Epidemiology of tardive dyskinesia: Is risk declining with modern antipsychotics?

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.

Putative role of immune reactions in the mechanism of tardive dyskinesia

The term extrapyramidal disorders is most often used for conditions such as Parkinson's disease or Huntington's disease, but also refers to a group of extrapyramidal side effects of antipsychotics (EPS), such as tardive dyskinesia (TD). After a brief description of some clinical features of TD, this article summarizes the relatively scarce results of research on a possible link between mainly cytokine levels and TD. This data was found by systematically searching Pubmed and Embase. The limitations of these types of studies are a major obstacle to interpretation. After describing relevant aspects of the neuroinflammatory response and the neuroanatomical backgrounds of EPS, a new hypothesis for the origin of TD is presented with emphasis on dysfunctions in the striosomal compartment of the striatum and the dorsal diencephalic connection system (DDCS). It is postulated that (partly immunologically-induced) increase in oxidative stress and the dopamine-dependent immune response in classic TD proceed primarily via the DDCS, which itself is activated from evolutionarily older parts of the forebrain. Neuroinflammatory responses in the choroid plexus of the third ventricle may contribute due to its proximity to the habenula. It is concluded that direct evidence for a possible role of inflammatory processes in the mechanism of TD is still lacking because research on this is still too much of a niche, but there are indications that warrant further investigation.

Improvement of Tardive Dyskinesias with Olanzapine

Tardive dyskinesia (TD) is characterized by abnormal and involuntary movements that generally occur after prolonged exposure to neuroleptic medications. In this article, we present the case of a 29-year-old man with schizophrenia who developed TD following treatment with haloperidol. Despite various attempts with benzodiazepines, amantadine, and anticholinergics, the dyskinesias persisted. However, after 2 years of treatment with olanzapine alone, a progressive improvement occurred, leading to the complete disappearance of the dyskinesias. We also provide a brief review of reported cases of antipsychotic-induced TD that has improved with olanzapine.

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.

The Outcome of Antipsychotics-induced Tardive Syndromes: A Ten-year Follow-up Study

Objective

Tardive syndrome (TS) is an umbrella term used to describe a group of abnormal movement disorders caused by chronic exposure to dopamine receptor blocking agents. Few follow-up studies have been performed on the outcome of TS in patients using antipsychotics. The purpose of our study was to investigate the prevalence, incidence, remission rate, and factors associated with remission in patients using antipsychotics.

Methods

This retrospective cohort study consisted of 123 patients who received continuous treatment of antipsychotics in a medical center in Taiwan, from April 1, 2011 to May 31, 2021. We assessed the demographic and clinical characteristics, prevalence, incidence, remission rate, and factors associated with remission in patients using antipsychotics. TS remission was defined as a Visual Analogue Scale score ≤ 3.

Results

Of the 92 patients who completed the 10-year follow-up, 39 (42.4%) were found to have at least one episode of TS, with tardive dyskinesia (TD) being the most prevalent subtype (51.3%). With regard to concurrent physical illness, a history of extrapyramidal symptoms were significant risk factors for TS. During the 10-year follow-up period, the remission rate of TS was 74.3%. The use of antioxidants including vitamin B6 and piracetam was related to the remission of TS. Patients with tardive dystonia had a higher remission rate (87.5%) compared to TD (70%).

Conclusion

Our study suggests that TS may be a treatable condition, and the key to a better outcome is early detection and prompt intervention, including closely monitoring antipsychotics-related TS symptoms and using antioxidants.

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.

Atypical dyskinesias under treatment with antipsychotic drugs: Report from the AMSP multicenter drug safety project

OBJECTIVES

The aim of this study was to describe atypical dyskinesias (AtypDs) occurring during treatment with antipsychotic drugs (APDs). AtypDs are dyskinesias showing either an unusual temporal relationship between onset of treatment and start of the adverse drug reaction (ADR) or an unusual presentation of clinical symptoms.

METHODS

Data on the utilisation of APDs and reports of severe APD-induced AtypDs were collected using data from the observational pharmacovigilance programme - 'Arzneimittelsicherheit in der Psychiatrie (English: drug safety in psychiatry)' (AMSP) - from 1993 to 2016.

RESULTS

A total of 495,615 patients were monitored, of which 333,175 were treated with APDs. Sixty-seven cases (0.020%) of severe AtypDs under treatment with APDs were registered. The diagnoses of schizophrenic disorders as well as organic mental disorders were related to significantly higher rates of AtypDs. Second-generation antipsychotic drugs (SGAs) showed slightly higher rates of AtypDs (0.024%) than high-potency (0.011%) or low-potency first-generation antipsychotic drugs (FGAs; 0.006%). In 41 cases (61.2%), two or more drugs were found to cause AtypDs.

CONCLUSIONS

Our study indicates that AtypDs are rare ADRs. SGAs may have a higher risk for the occurrence of AtypDs than FGAs. Clinicians should be aware of this ADR and patients should be monitored and examined carefully.

Impact of drug-induced Parkinsonism and tardive dyskinesia on health-related quality of life in schizophrenia

BACKGROUND

Both drug-induced Parkinsonism (DIP) and tardive dyskinesia (TD) have been shown to be associated with lower health-related quality of life (HRQOL) in schizophrenia, but few studies have examined their relative impact.

AIMS

This study aimed to examine and compare the association of DIP and TD with HRQOL in schizophrenia.

METHODS

In total, 903 patients with schizophrenia were assessed on the Positive and Negative Syndrome Scale (PANSS), Simpson-Angus Scale (SAS), and Abnormal Involuntary Movement Scale (AIMS). EuroQoL five-dimensional (EQ-5D-5L) utility scores were derived from PANSS scores via a previously validated algorithm and used as a measure of HRQOL.

RESULTS

In total, 160 (17.7%) participants had only DIP, 119 (13.2%) had only TD, and 123 (13.6%) had both DIP and TD. HRQOL was lowest for participants with both DIP and TD, followed by only DIP group, only TD group, and highest in the group with neither condition. HRQOL scores differed significantly between the four groups, F(3, 892) = 13.724, p < 0.001, ηp2 = 0.044). HRQOL of participants having only DIP or both DIP and TD was significantly lower than those having neither condition. There was no significant interaction between the presence of DIP and TD on the association with HRQOL.

