Does fast dissociation from the dopamine d(2) receptor explain the action of atypical antipsychotics?: A new hypothesis

Neurostructural, Neurofunctional, and Clinical Features of Chronic, Untreated Schizophrenia: A Narrative Review

Studies of individuals with chronic, untreated schizophrenia (CUS) can provide important insights into the natural course of schizophrenia and how antipsychotic pharmacotherapy affects neurobiological aspects of illness course and progression. We systematically review 17 studies on the neuroimaging, cognitive, and epidemiological aspects of CUS individuals. These studies were conducted at the Shanghai Mental Health Center, Institute of Mental Health at Peking University, and Huaxi MR Research Center between 2013 and 2021. CUS is associated with cognitive impairment, severe symptoms, and specific demographic characteristics and is different significantly from those observed in antipsychotic-treated individuals. Furthermore, CUS individuals have neurostructural and neurofunctional alterations in frontal and temporal regions, corpus callosum, subcortical, and visual processing areas, as well as default-mode and somatomotor networks. As the disease progresses, significant structural deteriorations occur, such as accelerated cortical thinning in frontal and temporal lobes, greater reduction in fractional anisotropy in the genu of corpus callosum, and decline in nodal metrics of gray mater network in thalamus, correlating with worsening cognitive deficits and clinical outcomes. In addition, striatal hypertrophy also occurs, independent of antipsychotic treatment. Contrasting with the negative neurostructural and neurofunctional effects of short-term antipsychotic treatment, long-term therapy frequently results in significant improvements. It notably enhances white matter integrity and the functions of key subcortical regions such as the amygdala, hippocampus, and striatum, potentially improving cognitive functions. This narrative review highlights the progressive neurobiological sequelae of CUS, the importance of early detection, and long-term treatment of schizophrenia, particularly because treatment may attenuate neurobiological deterioration and improve clinical outcomes.

Evaluation of the pharmacodynamic interaction effect of augmentation agents with clozapine in patients with treatment-resistant schizophrenia: A simulation study of clinical data

INTRODUCTION

The aim of the study was to evaluate interaction effect of various augmentation strategies with clozapine in patients with Treatment-resistant schizophrenia.

METHODS

Data was extracted for change in positive and negative syndrome scale (PANSS) or brief psychiatric rating scale (BPRS) scores for monotherapy with various antipsychotic agents alone and their combination with clozapine. Individual patient data was generated using simulation of data (factorial trial framework) from published clinical trials for sample sizes from eight to 400 to evaluate interaction effect through linear modeling. Dose equivalents were calculated, and best fit models were determined for simulated data.

RESULTS

The polynomial model was found to be the best fit for the simulated data to determine interaction effect of combination. The clozapine augmentation with risperidone and ziprasidone was found to be antagonistic, whereas it was additive for haloperidol, aripiprazole, and quetiapine. A synergistic effect was observed for ECT combined with clozapine (Interaction effect: -7.62; p <0.001). A sample size of 250-300 may be sufficient to demonstrate a clinically significant interaction in future trials.

CONCLUSION

Clozapine may be augmented with electroconvulsive therapy, leading to the enhancement of antipsychotic effect. Though some antipsychotics like aripiprazole demonstrate additive effects, they may also add to the adverse effects.

The effect of second-generation antipsychotics on anxiety/depression in patients with schizophrenia: A systematic review and meta-analysis

OBJECTIVE

Despite the high prevalence of anxiety in schizophrenia, no established guideline exists for the management of these symptoms. We aimed to synthesize evidence on the effect of second-generation antipsychotics (SGAs) on anxiety in patients with schizophrenia.

METHODS

We systematically searched Medline, Embase, PsycInfo, Web of Science, PubMed, and Cochrane library to identify randomized controlled trials of SGAs that reporting anxiety measures in schizophrenia. The search was limited to English-language articles published before February 2024. Data were pooled using a random-effects model.

RESULTS

Among 48 eligible studies, 29 (n = 7712) were included in the meta-analyses comparing SGAs to placebo, haloperidol, or another SGAs for their effect on anxiety/depression. SGAs had a small effect on anxiety/depression versus placebo (SMD = -0.28 (95 % CI [-0.34, -0.21], p < .00001, I2 = 47 %, n = 5576)) associated with efficacy for positive (z = 5.679, p < .001) and negative symptoms (z = 4.490, p < .001). Furthermore, SGAs were superior to haloperidol (SMD = -0.44, 95 % CI [-0.75, -0.13], p = .005, n = 1068) with substantial study-level heterogeneity (I2 = 85 %). Excluding one study of quetiapine in first-episode patients (SMD = -3.05, n = 73), SGAs showed a small effect on anxiety/depression versus haloperidol without heterogeneity (SMD = -0.23, 95 % CI [-0.35, -0.12], p = 01; I2 = %0). Risperidone's effect on anxiety/depression was comparable to olanzapine (SMD = -0.02, 95 % CI [-0.24,0.20], p = .87, I2 = 45 %, n = 753) and amisulpride (SMD = 0.27, 95 % CI [-1.08,0.61], p = .13, I2 = 50 %, n = 315).

CONCLUSION

While SGAs showed a small effect on anxiety/depression, the findings are inconclusive due to scarcity of research on comorbid anxiety in schizophrenia, heterogeneity of anxiety symptoms, and the scales used to measure anxiety. Further studies employing specific anxiety scales are required to explore antipsychotics, considering their receptor affinity and augmentation with serotonin/norepinephrine reuptake inhibitors or benzodiazepines for managing anxiety in schizophrenia.

Overcoming the barriers to identifying and managing treatment-resistant schizophrenia and to improving access to clozapine: A narrative review and recommendation for clinical practice

Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia (TRS). Although a large body of evidence supports its efficacy and favorable risk-benefit ratio in individuals who have failed two or more antipsychotics, clozapine remains underused. However, variations in clozapine utilization across geographic and clinical settings suggest that it could be possible to improve its use. In this narrative review and expert opinion, we summarized information available in the literature on the mechanisms of action, effectiveness, and potential adverse events of clozapine. We identified barriers leading to discouragement in clozapine prescription internationally, and we proposed practical solutions to overcome each barrier. One of the main obstacles identified to the use of clozapine is the lack of appropriate training for physicians: we highlighted the need to develop specific professional programs to train clinicians, both practicing and in residency, on the relevance and efficacy of clozapine in TRS treatment, initiation, maintenance, and management of potential adverse events. This approach would facilitate physicians to identify eligible patients and offer clozapine as a treatment option in the early stage of the disease. We also noted that increasing awareness of the benefits of clozapine among healthcare professionals, people with TRS, and their caregivers can help promote the use of clozapine. Educational material, such as leaflets or videos, could be developed and distributed to achieve this goal. The information provided in this article may be useful to improve disease burden and support healthcare professionals, patients, and caregivers navigating the complex pathways to TRS management.

Metabolic complications of psychotropic medications in psychiatric disorders: Emerging role of de novo lipogenesis and therapeutic consideration

Although significant advances have been made in understanding the patho-physiology of psychiatric disorders (PDs), therapeutic advances have not been very convincing. While psychotropic medications can reduce classical symptoms in patients with PDs, their long-term use has been reported to induce or exaggerate various pre-existing metabolic abnormalities including diabetes, obesity and non-alcoholic fatty liver disease (NAFLD). The mechanism(s) underlying these metabolic abnormalities is not clear; however, lipid/fatty acid accumulation due to enhanced de novo lipogenesis (DNL) has been shown to reduce membrane fluidity, increase oxidative stress and inflammation leading to the development of the aforementioned metabolic abnormalities. Intriguingly, emerging evidence suggest that DNL dysregulation and fatty acid accumulation could be the major mechanisms associated with the development of obesity, diabetes and NAFLD after long-term treatment with psychotropic medications in patients with PDs. In support of this, several adjunctive drugs comprising of anti-oxidants and anti-inflammatory agents, that are used in treating PDs in combination with psychotropic medications, have been shown to reduce insulin resistance and development of NAFLD. In conclusion, the above evidence suggests that DNL could be a potential pathological factor associated with various metabolic abnormalities, and a new avenue for translational research and therapeutic drug designing in PDs.

LC-MS/MS quantification of olanzapine in hair after alkaline digestion

Olanzapine (OLZ), a second-generation antipsychotic drug, is effective in the treatment of acute psychosis, schizophrenia, agitation, bipolar mania, and other psychiatric problems. Antipsychotics are prescribed drugs, which lead the drug abuser to illegal methods of access. This behavior also demonstrates the association of OLZ with criminal involvement, commonly observed at forensic crime scenes. The acute toxicity and even death resulting from OLZ exposure have been highlighted in numerous studies. Therefore, developing analytical techniques to detect OLZ is essential for forensic toxicology. This study aimed to develop a specific and reliable LC-MS/MS method for OLZ detection and quantification in hair samples. The method was validated in terms of selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), trueness, precision, and uncertainty. The range of linearity was between 0.1-100 ng/mg, with LOD and LOQ values established at 0.036 ng/mg and 0.1 ng/mg, respectively. All validation results are within acceptable parameters. The validated method has been applied to authentic hair samples. The variation of OLZ concentrations in 12 hair segments (2 from Case 1 and 10 from Case 2) from two drug-positive patients, ranging from 0.131 to 0.460 ng/mg, is presented in this study. Although several studies have been conducted to determine OLZ in hair samples using segmental analysis via hair solubilization, this study is the first to determine OLZ in hair samples after "digestion" with comparative parameters prior to chromatographic analysis.

