Aberrant resting-state functional connectivity of the globus pallidus interna in first-episode schizophrenia.

BACKGROUND: The striatal-pallidal pathway plays an important role in cognitive control and modulation of behaviors. Globus pallidus interna (GPi), as a primary output structure, is crucial in modulating excitation and inhibition. Studies of GPi in psychiatric illnesses are lacking given the technical challenges of examining this small and functionally diverse subcortical structure. METHODS: 71 medication-naïve first episode schizophrenia (FES) participants and 73 healthy controls (HC) were recruited at the Shanghai Mental Health Center. Clinical symptoms and imaging data were collected at baseline and, in a subset of patients, 8 weeks after initiating treatment. Resting-state functional connectivity of sub-regions of the GP were assessed using a novel mask that combines two atlases to create 8 ROIs in the GP. RESULTS: Baseline imaging data from 63 FES patients and 55 HC met quality standards and were analyzed. FES patients exhibited less negative connectivity and increased positive connectivity between the right anterior GPi and several cortical and subcortical areas at baseline compared to HC (PFWE < 0.05). Positive functional connectivity between the right anterior GPi and several brain areas, including the right dorsal anterior cingulate gyrus, was associated with severity of positive symptoms (PFWE < 0.05) and predicted treatment response after 8 weeks (n = 28, adjusted R2 = 0.486, p < 0.001). CONCLUSIONS: Our results implicate striatal-pallidal-thalamic pathways in antipsychotic efficacy. If replicated, these findings may reflect failure of neurodevelopmental processes in adolescence and early adulthood that decrease functional connectivity as an index of failure of the limbic/associative GPi to appropriately inhibit irrelevant signals in psychosis.

Microstructural and Microvascular Alterations in Psychotic Spectrum Disorders: A Three-Compartment Intravoxel Incoherent Imaging and Free Water Model.

BACKGROUND AND HYPOTHESIS: Microvascular and inflammatory mechanisms have been hypothesized to be involved in the pathophysiology of psychotic spectrum disorders (PSDs). However, data evaluating these hypotheses remain limited. STUDY DESIGN: We applied a three-compartment intravoxel incoherent motion free water imaging (IVIM-FWI) technique that estimates the perfusion fraction (PF), free water fraction (FW), and anisotropic diffusion of tissue (FAt) to examine microvascular and microstructural changes in gray and white matter in 55 young adults with a PSD compared to 37 healthy controls (HCs). STUDY RESULTS: We found significantly increased PF, FW, and FAt in gray matter regions, and significantly increased PF, FW, and decreased FAt in white matter regions in the PSD group versus HC. Furthermore, in patients, but not in the HC group, increased PF, FW, and FAt in gray matter and increased PF in white matter were significantly associated with poor performance on several cognitive tests assessing memory and processing speed. We additionally report significant associations between IVIM-FWI metrics and myo-inositol, choline, and N-acetylaspartic acid magnetic resonance spectroscopy imaging metabolites in the posterior cingulate cortex, which further supports the validity of PF, FW, and FAt as microvascular and microstructural biomarkers of PSD. Finally, we found significant relationships between IVIM-FWI metrics and the duration of psychosis in gray and white matter regions. CONCLUSIONS: The three-compartment IVIM-FWI model provides metrics that are associated with cognitive deficits and may reflect disease progression.

Longitudinal study of inflammation and relapse in schizophrenia.

