Patients With First-Episode Negative Symptom-Dominant Psychosis.

Importance: Available antipsychotic medications are predominantly used to treat positive symptoms, such as hallucinations and delusions, in patients with first-episode psychosis (FEP). However, treating negative and cognitive symptoms, which are closely related to functional outcomes, remains a challenge. Objective: To explore the cognitive characteristics of patients with negative symptom-dominant (NSD) psychosis. Design, Setting, and Participants: This large-scale cross-sectional study of patients with FEP was led by the Shanghai Mental Health Center in China from 2016 to 2021, with participants recruited from 10 psychiatric tertiary hospitals. A comprehensive cognitive assessment was performed among 788 patients with FEP who were drug-naive. Symptom profiles were determined using the Positive and Negative Symptoms Scale (PANSS), and NSD was defined as a PANSS score for negative symptoms higher than that for positive and general symptoms. Positive symptom-dominant (PSD) and general symptom-dominant (GSD) psychosis were defined similarly. Data were analyzed in 2023. Exposure: Psychotic symptoms were categorized into 3 groups: NSD, PSD, and GSD. Main Outcomes and Measures: Neurocognitive performance, assessed using the Chinese version of the Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery. Results: This study included 788 individuals with FEP (median age, 22 [IQR, 17-28] years; 399 men [50.6%]). Patients with NSD exhibited more-pronounced cognitive impairment than did those with PSD or GSD. Specifically, cognitive differences between the NSD and PSD group, as well as between the NSD and GSD group, were most notable in the processing speed and attention domains (Trail Making [F = 4.410; P = .01], Symbol Coding [F = 4.957; P = .007], Verbal Learning [F = 3.198; P = .04], and Continuous Performance [F = 3.057; P = .05]). Patients with PSD and GSD showed no significant cognitive differences. Cognitive impairment was positively associated with the severity of negative symptoms. Most of the cognitive function tests used were able to differentiate patients with NSD from those with PSD and GSD, with significant differences observed across a range of tests, from Brief Visuospatial Memory Test-Revised (χ2 = 3.968; P = .05) to Brief Assessment of Cognition in Schizophrenia symbol coding (χ2 = 9.765; P = .002). Conclusions and Relevance: The findings of this cross-sectional study of patients with FEP suggest the presence of a clinical subtype characterized by a predominance of negative symptoms and cognitive impairment.

Gradually tapering off antipsychotics: lessons for practice from case studies and neurobiological principles.

PURPOSE OF REVIEW: There has been an increasing focus on deprescribing in psychiatry recently, particularly of antipsychotic medication, with recognition that not all patients with psychotic disorders require lifelong medication. We summarize some empirical and theoretical papers, and examine case studies to provide instruction on this topic. RECENT FINDINGS: Recent studies have found that slower tapering (over months or longer) of antipsychotics is associated with a lower relapse rate than quicker tapering (weeks). Case studies presented suggest that the process of reduction is associated with the precipitation or exacerbation of psychotic symptoms and that a slower process of reduction may minimize this effect. This may be because faster reductions cause greater disruption of homeostatic equilibria, provoking psychotic symptoms either as direct withdrawal symptoms or consequences of nonpsychotic withdrawal symptoms (e.g. insomnia) - although not all patients will experience withdrawal symptoms. This suggests that smaller dose reductions, especially at lower doses, made very gradually, may minimize the risk of psychotic symptoms. SUMMARY: Slower tapering of antipsychotics may provide time for adaptations made to the presence of the medications to resolve, thus reducing the disruption to homeostatic equilibrium caused by dose reduction, potentially reducing the risk of relapse. Exacerbation of psychotic symptoms on antipsychotic reduction may not represent evidence of the need for a higher dose of antipsychotic on a long-term basis but may indicate the need for more gradual reduction. Gradual reduction of antipsychotics, especially after long-term use in clinical practice is prudent.

G protein-specific mechanisms in the serotonin 5-HT2A receptor regulate psychosis-related effects and memory deficits.