Chemogenetic Signaling in Space and Time: Considerations for Designing Neuroscience Experiments Using DREADDs

The use of designer receptors exclusively activated by designer drugs (DREADDs) has led to significant advances in our understanding of the neural circuits that govern behavior. By allowing selective control over cellular activity and signaling, DREADDs have become an integral tool for defining the pathways and cellular phenotypes that regulate sleep, pain, motor activity, goal-directed behaviors, and a variety of other processes. In this review, we provide a brief overview of DREADDs and discuss notable discoveries in the neurosciences with an emphasis on circuit mechanisms. We then highlight methodological approaches to achieve pathway specific activation of DREADDs. Finally, we discuss spatial and temporal constraints of DREADDs signaling and how these features can be incorporated into experimental designs to precisely dissect circuits of interest.

Dissociation and recovery in psychosis - an overview of the literature

Background

The relationship between dissociation and recovery from psychosis is a new topic, which could attract the interest of the researchers in the field of dissociation due to its relevance to their daily clinical practice. This review brings together a diversity of international research and theoretical views on the phenomenology of dissociation, psychosis and recovery and provides a synthesis by narrative and tabulation of the existing knowledge related to these concepts.

Aims

The objective was to make a synthesis by narrative and tabulation about what is known on the topic.

Methods

The systematic search was conducted according to the PRISMA-statement in the databases Medline, PsycInfo, PubMed and Google Scholar. 2110 articles were selected according to the inclusion and exclusion criteria detailed in the methods, and 19 records were included in the review.

Outcomes

None of the included publications put together, in the same conceptualisation or hypothesis, dissociation and the recovery from an episode of psychosis, therefore this matter remains unstudied at this time.

Conclusion

The process of reviewing the existing scientific literature in the field of dissociation and recovery from psychosis has been very useful for charting the direction that future research will take.

A Systematic Review of Clozapine Concentration-Dose Ratio from Therapeutic Drug Monitoring Studies in Children and Adolescents Treated with Clozapine for Mental Disorders

BACKGROUND

Therapeutic drug monitoring of clozapine in children and adolescents has received insufficient attention. Calculation of concentration-to-dose (C/D) ratios from trough steady-state concentrations estimate drug clearance.

METHODS

A systematic electronic literature search was conducted in 3 article databases from inception until January 10, 2023, and articles reporting clozapine concentrations in children and adolescents were retrieved. The pharmacokinetic quality of the studies was assessed, and clozapine C/D ratios were calculated using the sample mean clozapine dose and concentration.

RESULTS

Of the 37 articles of potential interest, only 7 reported clozapine trough and steady-state concentrations. After excluding case reports and a study confounded by fluvoxamine, 4 studies on psychosis from Europe and the United States were included. The clozapine C/D ratios were similar to published adult values and ranged from 0.82 to 1.24 with a weighted mean of 1.08 ng/mL per mg/d. The weighted means were 334 mg/d for the dose and 380 ng/mL for the concentration. The stratified analysis of the weighted mean clozapine C/D ratios from 2 studies showed lower values in 52 male (1.05 ng/mL per mg/d) than in 46 female (1.46 ng/mL per mg/d) children and adolescents, with values similar to those reported for European adult nonsmokers. Two female adolescents had high clozapine C/D ratios (2.54 ng/mL per mg/d), an Asian American patient with borderline obesity and a patient with intellectual disability with low dosage (mean = 102 mg/d) and concentration (mean = 55 ng/mL).

CONCLUSIONS

Reports on clozapine therapeutic drug monitoring in children and adolescents are limited in number and quality. Future studies should focus on basic pharmacokinetic issues, such as stratification by sex, smoking, and relevant comedications with inductive or inhibitory properties.

The central role of the Thalamus in psychosis, lessons from neurodegenerative diseases and psychedelics

The PD-DLB psychosis complex found in Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB) includes hallucinations, Somatic Symptom/Functional Disorders, and delusions. These disorders exhibit similar presentation patterns and progression. Mechanisms at the root of these symptoms also share similarities with processes promoting altered states of consciousness found in Rapid Eye Movement sleep, psychiatric disorders, or the intake of psychedelic compounds. We propose that these mechanisms find a crucial driver and trigger in the dysregulated activity of high-order thalamic nuclei set in motion by ThalamoCortical Dysrhythmia (TCD). TCD generates the loss of finely tuned cortico-cortical modulations promoted by the thalamus and unleashes the aberrant activity of the Default Mode Network (DMN). TCD moves in parallel with altered thalamic filtering of external and internal information. The process produces an input overload to the cortex, thereby exacerbating DMN decoupling from task-positive networks. These phenomena alter the brain metastability, creating dreamlike, dissociative, or altered states of consciousness. In support of this hypothesis, mind-altering psychedelic drugs also modulate thalamic-cortical pathways. Understanding the pathophysiological background of these conditions provides a conceptual bridge between neurology and psychiatry, thereby helping to generate a promising and converging area of investigation and therapeutic efforts.

Fronto-striato-thalamic circuit connectivity and neuromelanin in schizophrenia: an fMRI and neuromelanin-MRI study

Changes in dopamine and fronto-striato-thalamic (FST) circuit functional connectivity are prominent in schizophrenia. Dopamine is thought to underlie connectivity changes, but experimental evidence for this hypothesis is lacking. Previous studies examined the association in some of the connections using positron emission tomography (PET) and functional MRI (fMRI); however, PET has disadvantages in scanning patients, such as invasiveness. Excessive dopamine induces neuromelanin (NM) accumulation, and NM-MRI is suggested as a noninvasive proxy measure of dopamine function. We aimed to investigate the association between NM and FST circuit connectivity at the network level in patients with schizophrenia. We analysed substantia nigra NM-MRI and resting-state fMRI data from 29 schizophrenia patients and 63 age- and sex-matched healthy controls (HCs). We identified the FST subnetwork with abnormal connectivity found in schizophrenia patients compared to that of HCs and investigated the relationship between constituting connectivity and NM-MRI signal. We found a higher NM signal (t = -2.12, p = 0.037) and a hypoconnected FST subnetwork (FWER-corrected p = 0.014) in schizophrenia patients than in HCs. In the hypoconnected subnetwork of schizophrenia patients, lower left supplementary motor area-left caudate connectivity was associated with a higher NM signal (β = -0.38, p = 0.042). We demonstrated the association between NM and FST circuit connectivity. Considering that the NM-MRI signal reflects dopamine function, our results suggest that dopamine underlies changes in FST circuit connectivity, which supports the dopamine hypothesis. In addition, this study reveals implications for the future use of NM-MRI in investigations of the dopamine system.

Treatment of severe tardive dyskinesia with concurrent administration of olanzapine, clonazepam, baclofen, and gabapentin: a case report

BACKGROUND

Long-term use of antipsychotics or other dopamine antagonists can result in the extrapyramidal side effect of tardive dyskinesia (TD).Case presentation: An 18-year-old female patient experienced abnormal speech and behavior and because of an equivocal diagnosis, she was given daily doses of 300 mg of quetiapine and 60 mg of ziprasidone. She had used these medications for 2 years before the appearance of involuntary abnormal movements. These movements, which were classified as TD, steadily worsened and markedly interfered with her daily life. Following a trial-and-error course of therapy with vitamin E, vitamin B6, amantadine, valproic acid sodium, lorazepam, and diazepam, the drugs were gradually reduced and stopped, yet the aberrant movements persisted. Finally, the patient was given olanzapine, clonazepam, baclofen, and gabapentin. The Abnormal Involuntary Movement Scale was used to assess changes in the patient's condition. Her TD was efficiently managed through co-administration of olanzapine, clonazepam, baclofen, and gabapentin.

CONCLUSIONS

The possibility of TD inducing by antipsychotic use is a clinical concern, even though atypical antipsychotics decrease the incidence of extrapyramidal side effects, and it cannot be entirely excluded. This report provides useful insights into the management of TD and will help clinicians manage similar cases.

