Extrastriatal dopamine D-2 receptors in Parkinson's disease: a longitudinal study

: Kaasinen V, Aalto S, Nagren K, Hietala J, Sonninen P, Rinne JO

Publisher: SPRINGER-VERLAG WIEN

: 2003

: Journal of Neural Transmission

: JOURNAL OF NEURAL TRANSMISSION

: J NEURAL TRANSM

: 110

: 6

: 591

: 601

: 11

: 0300-9564

DOI: https://doi.org/10.1007/s00702-003-0816-x

Most antiparkinsonian drugs are known to act through central dopamine D-2 receptor agonism. A previous longitudinal positron emission tomography (PET) study has indicated that, in the striatum of Parkinson's disease (PD) patients, dopamine D-2 receptor binding declines at a relatively fast annual rate of 2-4% (compared to the rate of < 1%/year in healthy individuals). In the present study, the examination of longitudinal changes in D-2 receptors was extended to extrastriatal brain regions in PD. Eight early PD patients were examined twice with PET, similar to3 years apart, using a high-affinity extrastriatal D-2/D-3 receptor tracer, [C-11]FLB 457. Both the MRI-referenced region-of-interest method and the voxel-based statistical analysis method were used independently in the analysis. Regional D-2-like availabilities (binding potentials) in the left dorsolateral prefrontal cortex, the left temporal cortex and the left and right medial thalami were significantly decreased at the second examination by 20-37% (corresponding to an annual decline of 6-11%). Thus, the annual loss of extrastriatal D-2 availability in PD is up to three times faster than the rate previously reported in the putamen. Our longitudinal study shows first evidence concerning cortical D-2 receptor loss in the progression of PD, although it is not possible to distinguish between the effects of the therapy and the disease.