CONCLUSIONS

DIP was the main antipsychotic-induced movement disorder associated with a poorer HRQOL in patients with schizophrenia. Therefore, clinicians should focus on prevention, detection, and effective management of DIP to optimize HRQOL in patients with schizophrenia.

Long-term effects of pallidal deep brain stimulation in tardive dystonia: a follow-up of 5-14 years

Introduction

Pallidal DBS is an established treatment for severe isolated dystonia. However, its use in disabling and treatment-refractory tardive syndromes (TS) including tardive dyskinesia and tardive dystonia (TD) is less well investigated and long-term data remain sparse. This observational study evaluates long-term effects of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in patients with medically refractory TS.

Methods

We retrospectively analyzed a cohort of seven TD patients with bilateral GPi-DBS. Involuntary movements, dystonia and disability were rated at long-term follow-up (LT-FU) after a mean of 122 ± 33.2 SD months (range 63–171 months) and compared to baseline (BL), short-term (ST-FU; mean 6 ± 2.0 SD months) and 4-year follow-up (4y-FU; mean 45 ± 12.3 SD months) using the Abnormal Involuntary Movement Scale (AIMS) and the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS), respectively. Quality of life and mood were evaluated using the SF36 and Beck Depression Index (BDI) questionnaires, respectively.

Results

At LT-FU patients had improved by 73% ± 14.2 SD in involuntary movements and 90% ± 1.0 SD in dystonia. Mood had improved significantly whereas quality of life remained unchanged compared to baseline. No serious long-lasting stimulation-related adverse events (AEs) were observed. Three patients of this cohort presented without active stimulation and ongoing symptom relief at long-term follow-up after 3–10 years of continuous DBS.

Conclusion

Pallidal DBS is a safe and effective long-term TD treatment. Even more interesting, three of our patients could stop stimulation after several years of DBS without serious relapse. Larger studies need to explore the phenomenon of ongoing symptom relief after DBS cessation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-10965-8.

Current perspectives on the epidemiology and burden of tardive dyskinesia: a focused review of the clinical situation in Japan

Tardive dyskinesia (TD) is a movement disorder that can develop with the use of dopamine receptor-blocking agents and is most commonly caused by antipsychotics. The use of antipsychotics is expanding, which may lead to an increased number of patients experiencing TD. To summarise the current knowledge of the epidemiology and risk factors for TD in Japan, we reviewed articles related to the current state of knowledge around TD identified through a PubMed search, and held a roundtable discussion of experts in Japan on 9 September 2021 to form the basis of the opinion presented within this review. The true prevalence of TD among patients treated with antipsychotics is not well characterised; it is reported to be between 15% and 50% globally and between 6.5% and 7.7% in Japan. Potential barriers to timely treatment of TD include the stigma surrounding mental health issues and the lack of data regarding TD in Asian patients. This review summarises the current knowledge of the epidemiology, challenges to TD diagnosis and risk factors for TD in Japan. Recent strategies for symptom monitoring and early diagnosis, as well as consensus recommendations are included. Achieving a high level of awareness of TD among physicians who treat patients with psychiatric disorders is of great importance and physicians should ensure that patients with psychiatric disorders receiving antipsychotics are proactively monitored for signs of TD.

PLAIN LANGUAGE SUMMARY

Plain Language Summary (In Japanese).

VISUAL SUMMARY

Visual Summary (In Japanese).

Prevalence, clinical correlates and risk factors associated with Tardive Dyskinesia in Chinese patients with schizophrenia

Tardive Dyskinesia (TD) is a serious, nonrhythmic and iatrogenic movement disorder, and is a common comorbidity in patients with schizophrenia (SZ). The main goal of this study was to investigate the prevalence, clinical correlates, and risk factors of TD in Chinese patients with chronic SZ, which has not been fully studied. This study adopted a cross-sectional design. A total of 901 Chinese inpatients with SZ were recruited between 2008 and 2011. We used the Abnormal Involuntary Movement Scale (AIMS) to measure the severity of TD, and the Positive and Negative Syndrome Scale (PANSS) was used to measure the psychopathological symptoms of SZ. Blood samples were also collected for routine blood tests, including the levels of triglyceride (TG), cholesterol (CHO), HDL-cholesterol (HDL-CHO), LDL-cholesterol (LDL-CHO), Apolipoprotein A1 (ApoA1), and Apolipoprotein B (ApoB). Overall, 36% of patients with SZ had TD. Compared with the non-TD patients, the TD patients were more likely to be men, had older age, lower education level, higher smoking rate, higher hospitalization frequency, and longer duration of illness (DOI). Further, compared with the non-TD patients, the TD patients had higher PANSS total, PANSS negative subscale, and cognitive subscale scores, but had lower depressive subscale scores and lower mean levels of metabolic biomarkers, including TG, CHO, HDL-CHO, LDL-CHO, ApoA1 and ApoB. Moreover, binary regression analysis showed that antipsychotic type, BMI, gender, age, HDL-CHO, and ApoB were associated with TD. Our findings indicate that TD is a common movement disorder in patients with chronic SZ, with certain demographic and clinical variables being risk factors for the development of TD.

Tardive syndrome: An update and mini-review from the perspective of phenomenology

Tardive syndrome (TS) is a group of movement disorders caused by the long-term use of dopamine receptor blocking agents. The phenotypic presentation of TS is diverse, ranging from the most well-characterized symptom of tardive dyskinesia to other symptoms, including dystonia, akathisia, myoclonus, parkinsonism, tremor, and tics. These tardive symptoms are distinct not only in their phenomenology but also in their clinical outcomes. However, our knowledge of the pathophysiology and management of TS is almost exclusively based on tardive dyskinesia. First-generation antipsychotics have a higher risk of inducing TS and have largely been replaced by second-generation antipsychotics with a lower risk of TS. However, patients with off-label use of second-generation antipsychotics are still at risk of developing TS. Thus, the management of TS remains a challenging and important issue for physicians. In this review, we update the information on the epidemiology, phenomenology, and treatment of TS from the perspective of the specific form of TS.

