Tardive Syndromes

PURPOSE OF REVIEW

This article reviews the history, nosology, clinical features, epidemiology, and treatment of tardive syndromes.

RECENT FINDINGS

The major advance in the field of tardive syndromes has been the development and US Food and Drug Administration (FDA) approval of two vesicular monoamine transporter type 2 inhibitors, valbenazine and deutetrabenazine, for treating tardive syndromes. These medications are derivatives of tetrabenazine and reduce dyskinetic movements by reducing dopamine stimulation. Treatment is not curative, and the medications reduce, or "mask," symptoms but presumably without adding to the long-term risk of increased involuntary movements believed to accrue from suppressive treatment with dopamine receptor-blocking drugs. A confounding advance has been the accumulation of data finding that second-generation antipsychotics, also known as atypical antipsychotics, may not be safer than first-generation antipsychotics in causing tardive syndromes. The public health risk of tardive syndromes may actually have increased as some second-generation antipsychotics, widely promoted to both doctors and patients, are increasingly used as antidepressants.

SUMMARY

Tardive syndromes remain a public health risk. Second-generation antipsychotics have not been proven to have less risk than first-generation drugs in causing tardive syndromes and are nevertheless being used more widely to treat depression, bipolar disease, and insomnia. Symptomatic treatment for tardive syndromes is available, although expensive.

Tardive dyskinesia: Out of the shadows

The approvals of the first two medications, valbenazine and deutetrabenazine, to treat tardive dyskinesia have ushered in a new era in neuropsychiatric care. Tardive syndromes are defined as delayed onset, persistent movement disorders or sensory phenomena that occur in association with exposure to dopamine receptor blocking agents (DRBAs). Their underlying pathophysiology remains to be fully elucidated, but clinicians can conceptualize tardive syndromes as persistent dopamine supersensitivity states. Tardive syndromes can potentially cause distress, disfigurement, embarrassment, and dysfunction, and are often permanent. Therefore, practitioners who prescribe DRBAs should be aware of this potential, carefully assess the risk/benefit ratio when considering the use of these medications, and be sure that patients are appropriately informed. Patients on DRBAs should be monitored for the development of tardive syndromes, including through the use of regularly scheduled Abnormal Involuntary Movement Scale (AIMS) (or similar) examinations. Clinicians prescribing DRBAs should be familiar with the diagnosis and management of tardive syndromes, and be able to institute treatment or refer patients when treatment is appropriate. Future research may focus on the potential benefit of earlier introduction of VMAT2 inhibitors to delay onset or progression of tardive syndromes. More effective treatments are still needed, as are effective, well-tolerated antipsychotics that do not cause tardive syndromes.

Co-treatment with imipramine averted haloperidol-instigated tardive dyskinesia: Association with serotonin in brain regions

Outcome of imipramine (IMI) treatment was scrutinized on progression of haloperidol instigated tardive dyskinesia (TD). 0.2 mg/kg/rat dosage of haloperidol provided orally to rats for 2 weeks enhanced vacuous chewing movements that escalated when the process proceeded for 5 weeks. Following 2 weeks co-injection 5 mg/kg dosage of IMI was diminished haloperidol-instigated VCMs and fully averted following five weeks. The potency of 8-OH-DPAT-instigated locomotor activity exhibited higher in saline+haloperidol treated rats while not observed in IMI+ haloperidol treated rats. 8-OH-DPAT-instigated low 5-hydroxytryptamine (5-HT; serotonin) metabolism was higher in saline+ haloperidol treated rats when compare to IMI+ haloperidol treated rats in both regions of brain (striatum and midbrain). It is recommended that IMI possibly competent in averting TD, in cases receiving treatment to antipsychotics.