Non-motor symptoms in dystonia: from prevalence to pathophysiology

Dystonia is a movement disorder in which patients suffer from involuntary repetitive movements and/or abnormal postures. In addition to the problems with movement, patients also have non-motor symptoms, such as psychiatric symptoms, sleep problems and fatigue. These non-motor symptoms often remain underexposed, but they do have a great influence on the quality of life.
In this dissertation the non-motor symptoms are investigated in three forms of dystonia: dopa-responsive dystonia (DRD), myoclonus dystonia (M-D) and cervical dystonia. In all these forms of dystonia, non-motor symptoms were more prevalent than in people without dystonia (57-74% vs. 29%). In addition, we observed that certain psychiatric symptoms were more frequently present in specific forms of dystonia. M-D patients were relatively more likely to suffer from a obsessive-compulsive disorder, whereas DRD patients often had an anxiety disorder. Another important finding is that the non-motor symptoms had a great impact on the patients' quality of life, even more than the movement disorder itself. These results show the need for an adequate and personalised treatment of the non-motor symptoms.
The second part of this dissertation focuses on the role of the messenger substance serotonin in the symptoms of dystonia. On different levels, both in the blood and in the brains, we found small changes in the metabolism of serotonin, and moreover, there sometimes appeared to be a correlation with the non-motor symptoms. This shows that serotonin possibly plays a role in the non-motor symptoms. Further research may eventually lead to better treatment options for the patients.