["Addition of catechol-O-methyltransferase inhibitors to a conventional levodopa/dopadecarboxylase inhibitor regimen improves motor symptoms in patients with Parkinson's disease. Optimizing dopamine substitution is also beneficial for nonmotor features.", 'To investigate the efficacy of supplemental tolcapone intake on nonmotor symptoms.', "A total of 125 levodopa-treated patients additionally took tolcapone in this observational trial. Initially and following 4 weeks of tolcapone intake, the neurologist scored with Unified Parkinson's Disease Rating Scale parts I, II, IV, the nonmotor symptoms scale for Parkinson's disease and recorded the off time. The patients rated themselves with the EuroQuol, its visual analogue scale and the nonmotor screening questionnaire. Caregivers reported the daily duration of care giving.", "All scores improved except for Unified Parkinson's Disease Rating Scale part IV and domains 4, 5 and 8 of the nonmotor symptoms scale for Parkinson's disease."] Does tolcapone addition improve Parkinson 's disease associated nonmotor symptoms?