Objective: The current study investigated the differences of dopaminergic and metabolic patterns between the young-onset subtype of Parkinson’s disease (YOPD) and the late-onset subtype (LOPD) by 11C-CFT and 18F-FDG positron emission tomography (PET) imaging, and explored whether the cerebral regions involved correlated with the clinical features in corresponding PD subtype.

Background: The YOPD and LOPD may differ from the drug responsiveness, non-motor manifestations, motor complications.The pathophysiology underlying these differences remains to be elucidated.

Methods: 103 PD subjects underwent cerebral PET with both 11C-CFT and 18F-FDG were recruited in this study. Two sub-regional parameters (caudate/putamen ratio and asymmetry index) were calculated to measure the spatial pattern of striatal dopaminergic dysfunction. Expression value for the PD motor-related metabolic pattern (PDRP) was computed for each subject. The differences of dopaminergic and metabolic patterns between the two subtypes were then analyzed. The average tracer uptakes in the cerebral regions we found were correlated with the clinical characteristics of different PD subtype.

Results: We recruited 42 YOPD and 61 LOPD with 11C-CFT and 18F-FDG PET imaging in the current study. The caudate/anterior putamen ratios (r=-0.507, P<0.001) and caudate/posterior putamen(r=-0.243, P=0.018) ratios were significantly higher in YOPD. When controlling for age of participants, significantly inverse correlations between age of onset and caudate/putamen ratios only exist in the ipsilateral side to the most affected side of the body (r =-0.377, P < 0.001 for caudate/anterior putamen ratios and r=-0.306, P < 0.001 for caudate/posterior putamen ratios). In the 18F-FDG PET, YOPD patients exhibited hypermetabolism in the caudate, medial frontal gyrus, superior temporal gyrus and superior parietal lobule; and hypometabolism in cerebellum, putamen and occipital gyrus, even though the PDRP values between the two subgroups were similar. Furthermore, caudate and putamen FDG uptake values correlated with the dopaminergic patterns indicated by DAT bindings. These differences may be explained by some clinical characteristics of the onset-related PD subtypes of PD.

Conclusions: Comparing with the LOPD patients, the YOPD subtype exhibits a more sparing caudate to putamen in both 11C-CFT and 18F-FDG PET imaging.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dopaminergic-and-metabolic-network-activities-in-onset-related-subtypes-of-parkinsons-disease-a-dual-tracer-positron-emission-tomography-study/