Review of withdrawal catatonia: what does this reveal about clozapine?

Catatonia and epilepsy: An underappreciated relationship

Catatonia is currently conceived in the major diagnostic manuals as a syndrome with a range of possible psychiatric and general medical underlying conditions. It features diverse clinical signs, spanning motor, verbal and behavioural domains and including stupor, catalepsy, mutism, echolalia, negativism and withdrawal. The existing literature suggests that seizure activity may underlie catatonia in approximately 2% of cases. There are three possible temporal relationships between catatonia and seizure activity: (1) ictal catatonia, in which catatonia is a presentation of non-convulsive status epilepticus; (2) postictal catatonia, in which catatonia follows a seizure, and (3) interictal catatonia, in which catatonia and seizures occur in the same individual without any clear temporal relationship between them. Electroencephalographic (EEG) abnormalities are common in catatonia, even in those cases with a presumed primary psychiatric origin, and often consist of generalised background slowing. Paradoxically, electroconvulsive therapy is an effective treatment for catatonia. There are several converging pieces of evidence suggesting that there may be underlying seizure activity in more cases of catatonia than has hitherto been recognised, though identification of these seizures may require intracranial EEG recording.

The Development a Pediatric Catatonia Clinical Roadmap for Clinical Care at Vanderbilt University Medical Center

INTRODUCTION

Pediatric catatonia is associated with a high degree of morbidity and mortality in children. However, pediatric catatonia is highly responsive to treatment if rapidly identified and appropriate interventions are administered. To our knowledge, there are no current publications which propose a systematic approach for the management of pediatric catatonia. The aim of our report was to create multidisciplinary clinical care roadmap for catatonia in the inpatient pediatric setting within Vanderbilt University Medical Center (VUMC).

METHODS

At VUMC, we formed a team of pediatric providers from child and adolescent psychiatry, rheumatology, neurology, pediatric hospital medicine, and pediatric psychology. Our team met on a regular basis over the course of 2022 - 2024 to review the current literature on pediatric catatonia and develop a consensus for clinical assessment and management.

RESULTS

We determined consensus recommendations from our VUMC multidisciplinary team for the following domains of pediatric catatonia inpatient clinical care: initial assessment of pediatric catatonia in the inpatient pediatric settings, medical and psychiatric work up for pediatric catatonia, the lorazepam challenge in pediatric populations, behavioral and environmental considerations, and the use of electroconvulsive therapy and alternative psychopharmacologic interventions in pediatric catatonia.

CONCLUSIONS

Pediatric catatonia is a condition associated with a high degree of morbidity and mortality but is responsive to treatment if diagnosed and treated early. The inpatient pediatric medical setting provides a unique opportunity for identification and treatment. Our clinical care roadmap provides tools for inpatient clinicians at VUMC to identify pediatric catatonia and initiate an evidence-based approach to medical workup, management, and clinical care. This approach has the potential to significantly improve longitudinal outcomes and quality of life improvements for children at VUMC with catatonia and their families.

When, Why and How to Re-challenge Clozapine in Schizophrenia Following Myocarditis

Clozapine-induced myocarditis (CIM) is among the most important adverse events limiting the use of clozapine as the most effective treatment for schizophrenia. CIM necessitates the immediate termination of clozapine, often resulting in its permanent discontinuation with considerable detrimental effects on patients' psychopathology and long-term outcome. Consequently, a clozapine re-challenge after CIM is increasingly regarded as a viable alternative, with published reports indicating a success rate of approximately 60%. However, published cases of re-challenges after CIM remain limited. Here, we provide a narrative review of the current state of research regarding the epidemiology, pathophysiology, risk factors, diagnosis and clinical management of CIM as well as a synthesis of current recommendations for re-challenging patients after CIM. This includes a step-by-step guide for this crucial procedure based on the current evidence regarding the pathophysiology and risk factors for CIM. Slow dose titration regimes and addressing risk factors including concomitant valproate and olanzapine are crucial both to prevent CIM and to ensure a safe and successful re-challenge. Furthermore, we discuss the utility of C-reactive protein, troponin, N-terminal-pro hormone and brain natriuretic peptide, therapeutic drug-monitoring and cardiac magnetic resonance imaging for CIM screening and diagnosis as well as for post-CIM re-challenges.

Impacts of exposure to and subsequent discontinuation of clozapine on tripartite synaptic transmission

BACKGROUND AND PURPOSE

Clozapine is an effective antipsychotic for treatment-resistant schizophrenia, but its discontinuation leads to discontinuation syndrome/catatonia complicated by benzodiazepine-resistance and rhabdomyolysis.

EXPERIMENTAL APPROACH

This study determined time-dependent effects of exposure and subsequent discontinuation of clozapine on expression of connexin43, 5-HT receptors, intracellular L-β-aminoisobutyrate (L-BAIBA) and 2nd-messengers and signalling of AMPK, PP2A and Akt in cultured astrocytes and rat frontal cortex.

KEY RESULTS

Intracellular L-BAIBA levels increased during clozapine exposure but immediately recovered after discontinuation. Both exposure to clozapine and L-BAIBA increased connexin43 and signalling of AMPK/Akt time-dependently, but reduced PP2A signalling, 5-HT receptor expression and IP3 level. These changes recovered within 2 weeks after discontinuation, while 5-HT receptors and IP3 transiently increased during the recovery process. L-BAIBA activated AMPK signalling, leading to attenuated PP2A signalling. Astroglial D-serine release was increased by clozapine exposure but continued to increase within 1 week after discontinuation via activation of IP3 receptor function.

CONCLUSION AND IMPLICATIONS

Clozapine discontinuation restored PP2A signalling due to decreased L-BAIBA, increased 5-HT receptor expression via probably enhanced 5-HT receptor recycling, but increased astroglial D-serine release persisted by transiently activated IP3 receptors via transiently increased IP3 level. Decreased L-BAIBA caused by clozapine discontinuation is, at least partially, involved in the transiently increased 5-HT receptor and astroglial D-serine release.