Effects of CATECHIN on reserpine-induced vacuous chewing movements: behavioral and biochemical analysis

This study evaluated the effect of (+)-catechin, a polyphenolic compound, on orofacial dyskinesia (OD) induced by reserpine in mice. The potential modulation of monoaminoxidase (MAO) activity, tyrosine hydroxylase (TH) and glutamic acid decarboxylase (GAD67) immunoreactivity by catechin were used as biochemical endpoints. The interaction of catechin with MAO-A and MAO-B was determined in vitro and in silico. The effects of catechin on OD induced by reserpine (1 mg/kg for 4 days, subcutaneously) in male Swiss mice were examined. After, catechin (10, 50 or 100 mg/kg, intraperitoneally) or its vehicle were given for another 20 days. On the 6th, 8th, 15th and 26th day, vacuous chewing movements (VCMs) and locomotor activity were quantified. Biochemical markers (MAO activity, TH and GAD67 immunoreactivity) were evaluated in brain structures. In vitro, catechin inhibited both MAO isoforms at concentrations of 0.34 and 1.03 mM being completely reversible for MAO-A and partially reversible for MAO-B. Molecular docking indicated that the catechin bound in the active site of MAO-A, while in the MAO-B it interacted with the surface of the enzyme in an allosteric site. In vivo, reserpine increased the VCMs and decreased the locomotor activity. Catechin (10 mg/kg), decreased the number of VCMs in the 8th day in mice pre-treated with reserpine without altering other behavioral response. Ex vivo, the MAO activity and TH and GAD67 immunoreactivity were not altered by the treatments. Catechin demonstrated a modest and transitory protective effect in a model of OD in mice.

Tardive syndromes

Dopamine receptor-blocking antipsychotics, first introduced into clinical practice in 1952, were hailed as a panacea in the treatment of a number of psychiatric disorders. However, within 5 years, this notion was to be shattered by the recognition of both acute and chronic drug-induced movement disorders which can accompany their administration. Tardive syndromes, denoting the delayed onset of movement disorders following administration of dopamine receptor-blocking (and also other) drugs, have diverse manifestations ranging from the classic oro-bucco-lingual dyskinesia, through dystonic craniocervical and trunk posturing, to abnormal breathing patterns. Although tardive syndromes have been an important part of movement disorder clinical practice for over 60 years, their pathophysiologic basis remains poorly understood and the optimal treatment approach remains unclear. This review summarises the current knowledge relating to these syndromes and provides clinicians with pragmatic, clinically focused guidance to their management.

VMAT2 inhibitors for the treatment of hyperkinetic movement disorders

Hyperkinetic movement disorders comprise a variety of conditions characterized by involuntary movements, which include but are not limited to tardive dyskinesia, chorea associated with Huntington's Disease, and tic disorders. The class of medications that have been used to treat these conditions includes Vesicular Monoamine Transporter-2 (VMAT2) inhibitors. In 2008, the FDA approved tetrabenazine as a treatment for chorea associated with Huntington's Disease. Optimization of the pharmacology of tetrabenazine has since led to the approval of two new VMAT2 inhibitors, deutetrabenazine and valbenazine. The objective of this review is to provide background on the role of VMAT in monoamine neurotransmission, the mechanism of VMAT2 inhibition on the treatment of hyperkinetic disorders (specifically tardive dyskinesia and chorea associated with Huntington's Disease), the pharmacology and pharmacokinetics of the commercially available VMAT2 inhibitors, and a summary of the clinical data to support application of these medications.

Clozapine and tardive dyskinesia in patients with schizophrenia: A systematic review

BACKGROUND

It is commonly recommended that a switch to clozapine be implemented in the face of tardive dyskinesia, even if current treatment involves another "atypical" agent. However, reports do indicate clozapine carries a liability for tardive dyskinesia.

AIMS

This review sought to evaluate clozapine in relation to tardive dyskinesia in the context of available evidence.

METHODS

Medline, Embase, and PsycINFO databases were searched for studies published in English, using the keywords: clozapine AND tardive dyskinesia OR TD. References from major review articles were searched for additional relevant publications. Studies were included if they investigated: tardive dyskinesia in clozapine-treated patients diagnosed with schizophrenia spectrum disorders, and reported on two or more assessments of tardive dyskinesia severity measured by the Abnormal Involuntary Movement Scale; or clozapine's tardive dyskinesia liability.

RESULTS

In total, 513 unique citations were identified and 29 reports met the inclusion criteria. Thirteen studies suggest clozapine reduces dyskinetic symptoms over time (n=905 clozapine-treated participants); however, the minimum required dose and effect of withdrawal requires further investigation. The majority of reports which address clozapine's liability for tardive dyskinesia are case studies (11 of 14 reports, 79%), and clozapine was only the first-line treatment in one of the remaining three studies reporting treatment-emergent dyskinetic symptoms with clozapine in 12% of patients. No significant between-drug differences were identified comparing clozapine's risk to other atypical antipsychotics.

CONCLUSIONS

Research to date supports switching to clozapine for the purpose of reducing tardive dyskinesia risk and/or treating existing tardive dyskinesia, but prospective randomized controlled trials are necessary if we are to substantiate existing recommendations.

Risk assessment and prediction of TD incidence in psychiatric patients taking concomitant antipsychotics: a retrospective data analysis

Background

Tardive dyskinesia (TD) is a serious, often irreversible movement disorder caused by prolonged exposure to antipsychotics; identifying patients at risk for TD is critical to preventing it. Predictive models for the occurrence of TD can improve patient monitoring and inform implementation of counteractive interventions. This study aims to identify risk factors associated with TD and to develop a model using a retrospective data analysis to predict the incidence of TD among patients taking antipsychotic medications.

