Imaging studies as biomarkers of Parkinsons disease

摘要

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease, affecting over 1 million people in the USA. PD is also the most common cause of parkinsonism, a clinical syndrome with a constellation of symptoms including bra-dykinesia, rigidity and resting tremor. The diagnosis of PD is based on a set of clinical criteria that focus on the motor signs of the disease. However, diagnostic accuracy is only 90% even in the hands of movement disorders experts. PD diagnosis is more prone to error early in the clinical course of the disease, even though the pathologic process leading to PD probably begins a decade or more before clinical signs are apparent. By the time patients are diagnosed, approximately 70-80% of striatal dopamine and over 50% of substantia nigra (SN) neurons have already been lost. Likewise, monitoring PD progression and medication responses is also subject to error as it primarily relies on relatively coarse and somewhat subjective measures of motor performance.