New Models of Frontal-Subcortical Skeletomotor Circuit Pathology in Tardive Dyskinesia

[Tardive dyskinesia following discontinuation of neuroleptic therapy in 87-year-old patient]

In the absence of a therapeutic alternative, the use of neuroleptics in geriatrics should be limited to the bare minimum, given their potentially serious deleterious effects in frail elderly patients. Dyskinesia is one of their most common side effects. Case of an elderly patient in whom the dyskinesia was revealed following abrupt cessation of a neuroleptic taken in the long term with discussions of the etiological hypotheses of this rare situation, which nevertheless deserve to be known.

Antipsychotic-induced Tardive dyskinesia: from biological basis to clinical management

INTRODUCTION

Tardive dyskinesia (TD) is a chronic and disabling movement disorder with a complex pathophysiological basis. A significant percentage of patients does not receive correct diagnosis, resulting in delayed or inaccurate treatment and poor outcome. Therefore, there is a critical need for prompt recognition, implementation of efficacious treatment regimens and long-term follow up of patients with TD. Areas covered: The current paper provides an overview of emerging data concerning proposed pathophysiology theories, epidemiology, risk factors, and therapeutic strategies for TD. Expert commentary: Despite considerable research efforts, TD remains a challenge in the treatment of psychosis as the available strategies remain sub-optimal. The best scenario will always be the prophylaxis or prevention of TD, which entails limiting the use of antipsychotics.

[Prevention and treatment of tardive dyskinesia caused by antipsychotic drugs]

INTRODUCTION

Tardive dyskinesia (TD) is a movement disorder of tongue, jawbone, trunk and/or limbs that may appear after a prolonged use of dopamine receptor blocking agents (after 3 months of treatment or after 1 month for patients over 60), and that are present during at least four consecutive weeks. TD is a frequent side effect of both classical neuroleptics and new generation antipsychotic drugs. The prevalence of iatrogenic TD is between 24 and 32 % after treatment with classical neuroleptics and about 13 % after treatment with a new generation antipsychotic.

OBJECTIVE

This paper presents an updated literature review of data on diagnosis, prevention and treatment of TD.

METHODS

We conducted a review of literature using the Medline Browser tool, screening studies from 1950 to 2013 in English or French with keywords « tardive dyskinesia », « tardive dystonia », and « abnormal movements caused by antipsychotic drugs ».

RESULTS

We first describe and define semeiological features of TD: dystonia, tremor, myoclonus, acathisie, chorea, ballism and athetosia. Secondarily, we resume the main differential diagnoses to exclude when confronted with this kind of movement disorders. Differential diagnoses for dyskinesia can be classified between primary (Parkinson and Huntington diseases) and secondary (Wilson disease, intoxication, metabolic abnormality, cerebrovascular accident) abnormal movements. Psychogenic TD can be evocated if previous pathologies are excluded in case of atypical clinical presentation. We detail the risk factors for TD. Endogenous risk factors are related to the patient's age, underlying psychiatric disease (bipolar disorder or Alzheimer dementia), addiction to alcohol or cocaine, female gender, or neurodevelopmental vulnerability. Iatrogenic risk factors are high doses of antipsychotics, long or intermittent administration, and particular pharmaceutical classes or associations of antipsychotics. As a comprehensive tool, we review the main physiopathological hypotheses to explain the occurrence of TD in some patients: hypersensitivity of D2 neuronal receptor or neurotoxicity associated with oxidative stress mechanisms. We also summarize the current guidelines for prevention and treatment of TD. Three successive curative strategies are suggested in the literature. First, the clinician can adapt the current antipsychotic treatment (switch to a new generation antipsychotic, diminution or cessation of antipsychotic drugs). If this first intervention is not pertinent or ineffective, the clinician can prescribe an antikinetic therapeutic agent, such as tetrabenazine, or an antioxidant. Review of the published studies does not show proof of efficacy of cholinergic or anticholinergic drugs, benzodiazepine or other GABAergic drugs, nor for amantadine. Non-medication therapeutics such as ECT and TMS are discussed, but the level of proof is insufficient to promote them as a curative treatment for TD. In case of high resistance and discomfort for the patient, a neurosurgical intervention should be discussed. These curative interventions are limited, emphasising the importance of TD prevention, by limiting the prescription and doses of antipsychotics, regularly evaluating their side effects and informing the patient of TD's risk.

CONCLUSION

We propose to practitioners a synthesised update of literature concerning a frequent iatrogenic effect of antipsychotics. Nevertheless, no solid guidelines have as yet been established, and further clinical studies are expected in order to better understand this frequent and discomforting side effect.