Methods

Adult patients with schizophrenia, major depressive disorder, or bipolar disorder taking oral antipsychotics were identified in a Medicaid claims database (covering six US states from 1997 to 2016) and divided into cohorts based on whether they developed TD within 1 year after the first observed claim for antipsychotics. Patient characteristics between cohorts were compared, and univariate Cox analyses were used to identify potential TD risk factors. A cross-validated version of the least absolute shrinkage and selection operator regression method was used to develop a parsimonious multivariable Cox proportional hazards model to predict diagnosis of TD.

Results

A total of 189,415 eligible patients were identified. Potential TD risk factors were identified based on the cohort analysis within a sample of 151,280 patients with at least 1 year of continuous eligibility. The prediction model had a clinically meaningful concordance of 70% and was well calibrated (P = 0.32 for Hosmer–Lemeshow goodness-of-fit test). Age (hazard ratio [HR] = 1.04, P < 0.001), diagnosis of schizophrenia (HR = 1.99, P < 0.001), antipsychotic dosage (up to 100 mg/day chlorpromazine equivalent; HR = 1.65, P < 0.01), and comorbid bipolar and related disorders (HR = 1.39, P < 0.01) were significantly associated with an increased risk of TD. Other potential risk factors included history of extrapyramidal symptoms (HR = 1.35), other movement disorders (parkinsonism, HR = 1.43; bradykinesia, HR = 1.44; tremors, HR = 2.12, and myoclonus, HR = 2.33), and diabetes (HR = 1.13). A modest reduction in the risk of TD was associated with the use of second-generation antipsychotics (HR = 0.85) versus first-generation drugs.

Conclusions

This study identified factors associated with development of TD among patients taking antipsychotics. The prediction model described herein can enable physicians to better monitor patients at high risk for TD and recommend appropriate treatment plans to help maintain quality of life.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1385-4) contains supplementary material, which is available to authorized users.

Tardive dyskinesia among patients using antipsychotic medications in customary clinical care in the United States

Background

Tardive dyskinesia (TD) is a movement disorder resulting from treatment with typical and atypical antipsychotics. An estimated 16–50% of patients treated with antipsychotics have TD, but this number may be underestimated. The objectives of this study were to build an algorithm for use in electronic health records (EHRs) for the detection and characterization of TD patients, and to estimate the prevalence of TD in a population of patients exposed to antipsychotic medications.

Methods

This retrospective observational study included patients identified in the Optum EHR Database who received a new or refill prescription for an antipsychotic medication between January 2011 and December 2015 (follow-up through June 2016). TD mentions were identified in the natural language–processed clinical notes, and an algorithm was built to classify the likelihood that the mention represented documentation of a TD diagnosis as probable, possible, unlikely, or negative. The final TD population comprised a subgroup identified using this algorithm, with ≥1 probable TD mention (highly likely TD).

Results

164,417 patients were identified for the antipsychotic population, with1,314 comprising the final TD population. Conservatively, the estimated average annual prevalence of TD in patients receiving antipsychotics was 0.8% of the antipsychotic user population. The average annual prevalence may be as high as 1.9% per antipsychotic user per year, allowing for a more-inclusive algorithm using both probable and possible TD. Most TD patients were prescribed atypical antipsychotics (1049/1314, 79.8%). Schizophrenia (601/1314, 45.7%), and paranoid and schizophrenia‐like disorders (277/1314, 21.1%) were more prevalent in the TD population compared with the entire antipsychotic drug cohort (13,308/164,417; 8.1% and 19,359/164,417; 11.8%, respectively).

Conclusions

Despite a lower TD prevalence than previously estimated and the predominant use of atypical antipsychotics, identified TD patients appear to have a substantial comorbidity burden that requires special treatment and management consideration.

Treatment Recommendations for Tardive Dyskinesia

BACKGROUND

Tardive dyskinesia is a movement disorder characterised by irregular, stereotyped, and choreiform movements associated with the use of antipsychotic medication. We aim to provide recommendations on the treatment of tardive dyskinesia.

METHODS

We performed a systematic review of studies of the treatment of tardive dyskinesia. Studies were rated for methodological quality using the American Academy of Neurology Risk of Bias Classification system. Overall level of evidence classifications and grades of recommendation were made using the Scottish Intercollegiate Guidelines Network framework.

RESULTS

Preventing tardive dyskinesia is of primary importance, and clinicians should follow best practice for prescribing antipsychotic medication, including limiting the prescription for specific indications, using the minimum effective dose, and minimising the duration of therapy. The first-line management of tardive dyskinesia is the withdrawal of antipsychotic medication if clinically feasible. Yet, for many patients with serious mental illness, the discontinuation of antipsychotics is not possible due to disease relapse. Switching from a first-generation to a second-generation antipsychotic with a lower D2 affinity, such as clozapine or quetiapine, may be effective in reducing tardive dyskinesia symptoms. The strongest evidence for a suitable co-intervention to treat tardive dyskinesia comes from tests with the new VMAT inhibitors, deutetrabenazine and valbenazine. These medications have not been approved for use in Canada.

CONCLUSION

Data on tardive dyskinesia treatment are limited, and the best management strategy remains prevention. More long-term safety and efficacy data are needed for deutetrabenazine and valbenazine, and their routine availability to patients outside of the USA remains in question.

Peeking at G-protein-coupled receptors through the molecular dynamics keyhole

Molecular dynamics is a state of the art computational tool for the investigation of biophysics phenomenon at a molecular scale, as it enables the modeling of dynamic processes, such as conformational motions, molecular solvation and ligand binding. The recent advances in structural biology have led to a bloom in published G-protein-coupled receptor structures, representing a solid and valuable resource for molecular dynamics studies. During the last decade, indeed, a plethora of physiological and pharmacological facets of this membrane protein superfamily have been addressed by means of molecular dynamics simulations, including the activation mechanism, allosterism and, very recently, biased signaling. Here, we try to recapitulate some of the main contributions that molecular dynamics has recently produced in the field.

