Instrumentally detected changes in motor functioning in patients with low levels of antipsychotic dopamine D2 blockade

Paul B. Fitzgerald, Shitij Kapur, Michael P. Caligiuri, Corey Jones, Simone Silvestri, Gary Remington, Robert B. Zipursky

Research output: Contribution to journalArticleResearchpeer-review

4 Citations (Scopus)


Extrapyramidal side-effects (EPSE) of antipsychotic medication are related to the occupancy of dopamine D2 receptors and there appears to be a threshold of D2 occupancy below which clinically EPSE are unlikely to occur. It is unclear whether there are motor changes produced by 'subthreshold' levels of D2 occupancy that are not detectable by clinical examination. This study was designed to investigate whether a number of electromechanical instrumental techniques could detect 'subthreshold' motor changes and whether these changes correlate with dopamine D2 occupancy as measured by [11C]-raclopride PET scan. Twenty medication naive patients were studied before and during treatment with low dose haloperidol. Instrumental techniques detected an asymmetrical worsening in motor function with drug treatment despite the failure of the group to experience significant EPSE. These changes did not correlate with D2 occupancy and measurements of rigidity, tremor, and bradykinesia did not closely inter-correlate. Copyright (C) 2000 American College of Neuropsychopharmacology.

Original languageEnglish
Pages (from-to)19-26
Number of pages8
Issue number1
Publication statusPublished - 1 Jan 2000
Externally publishedYes


  • Antipsychotic medication
  • D occupancy
  • Motor dysfunction
  • Parkinsonism
  • PET
  • Positron emisson tomography

Cite this