Genetic Factors Associated With Tardive Dyskinesia: From Pre-clinical Models to Clinical Studies

Profiling deutetrabenazine extended-release tablets for tardive dyskinesia and chorea associated with Huntington's disease

INTRODUCTION

Tardive dyskinesia (TD) and Huntington's disease (HD)-associated chorea are persistent and disabling hyperkinetic disorders that can be treated with vesicular monoamine transporter type 2 (VMAT2) inhibitors, including the recently approved once-daily (QD) formulation of deutetrabenazine (DTBZ ER). While its efficacy and safety profile have not been directly investigated, currently available data confirms bioequivalence and similar bioavailability to the twice-daily formulation (DTBZ BID).

AREAS COVERED

The authors briefly review the pivotal trials establishing efficacy of DTBZ for TD and HD-associated chorea, the pharmacokinetic data for bioequivalence between QD and BID dosing of DTBZ, as well as dose proportionality evidence, titration recommendations, and safety profile for DTBZ ER.

EXPERT OPINION

Long-term data show that DTBZ is efficacious and well tolerated for the treatment of TD and HD-associated chorea. DTBZ ER likely demonstrates therapeutic equivalence with no new safety signals. Due to the lack of comparative clinical trial data, no evidence-based recommendation about choice of VMAT2 inhibitor or switching between VMAT2 inhibitors can be made about best practice. Ultimately, QD dosing may offer the chance of improved medication adherence, an important consideration in patients with complex treatment regimens and/or patients with cognitive decline.

Tardive Dyskinesia with Antipsychotic Medication in Children and Adolescents: A Systematic Literature Review

BACKGROUND

Tardive dyskinesia (TD) is a persisting, and potentially irreversible, movement disorder associated with treatment with dopamine receptor antagonists. Few data are available on the risk of TD in children and adolescents treated with antipsychotic medication.

OBJECTIVE

To review the literature on incidence, risk factors, and treatment options for antipsychotic-associated TD in children and adolescents (aged < 18 years).

METHODS

Relevant articles were identified through a systematic search of Embase and Medline performed in January 2024. Methodological quality was assessed using the Newcastle-Ottawa Scale and Joanna Briggs Institute Critical Appraisal tools.

RESULTS

Thirteen studies were identified. The reported TD point prevalence was 5-20%, with higher rates in studies involving typical antipsychotics. Lower estimates (around 1%) emerged from analyses of clinical database data suggesting underdiagnosis in clinical practice. Risk factors included treatment with typical antipsychotics, higher doses, longer duration of exposure, older age, female gender, higher baseline Abnormal Involuntary Movements Scale (AIMS) scores, intellectual impairment, and perinatal complications.

CONCLUSION

Although relatively few cases have been reported in children and adolescents, TD remains a risk in this population. Individuals receiving antipsychotics should be monitored carefully for the emergence of abnormal movements. Other than dose reduction, discontinuation, or switch to a lower-risk antipsychotic, few interventions have demonstrated efficacy. The strongest evidence for pharmacological treatment is for VMAT-2 inhibitors (valbenazine and deutetrabenazine), but these drugs are not licensed for use in children. To reduce risk, antipsychotics should be prescribed only if necessary, at the minimum effective dose and for the minimum necessary duration.

Tardive dyskinesia in Asia- current clinical practice and the role of neurologists in the care pathway

Tardive dyskinesia (TD) is a movement disorder that can arise as a side effect of treatment with dopamine receptor-blocking agents (DRBAs), including antipsychotic drugs (APDs) used to manage psychotic illnesses. Second-generation APDs (SGAs) are often preferred to first-generation drugs due to their lower propensity to cause TD, however many SGAs-treated patients still develop the condition. Although TD is a global health concern, evidence regarding the occurrence of TD and how it is managed in Asian countries is currently limited. This article reports the results of a systematic review of the published literature on TD focusing on its prevalence, types of patients, knowledge of the condition, causative factors, and usual treatment pathways in clinical practice in Asian countries. Epidemiological data suggest that the prevalence of TD is increasing globally due to an overall rise in APD use, contributing factors being polypharmacy with multiple APDs, the use of higher than necessary doses, and off-label use for non-psychotic indications. Although exact prevalence figures for TD in Asian countries are difficult to define, there is a similar pattern of rising APD use which will result in increasing numbers of TD patients in this region. These issues need to be addressed and strategies developed to minimize TD risk and manage this disabling condition which impacts patients' quality of life and daily functioning. To date, both research into TD has been predominantly psychiatry focused and the perspectives from neurologists regarding the clinical management of this challenging condition are scarce. However, neurologists have an essential role in managing the movement disorders manifestations that characterize TD. Optimum management of TD, therefore, should ideally involve collaboration between psychiatrists and neurologists in joint care pathways, wherever practical. Collaborative pathways are proposed in this article, and the challenges that will need to be addressed in Asian countries to improve the care of people with TD are highlighted, with a focus on the neurologist's viewpoint and the implications for the management of TD globally.

