Decrease in Sense of Smell and Associated Cognitive Decline in Parkinson's Disease

Exclusion Criteria

• •other disorders which may resemble PD
• •subjects with definite dementia
• •subjects with unstable or severe medical disorders
• •subjects receiving neuroleptic, anticholinergic, or cholinesterase inhibitor drugs
• •subjects in whom MRI imaging is contraindicated
• •subjects who have received ionizing radiation that would, together with the current project exposures, exceed exposure limits permissible to research volunteers
• •pregnant