G protein-coupled receptors (GPCRs) are sophisticated signaling machines able to simultaneously elicit multiple intracellular signaling pathways upon activation. Complete (in)activation of all pathways can be counterproductive for specific therapeutic applications. This is the case for the serotonin 2 A receptor (5-HT2AR), a prominent target for the treatment of schizophrenia. In this study, we elucidate the complex 5-HT2AR coupling signature in response to different signaling probes, and its physiological consequences by combining computational modeling, in vitro and in vivo experiments with human postmortem brain studies. We show how chemical modification of the endogenous agonist serotonin dramatically impacts the G protein coupling profile of the 5-HT2AR and the associated behavioral responses. Importantly, among these responses, we demonstrate that memory deficits are regulated by Gαq protein activation, whereas psychosis-related behavior is modulated through Gαi1 stimulation. These findings emphasize the complexity of GPCR pharmacology and physiology and open the path to designing improved therapeutics for the treatment of stchizophrenia.

Psychosis as a disorder of muscarinic signalling: psychopathology and pharmacology.

Dopaminergic receptor antagonism is a crucial component of all licensed treatments for psychosis, and dopamine dysfunction has been central to pathophysiological models of psychotic symptoms. Some clinical trials, however, indicate that drugs that act through muscarinic receptor agonism can also be effective in treating psychosis, potentially implicating muscarinic abnormalities in the pathophysiology of psychosis. Here, we discuss understanding of the central muscarinic system, and we examine preclinical, behavioural, post-mortem, and neuroimaging evidence for its involvement in psychosis. We then consider how altered muscarinic signalling could contribute to the genesis and maintenance of psychotic symptoms, and we review the clinical evidence for muscarinic agents as treatments. Finally, we discuss future research that could clarify the relationship between the muscarinic system and psychotic symptoms.

The inflamed brain.

Autoimmune conditions underlie some cases of psychosis. Scientists are expanding their search for patients, who often benefit from treatment.

The association between maximal muscle strength, disease severity and psychopharmacotherapy among young to middle-aged inpatients with affective disorders - a prospective pilot study.

BACKGROUND: Motor alterations and lowered physical activity are common in affective disorders. Previous research has indicated a link between depressive symptoms and declining muscle strength primarily focusing on the elderly but not younger individuals. Thus, we aimed to evaluate the relationship between mood and muscle strength in a sample of N = 73 young to middle-aged hospitalized patients (18-49 years, mean age 30.7 years) diagnosed with major depressive, bipolar and schizoaffective disorder, with a focus on moderating effects of psychopharmacotherapy. The study was carried out as a prospective observational study at a German psychiatric university hospital between September 2021 and March 2022. METHODS: Employing a standardized strength circuit consisting of computerized strength training devices, we measured the maximal muscle strength (Fmax) using three repetitions maximum across four muscle regions (abdomen, arm, back, leg) at three time points (t1-t3) over four weeks accompanied by psychometric testing (MADRS, BPRS, YRMS) and blood lipid profiling in a clinical setting. For analysis of psychopharmacotherapy, medication was split into activating (AM) and inhibiting (IM) medication and dosages were normalized by the respective WHO defined daily dose. RESULTS: While we observed a significant decrease of the MADRS score and increase of the relative total Fmax (rTFmax) in the first two weeks (t1-t2) but not later (both p < .001), we did not reveal a significant bivariate correlation between disease severity (MADRS) and muscle strength (rTFmax) at any of the timepoints. Individuals with longer disease history displayed reduced rTFmax (p = .048). IM was significantly associated with decreased rTFmax (p = .032). Regression models provide a more substantial effect of gender, age, and IM on muscle strength than the depressive episode itself (p < .001). CONCLUSIONS: The results of the study indicate that disease severity and muscle strength are not associated in young to middle-aged inpatients with affective disorders using a strength circuit as observational measurement. Future research will be needed to differentiate the effect of medication, gender, and age on muscle strength and to develop interventions for prevention of muscle weakness, especially in younger patients with chronic affective illnesses.

Antipsychotic Medication Continuation vs Taper and Discontinuation in Patients With Schizophrenia and Other Nonaffective Psychotic Disorders.