Catatonia

Catatonia is a neuropsychiatric disorder characterized by motor, affective and cognitive-behavioural signs, which lasts from hours to days. Intensive research over the past two decades has led to catatonia being recognized as an independent diagnosis in the International Classification of Diseases, 11th Revision (ICD-11) since 2022. Catatonia is found in 5-18% of inpatients on psychiatric units and 3.3% of inpatients on medical units. However, in an unknown number of patients, catatonia remains unrecognized and these patients are at risk of life-threatening complications. Hence, recognizing the symptoms of catatonia early is crucial to initiate appropriate treatment to achieve a favourable outcome. Benzodiazepines such as lorazepam and diazepam, electroconvulsive therapy, and N-methyl-D-aspartate antagonists such as amantadine and memantine, are the cornerstones of catatonia therapy. In addition, dopamine-modulating second-generation antipsychotics (for example, clozapine and aripiprazole) are effective in some patient populations. Early and appropriate treatment combined with new screening assessments has the potential to reduce the high morbidity and mortality associated with catatonia in psychiatric and non-psychiatric settings.

Gaps and Controversies in Catatonia as a Movement Disorder

The term "catatonia" was introduced by German psychiatrist Karl Kahlbaum in 1874. Although historically tied to schizophrenia, catatonia exhibits a diverse range of phenotypes and has been observed in various medical and neuropsychiatric conditions. Its intrinsic movement characteristics and association with hypokinetic and hyperkinetic phenomenologies place catatonia within the purview of movement disorders. Despite the presence of catatonia in psychiatry literature for over 150 years, many gaps and controversies persist regarding its etiopathogenesis, phenomenology, diagnostic criteria, and treatment. The current versions of the International Classification of Diseases (ICD-11) and the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) require clinicians to identify any three signs of 15 (ICD-11) or 12 (DSM-5) for the diagnosis of catatonia. Catalepsy and waxy flexibility are the only motor features with high specificity for the diagnosis. We highlight the gaps and controversies in catatonia as a movement disorder, emphasize the lack of a clear definition, and discuss the inconsistencies in the description of various catatonic signs. We propose the exploration of a bi-axial classification framework similar to that used for dystonia and tremor to encourage the evaluation of underlying etiologies and to guide therapeutic decisions to improve the outcome of these patients. © 2024 International Parkinson and Movement Disorder Society.

The C886T Mutation in the Th Gene Reduces the Activity of Tyrosine Hydroxylase in the Mouse Brain

Tyrosine hydroxylase (TH) catalyzes hydroxylation of L-tyrosine to L-3,4-dihydroxyphenylalanine, the initial and rate-limiting step in the synthesis of dopamine, noradrenaline, and adrenaline. Mutations in the human TH gene are associated with hereditary motor disorders. The common C886T mutation identified in the mouse Th gene results in the R278H substitution in the enzyme molecule. We investigated the impact of this mutation on the TH activity in the mouse midbrain. The TH activity in the midbrain of Mus musculus castaneus (CAST) mice homozygous for the 886C allele was higher compared to C57BL/6 and DBA/2 mice homozygous for the 886T allele. Notably, this difference in the enzyme activity was not associated with changes in the Th gene mRNA levels and TH protein content. Analysis of the TH activity in the midbrain in mice from the F2 population obtained by crossbreeding of C57BL/6 and CAST mice revealed that the 886C allele is associated with a high TH activity. Moreover, this allele showed complete dominance over the 886T allele. However, the C886T mutation did not affect the levels of TH protein in the midbrain. These findings demonstrate that the C886T mutation is a major genetic factor determining the activity of TH in the midbrain of common laboratory mouse strains. Moreover, it represents the first common spontaneous mutation in the mouse Th gene whose influence on the enzyme activity has been demonstrated. These results will help to understand the role of TH in the development of adaptive and pathological behavior, elucidate molecular mechanisms regulating the activity of TH, and explore pharmacological agents for modulating its function.

Drug-related catatonia in youths: real-world insights from the WHO Safety Database

Catatonia is characterized by psychomotor alterations and reduced contact with the environment. Initially linked to schizophrenia, it also occurs in mood disorders or organic conditions. In children, catatonia remains poorly delineated, despite dramatically increasing the risk of premature death. As data on pediatric drug-induced catatonia bears many uncertainties, we aimed to characterize its age-dependent patterns, using real-world data from the WHO safety database (VigiBase®).VigiBase® was queried for all reports of catatonia registered up to December 8th 2022. Reports involving patients <18 years were classified into 3 groups: ≤23 months, 2-11 years, and 12-17 years. Disproportionality analyses relied on the Reporting Odds Ratio (ROR), and the positivity of the lower end of the 95% confidence interval of the Information Component (IC) was required to suspect a signal. Catatonia was evoked in 421 pediatric reports. In infants, vaccines were leading. In children, the main signals involved haloperidol (ROR 104.3; 95% CI 45.6-238.5), ondansetron (ROR 40.5; 95% CI 16.5-99.5), and ciclosporin (ROR 27.4; 95% CI 13.8-54.1). In adolescents, chlorpromazine (ROR 199.1; 95% CI 134.8-294.1), benzatropine (ROR 193; 95% CI 104.1-361.6), and olanzapine (ROR 135.7; 95% CI 104.6-175.9) reached the highest RORs. In infants, catatonia was related to vaccines, it was ascribed to multiple drugs in children, and mainly to psychotropic drugs in adolescents. Less suspected drugs, such as ondansetron, were highlighted. Despite limitations inherent in spontaneous reporting systems, this study supports that a careful anamnesis is warranted to separate catatonia associated with medical conditions from drug-induced catatonia in pediatric patients.

