Rare, neurologic disorders, such as Tourette’s syndrome, which, to the contrary, is argued to be a neuropsychiatric disorder in a Journal of Neuroscience review, are not often viewed as a critical public health concern. Stigma associated with Tourette’s is well documented in Hollywood (TV and movies)
and while we, including myself, may laugh at this (dark comedy) medical disease, extensive research has been conducted across the past century in order to understand its genetic and neuroanatomical etiologies, symptomatologies, and treatment strategies in human and animal models.
Tourette’s has long been characterized as a neurologic disorder manifest from altered circuitry and volumetric changes in the basal ganglia, the thalamus, and cerebellum. It is no surprise that neuroanatomical pathologies in/to these major brain regions underlie the disorder’s manifestation and severity, which primarily result in a series of motor tics, and though less frequently, vocal tics, because all of these brain areas directly gate the execution and integration of motor movements/information. Nonetheless, recent evidence from epidemiological studies have found that individuals with Tourette’s are also predisposed to a spectrum of psychiatric disorders, including depression, anxiety, OCD, and ADHD, which lends credence to the argument that Tourette’s should be re-classified as a neuropsychiatric disorder. This reclassification can be further substantiated through increased study in animal models of the disease, which, to date, are engineered by disrupting dopamine neuromodulatory systems, specifically at D1 receptors and DAT (reuptake) transporters. Much of the general public now understands that perturbations in dopaminergic systems is the root of many neurologic and psychiatric diseases
Twin studies also suggest strong, genetic inheritability, such that the concordance of Tourette’s in monozygotic (identical) twins (likelihood that both have been diagnosed) is 77-94%, and only 23% in dizygotic (fraternal) twins. Genetic polymorphisms of the DAT transporter have also been identified.
So what is the next step? Current treatment strategies have focused on dopamine antagonists. This may certainly reduce symptomatologies of Tourette’s (tics, OCD-like behavior, hyperactivity, restlessness (poor sleep)), but this doesn’t result in long-term remission of the disease, even if the symptoms decrease in severity with age. Deep brain stimulation may be one option. Although this treatment strategy was inadequately discussed in the paper, deep brain stimulation has certainly become efficacious for Parkinson’s patients, which also manifests from disruption to the complicated excitation/inhibition circuitry of the basal ganglia, but unlike Tourette’s, escalates in severity with age. All in all, it seems that there is enough active research being done to discover novel, disrupted pathways that contribute to Tourette’s pathology and refine current treatment strategies.
Felling RJ, & Singer HS (2011). Neurobiology of tourette syndrome: current status and need for further investigation. The Journal of neuroscience : the official journal of the Society for Neuroscience, 31 (35), 12387-95 PMID: 21880899