Schizophrenia is a major mental illness that is managed with long-term antipsychotic medication as a standard of care. Antipsychotic medications, however, are associated with many subjective and objective adverse effects. These adverse effects have driven the study of risk-mitigation strategies such as targeted intermittent therapy and dose reduction and drug discontinuation. Randomized controlled trials (RCTs) of these strategies have been synthesized in meta-analysis; both strategies have been associated with no functional benefits and with an increased risk of relapse. The RCTs, however, have been criticized because, in many, patients were abruptly switched to the target dose or too rapidly tapered, thereby predisposing the RCT to failure of the intervention. Two important RCTs examined gradual individualized dose reduction and discontinuation. One, conducted in first-episode psychosis patients who were free from positive symptoms for 6 months, found that, at 18-month follow-up, dose reduction was associated with a higher risk of relapse (number needed to harm [NNH] = 5) and with no functional benefits. However, after return to routine clinical care, at a 7-year follow-up, the dose reduction group had better functional outcomes and similar clinical outcomes relative to the maintenance treatment group. The other RCT, conducted in patients with relapsing psychosis, found that, at a 2-year follow-up, dose reduction was associated with a higher risk of relapse (NNH = 5) and with no improvements in social, cognitive, quality of life, satisfaction, and other domains. Many large nationwide observational studies have found that antipsychotic discontinuation by patients with first-episode psychosis and schizophrenia is associated with increased relapse, rehospitalization, suicide mortality, cardiovascular mortality, and all-cause mortality. There is also the ethical matter that attempts to identify the few who may benefit from antipsychotic dose reduction and discontinuation may compromise the health and stability of the many who require long-term maintenance treatment.

Long-term persistence of the risk of agranulocytosis with clozapine compared with other antipsychotics: a nationwide cohort and case-control study in Finland.

BACKGROUND: Agranulocytosis is a life-threatening side-effect of clozapine, the only approved drug for treatment-resistant schizophrenia. The long-term profile of this complication has not yet been well established. Here we aim to describe the risk of clozapine-induced agranulocytosis over the long term. METHODS: We used the entire population of Finland to identify people diagnosed with schizophrenia or schizoaffective disorder between 1972 and 2014 and developed a Kaplan-Meier model of time to diagnosis of agranulocytosis during clozapine versus non-clozapine treatment over a 22-year observation period (1996 to 2017). Next, we developed a nested case-control model for agranulocytosis matching by sex, age, time since diagnosis, and being in the incident cohort on a 1 to 5 ratio. Various durations of use for clozapine and non-clozapine antipsychotic treatment were compared to the modal antipsychotic use duration, deriving adjusted odds ratios (aORs) in a multivariable regression model. Recurrence and lethality rates for clozapine-induced agranulocytosis were described. These data reflect on all individuals with lived experience of schizophrenia in Finland during the study time, although individuals with lived experience were not included in the design of the study. FINDINGS: We identified 61 769 people with schizophrenia or schizoaffective disorder (14 037 individuals treated with clozapine and 47 732 individuals treated with non-clozapine antipsychotics), with a mean age of 46·67 years (IQR 34·44-57·61), of whom 30 721 (49·7%) were female and 31 048 (50·3%) were male (data on ethnicity not available). Among those, 398 individuals were diagnosed with agranulocytosis (231 individuals treated with clozapine and 167 individuals treated with non-clozapine antipsychotics), representing a cumulative incidence of agranulocytosis for 1·37% (95% CI 0·58-3·16) on clozapine and 0·13% (0·04-0·23) on non-clozapine antipsychotics. In the case (n=398) versus control (n=1987) model, the risk of clozapine-induced agranulocytosis decreased steeply over time from an aOR of 36·01 (95% CI 16·79-77·22) for less than 6 months on clozapine to 4·38 (1·86-10·34) for clozapine use of 54 months or more. Only one of 3559 individuals starting clozapine died because of clozapine-induced agranulocytosis. INTERPRETATION: The risk of clozapine-induced agranulocytosis decreases steeply over time but might be persistently greater than that of non-clozapine antipsychotics. This long-term risk excess seems small in absolute terms compared with the known magnitude of the advantages of clozapine in relevant outcomes, including life expectancy. Given the widespread underuse of clozapine, relaxing the long-term neutrophil monitoring could favour the advantages of long-term clozapine use, including greater life expectancy, without incurring the intolerable risk of clozapine-induced agranulocytosis. FUNDING: Northwell Health and Sigrid Jusèlius Foundation.

Clozapine Use Among People With Psychotic Disorders Who Experience Specific Indications for Clozapine.