Recurrent high creatine kinase levels under clozapine treatment - a case report assessing a suspected adverse drug reaction

Suspected adverse drug reactions (ADRs) during treatment with clozapine often prompt therapeutic drug monitoring (TDM) in clinical practice. Currently, there is no official recommendation for pharmacogenetic (PGx) testing in the context of clozapine therapy. In this case report, we demonstrate and discuss the challenges of interpreting PGx and TDM results highlighting the possibilities and limitations of both analytical methods. A 36-year-old male patient with catatonic schizophrenia was treated with clozapine. He experienced multiple hospitalizations due to elevated creatine kinase (CK) levels (up to 9000 U/L, reference range: 30-200 U/L). With no other medical explanation found, physicians suspected clozapine-induced ADRs. However, plasma levels of clozapine were consistently low or subtherapeutic upon admission, prompting us to conduct a PGx analysis and retrospectively review the patient's TDM data, progress notes, and discharge reports. We investigated two possible hypotheses to explain the symptoms despite low clozapine plasma levels: Hypothesis i. suggested the formation and accumulation of a reactive intermediate metabolite due to increased activity in cytochrome P450 3A5 and reduced activity in glutathione S-transferases 1, leading to myotoxicity. Hypothesis ii. proposed under-treatment with clozapine, resulting in ineffective clozapine levels, leading to a rebound effect with increased catatonic symptoms and CK levels. After considering both data sources (PGx and TDM), hypothesis ii. appeared more plausible. By comprehensively assessing all available TDM measurements and examining them in temporal correlation with the drug dose and clinical symptoms, we observed that CK levels normalized when clozapine plasma levels were raised to the therapeutic range. This was achieved through hospitalization and closely monitored clozapine intake. Therefore, we concluded that the symptoms were not an ADR due to altered clozapine metabolism but rather the result of under-treatment. Interpreting TDM and PGx results requires caution. Relying solely on isolated PGx or single TDM values can result in misinterpretation of drug reactions. We recommend considering the comprehensive patient history, including treatment, dosages, laboratory values, clinic visits, and medication adherence.

Catatonia and Opioid Withdrawal: A Case Report

In this case report, we present an 82-year-old female who was diagnosed with catatonia after she exhibited immobility, mutism, withdrawal, and stereotypy during a hospitalization for altered mental status. Fentanyl was found in her urine toxicology, and it was later discovered that she had been taking non-prescription pills from Mexico that were likely the source of the fentanyl. Her catatonia quickly remitted with benzodiazepine treatment. This case underscores previously unknown risks of substance use, which has grown especially important to psychiatric care considering how rampant the opioid epidemic has become. More so, these risks extend beyond opioid use disorders since other non-prescription drugs are commonly laced with fentanyl. Not only does this education need to be given to providers and patients alike, but further research should be conducted to establish and quantify the risk of catatonia with opioid withdrawal.

Rethinking Clozapine: Lights and Shadows of a Revolutionary Drug

The current literature globally highlights the efficacy of Clozapine in several psychiatric disorders all over the world, with an FDA indication for reducing the risk of repeated suicidal behavior in patients with schizophrenia or schizoaffective disorder. A growing field of research is also stressing a possible broader beneficial effect of Clozapine in promoting neuroprotection and neurotrophism. However, this drug is linked to several life-threatening side effects, such as agranulocytosis, myocarditis and seizures, that limit its use in daily clinical practice. For this work, a search was performed on PubMed using the terms "Clozapine indications", "Clozapine adverse effects", "Clozapine regenerative effects", and "Clozapine neuroplasticity" with the aim of reviewing the scientific literature on Clozapine's treatment indications, adverse effects and potential regenerative role. The results confirmed the efficacy of clozapine in clinical practice, although limited by its adverse effects. It appears crucial to raise awareness among clinicians about the potential benefits of using Clozapine, as well educating medical personnel about its risks and the early identification of possible adverse effects and their management.

Structural alterations of amygdala and hypothalamus contribute to catatonia

At present, current diagnostic criteria and systems neglect affective symptom expression in catatonia. This potentially serious omission could explain why putative contributions of limbic system structures, such as amygdala, hippocampus or hypothalamus, to catatonia in schizophrenia spectrum disorders (SSD) have been scarcely investigated so far. To determine whether topographical alterations of the amygdala, hippocampus and hypothalamus contribute to catatonia in SSD patients, we conducted structural magnetic resonance imaging (MRI) of SSD patients with (SSD-Cat, n = 30) and without (SSD-nonCat, n = 28) catatonia as defined by a Northoff Catatonia Rating Scale (NCRS) total score of ≥3 and =0, respectively, in comparison with healthy controls (n = 20). FreeSurfer v7.2 was used for automated segmentation of the amygdala and its 9 nuclei, hippocampus and its 21 subfields and hypothalamus and its associated 5 subunits. SSD-Cat had significantly smaller anterior inferior hypothalamus, cortical nucleus of amygdala, and hippocampal fimbria volumes when compared to SSD-nonCat. SSD-Cat had significantly smaller amygdala, hippocampus and hypothalamus whole and subunit volumes when compared to healthy controls. In SSD-Cat according to DSM-IV-TR (n = 44), we identified positive correlations between Brief Psychiatric Rating Scale (BPRS) item #2 (reflecting anxiety) and respective amygdala nuclei as well as negative correlation between NCRS behavioral score and hippocampus subiculum head. The lower volumes of respective limbic structures involved in affect regulation may point towards central affective pathomechanisms in catatonia.

Treatment of schizophrenia with catatonic symptoms: A narrative review

Catatonia is a neuropsychiatric syndrome consisting of psychomotor abnormalities caused by a broad range of disorders affecting brain function. While the nosological status of catatonia is no longer restricted to a subtype of schizophrenia in standardized diagnostic systems, the character, course, and clinical significance of catatonia in people with schizophrenia remain unclear. Evidence suggests that catatonia could be a nonspecific state-related phenomenon, a fundamental core symptom dimension of schizophrenia, or a subcortical variant of schizophrenia. Either way, the validity of catatonia in schizophrenia is clinically significant only insofar as it predicts prognosis and response to treatment. Most contemporary clinical trials of antipsychotics have targeted schizophrenia as an overly broad unitary psychosis neglecting any differential response defined by phenomenology or course. However, early naturalistic studies showed that catatonia predicted poor response to first-generation antipsychotics in chronic schizophrenia and case reports cautioned against the risk of triggering neuroleptic malignant syndrome. More recent studies suggest that second-generation antipsychotics, particularly clozapine, may be effective in schizophrenia with catatonic symptoms, while small randomized controlled trials have found that the short-term response to ECT may be faster and more significant. Based on available data, conclusions are limited as to whether antipsychotics are as effective and safe in acute and chronic schizophrenia with catatonic symptoms compared to other treatments and compared to schizophrenia without catatonia. Further studies of the pathophysiology, phenomenology, course and predictive value of catatonia in schizophrenia are worthwhile.