A systematic review of neuroimaging studies of clozapine-resistant schizophrenia

This systematic review aimed to review neuroimaging studies comparing clozapine-resistant schizophrenia patients with clozapine-responding patients, and with first-line antipsychotic responding (FLR) patients. A total of 19 studies including 6 longitudinal studies were identified. Imaging techniques comprised computerized tomography (CT, n = 3), structural magnetic resonance imaging (MRI, n = 7), magnetic resonance spectroscopy (MRS, n = 5), functional MRI (n = 1), single-photon emission computerized tomography (SPECT, n = 3) and diffusion tensor imaging (DTI, n = 1). The most consistent finding was hypo-frontality in the clozapine-resistant group compared with the clozapine-responding group with possible differences in frontal-striatal-basal ganglia circuitry as well as the GABA level between the two treatment-resistant groups. Additional statistically significant findings were reported when comparing clozapine-resistant patients with the FLR group, including lower cortical thickness and brain volume of multiple brain regions as well as lower Glx/Cr level in the dorsolateral prefrontal cortex. Both treatment-resistant groups were found to have extensive differences in neurobiological features in comparison with the FLR group. Overall results suggested treatment-resistant schizophrenia is likely to be a neurobiological distinct type of the illness. Clozapine-resistant and clozapine-responding schizophrenia are likely to have both shared and distinct neurobiological features. However, conclusions from existing studies are limited, and future multi-center collaborative studies are required with a consensus clinical definition of patient samples, multimodal imaging tools, and longitudinal study designs.

A Novel Gliotransmitter, L-β-Aminoisobutyric Acid, Contributes to Pathophysiology of Clinical Efficacies and Adverse Reactions of Clozapine

Clozapine is listed as one of the most effective antipsychotics and has been approved for treating treatment-resistant schizophrenia (TRS); however, several type A and B adverse reactions, including weight gain, metabolic complications, cardiotoxicity, convulsions, and discontinuation syndromes, exist. The critical mechanisms of clinical efficacy for schizophrenia, TRS, and adverse reactions of clozapine have not been elucidated. Recently, the GABA isomer L-β-aminoisobutyric acid (L-BAIBA), a protective myokine in the peripheral organs, was identified as a candidate novel transmission modulator in the central nervous system (CNS). L-BAIBA activates adenosine monophosphate-activated protein kinase (AMPK) signalling in both the peripheral organs and CNS. Activated AMPK signalling in peripheral organs is an established major target for treating insulin-resistant diabetes, whereas activated AMPK signalling in the hypothalamus contributes to the pathophysiology of weight gain and metabolic disturbances. Clozapine increases L-BAIBA synthesis in the hypothalamus. In addition, the various functions of L-BAIBA in the CNS have recently been elucidated, including as an activator of GABA-B and group-III metabotropic glutamate (III-mGlu) receptors. Considering the expressions of GABA-B and III-mGlu receptors (localised in the presynaptic regions), the activation of GABA-B and III-mGlu receptors can explain the distinct therapeutic advantages of clozapine in schizophrenia or TRS associated with N-methyl-D-aspartate (NMDA) receptor disturbance compared with other atypical antipsychotics via the inhibition of the persistent tonic hyperactivation of thalamocortical glutamatergic transmission in the prefrontal cortex. L-BAIBA has also been identified as a gliotransmitter, and a detailed exploration of the function of L-BAIBA in tripartite synaptic transmission can further elucidate the pathophysiology of effectiveness for treating TRS and/or specific adverse reactions of clozapine.

Historical developments, hotspots, and trends in tardive dyskinesia research: a scientometric analysis of 54 years of publications

Background

Since being recognized as an important drug-induced clinical entity during the 1960s, tardive dyskinesia (TD) has generated an extensive body of research seeking to understand its clinical characteristics, epidemiology, pathophysiology and management. Modern scientometric approaches allow interactive visualization of large bodies of literature to identify trends and hotspots within knowledge domains. This study thus aimed to provide a comprehensive scientometric review of the TD literature.

Methods

Web of Science was searched for articles, reviews, editorials and letters with the term "tardive dyskinesia" in the title, abstract, or keywords through 12/31/2021. A total of 5,228 publications and 182,052 citations were included. Annual research output, prominent research areas, authors, affiliations and countries were summarized. VOSViewer and CiteSpace were used for bibliometric mapping and co-citation analysis. Structural and temporal metrics were used to identify key publications in the network.

Results

TD-related publications peaked in the 1990s, gradually declined after 2004, and showed a further small increase after 2015. The most prolific authors were Kane JM, Lieberman JA, and Jeste DV overall (1968-2021), and Zhang XY, Correll CU and Remington G in the last decade (2012-2021). The most prolific journal was the Journal of Clinical Psychiatry overall, and the Journal of Psychopharmacology in the last decade. Knowledge clusters in the 1960-1970s dealt with clinical and pharmacological characterization of TD. In the 1980s, epidemiology, clinical TD assessment, cognitive dysfunction and animal models predominated. During the 1990s, research diverged into pathophysiological studies, especially oxidative stress, and clinical trials on atypical antipsychotics, with a focus on clozapine and bipolar disorder. In the 1990-2000s, pharmacogenetics emerged. More recent clusters include serotonergic receptors, dopamine-supersensitivity psychosis, primary motor abnormalities of schizophrenia, epidemiology/meta-analyses, and advances in TD treatment, particularly vesicular monoamine transporter-2 inhibitors since 2017.

Conclusion

This scientometric review visualized the evolution of scientific knowledge on TD over more than five decades. These findings will be useful for researchers to find relevant literature when writing scientific articles, choosing appropriate journals, finding collaborators or mentors for research, and to understand the historical developments and emerging trends in TD research.

The Hypothalamic-Pituitary-Gonadal Axis in Men with Schizophrenia

Schizophrenia is a severe mental disorder with a chronic, progressive course. The etiology of this condition is linked to the interactions of multiple genes and environmental factors. The earlier age of onset of schizophrenia, the higher frequency of negative symptoms in the clinical presentation, and the poorer response to antipsychotic treatment in men compared to women suggests the involvement of sex hormones in these processes. This article aims to draw attention to the possible relationship between testosterone and some clinical features in male schizophrenic patients and discuss the complex nature of these phenomena based on data from the literature. PubMed, Web of Science, and Google Scholar databases were searched to select the papers without limiting the time of the publications. Hormone levels in the body are regulated by many organs and systems, and take place through the neuroendocrine, hormonal, neural, and metabolic pathways. Sex hormones play an important role in the development and function of the organism. Besides their impact on secondary sex characteristics, they influence brain development and function, mood, and cognition. In men with schizophrenia, altered testosterone levels were noted. In many cases, evidence from available single studies gave contradictory results. However, it seems that the testosterone level in men affected by schizophrenia may differ depending on the phase of the disease, types of clinical symptoms, and administered therapy. The etiology of testosterone level disturbances may be very complex. Besides the impact of the illness (schizophrenia), stress, and antipsychotic drug-induced hyperprolactinemia, testosterone levels may be influenced by, i.a., obesity, substances of abuse (e.g., ethanol), or liver damage.

"Unvoluntary" Movement Disorders: Distinguishing between Tics, Akathisia, Restless Legs, and Stereotypies

Tics, stereotypies, akathisia, and restless legs fall at different places on the spectrum of discrete, unwanted and potentially disabling motor routines. Unlike tremor, chorea, myoclonus, or dystonia, this subgroup of abnormal movements is characterized by the subject's variable ability to inhibit or release undesired motor patterns on demand. Though it may be sometimes clinically challenging, it is crucial to distinguish these "unvoluntary" motor behaviors because secondary causes and management approaches differ substantially. To this end, physicians must consider the degree of repetitiveness of the movements, the existence of volitional control, and the association with sensory symptoms, or cognitive-ideational antecedent. This review aims to summarize the current existing knowledge on phenomenology, diagnosis, and treatment of tics, stereotypies, akathisia, and restless leg syndrome.

Fluphenazine-Induced Neurotoxicity with Acute Almost Transient Parkinsonism and Permanent Memory Loss: Lessons from a Case Report

We report the singular case of a 31-year-old woman who developed very serious Fluphenazine-induced parkinsonism over a few days due to a doubly incongruent drug prescription by indication and dosage having been applied to a healthy subject over one week instead of seven months. Unlike gradual drug-induced parkinsonism, our patient experienced acute extrapyramidal syndrome (EPS), reaching significant motor and sphincter disability in just a few days, followed by a gradual incomplete recovery over more than six months. In fact, after drug discontinuation, hypomimia and slight left hemi-somatic rigidity with bradykinesia remained, as well as stable non-progressive memory disturbances. Despite bio-humoral and instrumental investigations and DaTScan were negative, MRI post-analysis evidenced a 6.5% loss in brain volume. Specifically, irreversible cortical and sub-cortical grey matter reduction and cerebrospinal fluid space enlargement with spared white matter were found. Our observations suggest that the sudden availability of Fluphenazine results in a kind of plateau effect of parkinsonism presentation, partially reversible due to the neurotoxic drug effect on the cortical and sub-cortical grey matter, resulting in asymmetric EPS and stable memory loss, respectively. Our report confirms the debated neurotoxicity of first-generation neuroleptics and the postulated theory of differential susceptibility to the cytotoxic stressors on the central nervous system.

