Good, Kimberley PRobertson, Harold A
Nova Scotia Health Authority (Halifax)
Early and preclinical diagnosis of Parkinson's disease using olfactory testing and Diffusion Tensor Imaging of olfactory bulb and substantia nigra.
Clinical Parkinson’s disease (PD) can only be diagnosed when most dopamine neurons are damaged or have already died. It is important that better ways be found to detect early PD. Years before PD motor symptoms are present, changes occur in olfaction and sleep. By themselves, these changes are not enough to reveal that PD is developing. We suggest that the combination of smell testing with tests of sleep behavior and with a sensitive magnetic resonance imaging technique called diffusion tensor imaging (DTI) will together allow us to detect PD years before motor symptoms appear. There are new treatments that might be able to stop PD at this very early stage, before lasting damage is done or motor changes are seen. Our study is divided into 2 phases. In Phase I (partly supported by Parkinson Society Canada) we studied 14 newly diagnosed PD patients and compared them to 14 healthy control subjects. In agreement with many studies, the sense of smell was impaired in the PD patients. Diffusion tensor imaging revealed a significant decrease in a measure of water diffusion in olfactory tract and bulb, extending earlier findings. Changes were also found in the substantia nigra of PD patients. Phase Ib of our proposed study is to look at cognition first in our PD patients then in a population of patients with cognitive impairment. Finally, the large part of our proposed study (Phase II) is to see if we can detect PD in people at risk for PD but who do not yet have PD. We will scan using a smell identification test a large population (1,200 subjects) of neurologically normal subjects (age-matched siblings of PD patients). Subjects with the lowest 10% and highest 10% in smell testing will be assessed for sleep disorders and scanned using DTI. Subjects with sleep disorders will have a high risk for PD. Our study will determine whether the combination of tests for olfaction, sleep disorders and DTI will allow effective detection of early stage PD.