Clozapine Withdrawal Catatonia: A Case Report

Catatonia, which is associated with gamma-aminobutyric acid (GABA) hypoactivity, often responds robustly to benzodiazepines. It has been reported to be a consequence of abrupt discontinuation of clozapine, an antipsychotic used for treatment-resistant schizophrenia. Clozapine discontinuation, sometimes necessitated by medical concerns, can carry the risk of adverse outcomes, including catatonia. We present the case of a 66-year-old African-American male with schizoaffective disorder (depressive subtype) and a complex medical history. He discontinued clozapine abruptly due to medication unavailability, and, seven days later, presented with catatonic symptoms, initially unrecognized by emergency room clinicians. His symptoms included self-neglect, auditory hallucinations, isolation, psychomotor retardation, fixed gaze, and thought blocking. An attempt to reinstate clozapine led to orthostatic hypotension, prompting admission to an inpatient psychiatry unit. Attempt to initiate risperidone for psychosis worsened the catatonia, which then responded rapidly to intravenous lorazepam challenge. This facilitated the re-introduction of clozapine with slow re-titration.

Clozapine as a treatment for catatonia: A systematic review

Catatonia is a neuropsychiatric disorder characterised by altered movement, speech, and behaviour. Clozapine is an established therapy for treatment-resistant schizophrenia, but its role in catatonia has not been systematically examined. In this systematic review, we aimed to assess the evidence for clozapine as a treatment for catatonia. Full text original research articles in English where at least one patient with catatonia was treated with clozapine were included, provided catatonia did not occur solely in the context of neuroleptic malignant syndrome. Results were tabulated with calculations of summary statistics presented. Risk of bias was assessed with the Tool for Evaluating the Methodological Quality of Case Reports and Case Series. 182 patients were included, 81 from cohort studies and 101 from case reports or case series. 119/182 patients (65 %) had a specified underlying diagnosis of schizophrenia. Over 80 % of reported patients with catatonia had at least partial remission following treatment with clozapine across both cohort studies and case reports and case series. Among the case reports and series, 24/101 patients (23.8 %) followed clozapine withdrawal. Overall, 25 studies were of low quality, 60 of moderate quality and 8 of high quality. Our findings should be interpreted with caution, as the reliance on case reports, case series and small cohort studies is susceptible to reporting biases, regression to the mean and confounding by other treatments. Future research could use large healthcare databases to ascertain outcomes in those on clozapine with a history of catatonia given the difficulty and expense of conducting randomised controlled trials.

Brain mechanisms underlying catatonia: A systematic review

BACKGROUND

Catatonia is a complex psychomotor disorder characterized by motor, affective, and behavioral symptoms. Despite being known for almost 150 years, its pathomechanisms are still largely unknown.

METHODS

A systematic research on PubMed, Web of Science, and Scopus was conducted to identify neuroimaging studies conducted on group or single individuals with catatonia. Overall, 33 studies employing structural magnetic resonance imaging (sMRI, n = 11), functional magnetic resonance imaging (fMRI, n = 10), sMRI and fMRI (n = 2), functional near-infrared spectroscopy (fNIRS, n = 1), single positron emission computer tomography (SPECT, n = 4), positron emission tomography (PET, n = 4), and magnetic resonance spectroscopy (MRS, n = 1), and 171 case reports were retrieved.

RESULTS

Observational sMRI studies showed numerous brain changes in catatonia, including diffuse atrophy and signal hyperintensities, while case-control studies reported alterations in fronto-parietal and limbic regions, the thalamus, and the striatum. Task-based and resting-state fMRI studies found abnormalities located primarily in the orbitofrontal, medial prefrontal, motor cortices, cerebellum, and brainstem. Lastly, metabolic and perfusion changes were observed in the basal ganglia, prefrontal, and motor areas. Most of the case-report studies described widespread white matter lesions and frontal, temporal, or basal ganglia hypoperfusion.

CONCLUSIONS

Catatonia is characterized by structural, functional, perfusion, and metabolic cortico-subcortical abnormalities. However, the majority of studies and case reports included in this systematic review are affected by considerable heterogeneity, both in terms of populations and neuroimaging techniques, which calls for a cautious interpretation. Further elucidation, through future neuroimaging research, could have great potential to improve the description of the neural motor and psychomotor mechanisms underlying catatonia.

Catatonia: A Narrative Review for Hospitalists

Background

Catatonia is a complex psychomotor syndrome commonly associated with psychiatric disorders. However, hospitalists encounter this condition on medical floors, where it is typically due to an underlying medical, especially neurological, etiology. Delays in the diagnosis of catatonia are common and lead to worsened outcomes for patients, including a multitude of medical complications, such as venous thromboembolism and stasis ulcers. Catatonia due to a medical condition is less likely to respond to benzodiazepine therapy; identification and treatment of the underlying cause is crucial.

Methods

This article provides a practical review of the catatonia literature, with a focus on diagnosis, workup, and management of catatonia for patients admitted to medical hospitals.

Conclusions

With greater knowledge about catatonia, internists are uniquely positioned to recognize and initiate treatment.

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.

Clozapine for treatment refractory catatonia in individuals with autism spectrum disorder: a retrospective chart review study

BACKGROUND

Catatonia is increasingly recognized in individuals with autism spectrum disorder (ASD). Empirical data on treating catatonia in this population are limited. The purpose of this study is to provide naturalistic data on the use of clozapine for the treatment of catatonia in patients with ASD.

RESEARCH DESIGN AND METHODS

Medical records of 12 individuals with ASD and catatonia who received treatment with clozapine were reviewed. Treatment response to clozapine was rated by assigning a retrospective Clinical Global Impression Improvement scale (CGI-I) score.