INTRODUCTION: The clinical course of schizophrenia is often characterized by recurrent relapses. Blood inflammatory markers are altered in acute psychosis, and may be state markers for illness relapse in schizophrenia. Few studies have investigated longitudinal, intra-individual changes in inflammatory markers as a predictor of relapse. In the present study, we explored this association in a relapse prevention trial in patients with schizophrenia. METHODS: We analyzed blood inflammatory markers in 200 subjects, with a mean 11 samples per subject, during the 30 month Preventing Relapse in schizophrenia: Oral Antipsychotics Compared to Injectable: eValuating Efficacy (PROACTIVE) trial. Associations between longitudinal changes in inflammatory markers and relapse were analyzed using a within-subjects design. RESULTS: 70 (35 %) of subjects relapsed during the study period. There were no significant differences in mean inflammatory marker levels based on relapse status (yes/no). Baseline levels of inflammatory markers did not predict incident relapse. Among subjects who relapsed, there was a significant decrease in mean blood IL-6 (n = 38, p = 0.019) and IFN-γ (n = 44, p = 0.012) levels from the visit before the relapse to the visit after relapse. CONCLUSION: Although there was some evidence for inflammation as a potential state marker for acute psychosis, we did not find significant evidence for its utility as a relapse-predictive marker.

Hippocampal Subfield Volumes Predict Disengagement from Maintenance Treatment in First Episode Schizophrenia.

OBJECTIVES: Disengagement from treatment is common in first episode schizophrenia (FES) and is associated with poor outcomes. Our aim was to determine whether hippocampal subfield volumes predict disengagement during maintenance treatment of FES. METHODS: FES patients were recruited from sites in Boston, New York, Shanghai, and Changsha. After stabilization on antipsychotic medication, participants were randomized to add-on citalopram or placebo and followed for 12 months. Demographic, clinical and cognitive factors at baseline were compared between completers and disengagers in addition to volumes of hippocampal subfields. RESULTS: Baseline data were available for 95 randomized participants. Disengagers (n = 38, 40%) differed from completers (n = 57, 60%) by race (more likely Black; less likely Asian) and in more alcohol use, parkinsonism, negative symptoms and more impairment in visual learning and working memory. Bilateral dentate gyrus (DG), CA1, CA2/3 and whole hippocampal volumes were significantly smaller in disengagers compared to completers. When all the eight volumes were entered into the model simultaneously, only left DG volume significantly predicted disengagement status and remained significant after adjusting for age, sex, race, intracranial volume, antipsychotic dose, duration of untreated psychosis, citalopram status, alcohol status, and smoking status (P < .01). Left DG volume predicted disengagement with 57% sensitivity and 83% specificity. CONCLUSIONS: Smaller left DG was significantly associated with disengagement status over 12 months of maintenance treatment in patients with FES participating in a randomized clinical trial. If replicated, these findings may provide a biomarker to identify patients at risk for disengagement and a potential target for interventions.

Decreased basal ganglia and thalamic iron in early psychotic spectrum disorders are associated with increased psychotic and schizotypal symptoms.

Iron deficits have been reported as a risk factor for psychotic spectrum disorders (PSD). However, examinations of brain iron in PSD remain limited. The current study employed quantitative MRI to examine iron content in several iron-rich subcortical structures in 49 young adult individuals with PSD (15 schizophrenia, 17 schizoaffective disorder, and 17 bipolar disorder with psychotic features) compared with 35 age-matched healthy controls (HC). A parametric approach based on a two-pool magnetization transfer model was applied to estimate longitudinal relaxation rate (R1), which reflects both iron and myelin, and macromolecular proton fraction (MPF), which is specific to myelin. To describe iron content, a synthetic effective transverse relaxation rate (R2*) was modeled using a linear fitting of R1 and MPF. PSD patients compared to HC showed significantly reduced R1 and synthetic R2* across examined regions including the pallidum, ventral diencephalon, thalamus, and putamen areas. This finding was primarily driven by decreases in the subgroup with schizophrenia, followed by schizoaffective disorder. No significant group differences were noted for MPF between PSD and HC while for regional volume, significant reductions in patients were only observed in bilateral caudate, suggesting that R1 and synthetic R2* reductions in schizophrenia and schizoaffective patients likely reflect iron deficits that either occur independently or precede structural and myelin changes. Subcortical R1 and synthetic R2* were also found to be inversely related to positive symptoms within the PSD group and to schizotypal traits across the whole sample. These findings that decreased iron in subcortical regions are associated with PSD risk and symptomatology suggest that brain iron deficiencies may play a role in PSD pathology and warrant further study.

