Reply to 'Impulse control disorders are associated with lower ventral striatum dopamine D3 receptor availability in Parkinson's disease: A [11C]-PHNO PET study.'.

Pagano and collaborators have recently reported lower ventral striatum D3 receptor availability in Parkinson's disease using PET scan. Our group conducted the first postmortem study of individuals with PD who had ICD and related behaviours in life and reported lower alpha-synuclein pathology and D3R levels in the nucleus accumbens of such individuals. The findings by Pagano and co-authors of low D3R binding in PD patients at baseline, when taken together with our findings of lower Lewy pathology and D3R in the nucleus accumbens, favour the hypothesis that D3R levels are downregulated because of excessive synaptic dopamine.