title: Apomorphine delays simple reaction time in Parkinsonian patients.
abstract: BACKGROUND
  Parkinsonian patients have difficulty in the preparation and execution of movements, which translate into delayed performance of simple reaction time (SRT) paradigms.
  
  
  OBJECTIVE
  To examine short-term effects of an acute subcutaneous injection of the dopamine agonist apomorphine on the results of a SRT task.
  
  
  METHODS
  We studied a SRT paradigm in 26 non-fluctuating idiopathic Parkinsonian patients, before and 30, 60, 90 min after administration of apomorphine.
  
  
  RESULTS
  The reaction time (RT) was significantly delayed after apomorphine injection. We found no significant change in movement time (MT).
  
  
  CONCLUSIONS
  Delay of RT and the lack of response of MT to apomorphine administration may result from the sedative effects of apomorphine, overstimulation of postsynaptic dopaminergic receptors with subsequent inhibition of prefrontal cholinergic neurotransmission, and at least partial binding of apomorphine to presynaptic dopaminergic autoreceptors, which cause inhibition of locomotor activity. We suggest that future studies testing the capacity for reaction in Parkinsonian patients should consider the exact timing of the delivery of dopamine substituting drugs prior to the test.
authors.affiliation: Department of Neurology, St. Josef Hospital, Ruhr University Bochum, Gudrunstrasse 56, 44791 Bochum, Germany. thomas.mueller@ruhr-uni-bochum.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller
authors.forename: Sabine
authors.initials: S
authors.lastname: Benz
authors.forename: Horst
authors.initials: H
authors.lastname: Przuntek
mesh_terms: D000328:Adult; D000368:Aged; D000978:Antiparkinson Agents / Q000008:administration & dosage / Q000009:adverse effects*; D001058:Apomorphine / Q000008:administration & dosage / Q000009:adverse effects*; D003071:Cognition / Q000187:drug effects; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects*; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology; D011930:Reaction Time / Q000187:drug effects
chemical_list: D000978:Antiparkinson Agents; D001058:Apomorphine