RESULTS

Mean (SD) and median (IQR) age at initiation of clozapine treatment were 22.1 (7.7) and 20.4 (9.7) years, with a range of 10-39 years. Eleven of the 12 patients had received treatment with lorazepam prior to initiating clozapine and 9 of the 12 patients received concomitant treatment with lorazepam and clozapine. Eleven of the 12 patients (92%; 95% CI: 65%, 99%) responded to clozapine. All 12 patients remained on clozapine at the time of their most recent clinical note. All 12 patients (100%; 95% CI: 76%, 100%) experienced one or more adverse events, the most common of which was sedation (n = 11, 92%).

CONCLUSIONS

Overall, clozapine was associated with a high response rate for the treatment of catatonia in patients with ASD. These naturalistic data support the use of clozapine for the treatment of catatonia in patients with ASD for whom lorazepam is either ineffective or partially effective.

Enhanced L-β-Aminoisobutyric Acid Is Involved in the Pathophysiology of Effectiveness for Treatment-Resistant Schizophrenia and Adverse Reactions of Clozapine

Clozapine is an effective antipsychotic for the treatment of antipsychotic-resistant schizophrenia; however, specific types of A/B adverse effects and clozapine-discontinuation syndromes are also well known. To date, both the critical mechanisms of clinical actions (effective for antipsychotic-resistant schizophrenia) and the adverse effects of clozapine remain to be elucidated. Recently, we demonstrated that clozapine increased the synthesis of L-β-aminoisobutyric acid (L-BAIBA) in the hypothalamus. L-BAIBA is an activator of the adenosine monophosphate-activated protein kinase (AMPK), glycine receptor, GABA_A receptor, and GABA_B receptor (GABA_B-R). These targets of L-BAIBA overlap as potential targets other than the monoamine receptors of clozapine. However, the direct binding of clozapine to these aminoacidic transmitter/modulator receptors remains to be clarified. Therefore, to explore the contribution of increased L-BAIBA on the clinical action of clozapine, this study determined the effects of clozapine and L-BAIBA on tripartite synaptic transmission, including GABA_B-R and the group-III metabotropic glutamate receptor (III-mGluR) using cultured astrocytes, as well as on the thalamocortical hyper-glutamatergic transmission induced by impaired glutamate/NMDA receptors using microdialysis. Clozapine increased astroglial L-BAIBA synthesis in time/concentration-dependent manners. Increased L-BAIBA synthesis was observed until 3 days after clozapine discontinuation. Clozapine did not directly bind III-mGluR or GABA_B-R, whereas L-BAIBA activated these receptors in the astrocytes. Local administration of MK801 into the reticular thalamic nucleus (RTN) increased L-glutamate release in the medial frontal cortex (mPFC) (MK801-evoked L-glutamate release). Local administration of L-BAIBA into the mPFC suppressed MK801-evoked L-glutamate release. These actions of L-BAIBA were inhibited by antagonists of III-mGluR and GABA_B-R, similar to clozapine. These in vitro and in vivo analyses suggest that increased frontal L-BAIBA signaling likely plays an important role in the pharmacological actions of clozapine, such as improving the effectiveness of treating treatment-resistant schizophrenia and several clozapine discontinuation syndromes via the activation of III-mGluR and GABA_B-R in the mPFC.

Evidence-based consensus guidelines for the management of catatonia: Recommendations from the British Association for Psychopharmacology

The British Association for Psychopharmacology developed an evidence-based consensus guideline on the management of catatonia. A group of international experts from a wide range of disciplines was assembled. Evidence was gathered from existing systematic reviews and the primary literature. Recommendations were made on the basis of this evidence and were graded in terms of their strength. The guideline initially covers the diagnosis, aetiology, clinical features and descriptive epidemiology of catatonia. Clinical assessments, including history, physical examination and investigations are then considered. Treatment with benzodiazepines, electroconvulsive therapy and other pharmacological and neuromodulatory therapies is covered. Special regard is given to periodic catatonia, malignant catatonia, neuroleptic malignant syndrome and antipsychotic-induced catatonia. There is attention to the needs of particular groups, namely children and adolescents, older adults, women in the perinatal period, people with autism spectrum disorder and those with certain medical conditions. Clinical trials were uncommon, and the recommendations in this guideline are mainly informed by small observational studies, case series and case reports, which highlights the need for randomised controlled trials and prospective cohort studies in this area.

Second to none: rationale, timing, and clinical management of clozapine use in schizophrenia

Despite its enduring relevance as the single most effective and important evidence-based treatment for schizophrenia, underutilization of clozapine remains considerable. To a substantial degree, this is attributable to a reluctance of psychiatrists to offer clozapine due to its relatively large side-effect burden and the complexity of its use. This underscores the necessity for continued education regarding both the vital nature and the intricacies of clozapine treatment. This narrative review summarizes all clinically relevant areas of evidence, which support clozapine's wide-ranging superior efficacy - for treatment-resistant schizophrenia (TRS) and beyond - and make its safe use eminently feasible. Converging evidence indicates that TRS constitutes a distinct albeit heterogeneous subgroup of schizophrenias primarily responsive to clozapine. Most importantly, the predominantly early onset of treatment resistance and the considerable decline in response rates associated with its delayed initiation make clozapine an essential treatment option throughout the course of illness, beginning with the first psychotic episode. To maximize patients' benefits, systematic early recognition efforts based on stringent use of TRS criteria, a timely offer of clozapine, thorough side-effect screening and management as well as consistent use of therapeutic drug monitoring and established augmentation strategies for suboptimal responders are crucial. To minimize permanent all-cause discontinuation, re-challenges after neutropenia or myocarditis should be considered. Owing to clozapine's unique efficacy, comorbid conditions including substance use and most somatic disorders should not dissuade but rather encourage clinicians to consider clozapine. Moreover, treatment decisions need to be informed by the late onset of clozapine's full effects, which for reduced suicidality and mortality rates may not even be readily apparent. Overall, the singular extent of its efficacy combined with the high level of patient satisfaction continues to distinguish clozapine from all other available antipsychotics.