Identification and Characterization of ML321: A Novel and Highly Selective D2 Dopamine Receptor Antagonist with Efficacy in Animal Models That Predict Atypical Antipsychotic Activity

We have developed and characterized a novel D2R antagonist with exceptional GPCR selectivity - ML321. In functional profiling screens of 168 different GPCRs, ML321 showed little activity beyond potent inhibition of the D2R and to a lesser extent the D3R, demonstrating excellent receptor selectivity. The D2R selectivity of ML321 may be related to the fact that, unlike other monoaminergic ligands, ML321 lacks a positively charged amine group and adopts a unique binding pose within the orthosteric binding site of the D2R. PET imaging studies in non-human primates demonstrated that ML321 penetrates the CNS and occupies the D2R in a dose-dependent manner. Behavioral paradigms in rats demonstrate that ML321 can selectively antagonize a D2R-mediated response (hypothermia) while not affecting a D3R-mediated response (yawning) using the same dose of drug, thus indicating exceptional in vivo selectivity. We also investigated the effects of ML321 in animal models that are predictive of antipsychotic efficacy in humans. We found that ML321 attenuates both amphetamine- and phencyclidine-induced locomotor activity and restored pre-pulse inhibition (PPI) of acoustic startle in a dose-dependent manner. Surprisingly, using doses that were maximally effective in both the locomotor and PPI studies, ML321 was relatively ineffective in promoting catalepsy. Kinetic studies revealed that ML321 exhibits slow-on and fast-off receptor binding rates, similar to those observed with atypical antipsychotics with reduced extrapyramidal side effects. Taken together, these observations suggest that ML321, or a derivative thereof, may exhibit ″atypical″ antipsychotic activity in humans with significantly fewer side effects than observed with the currently FDA-approved D2R antagonists.

Decreased cortical gyrification and surface area in the left medial parietal cortex in patients with treatment-resistant and ultratreatment-resistant schizophrenia

AIM

Validating the vulnerabilities and pathologies underlying treatment-resistant schizophrenia (TRS) is an important challenge in optimizing treatment. Gyrification and surface area (SA), reflecting neurodevelopmental features, have been linked to genetic vulnerability to schizophrenia. The aim of this study was to identify gyrification and SA abnormalities specific to TRS.

METHODS

We analyzed 3T magnetic resonance imaging findings of 24 healthy controls (HCs), 20 responders to first-line antipsychotics (FL-Resp), and 41 patients with TRS, including 19 clozapine responders (CLZ-Resp) and 22 FL- and clozapine-resistant patients (patients with ultratreatment-resistant schizophrenia [URS]). The local gyrification index (LGI) and associated SA were analyzed across groups. Diagnostic accuracy was verified by receiver operating characteristic curve analysis.

RESULTS

Both CLZ-Resp and URS had lower LGI values than HCs (P = 0.041, Hedges g [g_H ] = 0.75; P = 0.013, g_H  = 0.96) and FL-Resp (P = 0.007, g_H  = 1.00; P = 0.002, g_H  = 1.31) in the left medial parietal cortex (Lt-MPC). In addition, both CLZ-Resp and URS had lower SA in the Lt-MPC than FL-Resp (P < 0.001, g_H  = 1.22; P < 0.001, g_H  = 1.75). LGI and SA were positively correlated in non-TRS (FL-Resp) (ρ = 0.64, P = 0.008) and TRS (CLZ-Resp + URS) (ρ = 0.60, P < 0.001). The areas under the receiver operating characteristic curve for non-TRS versus TRS with LGI and SA in the Lt-MPC were 0.79 and 0.85, respectively. SA in the Lt-MPC was inversely correlated with negative symptoms (ρ = -0.40, P = 0.018) and clozapine plasma levels (ρ = -0.35, P = 0.042) in TRS.

CONCLUSION

LGI and SA in the Lt-MPC, a functional hub in the default-mode network, were abnormally reduced in TRS compared with non-TRS. Thus, altered LGI and SA in the Lt-MPC might be structural features associated with genetic vulnerability to TRS.

Updated Perspectives on the Management of Drug-Induced Parkinsonism (DIP): Insights from the Clinic

Parkinsonism refers to the clinical combination of bradykinesia, rigidity, tremor, and postural instability. Parkinsonism is often neurodegenerative, but it can be secondary or iatrogenic, as in drug-induced parkinsonism (DIP), which is the topic of this review. We review the pathophysiology of DIP, differentiate DIP and idiopathic Parkinson's disease (PD), list culprit medications in the development of DIP, discuss the diagnosis of DIP as well as the motor and nonmotor signs and symptoms that can help with differentiation of DIP and PD, and detail the management of DIP.

Antipsychotic Abuse, Dependence, and Withdrawal in the Pediatric Population: A Real-World Disproportionality Analysis

Antipsychotic drugs (APs) aim to treat schizophrenia, bipolar mania, and behavioral symptoms. In child psychiatry, despite limited evidence regarding their efficacy and safety, APs are increasingly subject to off-label use. Studies investigating addictology-related symptoms in young people being scarce, we aimed to characterize the different patterns of AP misuse and withdrawal in children and adolescents relying on the WHO pharmacovigilance database (VigiBase^®, Uppsala Monitoring Centre, Sweden). Using the standardized MedDRA Query 'drug abuse, dependence and withdrawal', disproportionality for each AP was assessed with the reporting odds ratio and the information component. A signal was detected when the lower end of the 95% confidence interval of the information component was positive. Results revealed mainly withdrawal symptoms in infants (under 2 years), intentional misuse in children (2 to 11 years), and abuse in adolescents (12 to 17 years). Olanzapine, risperidone, aripiprazole, and quetiapine were disproportionately reported in all age groups, with quetiapine being subject to a specific abuse signal in adolescents. Thus, in adolescents, the evocation of possible recreational consumption may lead to addiction-appropriate care. Further, in young patients with a history of AP treatment, a careful anamnesis may allow one to identify misuse and its role in the case of new-onset symptoms.

Effects of cannabidiol on vacuous chewing movements, plasma glucose and oxidative stress indices in rats administered high dose risperidone

Atypical antipsychotics, despite their rapid dissociation from dopamine receptors and reduced tendency to induce oxidative stress, have been associated with difficult-to-manage movement disorders, including tardive dyskinesia (TD). The study set out to investigate the effects of cannabidiol (CBD), a potent antioxidant, on risperidone-induced behavioural and motor disturbances; namely vacuous chewing movements (VCM), and oxidative stress markers (e.g. superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), malondialdehyde (MDA), Nitric oxide (NO), and DPPH (2,2-diphenyl-1-picrylhydrazyl)). Oral risperidone (10 mg/kg) or oral CBD (5 mg/kg) were administered to six experimental groups. While risperidone alone was administered for 28 days, CBD concomitantly or in sequential order with risperidone, was administered for 28 days; and CBD alone was administered for 21 days. Behavioural, motor, and specific biochemical parameters, which included VCM, muscle tone, fasting blood sugar (FBS), and oxidative stress markers were assessed at different time points after the last dose of medication. Oral CBD (5 mg/kg) significantly reduced risperidone-induced elevated FBS when given after the administration of risperidone. Oral CBD also had effects on VCM when administered before risperidone and similarly, attenuated risperidone-induced increased muscle tone. It was also established that concomitant or sequential administration of CBD and risperidone did not have any adverse effects on cognition or locomotion. Both CBD and risperidone increased the activity of antioxidant enzymes and decreased the activity of pro-oxidant enzymes. This study suggests CBD could mitigate metabolic dysregulation and extrapyramidal side effects associated with risperidone without producing cognitive impairments.

Pathophysiological Mechanisms of Antipsychotic-Induced Parkinsonism

Among neurological adverse reactions in patients with schizophrenia treated with antipsychotics (APs), drug-induced parkinsonism (DIP) is the most common motility disorder caused by drugs affecting dopamine receptors. One of the causes of DIP is the disruption of neurotransmitter interactions that regulate the signaling pathways of the dopaminergic, cholinergic, GABAergic, adenosinergic, endocannabinoid, and other neurotransmitter systems. Presently, the development mechanisms remain poorly understood despite the presence of the considered theories of DIP pathogenesis.

Clozapine's multiple cellular mechanisms: What do we know after more than fifty years? A systematic review and critical assessment of translational mechanisms relevant for innovative strategies in treatment-resistant schizophrenia

Almost fifty years after its first introduction into clinical care, clozapine remains the only evidence-based pharmacological option for treatment-resistant schizophrenia (TRS), which affects approximately 30% of patients with schizophrenia. Despite the long-time experience with clozapine, the specific mechanism of action (MOA) responsible for its superior efficacy among antipsychotics is still elusive, both at the receptor and intracellular signaling level. This systematic review is aimed at critically assessing the role and specific relevance of clozapine's multimodal actions, dissecting those mechanisms that under a translational perspective could shed light on molecular targets worth to be considered for further innovative antipsychotic development. In vivo and in vitro preclinical findings, supported by innovative techniques and methods, together with pharmacogenomic and in vivo functional studies, point to multiple and possibly overlapping MOAs. To better explore this crucial issue, the specific affinity for 5-HT₂R, D1R, α_2c, and muscarinic receptors, the relatively low occupancy at dopamine D2R, the interaction with receptor dimers, as well as the potential confounder effects resulting in biased ligand action, and lastly, the role of the moiety responsible for lipophilic and alkaline features of clozapine are highlighted. Finally, the role of transcription and protein changes at the synaptic level, and the possibility that clozapine can directly impact synaptic architecture are addressed. Although clozapine's exact MOAs that contribute to its unique efficacy and some of its severe adverse effects have not been fully understood, relevant information can be gleaned from recent mechanistic understandings that may help design much needed additional therapeutic strategies for TRS.