Objective: To examine rates of clozapine use among people with psychotic disorders who experience specific indications for clozapine.Methods: Records data from 11 integrated health systems identified patients aged 18 years or older with recorded International Classification of Diseases, Tenth Revision, Clinical Modification, diagnoses of schizophrenia, schizoaffective disorder, or other psychotic disorder who experienced any of the 3 events between January 1, 2019, and December 31, 2019, suggesting indications for clozapine: a diagnosis of self-harm injury or poisoning, suicidal ideation diagnosed or in response to standardized assessments, and hospitalization or emergency department (ED) care for psychotic disorder despite treatment with 2 or more antipsychotic medications. Prescription dispensing data identified all clozapine use prior to or in the 12 months following each indication event. Analyses were conducted with aggregate data from each health system; no individual data were shared.Results: A total of 7,648 patients with psychotic disorder diagnoses experienced at least 1 indication event. Among 1,097 experiencing a self-harm event, 32 (2.9%) had any prior clozapine use, and 10 (0.9%) initiated clozapine during the following 12 months. Among 6,396 with significant suicidal ideation, 238 (3.7%) had any prior clozapine use, and 70 (1.1%) initiated clozapine over 12 months. Among 881 with hospitalization or ED visit despite pharmacotherapy, 77 (8.7%) had any prior clozapine treatment, and 41 (4.7%) initiated clozapine over 12 months. Among those with significant suicidal ideation, rates of both prior clozapine treatment and subsequent initiation varied significantly by race and ethnicity, with rates among Hispanic and non-Hispanic Black patients lower than among non Hispanic White patients.Conclusions: Initiating clozapine treatment is uncommon among people with psychotic disorders who experience events suggesting clozapine is indicated, with even lower rates among Black and Hispanic patients.

Parkinson's Disease Psychosis and the Marketing of Pimavanserin.

In 2016, Nuplazid (pimavanserin) became the first FDA-approved treatment for Parkinson's Disease Psychosis (PDP). We explored the possibility that PDP was a term created to market Nuplazid. We examined trends in perceptions of psychosis in Parkinson's disease from the 1990s to 2020 through MEDLINE search term frequency, neurology textbooks, guidance from professional societies, Acadia annual reports, sponsored websites, and a sponsored meeting held by the National Institutes of Health (NIH). We analyzed continuing medical education (CME) activities on PDP and analyzed the connection between payments by the manufacturer of pimavanserin and prescriptions. Our analysis of nine sponsored CME activities reveals misleading themes, including: PDP is common, progressive, and not always drug-induced; there is no such thing as a benign hallucination, and psychotic symptoms always worsen; PDP increases mortality; and competing treatments are ineffective or dangerous while pimavanserin is safe and effective for treating PDP. Industry-sponsored CME was used to disseminate inaccurate and misleading marketing messages on psychosis related to Parkinson's disease. Some professional societies and some textbooks also resisted the PDP label. Reframing PDP as a unique condition is a typical example of condition branding. The establishment of PDP expanded the use of pimavanserin and is likely to have resulted in many avoidable deaths.

COVID-19 pandemic and emergency department visits for psychosis: Visit volume, restraint use, medication use, psychiatric hospitalization, and length of stay.

BACKGROUND: Individuals with a schizophrenia spectrum disorder were at heightened risk for interruptions in psychiatric care during the coronavirus-19 (COVID 19) pandemic. There is limited work exploring the pandemic's impact on emergency department (ED) visit volume, use of restraint and parenteral medications, inpatient psychiatric (IP) hospitalization, and ED length of stay (LOS) among this population. METHODS: We retrospectively examined 2134 ED visits with a billing code for psychosis between March 1, 2019-February 28, 2021. We used Poisson regression analysis to compare ED visit volume between the pandemic and pre-pandemic periods. Restraint use, parenteral antipsychotic or benzodiazepine use, IP hospitalization, and ED LOS were compared between the two periods using chi-square tests and independent samples t-tests. RESULTS: Overall volume of psychosis-related ED visits during the pandemic did not differ significantly from the prior year. Rates of restraint use (16.2 % vs 11.6 %, p < .01), parenteral antipsychotic (22.6 % vs 14.9, p < .001), and parenteral benzodiazepine (22.3 % vs 16.3 %, p < .001) use were significantly higher during the pandemic. Fewer patients had an IP hospital disposition during the pandemic than the year prior (57.8 % vs. 61.9 %, p < .05). ED LOS was longer during the pandemic compared to pre-pandemic (28.37 h vs 20.26 h, p < .001). CONCLUSIONS: Although the volume of psychosis-related ED visits remained constant, restraint and parenteral medication use rates were significantly higher during the pandemic. ED LOS increased but fewer ED visits resulted in IP hospitalization. These findings underscore the importance of planning for increased acuity of psychosis ED presentations during public health emergencies.

Aripiprazole-induced quasi-neuroleptic malignant syndrome: two case reports.