Association Between the Use of Psychotropic Medications and the Risk of COVID-19 Infection Among Long-term Inpatients With Serious Mental Illness in a New York State-wide Psychiatric Hospital System.

Importance: Individuals with serious mental illness are at increased risk of severe COVID-19 infection. Several psychotropic medications have been identified as potential therapeutic agents to prevent or treat COVID-19 but have not been systematically examined in this population. Objective: To evaluate the associations between the use of psychotropic medications and the risk of COVID-19 infection among adults with serious mental illness receiving long-term inpatient psychiatric treatment. Design, Setting, and Participants: This retrospective cohort study assessed adults with serious mental illness hospitalized in a statewide psychiatric hospital system in New York between March 8 and July 1, 2020. The final date of follow-up was December 1, 2020. The study included 1958 consecutive adult inpatients with serious mental illness (affective or nonaffective psychoses) who received testing for SARS-CoV-2 by reverse transcriptase-polymerase chain reaction or antinucleocapsid antibodies and were continuously hospitalized from March 8 until medical discharge or July 1, 2020. Exposures: Psychotropic medications prescribed prior to COVID-19 testing. Main Outcomes and Measures: COVID-19 infection was the primary outcome, defined by a positive SARS-CoV-2 reverse transcriptase-polymerase chain reaction or antibody test result. The secondary outcome was COVID-19-related death among patients with laboratory-confirmed infection. Results: Of the 2087 adult inpatients with serious mental illness continuously hospitalized during the study period, 1958 (93.8%) underwent testing and were included in the study; 1442 (73.6%) were men, and the mean (SD) age was 51.4 (14.3) years. A total of 969 patients (49.5%) had laboratory-confirmed COVID-19 infection that occurred while they were hospitalized; of those, 38 (3.9%) died. The use of second-generation antipsychotic medications, as a class, was associated with decreased odds of infection (odds ratio [OR], 0.62; 95% CI, 0.45-0.86), whereas the use of mood stabilizers was associated with increased odds of infection (OR, 1.23; 95% CI, 1.03-1.47). In a multivariable model of individual medications, the use of paliperidone was associated with decreased odds of infection (OR, 0.59; 95% CI, 0.41-0.84), and the use of valproic acid was associated with increased odds of infection (OR, 1.39; 95% CI, 1.10-1.76). Clozapine use was associated with reduced odds of mortality in unadjusted analyses (unadjusted OR, 0.25; 95% CI, 0.10-0.62; fully adjusted OR, 0.43; 95% CI, 0.17-1.12). Conclusions and Relevance: In this cohort study of adults hospitalized with serious mental illness, the use of second-generation antipsychotic medications was associated with decreased risk of COVID-19 infection, whereas the use of valproic acid was associated with increased risk. Further research is needed to assess the mechanisms that underlie these findings.

Impairment in acquisition of conditioned fear in schizophrenia.

Individuals with schizophrenia show impairments in associative learning. One well-studied, quantifiable form of associative learning is Pavlovian fear conditioning. However, to date, studies of fear conditioning in schizophrenia have been inconclusive, possibly because they lacked sufficient power. To address this issue, we pooled data from four independent fear conditioning studies that included a total of 77 individuals with schizophrenia and 74 control subjects. Skin conductance responses (SCRs) to stimuli that were paired (the CS + ) or not paired (CS-) with an aversive, unconditioned stimulus were measured, and the success of acquisition of differential conditioning (the magnitude of CS + vs. CS- SCRs) and responses to CS + and CS- separately were assessed. We found that acquisition of differential conditioned fear responses was significantly lower in individuals with schizophrenia than in healthy controls (Cohen's d = 0.53). This effect was primarily related to a significantly higher response to the CS- stimulus in the schizophrenia compared to the control group. Moreover, the magnitude of this response to the CS- in the schizophrenia group was correlated with the severity of delusional ideation (p = 0.006). Other symptoms or antipsychotic dose were not associated with fear conditioning measures. In conclusion, individuals with schizophrenia who endorse delusional beliefs may be over-responsive to neutral stimuli during fear conditioning. This finding is consistent with prior models of abnormal associative learning in psychosis.

