Non-motor phenotype of dopa-responsive dystonia and quality of life assessment

Background: Dopa-responsive dystonia (DRD) is a young-onset neurometabolic disorder often presenting with a combination of parkinsonism and dystonia. The pathophysiology includes an impairment of dopaminergic and serotonergic neurotransmission. Uncontrolled reports suggest an increased frequency of neuropsychiatric abnormalities and sleep impairment. Methods: In 23 GCH1 mutation-positive DRD patients and 26 healthy controls, non-motor features and their effect on the quality of life (QoL) were assessed. Six patients underwent polysomnography (PSG). Results: Depressive and anxiety symptoms were not more common among DRD patients. Average sleep quality was similar across groups. This was also true for self-reported mean sleep onset (27.5 vs. 27.1min) and total sleep time (6.5 vs. 6.6h). Upon PSG, the number of spontaneous arousals was increased in four patients. QoL was impaired with respect to physical health. Sleep impairment and depressive but not anxiety symptoms were associated with lower QoL. Conclusion: The present results do not confirm the clinical impression and biologically plausible assumption of an increased frequency of non-motor symptoms in DRD. The impairment of QoL is associated with a decline of the physical condition only but not with other factors.