Opposing effects of clozapine and brexpiprazole on β-aminoisobutyric acid: Pathophysiology of antipsychotics-induced weight gain

Clozapine is one of the most effective antipsychotics and has the highest risk of weight gain and metabolic complications; however, the detailed pathophysiology of its clinical action and adverse reactions remains to be clarified. Therefore, the present study determined the chronic effects of clozapine (high risk of weight gain) and brexpiprazole (relatively low risk of weight gain) on intracellular and extracellular levels of β-aminoisobutyric acid (BAIBA) enantiomers, which are endogenous activators of AMP-activated protein kinase (AMPK). L-BAIBA is the dominant BAIBA enantiomer in the rat hypothalamus and cultured astrocytes, whereas L-BAIBA accounts for only approximately 5% of the total plasma BAIBA enantiomers. L-BAIBA displayed GABAB receptor agonistic action in the extracellular space and was released through activated astroglial hemichannels, whereas in the intracellular space, L-BAIBA activated AMPK signalling. Chronic administration of the effective doses of clozapine increased intracellular and extracellular levels of L-BAIBA in the hypothalamus and cultured astrocytes, whereas that of brexpiprazole decreased them. These results suggest that enhancing hypothalamic AMPK signalling by increasing intracellular L-BAIBA levels is, at least partially, involved in the pathophysiology of clozapine-induced weight gain and metabolic complications.

Malignant Catatonia: A Review for the Intensivist

Catatonia is a clinical syndrome characterized by psychomotor, neurological and behavioral changes. The clinical picture of catatonia ranges from akinetic stupor to severe motoric excitement. Catatonia can occur in the setting of a primary psychiatric condition such as bipolar disorder or secondary to a general medical illness like autoimmune encephalitis. Importantly, it can co-occur with delirium or coma. Malignant catatonia describes catatonia that presents with clinically significant autonomic abnormalities including change in temperature, blood pressure, heart rate, and respiratory rate. It is a life-threatening form of acute brain dysfunction that has several motoric manifestations and occurs secondary to a primary psychiatric condition or a medical cause. Many of the established predisposing and precipitating factors for catatonia such as exposure to neuroleptic medications or withdrawal states are common in the setting of critical illness. Catatonia typically improves with benzodiazepines and treatment of its underlying psychiatric or medical conditions, with electroconvulsive therapy reserved for catatonia refractory to benzodiazepines or for malignant catatonia. However, some forms of catatonia, such as catatonia secondary to a general medical condition or catatonia comorbid with delirium, may be less responsive to traditional treatments. Prompt recognition and treatment of catatonia are crucial because malignant catatonia may be fatal without treatment. Given the high morbidity and mortality associated with malignant catatonia, intensivists should familiarize themselves with this important and under-recognized condition.

Catatonia Due to General Medical Conditions in Psychiatric Patients: Implications for Clinical Practice

Catatonic syndrome is frequently observed over the course of severe mental disorders and general medical conditions, but when catatonia occurs in psychiatric patients with co-morbid medical or neurologic conditions, diagnosis and management may be challenging. Several medical conditions may cause catatonia in psychiatric patients, but some, such as brain injury, infections, hyponatremia and critical illness, may be most relevant in this population. Alongside appropriate etiologic treatment, benzodiazepines and electroconvulsive therapy in refractory cases are effective and safe, and may resolve catatonic syndrome rapidly. When newly-onset psychotic symptoms in catatonic patients with established psychotic disorders occur, delirium should be suspected and appropriately managed. An extensive clinical and laboratory diagnostic workup to determine the underlying etiology of catatonic syndrome should be carried out. In cases of acute multi-morbidity, the exact cause of catatonic syndrome in psychiatric patients may be unclear. It is recommended to avoid antipsychotic drugs in acutely catatonic patients, because they may exacerbate the catatonic symptoms. The akinetic type of catatonia should be differentiated from hypoactive delirium, as treatments for these syndromes differ substantially. When a psychiatric patient presents with symptomatology of both catatonia and delirium, treatment is particularly challenging.

Youth with severe mental illness and complex non-somatic motor abnormalities: conflicting conceptualizations and unequal treatment

Two emerging diagnostic concepts promote distinct treatments for youth with acute-onset motor abnormalities and severe concurrent psychiatric symptoms: Pediatric acute-onset neuropsychiatric syndrome (PANS) and pediatric catatonia. Both have institutional approval in parts of Europe and in the USA, meriting an unconditional comparison of supporting evidence. Here we report results of qualitative and quantitative analyses of literature and Swedish National Registry Data suggesting that (1) catatonic patients are liable to fulfilling diagnostic criteria for PANS, (2) three conservatively assessed PANS case-reports present with possible unrecognized catatonia, (3) lithium and electroconvulsive therapy usage frequencies in Swedish minors (exclusively recommended for severe mental illness) are strongly intercorrelated and unequally distributed across Swedish counties, (4) established severe mental disorders are rarely overtly considered amongst PANS-specific research and (5) best-available evidence treatments appear markedly superior for pediatric catatonia compared to PANS in both childhood and adolescence. Prioritizing treatments for pediatric catatonia in concerned subjects could markedly improve treatment outcomes.

Molecular and cellular mechanisms leading to catatonia: an integrative approach from clinical and preclinical evidence

This review aims to describe the clinical spectrum of catatonia, in order to carefully assess the involvement of astrocytes, neurons, oligodendrocytes, and microglia, and articulate the available preclinical and clinical evidence to achieve a translational understanding of the cellular and molecular mechanisms behind this disorder. Catatonia is highly common in psychiatric and acutely ill patients, with prevalence ranging from 7.6% to 38%. It is usually present in different psychiatric conditions such as mood and psychotic disorders; it is also a consequence of folate deficiency, autoimmunity, paraneoplastic disorders, and even autistic spectrum disorders. Few therapeutic options are available due to its complexity and poorly understood physiopathology. We briefly revisit the traditional treatments used in catatonia, such as antipsychotics, electroconvulsive therapy, and benzodiazepines, before assessing novel therapeutics which aim to modulate molecular pathways through different mechanisms, including NMDA antagonism and its allosteric modulation, and anti-inflammatory drugs to modulate microglia reaction and mitigate oxidative stress, such as lithium, vitamin B12, and NMDAr positive allosteric modulators.