Association Between Mental Health Disorders and Mortality Among Patients With COVID-19 in 7 Countries: A Systematic Review and Meta-analysis.

Importance: Heterogeneous evidence exists for the association between COVID-19 and the clinical outcomes of patients with mental health disorders. It remains unknown whether patients with COVID-19 and mental health disorders are at increased risk of mortality and should thus be targeted as a high-risk population for severe forms of COVID-19. Objective: To determine whether patients with mental health disorders were at increased risk of COVID-19 mortality compared with patients without mental health disorders. Data Sources: For this systematic review and meta-analysis, MEDLINE, Web of Science, and Google Scholar were searched from inception to February 12, 2021. Bibliographies were also searched, and the corresponding authors were directly contacted. The search paradigm was based on the following combination: (mental, major[MeSH terms]) AND (COVID-19 mortality[MeSH terms]). To ensure exhaustivity, the term mental was replaced by psychiatric, schizophrenia, psychotic, bipolar disorder, mood disorders, major depressive disorder, anxiety disorder, personality disorder, eating disorder, alcohol abuse, alcohol misuse, substance abuse, and substance misuse. Study Selection: Eligible studies were population-based cohort studies of all patients with identified COVID-19 exploring the association between mental health disorders and mortality. Data Extraction and Synthesis: Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was used for abstracting data and assessing data quality and validity. This systematic review is registered with PROSPERO. Main Outcomes and Measures: Pooled crude and adjusted odds ratios (ORs) for the association of mental health disorders with mortality were calculated using a 3-level random-effects (study/country) approach with a hierarchical structure to assess effect size dependency. Results: In total, 16 population-based cohort studies (data from medico-administrative health or electronic/medical records databases) across 7 countries (1 from Denmark, 2 from France, 1 from Israel, 3 from South Korea, 1 from Spain, 1 from the UK, and 7 from the US) and 19 086 patients with mental health disorders were included. The studies covered December 2019 to July 2020, were of good quality, and no publication bias was identified. COVID-19 mortality was associated with an increased risk among patients with mental health disorders compared with patients without mental health disorders according to both pooled crude OR (1.75 [95% CI, 1.40-2.20]; P < .05) and adjusted OR (1.38 [95% CI, 1.15-1.65]; P < .05). The patients with severe mental health disorders had the highest ORs for risk of mortality (crude OR: 2.26 [95% CI, 1.18-4.31]; adjusted OR: 1.67 [95% CI, 1.02-2.73]). Conclusions and Relevance: In this systematic review and meta-analysis of 16 observational studies in 7 countries, mental health disorders were associated with increased COVID-19-related mortality. Thus, patients with mental health disorders should have been targeted as a high-risk population for severe forms of COVID-19, requiring enhanced preventive and disease management strategies. Future studies should more accurately evaluate the risk for patients with each mental health disorder. However, the highest risk seemed to be found in studies including individuals with schizophrenia and/or bipolar disorders.

Quantitative Macromolecular Proton Fraction Mapping Reveals Altered Cortical Myelin Profile in Schizophrenia Spectrum Disorders.