New therapeutic opportunities for 5-HT2C receptor ligands in neuropsychiatric disorders

The 5-HT2C receptor (R) displays a widespread distribution in the CNS and is involved in the action of 5-HT in all brain areas. Knowledge of its functional role in the CNS pathophysiology has been impaired for many years due to the lack of drugs capable of discriminating among 5-HT2R subtypes, and to a lesser extent to the 5-HT1B, 5-HT5, 5-HT6 and 5-HT7Rs. The situation has changed since the mid-90s due to the increased availability of new and selective synthesized compounds, the creation of 5-HT2C knock out mice, and the progress made in molecular biology. Many pharmacological classes of drugs including antipsychotics, antidepressants and anxiolytics display affinities toward 5-HT2CRs and new 5-HT2C ligands have been developed for various neuropsychiatric disorders. The 5-HT2CR is presumed to mediate tonic/constitutive and phasic controls on the activity of different central neurobiological networks. Preclinical data illustrate this complexity to a point that pharmaceutical companies developed either agonists or antagonists for the same disease. In order to better comprehend this complexity, this review will briefly describe the molecular pharmacology of 5-HT2CRs, as well as their cellular impacts in general, before addressing its central distribution in the mammalian brain. Thereafter, we review the preclinical efficacy of 5-HT2C ligands in numerous behavioral tests modeling human diseases, highlighting the multiple and competing actions of the 5-HT2CRs in neurobiological networks and monoaminergic systems. Notably, we will focus this evidence in the context of the physiopathology of psychiatric and neurological disorders including Parkinson's disease, levodopa-induced dyskinesia, and epilepsy.

Treatment of neurolept-induced tardive dyskinesia

Tardive dyskinesia (TDK) includes orobuccolingual movements and "piano-playing" movements of the limbs. It is a movement disorder of delayed onset that can occur in the setting of neuroleptic treatment as well as in other diseases and following treatment with other drugs. The specific pathophysiology resulting in TDK is still not completely understood but possible mechanisms include postsynaptic dopamine receptor hypersensitivity, abnormalities of striatal gamma-aminobutyric acid (GABA) neurons, and degeneration of striatal cholinergic interneurons. More recently, the theory of synaptic plasticity has been proposed. Considering these proposed mechanisms of disease, therapeutic interventions have attempted to manipulate dopamine, GABA, acetylcholine, norepinephrine and serotonin pathways and receptors. The data for the effectiveness of each class of drugs and the side effects were considered in turn.

Striatal and cortical midline circuits in major depression: implications for suicide and symptom expression

BACKGROUND

In major depression, the neural mechanisms underlying suicide related thoughts and behaviors as well as the expression of other depressive symptoms are incompletely characterized. Evidence indicates that both the striatum and cortical midline structures (CMS) may be involved with both suicide and emotional dysregulation in unipolar illness. The aim of this study was to identify striatal-CMS circuits associated with current depression severity and suicidal ideation (SI) as well as a history of self-harm.

METHODS

Twenty-two male subjects with recurrent unipolar depression were studied using functional MRI. All subjects were unmedicated and without current psychiatric comorbidity. Correlational analyses were used to determine whether striatal-CMS functional connectivity was associated with any of the three clinical variables.

RESULTS

A network involving the bilateral striatum and anterior CMS was found to be associated with depressive symptom severity. Current SI was associated with a similar but less extensive circuit in the left hemisphere. A distinct striatal motor/sensory network was associated with self-harm behaviors, but not current SI or depression severity.

CONCLUSIONS

The striatal-anterior CMS circuit likely plays a significant role in the expression of depressive symptoms and SI. In contrast, a striatum-motor/sensory cortex network may be a trait marker of suicide-related behaviors. If replicated, this result might eventually lead to the development of a biomarker that would be useful for studies of pharmacologic and/or psychotherapeutic suicide prevention interventions.

Striatal and cortical midline activation and connectivity associated with suicidal ideation and depression in bipolar II disorder

BACKGROUND

Considerable evidence implicates dysfunction of striatal and cortical midline structure (CMS) circuitry in mood disorders. Whether such aberrations exist in bipolar II depression is unknown.

METHODS

Sixteen unmedicated subjects with bipolar II depression and 19 healthy controls were studied using functional MRI and a motor activation paradigm. Analyses of both activation and functional connectivity were conducted.

RESULTS

A history of suicidal ideation (SI) was negatively correlated with activation of the left putamen while depression severity was positively correlated with activation of the left thalamus. The superior bilateral putamen was simultaneously correlated with depression severity and anti-correlated with SI. Striatal functional connectivity was altered with the bilateral CMS and right inferior parietal lobule. Depression severity was correlated with strength of connectivity between the bilateral striatum and the right lingual gyrus and left cerebellum.