Pharmacological treatment of adult bipolar disorder

We summarize evidence supporting contemporary pharmacological treatment of phases of BD, including: mania, depression, and long-term recurrences, emphasizing findings from randomized, controlled trials (RCTs). Effective treatment of acute or dysphoric mania is provided by modern antipsychotics, some anticonvulsants (divalproex and carbamazepine), and lithium salts. Treatment of BD-depression remains unsatisfactory but includes some modern antipsychotics (particularly lurasidone, olanzapine + fluoxetine, and quetiapine) and the anticonvulsant lamotrigine; value and safety of antidepressants remain controversial. Long-term prophylactic treatment relies on lithium, off-label use of valproate, and growing use of modern antipsychotics. Lithium has unique evidence of antisuicide effects. Methods of evaluating treatments for BD rely heavily on meta-analysis, which is convenient but with important limitations. Underdeveloped treatment for BD-depression may reflect an assumption that effects of antidepressants are similar in BD as in unipolar major depressive disorder. Effective prophylaxis of BD is limited by the efficacy of available treatments and incomplete adherence owing to adverse effects, costs, and lack of ongoing symptoms. Long-term treatment of BD also is limited by access to, and support of expert, comprehensive clinical programs. Pursuit of improved, rationally designed pharmacological treatments for BD, as for most psychiatric disorders, is fundamentally limited by lack of coherent pathophysiology or etiology.

Tardive dyskinesia update: the syndrome

Tardive dyskinesia is a common iatrogenic neurological and neurobehavioural syndrome associated with the use of antidopaminergic medication, especially antipsychotics. Prior to the introduction of the newer antipsychotics in the 1990s, it was one of the major areas of psychiatric research but interest waned as the new drugs were reputed to have a reduced liability to extrapyramidal adverse effects in general, a claim now discredited by numerous pragmatic research studies. Early small-scale short-term prevalence studies were presented as evidence to support the assumption that patients on the newer drugs did indeed have a lower prevalence of tardive dyskinesia but recent large-scale review of studies with patients exposed for longer suggest that things have not changed. This article presents a clinical overview of a complex and varied syndrome in terms of its phenomenology, epidemiology and risk factors; a companion article will consider treatment. This overview aims to highlight tardive dyskinesia once again, especially to practitioners who have trained in an environment where this was considered mainly in historical terms.

LEARNING OBJECTIVES

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DECLARATION OF INTEREST

None.

Hospital utilization rates following antipsychotic dose reductions: implications for tardive dyskinesia

BACKGROUND

Data are limited on the benefits and risks of dose reduction in managing side effects associated with antipsychotic treatment. As an example, antipsychotic dose reduction has been recommended in the management of tardive dyskinesia (TD), yet the benefits of lowering doses are not well studied. However, stable maintenance treatment is essential to prevent deterioration and relapse in schizophrenia.

METHODS

A retrospective cohort study was conducted to analyze the healthcare burden of antipsychotic dose reduction in patients with schizophrenia. Medical claims from six US states spanning a six-year period were analyzed for ≥10% or ≥ 30% antipsychotic dose reductions compared with those from patients receiving a stable dose. Outcomes measured were inpatient admissions and emergency room (ER) visits for schizophrenia, all psychiatric disorders, and all causes, and TD claims.

RESULTS

A total of 19,556 patients were identified with ≥10% dose reduction and 15,239 patients with ≥30% dose reduction. Following a ≥ 10% dose reduction, the risk of an all-cause inpatient admission increased (hazard ratio [HR] 1.17; 95% confidence interval [CI] 1.11, 1.23; P < 0.001), and the risk of an all-cause ER visit increased (HR 1.09; 95% CI 1.05, 1.14; P < 0.001) compared with controls. Patients with a ≥ 10% dose reduction had an increased risk of admission or ER visit for schizophrenia (HR 1.27; 95% CI 1.19, 1.36; P < 0.001) and for all psychiatric disorders (HR 1.16; 95% CI 1.10, 1.23; P < 0.001) compared with controls. A dose reduction of ≥30% also led to an increased risk of admission for all causes (HR 1.23; 95% CI 1.17, 1.31; P < 0.001), and for admission or ER visit for schizophrenia (HR 1.31; 95% CI 1.21, 1.41; P < 0.001) or for all psychiatric disorders (HR 1.21; 95% CI 1.14, 1.29; P < 0.001) compared with controls. Dose reductions had no significant effect on claims for TD.

CONCLUSION

Patients with antipsychotic dose reductions showed significant increases in both all-cause and mental health-related hospitalizations, suggesting that antipsychotic dose reductions may lead to increased overall healthcare burden in some schizophrenia patients. This highlights the need for alternative strategies for the management of side effects, including TD, in schizophrenia patients that allow for maintaining effective antipsychotic treatment.

Investigation of the HSPG2 Gene in Tardive Dyskinesia - New Data and Meta-Analysis

Tardive dyskinesia (TD) is a movement disorder that may occur after extended use of antipsychotic medications. The etiopathophysiology is unclear; however, genetic factors play an important role. The Perlecan (HSPG2) gene was found to be significantly associated with TD in Japanese schizophrenia patients, and this association was subsequently replicated by an independent research group. To add to the evidence for this gene in TD, we conducted a meta-analysis specific to the relationship of HSPG2 rs2445142 with TD occurrence, while also adding our unpublished genotype data. Overall, we found a significant association of the G allele with TD occurrence (p = 0.0001); however, much of the effect appeared to originate from the discovery dataset. Nonetheless, most study samples exhibit the same trend of association with TD for the G allele. Our findings encourage further genetic and molecular studies of HSPG2 in TD.

Antipsychotic-Related Movement Disorders: Drug-Induced Parkinsonism vs. Tardive Dyskinesia-Key Differences in Pathophysiology and Clinical Management

Introduction

Drug-induced parkinsonism (DIP) and tardive dyskinesia (TD) are stigmatizing movement disorders associated with exposure to dopamine receptor blocking agents such as antipsychotics, but they differ in their pathophysiology and clinical management. Treatment for one may worsen the other, and there are important diagnostic clues that assist in making an accurate assessment and instituting a rational treatment plan.

Methods

A literature review was executed to identify articles relating to the presentation, pathophysiology, epidemiology, and management of DIP and TD.