Myelin abnormalities have been reported in schizophrenia spectrum disorders (SSD) in white matter. However, in vivo examinations of cortical myeloarchitecture in SSD, especially those using quantitative measures, are limited. Here, we employed macromolecular proton fraction (MPF) obtained from quantitative magnetization transfer imaging to characterize intracortical myelin organization in 30 SSD patients versus 34 healthy control (HC) participants. We constructed cortical myelin profiles by extracting MPF values at various cortical depths and quantified their shape using a nonlinearity index (NLI). To delineate the association of illness duration with myelin changes, SSD patients were further divided into 3 duration groups. Between-group comparisons revealed reduced NLI in the SSD group with the longest illness duration (>5.5 years) compared with HC predominantly in bilateral prefrontal areas. Within the SSD group, cortical NLI decreased with disease duration and was positively associated with a measure of spatial working memory capacity as well as with cortical thickness (CT). Layer-specific analyses suggested that NLI decreases in the long-duration SSD group may arise in part from significantly increased MPF values in the midcortical layers. The current study reveals cortical myelin profile changes in SSD with illness progression, which may reflect an abnormal compensatory mechanism of the disorder.

Effect of citalopram on hippocampal volume in first-episode schizophrenia: Structural MRI results from the DECIFER trial.

Hippocampal volume loss is prominent in first episode schizophrenia (FES) and has been associated with poor clinical outcomes and with BDNF genotype; antidepressants are believed to reverse hippocampal volume loss via release of BDNF. In a 12-month, placebo-controlled add-on trial of the antidepressant, citalopram, during the maintenance phase of FES, negative symptoms were improved with citalopram. We now report results of structural brain imaging at baseline and 6 months in 63 FES patients (34 in citalopram group) from the trial to assess whether protection against hippocampal volume loss contributed to improved negative symptoms with citalopram. Hippocampal volumetric integrity (HVI) did not change significantly in the citalopram or placebo group and did not differ between treatment groups, whereas citalopram was associated with greater volume loss of the right CA1 subfield. Change in cortical thickness was associated with SANS change in 4 regions (left rostral anterior cingulate, right frontal pole, right cuneus, and right transverse temporal) but none differed between treatment groups. Our findings suggest that minimal hippocampal volume loss occurs after stabilization on antipsychotic treatment and that citalopram's potential benefit for negative symptoms is unlikely to result from protection against hippocampal volume loss or cortical thinning.

Association of Aripiprazole With Reduced Hippocampal Atrophy During Maintenance Treatment of First-Episode Schizophrenia.

PURPOSE/BACKGROUND: Hippocampal volume loss in early schizophrenia has been linked with markers of inflammation and oxidative stress, and with less response of negative symptoms. Aripiprazole has been reported to preserve hippocampal volume and to reduce inflammation. METHODS/PROCEDURES: Study 1 was a 12-month multicenter randomized placebo-controlled trial of citalopram added to clinician-determined second-generation antipsychotic medication in 95 patients with first-episode schizophrenia (FES), 19 of whom received aripiprazole. We compared participants taking aripiprazole with those on other antipsychotics to determine whether those on aripiprazole had less hippocampal volume loss. We also examined peripheral biomarker data from medication-naive patients with schizophrenia receiving 8 weeks of antipsychotic treatment (n = 24) to see whether markers of inflammation and oxidative stress that previously predicted hippocampal volume differed between aripiprazole (n = 9) and other antipsychotics (study 2). FINDINGS/RESULTS: Aripiprazole was associated with a mean increase in hippocampal volume of 0.35% (SD, 0.80%) compared with a 0.53% decrease (SD, 1.2%) with other antipsychotics during the first year of maintenance treatment in patients with FES. This difference was significant after adjusting for age, sex, citalopram treatment, and baseline Brief Psychiatric Rating Scale score (B = 0.0079, P = 0.03). Aripiprazole was also associated with reduced concentrations of the inflammatory cytokines interleukin-8 and tumor necrosis factor (P < 0.01) during the first 8 weeks of treatment in medication-naive patients with FES. IMPLICATIONS/CONCLUSIONS: These results suggest that aripiprazole may protect against hippocampal atrophy via an anti-inflammatory mechanism, but these results require replication in larger, randomized trials, and the clinical relevance of hippocampal volume loss is not established.

Association of Psychiatric Disorders With Mortality Among Patients With COVID-19.

