Objective: To evaluate [18]FDG-PET single-subject perfusion patterns in Parkinson’s disease (PD) patients and their relationship with cognitive dysfunction and progression during five years of follow-up.

Background: Cognitive dysfunction is common in PD patients and variably progress during the disease course. Recently, an optimized statistical parametric mapping (SPM) standardized procedure (Perani et al. 2014) defined the specific FDG-PET hypometabolism pattern of Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), corticobasal syndrome (CBS) and frontotemporal dementia (FTD). Single subject FDG-PET pattern have never been evaluated in large series of PD patients with and without cognitive dysfunction.

Methods: Consecutive non demented PD patients underwent FDG-PET imaging and an extensive motor and cognitive assessment. The single subject PET pattern was evaluated blind to clinical diagnosis using a standard optimized SPM procedure (Perani et al. 2014). All patients underwent a five-years clinical follow-up in order to re-evaluate the final clinical diagnosis and progression.

Results: Fifty-four PD patients with normal cognition (n=37) and mild cognitive impairment (PD-MCI, n=17) entered the study. Blind FDG-PET classification allowed the identification of atypical brain metabolic patterns in 25 PD subjects (46%) who presented more often (p=0.04) MCI (n=12) compared with subjects with typical PD pattern (n=5). The study recognized specific DLB-like (n=12), AD-like (n=6) CBS-like (n=5), FTD-like (n=2) metabolic patterns, that often reflected specific cognitive impairment at a single-subject level. More patients with atypical FDG patterns (15 out of 25) progressed to cognitive impairment or dementia during clinical follow-up compared with subjects with the typical FDG PD-pattern (2 out of 29, p=0.001). However, they did not develop any specific clinical feature leading to a diagnosis of atypical parkinsonisms during 5 years follow-up.

Conclusions: Cognitive dysfunction in PD is heterogeneous and often associated with “atypical” single-subject FDG-PET pattern that also reflects deficits in specific cognitive domains. This FDG PET technique might identify PD patients with higher risk of progression to dementia.

Bibliography: Perani D, Della Rosa PA, Cerami C et al. Validation of an optimized SPM procedure for FDG-PET in dementia diagnosis in a clinical setting. Neuroimage Clin. 2014 Oct 24;6:445-54.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/single-subject-fdg-pet-patterns-and-cognitive-dysfunctions-in-parkinsons-disease/