Genetic Susceptibility to Tardive Dyskinesia and Cognitive Impairments in Chinese Han Schizophrenia: Role of Oxidative Stress-Related and Adenosine Receptor Genes

Objective

Tardive dyskinesia (TD) is a severe rhythmic movement disorder caused by long-term antipsychotic medication in chronic patients with schizophrenia (SCZ). We aimed to investigate the association between polymorphisms in oxidative stress-related genes (GSTM1, SOD2, NOS1, and NOS3) and adenosine receptor gene (ADORA2A), as well as their interactions, with the occurrence and severity of TD, and cognitive impairments in a Chinese Han population of SCZ patients.

Methods

Two hundred and sixteen SCZ patients were recruited and divided into TD group (n=157) and non-TD group (n=59). DNA extraction was performed by a high-salt method, followed by SNP genotyping using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The severity of TD, psychopathology and cognitive functioning were assessed using the Abnormal Involuntary Movement Scale (AIMS), the Positive and Negative Syndrome Scale (PANSS) and the Repeated Battery for Assessment of Neuropsychological Status (RBANS), respectively.

Results

The combination of GSTM1-rs738491, NOS1-rs738409 and ADORA2A-rs229883 was identified as the best three-point model to predict TD occurrence (p=0.01). Additionally, GSTM-rs738491 CC or NOS3-rs1800779 AG genotypes may be protective factors for psychiatric symptoms in TD patients. TD patients carrying the NOS1-rs738409 AG or ADORA2A-rs229883 TT genotypes exhibited poorer cognitive performance.

Conclusion

Our findings suggest that the interaction of oxidative stress-related genes and adenosine receptor gene may play a role in the susceptibility and severity of TD in Chinese Han SCZ patient. Furthermore, these genes may also affect the psychiatric symptoms and cognitive function of TD patients.

Efficacy and safety of Transcranial Direct Current Stimulation (tDCS) on cognitive function in chronic schizophrenia with Tardive Dyskinesia (TD): a randomized, double-blind, sham-controlled, clinical trial

OBJECTIVE

Previous studies have shown that transcranial direct current stimulation(tDCS) led to an improvement of cognitive function in patients with schizophrenia, but rare study has explored the effect of tDCS on long-term hospitalized chronic schizophrenia with tardive dyskinesia (TD). The present research explored if cognitive function in patients with long-term hospitalized chronic schizophrenia with TD could be improved through tDCS.

METHODS

This study is a randomized, double-blind, sham-controlled clinical trial. Of the 52 patients, 14 dropped out, and 38 completed the experiment. Thirty-eight patients on stable treatment regimens were randomly assigned to receive active tDCS(n = 21) or sham stimulation(n = 17) on weekdays of the first, third, and fifth weeks of treatment. Patients performed the Pattern Recognition Memory (PRM) and the Intra/Extradimensional Set Shift (IED) from the Cambridge Neuropsychological Test Automated Battery (CANTAB) at baseline and the end of week 3, week 5. Clinical symptoms were also measured at the baseline and the fifth week using the Scale for the Assessment of Negative Symptoms (SANS) and the Positive and Negative Syndrome Scale (PANSS). Side effects of tDCS were assessed with an experimenter-administered open-ended questionnaire during the whole experiment.

RESULTS

There were no significant differences in PRM and IED performance metrics, SANS total score and PANSS total score between active and sham tDCS groups at the end of week 5 (p > 0.05). Furthermore, there was a significant difference in the adverse effects of the tingling sensation between the two groups (p < 0.05), but there was no significant difference in other side effects (p > 0.05).

CONCLUSION

According to these findings, no evidence supports using anodal stimulation over the left dorsolateral prefrontal cortex to improve cognitive function in patients with long-term hospitalized chronic schizophrenia with TD.

A new era in the diagnosis and treatment of tardive dyskinesia

Tardive dyskinesia (TD) is a heterogeneous, hyperkinetic movement disorder induced by dopamine-receptor blocking agents that presents a unique challenge in the treatment of psychosis. Although acceptance of TD as a serious consequence of antipsychotic treatment was resisted initially, subsequent research by many investigators in psychopharmacology contributed to a rich store of knowledge on many aspects of the disorder. While basic neuroscience investigations continue to deepen our understanding of underlying motor circuitry, past trials of potential treatments of TD focusing on a range of theoretical targets were often inconclusive. Development of newer antipsychotics promised to reduce the risk of TD compared to older drugs, but their improved tolerability unexpectedly enabled an expanding market that paradoxically both increased the absolute number of patients at risk and diminished attention to TD which was relegated to legacy status. Fortunately, development and approval of novel vesicular monoamine transporter inhibitors offered evidence-based symptomatic treatment of TD for the first time and rekindled interest in the disorder. Despite recent progress, many questions remain for future research including the mechanisms underlying TD, genetic predisposition, phenomenological diversity, whether new cases are reversible, how to implement best practices to prevent and treat TD, and whether the development of novel antipsychotics free of the risk of TD is attainable. We owe our patients the aspirational goal of striving for zero prevalence of persistent symptoms of TD in anyone treated for psychosis.