IMAGING ENDOGENOUS DOPAMINE COMPETITION WITH [C-11] RACLOPRIDE IN THE HUMAN BRAIN

This study images dopamine release in response to a neurochemically specific challenge with the psychostimulant drug methylphenidate. Changes in synaptic dopamine induced by methylphenidate were evaluated with positron emission tomography and [C-11]raclopride, a D2 receptor radioligand that is sensitive to endogenous dopamine. Methylphenidate significantly decreased striatal [C-11]raclopride binding. The decrease was variable and was negatively correlated with age. Mood and anxiety at baseline, were also correlated with methylphenidate-induced DA changes. This strategy provides a tool to investigate the responsiveness of the dopamine system in the normal and diseased human brain and to investigate the neurochemical correlates of behavior. (C) 1994 Wiley-Liss, Inc.