High-speed memory scanning in Parkinson's disease: adverse effects of levodopa

Ann Neurol. 1991 Jun;29(6):670-3. doi: 10.1002/ana.410290616.


High-speed memory scanning as assessed by the Sternberg paradigm was studied in 12 nondemented patients with fluctuating Parkinson's disease and 13 age-matched healthy controls. Patients were first assessed before taking their morning dose of levodopa ("off") and again after that dose had produced full clinical effect ("on") after that dose had produced full clinical effect ("on"). Although motor components of the measured choice reaction time were slower in patients when off than in control subjects, memory scanning speed was not different. After levodopa (on), patients' motor time normalized, but cognitive processing speed became significantly slower when compared with previous performance in the off condition and with controls. Contrary to previous concepts of bradyphrenia in patients with Parkinson's disease, these results indicate that dopaminergic stimulation can reduce cognitive processing speed.

Publication types

  • Comparative Study

MeSH terms

  • Frontal Lobe / drug effects
  • Frontal Lobe / physiopathology
  • Humans
  • Levodopa / adverse effects*
  • Levodopa / therapeutic use
  • Memory Disorders / chemically induced*
  • Memory Disorders / physiopathology
  • Memory, Short-Term / drug effects*
  • Memory, Short-Term / physiology
  • Mental Recall / drug effects*
  • Mental Recall / physiology
  • Parkinson Disease / drug therapy
  • Parkinson Disease / psychology*
  • Psychological Tests
  • Receptors, Dopamine / drug effects
  • Receptors, Dopamine / physiology


  • Receptors, Dopamine
  • Levodopa