We propose to build on preliminary data evaluating non-dopaminergic/non-motor clinical biomarkers to more fully assess these markers at the threshold of Parkinson disease (PD).

Development of reliable biomarkers for both dopaminergic and non-dopaminergic manifestations of Parkinson disease (PD) and related disorders may dramatically accelerate research on PD etiology, pathophysiology, and therapeutics. Biomarkers are broadly defined as characteristics that are objectively measured and evaluated as indicators of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Specific biomarkers may be useful at the onset of neurodegeneration, the onset of disease, and/or to mark disease progression.

Two hundred patients who have undergone neurological evaluation by their general community neurologist and have a questionable diagnosis of PD will be recruited to participate in this study. Subjects will be referred by the neurologists to the Institute for Neurodegenerative Disorders (IND) in New Haven, CT.

All subjects will be clinically evaluated at IND by a two movement disorders experts. At the baseline visit all subjects will also undergo [123I]ß-CIT SPECT ANAM, voice acoustics, olfactory, Spiral and biochemical testing. Each movement disorders expert will make an initial clinical diagnosis at baseline and again within three months follow-up. At the three month visit one movement disorder expert will be provided the DAT imaging data and will review that data with the subjects and referral physician. The other movement disorders physician will remain blind to the imaging and all other biomarker data. The blinded movement disorders expert will provide a final clinical diagnosis at the 12 month follow-up visit, which will represent the 'gold standard' diagnosis in this study. Statistical analysis to determine the sensitivity and specificity of ANAM, voice acoustics, olfactory, Spiral and biochemical testing compared to [123I]ß-CIT SPECT, and the gold standard clinical diagnosis will be completed. All subjects with DAT deficit and 10% of those without DAT deficit will be asked to return for repeat evaluation at 24 months.

Inclusion Criteria:

• Older than 21
• Any parkinsonian symptoms
• Referral by community neurologist
• Parkinsonian symptoms for less than 2 years duration.
• Willingness to follow the study plan.

Exclusion Criteria:

• Pregnancy
• Significant medical disease including abnormalities on screening biochemical or hematological labs or abnormal electrocardiogram (ECG - tracing of the electrical activity of the heart)