Results

DIP and TD prevalence estimates range from approximately 20 to 35% among antipsychotic users, but may be higher in select populations. DIP often presents as bradykinesia and rigidity, as well as rhythmic tremor, and the majority of cases appear within hours to weeks of initiation of therapy with an antipsychotic, or if dosage of the antipsychotic is increased. TD onset is delayed, typically appearing after at least 3 months or longer of treatment, and patients will commonly present with involuntary, abnormal facial movements such as lip smacking, puckering, chewing, or tongue protrusion. DIP often resolves with discontinuation of the causative agent, but TD may be permanent. Broadly, proposed mechanisms underlying these adverse events include decreased dopamine concentrations in the nigrostriatal pathway of the striatum and dopamine hypersensitivity, for DIP and TD, respectively. Pharmacologic treatment approaches for DIP have commonly included anticholinergic agents such as benztropine; however, anticholinergic medications can make TD worse. Switching the antipsychotic medication to one with lower propensity for DIP is an option for some patients. Amantadine, a non-anticholinergic agent used for the treatment of DIP, may be preferred in patients with comorbid DIP and TD. In TD, treatment options include the new reversible vesicular monoamine 2 transporter inhibitors, valbenazine and deutetrabenazine.

Conclusions

It is important for clinicians to be able to recognize DIP and TD in patients using antipsychotics so that they can minimize the impact of these adverse events on their patients’ quality of life. Accurate diagnosis will drive the selection of the correct treatment.

Plain Language Summary

Plain language summary available for this article.

Deuterium Tetrabenazine for Tardive Dyskinesia

Tardive dyskinesia remains a significant, potentially stigmatizing or crippling adverse effect for any patient treated with an antipsychotic medication. While second- and third-generation antipsychotics have exhibited lower annual incidence rates for tardive dyskinesia than classic or first-generation agents, 3.9% versus 5.5%, the estimated incidence rate is only modestly lower. When coupled with the fact that second- and third-generation antipsychotic medications have come to be employed in treating a wider range of disorders (e.g., autism spectrum disorders, mood disorders, personality disorders, etc.), it is clear that the population of patients exposed to the risk of tardive dyskinesia has expanded. On April 3, 2017, the U.S. Food and Drug Administration (FDA) approved a deuterated version of tetrabenazine (Xenozine®) for the treatment of the involuntary choreic movements associated with Huntington's disease. More recent data, however, have indicated that deuterium tetrabenazine or deutetrabenazine (Austedo®) is effective in treating tardive dyskinesia. Moreover, like the other derivative of tetrabenazine, valbenazine (Ingrezza®), deutetrabenazine offers less frequent dosing and a better short-term adverse effect profile than that of tetrabenazine. Longer use in a broader range of patients, however, will be required to identify risks and benefits not found in short-term trials, as well as optimal use parameters for treatment of tardive dyskinesia.

Tardive dyskinesia: Epidemiology

The term tardive syndrome (TS) encompasses a few different phenomenologic conditions, some of which occur in isolation and others in association with each other. This, along with the unusual confound for a drug side effect, in which increased use of the drug improves the problem, and the need for most patients to continue taking the offending drug, makes understanding the epidemiology difficult and unreliable. While the change from the "first generation" to the "second generation" of antipsychotic drugs is generally believed to have reduced the incidence of TS, prospective research studies have not supported that contention. Published reports have found point prevalences of 13% with second generation antipsychotics and 32% with first, yet others have found no differences. One study found increasing rates of TS with a 68% prevalence by 25 years, while another found a decreased prevalence over time, due presumably to masking effects of the antipsychotic drugs. Regardless of the possible differences, it is clear that TS remains a significant and common problem associated with almost all antipsychotic drugs. There have also been scattered reports of TS caused by drugs not known to inhibit dopamine receptors. These are reviewed and were found to be often of dubious reliability.

Clinical significance of neurological abnormalities in psychosis

The neurological deficits in sensory and motor function in schizophrenia have been described using a confusing variety of terms, reflecting their uncertain relevance and significance to psychosis. In this article we explore the nature of neurological abnormalities in psychosis, describe their assessment and suggest their potential relevance for clinician and patient. We propose that the assessment of neurological abnormalities and extrapyramidal side-effects should figure in the assessment of any patient with psychosis, particularly at illness onset. Furthermore, we suggest that neurological abnormalities can inform prognostic predictions and help to identify patients with more complex future care needs.

Movement Disorders Associated With Antipsychotic Medication in People With Schizophrenia: An Overview of Cochrane Reviews and Meta-Analysis

Movement disorders associated with antipsychotic medications are relatively common, stigmatising, and potentially disabling. Their prevalence in people with psychosis who are prescribed second-generation antipsychotics (SGAs) is uncertain, as is their level of recognition by clinicinas. We conducted meta-analyses of randomised controlled trials included in the Cochrane Database of Systematic Reviews on schizophrenia and schizophrenia-like psychoses to estimate the prevalence of new-onset dystonia, akathisia, parkinsonism, and tremor with SGAs (amisulpride, asenapine, aripiprazole, clozapine, olanzapine, paliperidone, quetiapine, risperidone, L-sulpiride, and ziprasidone) approved in Canada and the UK, comparing them with haloperidol and chlorpromazine. We used a random effects model because of the heterogeneity between-studies in drug dosage and method of ascertainment of movement disorders. Our systematic search yielded 37 Cochrane systematic reviews (28 for SGAs), which generated 316 informative randomised controlled trials (243 for SGAs). With respect to SGAs, prevalence estimates ranged from 1.4% (quetiapine) to 15.3% (L-sulpiride) for dystonia, 3.3% (paliperidone) to 16.4% (L-sulpiride) for akathisia, 2.4% (asenapine) to 29.3% (L-sulpiride) for parkinsonism, and 0.2% (clozapine) to 28.2% (L-sulpiride) for tremor. Prevalence estimates were not influenced by treatment duration, the use of a flexible or fixed dosing scheme, or whether studies used validated instruments for the screening/rating of movement disorders. Overall, we found high overlap on the prevalence of new-onset movement disorders across different SGAs precribed for established psychoses. Variations in prevalence figures across antipsychotic medications were observed for the different movement disorders. Differences in pharmacological properties, such as for the dopamine D2 R association rate and serotonin 5-HT2A antagonism, could contribute to this variation.