LIMITATIONS

Only males experiencing an episode of major depression were studied.

CONCLUSIONS

Striatal and CMS circuit abnormalities likely contribute to the neurobiology of bipolar II depression. Altered connectivity of the striatum may directly impact depression severity. Further, dissociable components of activation associated with depression severity and suicidal ideation may exist. Finally, the motor activation paradigm used in this study appears to be a useful probe of some neural processes underlying bipolar II depression.

Tardive dyskinesia and other movement disorders secondary to aripiprazole

The objective of this report is to draw attention to tardive dyskinesia (TD) caused by aripiprazole, a third generation antipsychotic. TD has been traditionally attributed to typical (first-generation) antipsychotics, but other dopamine receptor blocking drugs and atypical (second- and third-generation) neuroleptics are emerging as an important cause of TD. We reviewed the medical records of patients with TD seen at the Baylor College of Medicine Movement Disorders Clinic between 2002 and 2010 to identify patients with TD associated with aripiprazole. Among 236 patients with TD seen over the specified period, 8 (3.4%) were found to have aripiprazole-associated TD. In 5 patients, TD occurred after exclusive exposure to aripiprazole. The mean age at onset was 55.8 ± 14.8 years with a female predominance. The average duration of treatment with aripiprazole was 18.4 ± 26.4 months. Oro-bucco-lingual stereotypy was seen in all patients. In most patients, TD did not spontaneously improve after stopping aripiprazole. Of the 5 patients treated with tetrabenazine, 4 improved during follow-up. Although aripiprazole, a third generation antipsychotic, has been promoted to have a low risk of TD, the drug accounts for about 3.5% of patients with TD evaluated in a movement disorders clinic. This largest reported series draws attention to the growing incidence of TD and other drug-induced movement disorders associated with "atypical antipsychotics."

Stimulation of serotonin2C receptors elicits abnormal oral movements by acting on pathways other than the sensorimotor one in the rat basal ganglia

Serotonin2C (5-HT(2C)) receptors act in the basal ganglia, a group of sub-cortical structures involved in motor behavior, where they are thought to modulate oral activity and participate in iatrogenic motor side-effects in Parkinson's disease and Schizophrenia. Whether abnormal movements initiated by 5-HT(2C) receptors are directly consequent to dysfunctions of the motor circuit is uncertain. In the present study, we combined behavioral, immunohistochemical and extracellular single-cell recordings approaches in rats to investigate the effect of the 5-HT(2C) agonist Ro-60-0175 respectively on orofacial dyskinesia, the expression of the marker of neuronal activity c-Fos in basal ganglia and the electrophysiological activity of substantia nigra pars reticulata (SNr) neuron connected to the orofacial motor cortex (OfMC) or the medial prefrontal cortex (mPFC). The results show that Ro-60-0175 (1 mg/kg) caused bouts of orofacial movements that were suppressed by the 5-HT(2C) antagonist SB-243213 (1 mg/kg). Ro-60-0175 (0.3, 1, 3 mg/kg) dose-dependently enhanced Fos expression in the striatum and the nucleus accumbens. At the highest dose, it enhanced Fos expression in the subthalamic nucleus, the SNr and the entopeduncular nucleus but not in the external globus pallidus. However, the effect of Ro-60-0175 was mainly associated with associative/limbic regions of basal ganglia whereas subregions of basal ganglia corresponding to sensorimotor territories were devoid of Fos labeling. Ro-60-0175 (1-3 mg/kg) did not affect the electrophysiological activity of SNr neurons connected to the OfMC nor their excitatory-inhibitory-excitatory responses to the OfMC electrical stimulation. Conversely, Ro-60-0175 (1 mg/kg) enhanced the late excitatory response of SNr neurons evoked by the mPFC electrical stimulation. These results suggest that oral dyskinesia induced by 5-HT(2C) agonists are not restricted to aberrant signalling in the orofacial motor circuit and demonstrate discrete modifications in associative territories.

Pelvic dyskinesia with an outstanding response to tetrabenazine

We report on a patient who presented an invalidating progressive pelvic dyskinesia while receiving different kinds of neuroleptic drugs for a psychiatric disorder. The clinical features and different drug-induced movement scales showed an outstanding improvement after tetrabenazine was started. To the best of our knowledge, this is the first case report of pelvic dyskinesia with good evolution and control of dyskinesias after treatment with tetrabenazine.