Physicochemical Insights on Terahertz Wave Diminished Side Effects of Drugs from Slow Dissociation

Dopamine D2 receptors (D2Rs) are one of the most intensely investigated and well-established drug targets for neuropsychiatric disorders. Selective D2R antagonists have been developed as efficacious antipsychotic drugs. Nevertheless, the potent drugs with necessarily high affinity are prone to slow dissociation, which invokes a plethora of severe side effects such as extrapyramidal symptoms, substantial weight gain, associated diabetes, etc. This has become a major barrier in treating psychiatric patients. In this work, we propose a physical method, terahertz wave modulation, to promote the dissociation of high-affinity antipsychotics and thus diminish the side effects. We have proven that a 4.0 THz wave could reduce the affinity by 71% between the D2R and a risperidone ligand and meanwhile expand the exit via conformation modulation, which promises an accelerated dissociation of risperidone. In addition, it is estimated that the enhancement of the dissociation rate due to lowered binding by terahertz irritation could constitute up to 8 orders of magnitude, which is fairly impressive and resembles the enzyme's catalysis. Also, acceleration of the dissociation rate could be adjusted by the irritation strength. This work elaborates the terahertz wave-modulated noncovalent interactions critical in cell signaling pathways. Most importantly, it demonstrates the feasibility of terahertz technologies intervening in receptor-ligand complex regulated diseases such as neurodegenerative disorders, metabolic diseases, etc.

Treatment Effect of Long-Term Antipsychotics on Default-Mode Network Dysfunction in Drug-Naïve Patients With First-Episode Schizophrenia: A Longitudinal Study

Background: The maintenance of antipsychotic treatment is an efficient way to prevent the relapse of schizophrenia (SCZ). Previous studies have identified beneficial effects of antipsychotics on brain structural and functional abnormalities during mostly the acute phase in SCZ, but seldom is known about the effects of long-term antipsychotics on the brain. The present study focused on the long-term antipsychotic effect on the default mode network (DMN) dysfunction in SCZ.

Methods: A longitudinal study of the functional connectivity (FC) of 11 DMN subdivisions was conducted in 86 drug-naive first-episode patients with SCZ at the baseline and after a long-term atypical antipsychotic treatment (more than 6 months) based on the resting-state functional magnetic resonance image. In total, 52 patients completed the follow-up of clinical and neuroimaging investigations.

Results: At the baseline, relative to healthy controls, altered connectivities within the DMN and between the DMN and the external attention system (EAS) were observed in patients. After treatment, along with significant relief of symptoms, most FC alterations between the DMN and the EAS at the baseline were improved after treatment, although the rehabilitation of FC within the DMN was only observed at the link between the posterior cingulate cortex and precuneus. Greater reductions in negative and positive symptoms were both related to the changes of DMN-EAS FC in patients.

Conclusion: Our findings provide evidence that maintenance antipsychotics on SCZ is beneficial for the improvement of DMN-EAS competitive imbalance, which may partly contribute to the efficient relapse prevention of this severe mental disorder.

Neutrophil Myeloperoxidase-Mediated N-Demethylation of Quetiapine Leads to N-Desalkylquetiapine, a Pharmacologically Active Cytochrome P450 Metabolite

The atypical antipsychotic drugs, quetiapine and clozapine, are associated with idiosyncratic drug reactions (such as agranulocytosis or neutropenia) that are thought to involve reactive metabolites. Neutrophil myeloperoxidase (MPO) metabolism of quetiapine is not well-studied, but is metabolized by cytochrome P450. Based on structural similarity to clozapine, we hypothesized that quetiapine can be metabolized by MPO and that there is overlap between cytochrome P450 and MPO metabolism of quetiapine. The interaction of quetiapine and clozapine with MPO and MPO chlorination activity was studied using UV-vis spectrophotometry. The metabolites were characterized using liquid chromatography-mass spectrometry (LC-MS), and electron paramagnetic resonance (EPR) spectroscopy was used for detecting drug-catalyzed glutathione oxidation. In the presence of quetiapine, MPO compound II accumulated for about 7.5 min, whereas in the presence of clozapine, MPO compound II was not observed as it was rapidly reduced back to the resting state. Increasing quetiapine concentrations resulted in a decrease in MPO chlorination activity, while the opposite result was found in the case of clozapine. UV-vis spectral studies showed no change when quetiapine was oxidized in the absence and presence of chloride anion (Cl^-, to catalyze chlorination reactions). Significant changes, however, were observed in the same assay with clozapine, where Cl^- appeared to hinder the rate of clozapine metabolism. The MPO-catalyzed hydroxylated and dealkylated metabolites of quetiapine and hydroxylated metabolites of clozapine were observed from the LC-MS analyses, particularly when Cl^- was included in the reaction. In addition, hydroxylated, dealkylated, and a proposed sulfoxide metabolite of quetiapine were also observed in the reaction catalyzed by human microsomes/NADPH. Lastly, compared to quetiapine, clozapine metabolism by MPO/H₂O₂ and glutathione produced more glutathionyl radicals using EPR spin trapping. In conclusion, MPO/H₂O₂/Cl^- was shown to metabolize quetiapine to S-oxidation and P450-like dealkylation products, and quetiapine metabolites were generally less reactive than clozapine.

Development of an intracellular quantitative assay to measure compound binding kinetics

Contemporary drug discovery typically quantifies the effect of a molecule on a biological target using the equilibrium-derived measurements of IC50, EC50, or KD. Kinetic descriptors of drug binding are frequently linked with the effectiveness of a molecule in modulating a disease phenotype; however, these parameters are yet to be fully adopted in early drug discovery. Nanoluciferase bioluminescence resonance energy transfer (NanoBRET) can be used to measure interactions between fluorophore-conjugated probes and luciferase fused target proteins. Here, we describe an intracellular NanoBRET competition assay that can be used to quantify cellular kinetic rates of compound binding to nanoluciferase-fused bromodomain and extra-terminal (BET) proteins. Comparative rates are generated using a cell-free NanoBRET assay and by utilizing orthogonal recombinant protein-based methodologies. A screen of known pan-BET inhibitors is used to demonstrate the value of this approach in the investigation of kinetic selectivity between closely related proteins.

14-3-3 Dysfunction in Dorsal Hippocampus CA1 (dCA1) Induces Psychomotor Behavior via a dCA1-Lateral Septum-Ventral Tegmental Area Pathway

While hippocampal hyperactivity is implicated in psychosis by both human and animal studies, whether it induces a hyperdopaminergic state and the underlying neural circuitry remains elusive. Previous studies established that region-specific inhibition of 14-3-3 proteins in the dorsal hippocampus CA1 (dCA1) induces schizophrenia-like behaviors in mice, including a novelty-induced locomotor hyperactivity. In this study, we showed that 14-3-3 dysfunction in the dCA1 over-activates ventral tegmental area (VTA) dopaminergic neurons, and such over-activation is necessary for eliciting psychomotor behavior in mice. We demonstrated that such hippocampal dysregulation of the VTA during psychomotor behavior is dependent on an over-activation of the lateral septum (LS), given that inhibition of the LS attenuates over-activation of dopaminergic neurons and psychomotor behavior induced by 14-3-3 inhibition in the dCA1. Moreover, 14-3-3 inhibition-induced neuronal activations within the dCA1-LS-VTA pathway and psychomotor behavior can be reproduced by direct chemogenetic activation of LS-projecting dCA1 neurons. Collectively, these results suggest that 14-3-3 dysfunction in the dCA1 results in hippocampal hyperactivation which leads to psychomotor behavior via a dCA1-LS-VTA pathway.

Pharmacogenetics of Antipsychotic Treatment in Schizophrenia

Antipsychotics are the mainstay treatment for schizophrenia. There is large variability between individuals in their response to antipsychotics, both in efficacy and adverse effects of treatment. While the source of interindividual variability in antipsychotic response is not completely understood, genetics is a major contributing factor. The identification of pharmacogenetic markers that predict antipsychotic efficacy and adverse reactions is a growing area of research and holds the potential to replace the current trial-and-error approach to treatment selection in schizophrenia with a personalized medicine approach.In this chapter, we provide an overview of the current state of pharmacogenetics in schizophrenia treatment. The most promising pharmacogenetic findings are presented for both antipsychotic response and commonly studied adverse reactions. The application of pharmacogenetics to schizophrenia treatment is discussed, with an emphasis on the clinical utility of pharmacogenetic testing and directions for future research.

