Hi Jean , I understand the reasoning for determining pre disease markers--given there are no neuroprotective products out there, except maybe Azilect which seems to be questioned all the time, I think as Paula noted this could be determined in a much easier, efficient way--have neurologists', MDS' staff, sniff test all their PD patients, and add info to a central data base. The imaging testing utilizing scans such as PET Beta Cit, etc all involve isotopes; many are difficult to obtain and store and who knows how long they stay around in one's body....It is not news that loss of smell precedes other Parkinson's symoptoms in patients. I have heard this observation since early 1980's (maybe 70's)at least, maybe before. seems the olfactory structures are the first to be affected by Lewy bodies and in addition, the olfactory bulb is dependent upon neurogenesis......there have been prospective studies of PD populations which concluded that "Yes, PD patients suffer olfactory loss prior to onset of PD symptoms" from 5 to 7 yrs period. How many more times must there be prospective studies to determine this? madelyn