Non-dopaminergic imaging biomarkers as tools for early PD - testing the Braak Hypothesis

Many recent studies have suggested that we need to expand research in Parkinson's disease to study symptoms other than the typical motor symptoms of tremor, slowness of movements, stiffness, and walking problems. Understanding non-motor symptoms (such as depression, memory loss, constipation, and sleep problems) is crucial because these symptoms are both very troubling and currently poorly treated. Even more importantly, research suggests that some of these symptoms occur as the earliest signs of PD and that it may be possible to recognize changes in the brain in early PD patients that may help us to understand what causes PD.

In this study we will examine PD patients at the threshold of symptoms using new brain imaging technologies. This imaging technology uses radioligands, very specific tags for brain chemicals known to be abnormal in PD, to measure early changes in brain chemistry and brain function. While many previous studies have utilized imaging techniques to study dopamine, the brain chemical responsible for the motor symptoms of PD, in this study we plan to evaluate norepinehrine and serotonin, two brain chemicals that may be responsible for the non-motor symptoms of PD. These new imaging tools may ultimately be useful in early diagnosis of PD and/or as research tools for understanding why patients develop some of the non-motor symptoms of PD. This approach hold great promise in improving our ability to identify PD early so that therapies can be initiated and monitored effectively.