Socio demographic, clinical, and side effect profile of patients on clozapine in Kashmir, North India

Background

Clozapine is an atypical second-generation antipsychotic belonging to the family of dibenzodiazepines. There is lack of literature on clozapine from this part of the world. So, our aim was to study the socio demographic, clinical and side effect profile of patients on clozapine in Kashmir.

Results

The mean age of the study group was 32.6 ± 8.9 years with majority being males (78.4%), unmarried (78.4%), unemployed (77.2%), and belonging to nuclear families (77.2%). Almost half of them resided in urban localities (51.1%) and studied upto middle school (55.7%). Around three- fourth (75%) of the patients had diagnosis of treatment-resistant schizophrenia. The mean dose of clozapine was 338.92 ± 158.11 mgs. Sedation (76.1%), hypersalivation (69.5%), constipation (46.6%), and weight gain (34.1%) were most common side effects noted in patients. 4.5% cases developed seizures while on clozapine. 2.3% patients developed agranulocytosis while 4.5% patients developed neutropenia on clozapine. The neutropenia was more pronounced in patients of schizophrenia with suicidal tendencies with doses of more than 400 mg.

Conclusions

We have used clozapine in a wide range of indications. Our patients seem to tolerate and respond to higher doses of clozapine and the prevalence of blood dyscrasias in our study sample was much higher than the rest of India.

The Role of Dopaminergic Genes in Probabilistic Reinforcement Learning in Schizophrenia Spectrum Disorders

Schizophrenia spectrum disorders (SZ) are characterized by impairments in probabilistic reinforcement learning (RL), which is associated with dopaminergic circuitry encompassing the prefrontal cortex and basal ganglia. However, there are no studies examining dopaminergic genes with respect to probabilistic RL in SZ. Thus, the aim of our study was to examine the impact of dopaminergic genes on performance assessed by the Probabilistic Selection Task (PST) in patients with SZ in comparison to healthy control (HC) subjects. In our study, we included 138 SZ patients and 188 HC participants. Genetic analysis was performed with respect to the following genetic polymorphisms: rs4680 in COMT, rs907094 in DARP-32, rs2734839, rs936461, rs1800497, and rs6277 in DRD2, rs747302 and rs1800955 in DRD4 and rs28363170 and rs2975226 in DAT1 genes. The probabilistic RL task was completed by 59 SZ patients and 95 HC subjects. SZ patients performed significantly worse in acquiring reinforcement contingencies during the task in comparison to HCs. We found no significant association between genetic polymorphisms and RL among SZ patients; however, among HC participants with respect to the DAT1 rs28363170 polymorphism, individuals with 10-allele repeat genotypes performed better in comparison to 9-allele repeat carriers. The present study indicates the relevance of the DAT1 rs28363170 polymorphism in RL in HC participants.

A preliminary genetic association study of GAD1 and GABAB receptor genes in patients with treatment-resistant schizophrenia

BACKGROUND

GABAergic system dysfunction has been implicated in the etiology of schizophrenia and of cognitive impairments in particular. Patients with treatment-resistant schizophrenia (TRS) generally suffer from profound cognitive impairments in addition to severe positive symptoms, suggesting that GABA system dysfunction could be involved more closely in patients with TRS.

METHODS AND RESULTS

In the present study, exome sequencing was conducted on fourteen TRS patients, whereby four SNPs were identified on GAD1, GABBR1 and GABBR2 genes. An association study for five SNPs including these 4 SNPs and rs3749034 on GAD1 as then performed among 357 patients with TRS, 682 non-TRS patients and 508 healthy controls (HC). The results revealed no significant differences in allelic and/or genetic distributions for any of the five SNPs. However, several subanalyses in comparisons between schizophrenia and HC groups, as well as between the three groups, showed nominal-level significance for rs3749034 on GAD1 and rs10985765/rs3750344 on GABBR2. In particular, in comparisons of female subjects, rigorous analysis for rs3749034 showed a statistical difference between the schizophrenia and HC groups and between the TRS and HC groups.

CONCLUSIONS

Several positive results in subanalyses suggested that genetic vulnerability in the GABA system to schizophrenia or TRS could be affected by sex or sampling area, and overall, that rs3749034 on GAD1 and rs10985765 on GABBR2 could be related to TRS. In the present study, only a few SNPs were examined; it is possible that other important genetic variants in other regions of GABA-related genes were not captured in this preliminary study.

Electron Transfer-Mediated Photodegradation of Phototoxic Antipsychotic Drug Quetiapine

Quetiapine (QTP) (1), a psychotropic agent belonging to a chemical class, dibenzothiazepine derivatives, is photosensitive and photolabile. Its photochemistry was studied in the presence of an electron donor N,N-dimethylaniline (DMA) and an electron acceptor 1,4-dicyanobenzene (DCB) under anaerobic conditions. This resulted in photoinduced electron transfer-mediated transformation of drug QTP. Irradiation of Quetiapine (QTP, 1) in the presence of electron donor N,N-dimethylaniline (DMA) under anaerobic conditions in a photochemical reactor afforded one major photoproduct 2 when irradiation of QTP (1) was carried out in the presence of electron acceptor 1,4-dicyanobenzene (DCB) under similar conditions; it afforded 3 as a major photoproduct. These photoproducts were isolated and characterized on the basis of their spectral (IR, UV, 1H NMR, 13C NMR, and mass spectra) studies. The photophysical properties of Quetiapine were also determined in several solvents to investigate the relevance of the molecular structure in their photophysics and consequently in their photochemistry.

Contrasting Typical and Atypical Antipsychotic Drugs

The beliefs that antipsychotic drugs (APDs) are 1) effective only to treat delusions and hallucinations (positive symptoms), 2) that typical and atypical APDs differ only in ability to cause extrapyramidal side effects, and 3) that their efficacy as antipsychotics is due solely to their dopamine D₂ receptor blockade are outmoded concepts that prevent clinicians from achieving optimal clinical results when prescribing an APD. Atypical APDs are often more effective than typical APDs in treating negative symptoms, cognitive impairment, and mood symptoms as well as reducing the risk for suicide and decreasing aggression. This applies not only to those diagnosed with schizophrenia or schizoaffective disorder but also to bipolar disorder, major depression, and other psychiatric diagnoses. The greater advantage of an atypical APD is not evident in all patients for every atypical APD due, in part, to individual differences in genetic and epigenetic endowment and differences in the pharmacology of the atypical APDs, their mode of action being far more complex than that of the typical APDs. A common misconception is that among the atypical APDs, only clozapine is effective for reducing psychosis in treatment-resistant schizophrenia. Aripiprazole, lurasidone, olanzapine, and risperidone also can be more effective than typical APDs for treatment-resistant schizophrenia; clozapine is uniquely indicated for reducing the risk for suicide. The ability of the atypical APDs to improve cognition and negative symptoms in some patients together with lower propensity to cause tardive dyskinesia (an underappreciated advantage) leads to better overall outcomes. These advantages of the atypical APDs in efficacy and safety are due, in part, to initiation of synaptic plasticity via direct and indirect effects of the atypical APDs on a variety of proteins, especially G proteins, and release of neurotrophins (e.g., brain-derived neurotrophic factor). The typical APDs beneficial effects on psychosis are mainly the result of D₂ receptor blockade, which can be associated with serious side effects and lack of tolerability.

Main interactions of dopamine and risperidone with the dopamine D2 receptor

Psychosis is one of the psychiatric disorders that is controlled by dopaminergic drugs such as antipsychotics that have affinity for the dopamine D2 receptor (DRD2). In this investigation we perform quantum chemical calculations of two molecules [dopamine and risperidone] within a large cavity of DRD2 that represents the binding site of the receptor. Dopamine is an endogenous neurotransmitter and risperidone is a second-generation antipsychotic. Non-covalent interactions of dopamine and risperidone with DRD2 are analyzed using the Quantum Theory of Atoms in Molecules (QTAIM) and the Non-Covalent Interaction index (NCI). The QTAIM results show that these molecules strongly interact with the receptor. There are 22 non-covalent interactions for dopamine and 54 for risperidone. The electron density evaluated at each critical binding point is small in both systems but it is higher for dopamine than for risperidone, indicating that the interactions of DRD2 with the first are stronger than with the second molecule. However, the binding energy is higher for risperidone (-72.6 kcal mol-1) than for dopamine (-22.8 kcal mol-1). Thus, the strength of the binding energy is due to the number of contacts rather than the strength of the interactions themselves. This could be related to the ability of risperidone to block DRD2 and may explain the efficacy of this drug for controlling the symptoms of schizophrenia, but likewise its secondary effects.