Valbenazine for Tardive Dyskinesia

Tardive dyskinesia (TD) remains a clinical concern for any patient who receives an antipsychotic. While the overall risk of developing TD is lower with newer antipsychotics compared to older agents, a significant number of patients who require long-term treatment will develop TD. Recently, valbenazine (brand name Ingrezza) became the first drug to be approved by the FDA specifically for the treatment of TD. In this New Drug Review, we summarize the basic pharmacology and clinical trial results for valbenazine. Valbenazine is a modified metabolite of the vesicular monoamine transporter 2 (VMAT-2) inhibitor tetrabenazine, which is approved for the treatment of the hyperkinetic movement disorder, Huntington's disease. In short-term clinical trials, valbenazine at a dose of 80 mg/day improved TD, with an effect size that is clinically significant (d=0.90). The effect size for the 40-mg/day dose was lower (d=0.52). Compared to tetrabenazine, valbenazine has better clinical characteristics (i.e., once-a-day dosing, better short-term side effect profile). However, only long-term experience in routine clinical populations can delineate valbenazine's full benefits, optimal dosing, and risks not identified during short-term registration trials.

High Incidence and Prevalence of Drug-Related Movement Disorders in Young Patients With Psychotic Disorders

BACKGROUND

Drug-related movement disorders (DRMDs) reduce quality of life and contribute to medication noncompliance of patients with psychotic disorders. Little is known about the epidemiology of DRMDs in relatively young patients a few years after onset of psychosis. This is an important period to study, as the impact of the antipsychotic treatment on the long-term potentiation of the neural pathways associated with psychotic disorders and DRMDs is still minimal. This study investigated the prevalence, incidence, persistence, and clinical correlates of DRMDs in patients during their first years after disease onset.

METHODS

The Genetic Risk and Outcome of Psychosis study is a longitudinal study of 1120 relatively young patients with nonaffective psychosis and a mean age and illness duration of 27 and 4 years, respectively. The following drug-related movement disorders were assessed at baseline and at the 3-year follow-up: parkinsonism, akathisia, tardive dyskinesia, and tardive dystonia. We determined prevalence, incidence, and persistence and investigated clinical correlates at and over the baseline and follow-up assessment.

RESULTS

Patients' mean age and illness duration at baseline were 27.1 and 4.3 years, respectively. In 4 patients, 1 developed a DRMD over the 3-year study period. Prevalence, incidence, and persistence rates were highest for parkinsonism (32%, 21%, and 53%) followed by akathisia (9%, 5%, and 17%) and tardive dyskinesia (4%, 3%, and 20%). Significant associations were found between DRMDs and the patients' age, IQ, and psychopathology.

CONCLUSIONS

The prevalence, persistence, and incidence of DRMDs in this sample were high despite the relatively young age, recent onset of the disorder, and treatment primarily with second-generation antipsychotics. These findings emphasize that screening, diagnosis, and treatment of DRMDs are still important.

Tardive Dyskinesia: A Historical Perspective

The goal of this column is to provide historical context on tardive dyskinesia (TD) to help the reader understand how the concept was studied and evolved over time. Psychiatrists today should understand this history and consider it in combination with more recent data on the neurobiology of TD, including data from animal studies. This combination of classic data with modern science can help readers develop a more complete understanding and lead to a more judicious use of the term TD, after consideration of all of the alternative causes of abnormal movements, including spontaneous dyskinesia (SD). We advocate that clinicians use the term SD when in doubt about the cause of a movement disorder in a given patient, as TD is never distinguishable from SD in a given patient but is instead an issue of a statistical odds ratio.

Unusual morphology of scapulae: incidence and dimensions of ossified ligaments and supraspinous bony tunnels for clinical consideration

INTRODUCTION

Knowledge of morphological variations of the suprascapular region is important in the management of entrapment neuropathy and interventional procedures. The objective of this study was to collect data on the morphological features and dimensions of ossified ligaments and unusual bony tunnels of scapulae from a North Indian population.

METHODS

A total of 268 adult human scapulae of unknown gender were obtained from the bone bank of the Department of Anatomy, Dayanand Medical College and Hospital, Ludhiana, Punjab, India. The scapulae were evaluated for the incidence of ossified superior transverse scapular ligaments (STSLs), ossified inferior transverse scapular ligaments (ITSLs) and bony tunnels (i.e. the bony canal between the suprascapular notch and spinoglenoid notch), found along the course of the suprascapular nerve (SSN). The dimensions of these structures were measured and noted down. Ossified STSLs were classified based on their shape (i.e. fan- or band-shaped) and the dimensions of the ossified suprascapular openings (SSOs) were measured.

RESULTS

Ossified STSLs were present in 26 (9.7%) scapulae. Among the 26 scapulae, 16 (61.5%) were fan-shaped (mean area of SSO 16.6 mm(2)) and 10 (38.5%) were band-shaped (mean area of SSO 34.2 mm(2)). Bony tunnels were observed in 2 (0.75%) specimens, while an ossified ITSL was observed in 1 (0.37%) specimen.

CONCLUSION

The data obtained in the present study augments the reference literature for SSN decompression and the existing anatomical databases, especially those on Indian populations. This data is useful to clinicians, radiologists and orthopaedic surgeons.

[Antipsychotic-induced tardive syndromes]

Tardive dyskinesia (TD) remains a relevant clinical problem despite the increasing use of new-generation antipsychotics. Antipsychotic-induced tardive syndromes are difficult to treat and have a low tendency of remission. Therefore, prophylaxis is of utmost importance, with the responsible use of antipsychotics as a prime desideratum. With respect to managing tardive dyskinesia, discontinuing the antipsychotic, if possible, albeit not backed up by unequivocal evidence, is still the main recommendation. If this is not possible, the switch to an antipsychotic with a lower TD risk is the next-preferred option. Other symptomatic treatments have been explored, but clinical trials have provided inhomogeneous results and only very few compounds are approved for the treatment of tardive dyskinesia. This manuscript summarizes the current evidence with respect to the phenomenology, course, prevention and treatment of tardive syndromes.