Importance: To date, the association of psychiatric diagnoses with mortality in patients infected with coronavirus disease 2019 (COVID-19) has not been evaluated. Objective: To assess whether a diagnosis of a schizophrenia spectrum disorder, mood disorder, or anxiety disorder is associated with mortality in patients with COVID-19. Design, Setting, and Participants: This retrospective cohort study assessed 7348 consecutive adult patients for 45 days following laboratory-confirmed COVID-19 between March 3 and May 31, 2020, in a large academic medical system in New York. The final date of follow-up was July 15, 2020. Patients without available medical records before testing were excluded. Exposures: Patients were categorized based on the following International Statistical Classification of Diseases, Tenth Revision, Clinical Modification diagnoses before their testing date: (1) schizophrenia spectrum disorders, (2) mood disorders, and (3) anxiety disorders. Patients with these diagnoses were compared with a reference group without psychiatric disorders. Main Outcomes and Measures: Mortality, defined as death or discharge to hospice within 45 days following a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test result. Results: Of the 26 540 patients tested, 7348 tested positive for SARS-CoV-2 (mean [SD] age, 54 [18.6] years; 3891 [53.0%] women). Of eligible patients with positive test results, 75 patients (1.0%) had a history of a schizophrenia spectrum illness, 564 (7.7%) had a history of a mood disorder, and 360 (4.9%) had a history of an anxiety disorder. After adjusting for demographic and medical risk factors, a premorbid diagnosis of a schizophrenia spectrum disorder was significantly associated with mortality (odds ratio [OR], 2.67; 95% CI, 1.48-4.80). Diagnoses of mood disorders (OR, 1.14; 95% CI, 0.87-1.49) and anxiety disorders (OR, 0.96; 95% CI, 0.65-1.41) were not associated with mortality after adjustment. In comparison with other risk factors, a diagnosis of schizophrenia ranked behind only age in strength of an association with mortality. Conclusions and Relevance: In this cohort study of adults with SARS-CoV-2-positive test results in a large New York medical system, adults with a schizophrenia spectrum disorder diagnosis were associated with an increased risk for mortality, but those with mood and anxiety disorders were not associated with a risk of mortality. These results suggest that schizophrenia spectrum disorders may be a risk factor for mortality in patients with COVID-19.

Effect of DAOA genetic variation on white matter alteration in corpus callosum in patients with first-episode schizophrenia.

D-amino acid oxidase activator (DAOA) gene, which plays a crucial role in the process of glutamatergic transmission and mitochondrial function, is frequently linked with the liability for schizophrenia. We aimed to investigate whether the variation of DAOA rs2391191 is associated with alterations in white matter integrity of first-episode schizophrenia (FES) patients; and whether it influences the association between white matter integrity, cognitive function and clinical symptoms of schizophrenia. Forty-six patients with FES and forty-nine healthy controls underwent DTI and were genotyped for DAOA rs2391191. Psychopathological assessments were performed by Brief Psychiatric Rating Scale (BPRS) and Scale for Assessment of Negative Symptoms (SANS). Cognitive function was assessed by MATRICS Consensus Cognitive Battery (MCCB). Schizophrenia patients presented lower fractional anisotropy (FA) and higher radial diffusivity (RD), mainly spreading over the corpus callosum and corona radiata compared with healthy controls. Compared with patients carrying G allele, patients with AA showed lower FA in the body of corpus callosum, and higher RD in the genu of corpus callosum, right superior and anterior corona radiata, and left posterior corona radiata. In patients carrying G allele, FA in body of corpus callosum was positively correlated with working memory, RD in genu of corpus callosum was negatively associated with the speed of processing, working memory, and the composite score of MCCB, while no significant correlations were found in AA homozygotes. In our study, patients with FES presented abnormal white matter integrity in corpus callosum and corona radiata. Furthermore, this abnormality was associated with the genetic variation of DAOA rs2391191, with AA homozygotes showing less white matter integrity in the corpus callosum. Our findings possibly provide further support to the evidence that DAOA regulates the process of glutamatergic neurotransmission and mitochondrial function in the pathophysiological mechanism of schizophrenia.