Schizophrenia: Antipsychotics and drug development

The introduction of chlorpromazine and the work that ensued provided the foundation to reposition schizophrenia as a biological illness. The present paper follows the evolution of antipsychotics and their shift from 'typical' to 'atypical'. Atypicality is reviewed in reference to its original definition, clozapine's role, and developments that now leave the concept's utility in question. In a similar fashion, drug development is reviewed in the context of the illness' multiple symptom domains, as well as differences captured by clinical staging and phenotyping. Collectively, the evidence argues for a more nuanced approach to drug development that aligns with the illness' heterogeneity and complexity. Just as 'atypical' as a descriptor for antipsychotics may be outdated, it may be time to set aside the notion of developing drugs that treat 'schizophrenia'.

Candidate Genes Encoding Dopamine Receptors as Predictors of the Risk of Antipsychotic-Induced Parkinsonism and Tardive Dyskinesia in Schizophrenic Patients

(1) Introduction: Extrapyramidal disorders form the so-called extrapyramidal syndrome (EPS), which is characterized by the occurrence of motor disorders as a result of damage to the basal ganglia and the subcortical-thalamic connections. Often, this syndrome develops while taking medications, in particular antipsychotics (APs). (2) Purpose: To review studies of candidate genes encoding dopamine receptors as genetic predictors of development of AP-induced parkinsonism (AIP) and AP-induced tardive dyskinesia (AITD) in patients with schizophrenia. (3) Materials and Methods: A search was carried out for publications of PubMed, Web of Science, Springer, and e-Library databases by keywords and their combinations over the last 10 years. In addition, the review includes earlier publications of historical interest. Despite extensive searches of these commonly used databases and search terms, it cannot be ruled out that some publications were possibly missed. (4) Results: The review considers candidate genes encoding dopamine receptors involved in pharmacodynamics, including genes DRD1, DRD2, DRD3, and DRD4. We analyzed 18 genome-wide studies examining 37 genetic variations, including single nucleotide variants (SNVs)/polymorphisms of four candidate genes involved in the development of AIP and AITD in patients with schizophrenia. Among such a set of obtained results, only 14 positive associations were revealed: rs1799732 (141CIns/Del), rs1800497 (C/T), rs6275 (C/T), rs6275 (C/T) DRD2; rs167771 (G/A) DRD3 with AIP and rs4532 (A/G) DRD1, rs6277 (C/T), rs6275 (C/T), rs1800497 (C/T), rs1079597 (A/G), rs1799732 (141CIns/Del), rs1045280 (C/G) DRD2, rs6280 (C/T), rs905568 (C/G) DRD3 with AITD. However, at present, it should be recognized that there is no final or unique decision on the leading role of any particular SNVs/polymorphisms in the development of AIP and AITD. (5) Conclusion: Disclosure of genetic predictors of the development of AIP and AITD, as the most common neurological adverse drug reactions (ADRs) in the treatment of patients with psychiatric disorders, may provide a key to the development of a strategy for personalized prevention and treatment of the considered complication of AP therapy for schizophrenia in real clinical practice.

Clozapine: Why Is It So Uniquely Effective in the Treatment of a Range of Neuropsychiatric Disorders?

Clozapine is superior to other antipsychotics as a therapy for treatment-resistant schizophrenia and schizoaffective disorder with increased risk of suicidal behavior. This drug has also been used in the off-label treatment of bipolar disorder, major depressive disorder (MDD), and Parkinson's disease (PD). Although usually reserved for severe and treatment-refractory cases, it is interesting that electroconvulsive therapy (ECT) has also been used in the treatment of these psychiatric disorders, suggesting some common or related mechanisms. A literature review on the applications of clozapine and electroconvulsive therapy (ECT) to the disorders mentioned above was undertaken, and this narrative review was prepared. Although both treatments have multiple actions, evidence to date suggests that the ability to elicit epileptiform activity and alter EEG activity, to increase neuroplasticity and elevate brain levels of neurotrophic factors, to affect imbalances in the relationship between glutamate and γ-aminobutyric acid (GABA), and to reduce inflammation through effects on neuron-glia interactions are common underlying mechanisms of these two treatments. This evidence may explain why clozapine is effective in a range of neuropsychiatric disorders. Future increased investigations into epigenetic and connectomic changes produced by clozapine and ECT should provide valuable information about these two treatments and the disorders they are used to treat.

A Method for Tapering Antipsychotic Treatment That May Minimize the Risk of Relapse

The process of stopping antipsychotics may be causally related to relapse, potentially linked to neuroadaptations that persist after cessation, including dopaminergic hypersensitivity. Therefore, the risk of relapse on cessation of antipsychotics may be minimized by more gradual tapering. There is converging evidence that suggests that adaptations to antipsychotic exposure can persist for months or years after stopping the medication-from animal studies, observation of tardive dyskinesia in patients, and the clustering of relapses in this time period after the cessation of antipsychotics. Furthermore, PET imaging demonstrates a hyperbolic relationship between doses of antipsychotic and D2 receptor blockade. We, therefore, suggest that when antipsychotics are reduced, it should be done gradually (over months or years) and in a hyperbolic manner (to reduce D2 blockade "evenly"): ie, reducing by one quarter (or one half) of the most recent dose of antipsychotic, equivalent approximately to a reduction of 5 (or 10) percentage points of its D2 blockade, sequentially (so that reductions become smaller and smaller in size as total dose decreases), at intervals of 3-6 months, titrated to individual tolerance. Some patients may prefer to taper at 10% or less of their most recent dose each month. This process might allow underlying adaptations time to resolve, possibly reducing the risk of relapse on discontinuation. Final doses before complete cessation may need to be as small as 1/40th a therapeutic dose to prevent a large decrease in D2 blockade when stopped. This proposal should be tested in randomized controlled trials.

Acute and Persistent Withdrawal Syndromes Following Discontinuation of Psychotropic Medications

Studies on psychotropic medications decrease, discontinuation, or switch have uncovered withdrawal syndromes. The present overview aimed at analyzing the literature to illustrate withdrawal after decrease, discontinuation, or switch of psychotropic medications based on the drug class (i.e., benzodiazepines, nonbenzodiazepine benzodiazepine receptor agonists, antidepressants, ketamine, antipsychotics, lithium, mood stabilizers) according to the diagnostic criteria of Chouinard and Chouinard [Psychother Psychosom. 2015;84(2):63-71], which encompass new withdrawal symptoms, rebound symptoms, and persistent post-withdrawal disorders. All these drugs may induce withdrawal syndromes and rebound upon discontinuation, even with slow tapering. However, only selective serotonin reuptake inhibitors, serotonin noradrenaline reuptake inhibitors, and antipsychotics were consistently also associated with persistent post-withdrawal disorders and potential high severity of symptoms, including alterations of clinical course, whereas the distress associated with benzodiazepines discontinuation appears to be short-lived. As a result, the common belief that benzodiazepines should be substituted by medications that cause less dependence such as antidepressants and antipsychotics runs counter the available literature. Ketamine, and probably its derivatives, may be classified as at high risk for dependence and addiction. Because of the lag phase that has taken place between the introduction of a drug into the market and the description of withdrawal symptoms, caution is needed with the use of newer antidepressants and antipsychotics. Within medication classes, alprazolam, lorazepam, triazolam, paroxetine, venlafaxine, fluphenazine, perphenazine, clozapine, and quetiapine are more likely to induce withdrawal. The likelihood of withdrawal manifestations that may be severe and persistent should thus be taken into account in clinical practice and also in children and adolescents.

Low continuation of antipsychotic therapy in Parkinson disease - intolerance, ineffectiveness, or inertia?

Background

Antipsychotics are used in Parkinson disease (PD) to treat psychosis, mood, and behavioral disturbances. Commonly used antipsychotics differ substantially in their potential to worsen motor symptoms through dopaminergic receptor blockade. Recent real-world data on the use and continuation of antipsychotic therapy in PD are lacking. The objectives of this study are to (1) examine the continuation of overall and initial antipsychotic therapy in individuals with PD and (2) determine whether continuation varies by drug dopamine receptor blocking activity.

Methods

We conducted a retrospective cohort study using U.S. commercially insured individuals in Optum 2001–2019. Adults aged 40 years or older with PD initiating antipsychotic therapy, with continuous insurance coverage for at least 6 months following drug initiation, were included. Exposure to pimavanserin, quetiapine, clozapine, aripiprazole, risperidone, or olanzapine was identified based on pharmacy claims. Six-month continuation of overall and initial antipsychotic therapy was estimated by time to complete discontinuation or switching to a different antipsychotic. Cox proportional hazards models evaluated factors associated with discontinuation.

Results

Overall, 38.6% of 3566 PD patients in our sample discontinued antipsychotic therapy after the first prescription, 61.4% continued with overall treatment within 6 months of initiation. Clozapine use was too rare to include in statistical analyses. Overall therapy discontinuation was more likely for those who initiated medications with known dopamine-receptor blocking activity (adjusted hazard ratios 1.76 [95% confidence interval 1.40–2.20] for quetiapine, 2.15 [1.61–2.86] for aripiprazole, 2.12 [1.66–2.72] for risperidone, and 2.07 [1.60–2.67] for olanzapine), compared with serotonin receptor-specific pimavanserin. Initial antipsychotic therapy discontinuation also associated with greater dopamine-receptor blocking activity medication use – adjusted hazard ratios 1.57 (1.28–1.94), 1.88 (1.43–2.46), 2.00 (1.59–2.52) and 2.03 (1.60–2.58) for quetiapine, aripiprazole, risperidone, and olanzapine, respectively, compared with pimavanserin. Similar results were observed in sensitivity analyses.