A Case Report of Excessive Use of Clozapine Combined With Clonazepam

INTRODUCTION

For patients with schizophrenia, clozapine (CLZ) in combination with clonazepam (CLNAZ) is one of the viable therapeutic options. We successfully reduced the doses of CLZ and CLNAZ to the safe range of a polydrug abuse patient. As far as we know, this is the first case of this problem. As there are no relevant guidelines to reduce CLZ or CLNAZ, we hope to share this case to provide a reference for the prevention and treatment of similar patients with multidrug abuse.

CASE PRESENTATION

This case report describes a 46-year-old male with a 24-year history of schizophrenia. His main clinical manifestations are auditory hallucinations, persecutory delusion, and emotional instability. In 2012, the patient started taking rifampicin due to tuberculosis and gradually overused CLZ and CLNAZ. Before admission, he took 1,275 mg of CLZ every day and 26 mg of CLNAZ every night. With the help of Therapeutic Drug Monitoring (TDM) and pharmacogenetic testing, we gradually reduced his daily dose of CLZ and CLNAZ and formulated a more reasonable dosing schedule for him. At the time of discharge, the patient took CLZ 450 mg per day and CLNAZ 2 mg per night, with no obvious symptoms of psychosis.

CONCLUSION

In the process of drug maintenance treatment of schizophrenia, it is necessary to adopt TDM strategy to reduce and treat the abuse of multiple prescription drugs.

Catatonic Episodes Related to Substance Use: A Cross-Sectional Study Using Electronic Healthcare Records

Objective: Substance use has increasingly been linked to the onset of catatonic episodes; however, no large observational studies have examined this association. This study aimed to identify catatonic episodes temporally associated with acute intoxication, withdrawal or chronic substance use, investigate which substances were involved, and compare clinical characteristics of substance-related and non-substance-related catatonic episodes. Methods: This study retrospectively identified all catatonic episodes recorded in an electronic case register hosted at a large secondary mental health trust in London, UK. Episodes were categorized as substance-related if the clinical record reported either a positive urine drug screen, an ICD-10 diagnosis of a mental or behavioral disorder due to substance use, or documented substance use between two weeks prior to the catatonic episode and the date of the catatonic episode. Results: 108 of 2130 catatonic episodes (5.1%) were deemed substance-related. The number of contemporaneously reported substance-related episodes increased between 2007 and 2016 [r = 0.72, p = 0.02]. Episodes in the context of acute intoxication (n = 54) were most frequently related to cannabis (n = 31) or cocaine (n = 5) use, whilst those in the context of drug withdrawal (n = 8) were most commonly related to alcohol, opioids and benzodiazepines. There were 50 episodes of catatonia associated with chronic substance use without intoxication or withdrawal, of which the majority were related to cannabis use (n = 37). 21 episodes had overlapping intoxication, withdrawal and chronic use of different substances within an episode. Compared to catatonic episodes not related to substance use, episodes of substance-related catatonia occurred in individuals who were younger (mean age 31.3 years [SD 12.2] vs 35.7 years [SD 16.3], p = 0.01) and more likely to be men (74.0% vs 54.3%, p < 0.001). The clinical features of catatonia were similar between the two groups. Conclusions: A relatively small proportion of catatonic episodes were temporally associated with reported substance use within their electronic records. Substance-related catatonic episodes were mostly related to cannabis use, but other substances including cocaine, alcohol, opioids and benzodiazepines were sometimes implicated. This is likely an underestimate of substance-related catatonia use due to issues with documentation and appropriate investigation.

Catatonia: Clinical Overview of the Diagnosis, Treatment, and Clinical Challenges

Catatonia is a syndrome that has been associated with several mental illness disorders but that has also presented as a result of other medical conditions. Schizophrenia and other psychiatric disorders such as mania and depression are known to be associated with catatonia; however, several case reports have been published of certain medical conditions inducing catatonia, including hyponatremia, cerebral venous sinus thrombosis, and liver transplantation. Neuroleptic Malignant Syndrome and anti-NMDA receptor encephalitis are also prominent causes of catatonia. Patients taking benzodiazepines or clozapine are also at risk of developing catatonia following the withdrawal of these medications—it is speculated that the prolonged use of these medications increases gamma-aminobutyric acid (GABA) activity and that discontinuation may increase excitatory neurotransmission, leading to catatonia. The treatment of catatonia often involves the use of benzodiazepines, such as lorazepam, that can be used in combination therapy with antipsychotics. Definitive treatment may be found with electroconvulsive therapy (ECT). Aberrant neuronal activity in different motor pathways, defective neurotransmitter regulation, and impaired oligodendrocyte function have all been proposed as the pathophysiology behind catatonia. There are many clinical challenges that come with catatonia and, as early treatment is associated with better outcomes, it becomes imperative to understand these challenges. The purpose of this manuscript is to provide an overview of these challenges and to look at clinical studies regarding the pathophysiology, diagnosis, and treatment of as well as the complications and risk factors associated with catatonia.

Reducing the Risk of Withdrawal Symptoms and Relapse Following Clozapine Discontinuation-Is It Feasible to Develop Evidence-Based Guidelines?

Clozapine is the only antipsychotic that is effective in treatment-resistant schizophrenia. However, in certain clinical situations, such as the emergence of serious adverse effects, it is necessary to discontinue clozapine. Stopping clozapine treatment poses a particular challenge due to the risk of psychotic relapse, as well as the development of withdrawal symptoms. Despite these challenges for the clinician, there is currently no formal guidance on how to safely to discontinue clozapine. We assessed the feasibility of developing evidence-based recommendations for (1) minimizing the risk of withdrawal symptoms, (2) managing withdrawal phenomena, and (3) commencing alternatives treatment when clozapine is discontinued. We then evaluated the recommendations against the Appraisal of Guidelines for Research and Evaluation (AGREE) II criteria. We produced 19 recommendations. The majority of these recommendation were evidence-based, although the strength of some recommendations was limited by a reliance of studies of medium to low quality. We discuss next steps in the refinement and validation of an evidence-based guideline for stopping clozapine and identify key outstanding questions.

