Parkinson disease (PD) is a progressive neurodegenerative disorder commonly resulting in the loss of motor function, in nonmotor symptoms, and in cognitive decline. It affects 4.1 to 4.6 million people worldwide, and its prevalence is predicted to more than double by 2030.¹ Strong evidence has emerged that mitochondrial dysfunction and increased oxidative stress play a pivotal role in the pathogenesis of PD, providing a robust scientific rationale for testing potential “neuroprotectants” that target these processes.^2-4 Coenzyme Q10 (CoQ10) is a key component of the electron transport chain responsible for mitochondrial adenosine triphosphate generation, leads to decreased free radical generation, and, in its reduced form, acts as a powerful antioxidant.⁵ Coenzyme Q10 levels and redox status have been shown to be altered in individuals with PD,⁶ and CoQ10 has neuroprotective effects in multiple in vitro and animal models of neuronal toxicity, including the MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) model of PD.⁷ Finally, CoQ10 has shown promising clinical benefits in small human studies of progressive supranuclear palsy, Huntington disease, and Friedreich ataxia.^8-10

Quiz Ref ID Huntington disease is a hereditary, progressive, neurodegenerative disease characterized by involuntary movements, cognitive dysfunction, and psychiatric symptoms. Huntington disease is caused by an exon 1 CAG (cytosine-adenine-guanine [amino acid sequence]) trinucleotide expansion in the huntingtin (HTT) gene (NC_000004.12; http://www.ncbi.nlm.nih.gov/nuccore/568815594).¹ A prominent Huntington disease symptom is chorea, an involuntary, sudden movement that can affect any muscle and flow randomly across body regions.² Chorea can interfere with daily functioning and increase the risk of injury.³

Objective: To determine the efficacy and safety of deutetrabenazine as a treatment for tardive dyskinesia (TD). Methods: One hundred seventeen patients with moderate to severe TD received deutetrabenazine or placebo in this randomized, double-blind, multicenter trial. Eligibility criteria included an Abnormal Involuntary Movement Scale (AIMS) score of ≥6 assessed by blinded central video rating, stable psychiatric illness, and stable psychoactive medication treatment. Primary endpoint was the change in AIMS score from baseline to week 12. Secondary endpoints included treatment success at week 12 on the Clinical Global Impression of Change (CGIC) and Patient Global Impression of Change. Results: For the primary endpoint, deutetrabenazine significantly reduced AIMS scores from baseline to week 12 vs placebo (least-squares mean [standard error] −3.0 [0.45] vs −1.6 [0.46], p = 0.019). Treatment success on CGIC (48.2% vs 40.4%) favored deutetrabenazine but was not significant. Deutetrabenazine and placebo groups showed low rates of psychiatric adverse events: anxiety (3.4% vs 6.8%), depressed mood/depression (1.7% vs 1.7%), and suicidal ideation (0% vs 1.7%, respectively). In addition, no worsening in parkinsonism, as measured by the Unified Parkinson9s Disease Rating Scale motor subscale, was noted from baseline to week 12 in either group. Conclusions: In patients with TD, deutetrabenazine was well tolerated and significantly reduced abnormal movements. Classification of evidence: This study provides Class I evidence that in patients with TD, deutetrabenazine reduces AIMS scores.

Surgical therapies for Tourette syndrome have been used since the early 1960s. Ablative procedures were initially used to target specific areas of the brain; these approaches revealed inconsistent, but in many cases reasonably positive, clinical outcomes, particularly on motor tics. Ablative surgical procedures did not become mainstream and largely disappeared from the treatment arsenal for Tourette syndrome.¹ Deep brain stimulation (DBS) for Tourette syndrome, introduced in 1999,² is a surgical therapy that uses an implantable device to deliver electrical stimulation to specific and carefully targeted brain structures. Deep brain stimulation is approved by the US Food and Drug Administration and Conformité Européene Mark approved in the European Union for the treatment of selected cases of Parkinson disease and essential tremor. Deep brain stimulation has a Conformité Européene Mark for selected cases of primary and secondary dystonia.³ Deep brain stimulation also received approval from the US Food and Drug Administration under a humanitarian device exemption for dystonia and obsessive-compulsive disorder.⁴ Although DBS is not approved for Tourette syndrome in the United States and other countries, multiple single reports and case series have collectively demonstrated that DBS could be a potentially valuable therapy for select cases of severe medication-resistant Tourette syndrome. A recent systematic review and meta-analysis of 57 studies including 156 cases of DBS for Tourette syndrome reported an overall improvement of 53% as measured by the total Yale Global Tic Severity Scale (YGTSS) score.⁵