Conclusions

Over one-third of individuals with PD discontinued antipsychotic therapy, especially if the initial drug has greater dopamine-receptor blocking activity. Understanding the drivers of antipsychotic discontinuation, including ineffectiveness, potentially inappropriate use, clinician inertia, patient adherence and adverse effects, is needed to inform clinical management of psychosis in PD and appropriate antipsychotic use in this population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02265-x.

Augmentation of Antipsychotic Medications with Low-Dose Clozapine in Treatment-Resistant Schizophrenia-Case Reports and Discussion

Treatment resistance in schizophrenia is often encountered in clinical practice, with clozapine usually recommended as the appropriate therapy. However, where clozapine proves ineffective or cannot be tolerated due to side effects, treatment options are limited. In patients within forensic mental health services, residual symptomatology often presents a barrier to discharge and can have lasting effects on prospects for rehabilitation as well as risk to self and others. This paper presents a review of the relevant literature and three cases of a novel approach, utilising clozapine in doses usually considered subtherapeutic, in combination with the primary antipsychotic treatment. In all three patients, it improved clinical efficacy as well as tolerability, resulting in improvement that allowed discharge from the forensic hospital.

Brain activity and connectivity differences in reward value discrimination during effort computation in schizophrenia

Negative symptoms in the motivational domain are strongly correlated with deficits in social and occupational functioning in schizophrenia. However, the neural substrates underlying these symptoms remain largely unknown. Twenty-eight adults with schizophrenia and twenty healthy volunteers underwent functional magnetic resonance while completing a lottery game designed to capture reward-related cognitive processes. Each trial demanded an initial investment of effort in form of key presses to increase the odds of winning. Brain activity in response to different reward cues (1 euro versus 1 cent) was compared between groups. Whereas controls invested more effort in improving their chances to win 1 euro compared to 1 cent in the lottery game, patients invested similarly high amounts of effort in both reward conditions. The neuroimaging analysis revealed lower neural activity in the bilateral caudate and cingulo-opercular circuits and decreased effective connectivity between reward-associated areas and neural nodes in the frontoparietal and salience network in response to high- versus low-reward conditions in schizophrenia patients compared to controls. Effective connectivity differences across conditions were associated with amotivation symptoms in patients. Overall, our data provide the evidence of alterations in neural activity in the caudate and cingulo-opercular "task maintenance" circuits and frontoparietal effective connectivity with reward-associated nodes as possible underlying mechanisms of reward value discrimination deficits affecting effort computation in schizophrenia.

Sex differences in the association between serum BDNF and cognitive impairment in schizophrenia patients using various antipsychotics

BACKGROUND

Cognitive impairment is one of the core symptoms of schizophrenia patients. There are often various differences in the efficacy of different antipsychotics in the treatment of cognitive impairment by sex. The purpose of this study was to explore whether there are gender differences in the association between serum BDNF levels and cognitive performance in patients with schizophrenia taking different antipsychotics.

METHODS

We used Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess the cognitive function of three groups of schizophrenia patients (420 on clozapine, 183 on risperidone, 215 on typical antipsychotic drugs) and 467 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess schizophrenia symptoms of patients. Enzyme-Linked ImmunoSorbent Assay was used to measure serum brain-derived neurotrophic factor (BDNF) levels.

RESULTS

Among the patients taking clozapine and typical antipsychotic drugs, the RBANS total score, immediate memory, attention, and delayed memory subscores in females were higher than those in males (all p < 0.05). The RBANS total score and the delayed memory subscores in female patients taking risperidone were higher than those in male patients (all p < 0.05). Significant correlation between BDNF and cognition only existed in male patients taking clozapine, male patients taking risperidone, and male and female patients taking typical antipsychotic drugs (all p < 0.05).

CONCLUSION

Regardless of antipsychotic effect, the cognitive function of female patients is better compared to that of male patients. For male patients, the association between BDNF and cognitive performance exists in each medication group. For female patients, this significant association was only shown in the typical antipsychotic group, but not in the clozapine and risperidone groups.

Recognition and Management of Antipsychotic-Induced Parkinsonism in Older Adults: A Narrative Review

Background: Parkinsonism is a common side-effect of antipsychotic drugs especially in older adults, who also present with a higher frequency of neurodegenerative disorders like Idiopathic Parkinson’s disease (IPD). Distinguishing between antipsychotic-induced parkinsonism (AIP) and IPD is challenging due to clinical similarities. Up to 20% of older adults may suffer from persisting parkinsonism months after discontinuation of antipsychotics, suggesting underlying neurodegeneration. A review of the literature on AIP in older adults is presented, focusing on epidemiology, clinical aspects, and management. Methods: A literature search was undertaken on EMBASE, MEDLINE and PsycINFO, for articles on parkinsonism induced by antipsychotic drugs or other dopamine 2 receptor antagonists in subjects aged 65 or older. Results: AIP in older adults is the second most common cause of parkinsonism after IPD. Older age, female gender, exposure to high-potency first generation antipsychotics, and antipsychotic dosage are the main risk factors. The clinical presentation of AIP resembles that of IPD, but is more symmetrical, affects upper limbs more, and tends to have associated motor phenomena such as orofacial dyskinesias and akathisia. Presence of olfactory dysfunction in AIP suggests neurodegeneration. Imaging of striatal dopamine transporters is widely used in IPD diagnosis and could help to distinguish it from AIP. There is little evidence base for recommending pharmacological interventions for AIP, the best options being dose-reduction/withdrawal, or switching to a second-generation drug. Conclusions: AIP is a common occurrence in older adults and it is possible to differentiate it from IPD. Further research is needed into its pathophysiology and on its treatment.

Beyond Dopamine Receptor Antagonism: New Targets for Schizophrenia Treatment and Prevention

Treatment of schizophrenia (SCZ) historically relies on the use of antipsychotic drugs to treat psychosis, with all of the currently available antipsychotics acting through the antagonism of dopamine D2 receptors. Although antipsychotics reduce psychotic symptoms in many patients, they induce numerous undesirable effects and are not effective against negative and cognitive symptoms. These highlight the need to develop new drugs to treat SCZ. An advanced understanding of the circuitry of SCZ has pointed to pathological origins in the excitation/inhibition balance in regions such as the hippocampus, and restoring function in this region, particularly as a means to compensate for parvalbumin (PV) interneuron loss and resultant hippocampal hyperactivity, may be a more efficacious approach to relieve a broad range of SCZ symptoms. Other targets, such as cholinergic receptors and the trace amine-associated receptor 1 (TAAR1), have also shown some promise for the treatment of SCZ. Importantly, assessing efficacy of novel compounds must take into consideration treatment history of the patient, as preclinical studies suggest prior antipsychotic treatment may interfere with the efficacy of these novel agents. However, while novel therapeutic targets may be more effective in treating SCZ, a more effective approach would be to prevent the transition to SCZ in susceptible individuals. A focus on stress, which has been shown to be a predisposing factor in risk for SCZ, is a possible avenue that has shown promise in preclinical studies. Therefore, therapeutic approaches based on our current understanding of the circuitry of SCZ and its etiology are likely to enable development of more effective therapeutic interventions for this complex disorder.

Regulation of monoamine levels by typical and atypical antipsychotics in Caenorhabditis elegans mutant for nuclear distribution element genes

Mammalian nuclear distribution genes encode proteins with essential roles in neuronal migration and brain formation during embryogenesis. The implication of human nuclear distribution genes, namely nudC and NDE1 (Nuclear Distribution Element 1)/NDEL1 (Nuclear Distribution Element-Like 1), in psychiatric disorders including schizophrenia and bipolar disorder, has been recently described. The partial loss of NDEL1 expression results in neuronal migration defects, while ndel1 null knockout (KO) leads to early embryonic lethality in mice. On the other hand, loss-of-function of the orthologs of nuclear distribution element genes (nud) in Caenorhabditis elegans renders viable worms and influences behavioral endophenotypes associated with dopaminergic and serotoninergic pathways. In the present work, we evaluated the role of nud genes in monoamine levels at baseline and after the treatment with typical or atypical antipsychotics. Dopamine, serotonin and octopamine levels were significantly lower in homozygous loss-of-function mutant worms KO for nud genes compared with wild-type (WT) C. elegans at baseline. While treatment with antipsychotics determined significant differences in monoamine levels in WT, the nud KO mutant worms appear to respond differently to the treatment. According to the best of our knowledge, we are the first to report the influence of nud genes in the monoamine levels changes in response to antipsychotic drugs, ultimately placing the nuclear distribution genes family at the cornerstone of pathways involved in the modulation of monoamines in response to different classes of antipsychotic drugs.