Clinical Experience With Intramuscular Clozapine

Clozapine is the most effective antipsychotic for patients with treatment-refractory schizophrenia, but many refuse to accept oral clozapine therapy. Intramuscular (IM) clozapine represents a convenient alternative for their treatment. The aim of this review is to summarize studies investigating IM clozapine administration. When initially developed, clozapine was also provided as an IM formulation, but the manufacturer later discontinued its production. Recently, IM clozapine became again available as an unlicensed product distributed by the Dutch company Apotheek A15. The use of IM clozapine has been reported in older studies on clozapine's adverse effects. It has also been described in detail in 5 more recent and generally smaller (n = 7 - 59) retrospective studies in patients refusing to take oral clozapine. In addition, its administration has been noted in 5 case reports. IM clozapine has been used at approximately ½ of the dose of oral clozapine due to pharmacokinetic considerations. It has been used in doses of up to 500 mg per day and for up to 99 days of treatment. The majority of patients (between 60 and 100%) were successfully transitioned to oral clozapine within a few days of IM treatment, and improvement in their condition was sustained during the long-term follow-up. Side effects of IM clozapine were similar to those of oral clozapine, but its sedative and cardiovascular effects (hypotension and tachycardia) had faster onset following IM administration. After long-term use, clozapine injections lead to local swelling and to the formation of painful nodules in some patients. In summary, IM clozapine may facilitate successful transition to oral clozapine in most patients, and it definitely represents a valuable tool for addressing refusal of oral clozapine in patients with treatment-refractory schizophrenia. More studies, especially focused on its safety, are, however, needed to better understand the limitations of this novel treatment approach.

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.

Clozapine Withdrawal-Induced Malignant Catatonia or Neuroleptic Malignant Syndrome: A Case Report and a Brief Review of the Literature

ABSTRACT

In our brief literature review, we discuss the changes in the concept of catatonia as well as its various types and symptoms. We also succinctly review the possible symptoms of clozapine withdrawal. In addition, we analyze the main features of the very few published cases of clozapine withdrawal-induced catatonia and the relationship between neuroleptic malignant syndrome and the malignant subtype of catatonia. Furthermore, we present the case of a 29-year-old male patient with schizophrenia in whom a malignant catatonic episode/neuroleptic malignant syndrome (with negativism, stupor, mutism, autonomic signs [eg, fever, hyperhidrosis], and elevated creatine kinase levels) began 5 days after the patient decided arbitrarily to cease his clozapine treatment. His catatonic symptoms quickly (ie, within a few days) resolved after the reinstitution of clozapine. Finally, we attempt to provide a theoretical explanation for the surprising finding in the literature that the withdrawal of clozapine, unlike the withdrawal of any other antipsychotics, may be associated with catatonia (frequently its malignant subtype). The take-home message of our case is that clinicians should bear in mind the risk of catatonia (especially the malignant subtype of it) after the prompt withdrawal of clozapine therapy.

Case of paediatric catatonia precipitated by antipsychotic withdrawal in a child with autism spectrum disorder

A 13-year-old girl with moderate intellectual disability and autism spectrum disorder (ASD) was admitted to the paediatric high-dependency unit following an 8-week history of altered mental status and motor behaviour. Her symptoms emerged followed shortly after discontinuation of risperidone, an atypical antipsychotic previously commenced to manage disruptive behaviour associated with ASD. On physical examination, the patient presented with negativism, grimacing, automatic obedience, waxy flexibility and ambitendency. Blood tests, neuroimaging and lumbar puncture failed to reveal an acute infectious or neurological precipitant. She responded immediately to a trial of intramuscular lorazepam titrated to a total daily dose of 12 mg. This case presents challenges of accurately diagnosing and managing catatonic symptoms in adolescent patients with ASD. We also discuss the potential risk of precipitating catatonia following the discontinuation of antipsychotic treatment that has been prescribed for a prolonged duration.

Clozapine discontinuation withdrawal symptoms in schizophrenia

Clozapine is an atypical antipsychotic used in treatment-resistant schizophrenia. Whilst clozapine is highly effective, there are some clinical scenarios, such as the emergence of severe side effects, that necessitate its discontinuation. There is an emerging literature suggesting that discontinuing antipsychotics, in particular clozapine, can cause an array of withdrawal symptoms. We review the evidence for the existence of clozapine-induced withdrawal symptoms, and in particular focus on withdrawal-associated psychosis, cholinergic rebound, catatonia and serotonergic discontinuation symptoms. To date, there has been surprisingly little clinical guidance on how to minimise the likeliness of withdrawal symptoms in patients who are stopped on clozapine abruptly or gradually. We discuss the key outstanding questions in this area and why there is a need for guidance on the management of withdrawal symptoms associated with clozapine discontinuation.

All roads lead to the motor cortex: psychomotor mechanisms and their biochemical modulation in psychiatric disorders

Psychomotor abnormalities have been abundantly observed in psychiatric disorders like major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SCH). Although early psychopathological descriptions highlighted the truly psychomotor nature of these abnormalities, more recent investigations conceive them rather in purely motor terms. This has led to an emphasis of dopamine-based abnormalities in subcortical-cortical circuits including substantia nigra, basal ganglia, thalamus, and motor cortex. Following recent findings in MDD, BD, and SCH, we suggest a concept of psychomotor symptoms in the literal sense of the term by highlighting three specifically psychomotor (rather than motor) mechanisms including their biochemical modulation. These include: (i) modulation of dopamine- and substantia nigra-based subcortical-cortical motor circuit by primarily non-motor subcortical raphe nucleus and serotonin via basal ganglia and thalamus (as well as by other neurotransmitters like glutamate and GABA); (ii) modulation of motor cortex and motor network by non-motor cortical networks like default-mode network and sensory networks; (iii) global activity in cortex may also shape regional distribution of neural activity in motor cortex. We demonstrate that these three psychomotor mechanisms and their underlying biochemical modulation are operative in both healthy subjects as well as in MDD, BD, and SCH subjects; the only difference consists in the fact that these mechanisms are abnormally balanced and thus manifest in extreme values in psychiatric disorders. We conclude that psychomotor mechanisms operate in a dimensional and cross-nosological way as their degrees of expression are related to levels of psychomotor activity (across different disorders) rather than to the diagnostic categories themselves. Psychomotor mechanisms and their biochemical modulation can be considered paradigmatic examples of a dimensional approach as suggested in RDoC and the recently introduced spatiotemporal psychopathology.