BACKGROUND: Significant elevation of creatine kinase levels (above three digits) and leucocytosis in the absence of muscle rigidity, tremors, or autonomic dysfunction can pose a real challenge in the context of antipsychotic treatment as an early herald of neuroleptic malignant syndrome. CASE PRESENTATION: We present here two cases of adult male patients of Black British heritage, ages 51 years and 28 years, respectively. Both received a diagnosis of schizoaffective disorder and presented with massive increase of creatine kinase blood level after aripiprazole depot administration, one with pernicious increase associated with silent neuroleptic malignant syndrome, and the second with asymptomatic benign enzyme elevation. CONCLUSION: Though aripiprazole use is less likely to cause neuroleptic malignant syndrome, on rare occasions it can produce massive symptomatic or asymptomatic increase in serum creatine kinase enzyme levels, raising the need for close monitoring, especially at the initial doses of the drug.

Higher-order functional brain networks and anterior cingulate glutamate + glutamine (Glx) in antipsychotic-naïve first episode psychosis patients.

Human connectome studies have provided abundant data consistent with the hypothesis that functional dysconnectivity is predominant in psychosis spectrum disorders. Converging lines of evidence also suggest an interaction between dorsal anterior cingulate cortex (dACC) cortical glutamate with higher-order functional brain networks (FC) such as the default mode (DMN), dorsal attention (DAN), and executive control networks (ECN) in healthy controls (HC) and this mechanism may be impaired in psychosis. Data from 70 antipsychotic-medication naïve first-episode psychosis (FEP) and 52 HC were analyzed. 3T Proton magnetic resonance spectroscopy (1H-MRS) data were acquired from a voxel in the dACC and assessed correlations (positive FC) and anticorrelations (negative FC) of the DMN, DAN, and ECN. We then performed regressions to assess associations between glutamate + glutamine (Glx) with positive and negative FC of these same networks and compared them between groups. We found alterations in positive and negative FC in all networks (HC > FEP). A relationship between dACC Glx and positive and negative FC was found in both groups, but when comparing these relationships between groups, we found contrasting associations between these variables in FEP patients compared to HC. We demonstrated that both positive and negative FC in three higher-order resting state networks are already altered in antipsychotic-naïve FEP, underscoring the importance of also considering anticorrelations for optimal characterization of large-scale functional brain networks as these represent biological processes as well. Our data also adds to the growing body of evidence supporting the role of dACC cortical Glx as a mechanism underlying alterations in functional brain network connectivity. Overall, the implications for these findings are imperative as this particular mechanism may differ in untreated or chronic psychotic patients; therefore, understanding this mechanism prior to treatment could better inform clinicians.Clinical trial registration: Trajectories of Treatment Response as Window into the Heterogeneity of Psychosis: A Longitudinal Multimodal Imaging Study, NCT03442101 . Glutamate, Brain Connectivity and Duration of Untreated Psychosis (DUP), NCT02034253 .

Exploring clozapine use in severe psychiatric symptoms associated with autism spectrum disorder: A scoping review.

BACKGROUND: Patients with autism spectrum disorder (ASD) may experience severe psychiatric symptoms, often unresponsive to conventional pharmacological therapies, highlighting the need for more effective alternatives. AIMS: This study aims to map and synthesize evidence on the use of clozapine as a therapeutic option for managing severe psychiatric symptomatology co-occurring with ASD. METHODS: We conducted a scoping review on multiple sources following the JBI guidelines. The search strategy was inclusive, targeting both peer-reviewed publications and gray literature presenting empirical data on the use of clozapine therapy for patients with ASD accompanied by comorbid psychiatric symptoms. Two independent evaluators performed the selection of studies, data extraction, and critical appraisal. RESULTS: The review included 46 studies, encompassing 122 ASD individuals who received clozapine therapy. The sources of evidence comprise 31 case reports, 8 case series, 6 retrospective observational studies, and 1 quasi-experimental prospective study. The tables present the findings along with a narrative summary. Clozapine treatment demonstrated benefits in four groups of severe and treatment-resistant psychiatric symptoms in ASD patients: disruptive behaviors, psychotic symptoms, catatonia, and mood symptoms. Although side effects were common, tolerability was generally satisfactory. However, severe adverse events, such as seizures, moderate neutropenia, and myocarditis, underscore the need for intensive clinical monitoring. CONCLUSIONS: While clozapine shows promise as a pharmacological intervention for severe psychopathologies in ASD, more rigorous clinical studies are required to elucidate its efficacy and safety in this population. The limited robustness of the evidence calls for caution, signaling an early research stage into this topic.