Examining endogenous dopamine in treated XXXX using [(11)C]-(+)-PHNO positron emission tomography: A pilot study.

@entity1 @entity161
BACKGROUND: Using positron emission tomography (PET) it is possible to estimate endogenous dopamine (DA) occupying D2/3 receptors (D2/3R) in the living @entity1 brain. @entity1 with @entity161 ( @entity161 ) (previously medicated and na  ve) have increased endogenous DA occupying D2/3R in the caudate. It is unknown whether currently medicated @entity1 demonstrate increased DA levels at D2/3R. Moreover, DA levels have not been estimated in @entity161 using agonist radiotracers, which may offer a more sensitive quantification over antagonists. METHODS: Using the agonist radiotracer [(11)C]-(+)-PHNO, DA levels were estimated at D2/3R (  BPND) in three @entity1 with @entity161 (male, mean age=30  16). @entity1 were currently being treated long-term with Olanzapine (147  88nmol/L). Results were compared to ten healthy controls (HCs). RESULTS: Medicated @entity1 with @entity161 had greater   BPND in the left caudate (U=2, Z=-2.20, p=.03) and right putamen (U=2, Z=-2.20, p=.03). No differences were observed in the ventral striatum or globus pallidus. CONCLUSIONS: It is possible to estimate endogenous DA at D2/3R in @entity161 @entity1 currently taking antipsychotics. Despite medication, @entity1 continue to have increased endogenous DA at D2/3R. This lends more biological support to the clinical observation that relapses in symptoms can occur in the face of complete antipsychotic discontinuation. Future studies with larger samples are warranted.
