Staging of serotonergic dysfunction in Parkinson's Disease: An in vivo11C-DASB PET study

Thirty Parkinson's disease (PD) patients were divided into three equal groups according to their disease duration while 10 normal healthy volunteers matched for age and sex served as a control group. Striatal and extrastriatal serotonergic function was studied with 11C-DASB PET, a marker of serotonin transporter availability. 11C-DASB binding was correlated with disease disability and exposure to dopaminergic therapy. We found significant 11C-DASB binding reductions in striatal, brainstem, and cortical regions in PD but no correlations were evident between 11C-DASB binding and UPDRS scores, Hoehn &Yahr staging, disease duration and level of exposure to dopaminergic therapy. Our results suggest that progressive non-linear serotonergic dysfunction occurs in PD but it does not determine levels of disability. Additionally, chronic exposure to dopaminergic therapy does not appear to influence SERT binding.