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 of the critical brain areas have degenerated. It is important that better ways be found to detect early PD. Years before tremors begin, changes occur in the sense of smell (olfaction), in brain structure and in sleep patterns. By themselves, these changes are not enough to reveal that PD is developing. We suggest that the combination of smell testing with assessments of sleep behaviour along with a sensitive magnetic resonance imaging called diffusion tensor imaging (DTI) will allow us to detect PD years earlier. 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. For the proposed study, we wish to follow up our earlier findings of poor sense of smell and changes in DTI measures to include a battery of brain function tests (cognitive) and an assessment of sleep patterns our PD patients and our healthy control group and in a group of patients with early Alzheimers disease. Finally, the large part of our proposed study is to see if we can detect PD in people at risk for PD, but do not yet have PD. We will screen, using a scratch-and-sniff smell identification test, a large population (1,200 subjects) of healthy, siblings of PD patients. The 10% lowest- and 10% highest-scoring subjects will be assessed for sleep disorders, have cognitive tests administered and scanned using DTI. We will follow all studied individuals for 5 years. Our study will examine whether the combination of tests for olfaction, cognitive function, sleep disorders and brain structure will allow for effective detection of early stage Parkinson's disease.