Psychiatric comorbidities in dystonia: Emerging concepts

Psychiatric disorders are highly prevalent in patients with dystonia and have a profound effect on quality of life. Patients with dystonia frequently meet criteria for anxiety disorders, especially social phobia, and major depressive disorder. Deficits in emotional processing have also been demonstrated in some dystonia populations. Onset of psychiatric disturbances in patients with dystonia often precedes onset of motor symptoms, suggesting that the pathophysiology of dystonia itself contributes to the genesis of psychiatric disturbances. This article examines the hypothesis that mood and anxiety disorders are intrinsic to the neurobiology of dystonia, citing the available literature, which is derived mostly from research on focal isolated dystonias. Limitations of studies are identified, and the role of emotional reactivity, especially in the context of pain secondary to dystonia, is recognized. Available evidence underscores the need to develop dystonia assessment tools that incorporate psychiatric measures. Such tools would allow for a better understanding of the full spectrum of dystonia presentations and facilitate research on the treatment of dystonia as well as the treatment of psychiatric illnesses in the context of dystonia. This article, solicited for a special Movement Disorders issue on novel research findings and emerging concepts in dystonia, addresses the following issues: (1) To what extent are psychiatric disturbances related to the pathophysiology of dystonia? (2) What is the impact of psychiatric disturbances on outcome measures of current assessment tools for dystonia? (3) How do psychiatric comorbidities influence the treatment of dystonia? Answers to these questions will lead to an increased appreciation of psychiatric disorders in dystonia, a better understanding of brain physiology, more nuanced research questions pertaining to this population, better clinical scales that can be used to further patient management and research, and improved patient outcomes.