Successful Management of Tardive Dyskinesia with Quetiapine and Clonazepam in a Patient of Schizophrenia with Type 2 Diabetes Mellitus

Tardive dyskinesia is one of the most significant side effects of antipsychotic medications. Antipsychotic treated schizophrenia patients with diabetes mellitus are more likely to develop tardive dyskinesia than those without diabetes. Clozapine is probably best supported for management of tardive dyskinesia. But clozapine has been strongly linked to hyperglycaemia and impaired glucose tolerance, so it is not preferred in patients with diabetes mellitus. We present a case of 35-year-old male with a diagnosis of schizophrenia and type 2 diabetes mellitus with tardive dyskinesia, who was successfully treated with quetiapine and clonazepam.

Employing proteomics to unravel the molecular effects of antipsychotics and their role in schizophrenia

Schizophrenia is an incurable neuropsychiatric disorder managed mostly by treatment of the patients with antipsychotics. However, the efficacy of these drugs has remained only low to moderate despite intensive research efforts since the early 1950s when chlorpromazine, the first antipsychotic, was synthesized. In addition, antipsychotic treatment can produce often undesired severe side effects in the patients and addressing these remains a large unmet clinical need. One of the reasons for the low effectiveness of these drugs is the limited knowledge about the molecular mechanisms of schizophrenia, which impairs the development of new and more effective treatments. Recently, proteomic studies of clinical and preclinical samples have identified changes in the levels of specific proteins in response to antipsychotic treatment, which have converged on molecular pathways such as cell communication and signaling, inflammation and cellular growth, and maintenance. The findings of these studies are summarized and discussed in this review and we suggest that this provides validation of proteomics as a useful tool for mining drug mechanisms of action and potentially for pinpointing novel molecular targets that may enable development of more effective medications.

Tardive Blepharospasm and Meige Syndrome during Treatment with Quetiapine and Olanzapine

Meige syndrome, which has been presented in tardive syndromes, is a form of blepharospasm accompanied by oromandibular dystonia with manifestations over the face, jaw, and neck. A blepharospasm can be induced by antihistamines, dopaminomimetic or sympathomimetic drugs, or long-term exposure to dopamine antagonists. Atypical antipsychotics have less extrapyramidal side effects because of a weak dopamine D2 receptor binding affinity or a strong antagonistic effect to serotonin 5-HT2a receptor and have been known to cause less tardive dyskinesia than typical antipsychotics. Thus, in literature, atypical antipsychotics are recommended for the treatment of psychosis in cases of tardive dyskinesia. The potential risk factors associated with the development of tardive dyskinesia are extrapyramidal symptoms' history, diabetes mellitus, affective disorder, female gender, older age, and long-term therapy with neuroleptics at higher dosages. As reported below, a patient with an affective disorder who had quetiapine-induced oromandibular dystonia and olanzapine-induced Meige syndrome after antipsychotic augmentation in different stages of the disease process was presented.

Tardive Syndromes are Rarely Reversible after Discontinuing Dopamine Receptor Blocking Agents: Experience from a University-based Movement Disorder Clinic

BACKGROUND

Several studies have examined reversibility of tardive syndromes (TS), primarily in psychotic patients who are maintained on dopamine receptor blocking drugs. The results have varied widely. However, few have assessed remission rates after discontinuing the offending agents. This study evaluated reversibility of TS in patients who permanently withdrew the causative agent(s). We also examined for any possible clinical predictors of reversibility.

METHODS

A retrospective cohort of 108 TS patients was studied. Most of the patients were not psychotic; most patients were being treated either for a mood disorder with atypical antipsychotics or for a gastrointestinal disturbance with metoclopramide. Patients were stratified on the basis of reversibility, and statistical tests were used for subgroup comparisons of relevant clinical variables. Logistic regression was undertaken to identify clinical variables predictive of reversibility.

RESULTS

Only 13% of the cohort experienced reversibility of the TS, 2% without medical intervention. When stratified by reversibility, there were no significant differences in any study variables between subgroups. None of the study variables predicted reversibility in the logistic regression.

DISCUSSION

Our study demonstrated a low remission rate for TS in a cohort of psychiatric and non-psychiatric patients seen in a movement disorder clinic after the offending agents were completely withdrawn. Such a finding has significant prognostic implications. It is possible that limitations of the retrospective design may have resulted in an underestimation. There is a clear need for prospective, multicenter, clinical trials in populations that can be safely withdrawn from dopamine receptor blocking agents so that true remission rates can be measured.

Psychotropic drugs and bruxism

INTRODUCTION

Sleep and awake bruxism is defined as 'a parafunctional activity including clenching, bracing, gnashing, and grinding of the teeth'. Some evidence suggests that bruxism may be caused by, or associated with, alterations in the CNS neurotransmission. Several classes of psychotropic drugs interfering with CNS activity may potentially contribute to bruxism. Thus, the purpose of this study was to examine relevant peer-reviewed papers to identify and describe the various classes of psychotropic substances that may cause, exacerbate or reduce bruxism as the result of their pharmacological action in CNS neurons.

AREAS COVERED

A literature search from 1980 to the present was performed using PubMed database. The term 'bruxism' was used in association with 'psychotropic', 'dopamine (DA)', 'serotonin', 'histamine', 'antipsychotics', 'antidepressants', 'antihistaminergics' and 'stimulants'.

EXPERT OPINION

Studies on the effects of DA agonists (Levo-DOPA, psychostimulants) and antagonists (antipsychotics) identified a central role of DA in the pathogenesis of pharmacologically induced bruxism. Important information from studies on drugs acting on serotonin neurotransmission (antidepressants) was recognized. Other mechanisms involving different neurotransmitters are emerging. This is the case of antihistaminergic drugs which may induce bruxism as a consequence of their disinhibitory effect on the serotonergic system.