D-cycloserine augmentation of cognitive behavioral therapy for delusions: A randomized clinical trial.

OBJECTIVE: D-cycloserine (DCS) promotes consolidation of extinction learning. This study extends earlier work by examining whether DCS can enhance cognitive behavioral therapy (CBT) for delusions. METHODS: Adults reporting moderate or greater delusions were randomly assigned to receive 50 mg of DCS or placebo prior to 10 weekly CBT sessions. The primary outcome was change in severity of delusions measured with the Psychotic Symptom Rating Scale delusion subscale (PSYRATS-D). Secondary outcomes included persistence of response at 3 and 6 month follow-up and the effects of DCS on memory consolidation and cognitive flexibility. Fifty-eight participants were randomized and 44 completed the trial. RESULTS: The DCS and placebo groups did not differ in change from baseline to end of CBT on PSYRATS-D, nor did DCS improve memory consolidation or cognitive flexibility compared to placebo. However, at the 3 month follow-up visit (week 24), 47% of participants who completed treatment with DCS reported a 20% or greater decrease on PSYRATS-D compared to 15% in the placebo group (p = .04). Change in distress across CBT sessions interacted with treatment group to predict change from baseline to week 24 in PSYRATS-D total score (p = .03) such that response at week 24 was greatest in DCS-treated participants who experienced a decrease in distress during CBT sessions. CONCLUSIONS: DCS augmentation of CBT did not improve delusions compared to placebo during treatment; however, DCS was associated with a higher response rate at 3-month follow-up. DCS may produce a delayed therapeutic effect, associated with successful CBT sessions, but this finding requires replication.

Blood Levels to Optimize Antipsychotic Treatment in Clinical Practice: A Joint Consensus Statement of the American Society of Clinical Psychopharmacology and the Therapeutic Drug Monitoring Task Force of the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie.

OBJECTIVE: The quantification of antipsychotic levels in blood, also known as therapeutic drug monitoring (TDM), is a potentially useful tool of modern personalized therapy that can be applied to augment antipsychotic use and dosing decisions. The application of TDM for antipsychotics can be helpful in numerous challenging clinical scenarios, such as lack of therapeutic response, relapse, or adverse drug reactions (ADRs) related to antipsychotic treatment. The benefits of TDM may be particularly evident in the treatment of highly vulnerable patient subgroups, such as children, adolescents, pregnant women, and the elderly. The main aim of this article is to aid clinicians who routinely prescribe antipsychotics to successfully apply TDM in routine clinical practice in order to help optimize the efficacy and safety of those antipsychotics. PARTICIPANTS: Participants were clinicians and researchers, members of the American Society of Clinical Psychopharmacology, and the Therapeutic Drug Monitoring Task Force of the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (Association of Neuropsychopharmacology and Pharmacopsychiatry). EVIDENCE: TDM literature on antipsychotics was critically reviewed to provide a condensed clinical decision-making algorithm with therapeutic reference ranges for blood antipsychotic levels, within which patients are most likely to respond and tolerate treatment, although TDM is not equally recommended/supported for all antipsychotics. CONSENSUS PROCESS: A preliminary draft was prepared and circulated to the writing group members. Consensus was achieved in all cases, and resulting recommendations focused on following areas: steady-state and sampling time, levels of recommendations, indications, therapeutic reference ranges and laboratory alert levels, practical issues, and interpretation, as well as limitations. CONCLUSIONS: The utilization of TDM as a tool for problem solving in antipsychotic treatment offers a unique method to improve safety and efficacy. This consensus statement summarizes essential information on the routine use of TDM for antipsychotics and encourages clinicians to perform TDM with the appropriate indications as part of the clinical decision-making process.