title: Motor and cognitive placebo-/nocebo-responses in Parkinson's disease patients with deep brain stimulation.
abstract: Expectation contributes to placebo and nocebo responses in Parkinson's disease (PD). Subthalamic nucleus (STN) deep brain stimulation (DBS) improves proximal more than distal movements whereas it impairs executive cognitive function such as verbal fluency (VF). We investigated how expectation modulates the pattern of motor improvement in STN-DBS and its interaction with VF. In a within-subject-design, expectation of 24 hypokinetic-rigid PD patients regarding the impact of STN-DBS on motor symptoms was manipulated by verbal suggestions (positive [placebo], negative [nocebo], neutral [control]). Patients participated with (MedON) and without (MedOFF) antiparkinsonian medication. Motor function was assessed by Unified Parkinson's Disease Rating Scale and quantitative kinematic analysis of proximal alternating hand and distal finger tapping. VF was quantified by lexical and semantic tests. In MedOFF, expectation significantly affected proximal but not distal movements resulting in better performance in the placebo than in the nocebo condition. Placebo responders with improvement of ≥25% were characterized by a trend for impaired lexical VF. These results indicate that positive motor expectations exert both motor placebo and cognitive nocebo responses by further enhancing the STN-DBS-effect on proximal movements and by impairing VF. The placebo response on motor performance resembles the clinically known STN-DBS-effect with stronger improvement in proximal than distal movements. The nocebo response on VF is likely due to implicit learning mechanisms associated with an expectation-induced placebo response on motor performance.
authors: Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University of Duesseldorf, Universitaetsstr. 1, 40225 Duesseldorf, Germany.
authors: Ariane
authors: A
authors: Keitel
authors: Lars
authors: L
authors: Wojtecki
authors: Jan
authors: J
authors: Hirschmann
authors: Christian J
authors: CJ
authors: Hartmann
authors: Stefano
authors: S
authors: Ferrea
authors: Martin
authors: M
authors: Südmeyer
authors: Alfons
authors: A
authors: Schnitzler
mesh_terms: D000328:Adult; D000368:Aged; D003072:Cognition Disorders / Q000209:etiology / Q000628:therapy*; D046690:Deep Brain Stimulation / Q000379:methods* / Q000523:psychology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications / Q000523:psychology / Q000628:therapy; D015990:Placebo Effect; D011597:Psychomotor Performance; D012720:Severity of Illness Index; D020531:Subthalamic Nucleus / Q000502:physiology; D011795:Surveys and Questionnaires; D014706:Verbal Learning