Progression of dopaminergic dysfunction in a LRRK2 kindred: A multitracer PET study

Objective: Little is known about the progression of dopaminergic dysfunction in LRRK2associated Parkinson disease (PD). We sought to characterize the neurochemical progression with multitracer PET in asymptomatic members of parkinsonian kindred (family D, Western Nebraska) carrying LRRK2 (R1441C) mutation. Method: Thirteen family D subjects underwent PET scans of presynaptic dopaminergic integrity and five subjects were rescanned 2 to 3 years later. Results: In subjects 8, 9 (mutation carriers), and 13 (genealogically at risk subject), there was a decline in PET markers over the course of the study that was significantly greater than the expected rate of decline in healthy controls. Reduced dopamine transporter binding was the earliest indication of subclinical dopaminergic dysfunction and progression to clinical disease was generally associated with the emergence of abnormal fluorodopa uptake. Conclusion: PET study of presymptomatic members of our LRRK2 kindred revealed dopaminergic dysfunction that progressed over time. This represents an ideal group to study the natural history of early disease and the potential effects of neuroprotective interventions.