The investigators propose using DaTscan in patients with REM sleep behavior disorder (RBD), mild cognitive impairment (MCI), Parkinson's disease (PD), dementia with Lewy bodies (DLB), Alzheimer's disease (AD), and other neurodegenerative syndromes and disorders, to test several hypotheses - some confirmatory, and some novel. Such use will provide new data on the potential clinical and research utility of DaTscan in neurodegenerative diseases. The findings on DaTscan will be correlated with clinical diagnoses and other multimodal imaging studies (e.g., MRI, MRS, FDG-PET, and amyloid-PET) to enhance our understanding of neurodegenerative diseases.

Lewy body disease (LBD) is one of the most common neurodegenerative diseases and second only to Alzheimer's disease in terms of prevalence, disability, and societal/financial burden. The phenotypic variability of LBD is striking, as it can manifest as the well-known disorder of Parkinson's disease without (PD) and with dementia (PDD), as well as DLB, MCI, REM sleep behavior disorder (RBD), pure autonomic failure (PAF), and other syndromes.

One biomarker which is both highly sensitive and specific for evolving LBD in the setting of dementia is DaTscan [Ioflupane (123I)] imaging, in which loss of functional dopaminergic neuron terminals in the striatum as assessed by DaTscan reflects underlying LBD in those with dementia and particularly dementia with Lewy bodies (DLB). DaTscan is the one of the first radiopharmaceutical agents available to detect DaT distribution within the brain. DaTscan imaging involves injection of the Ioflupane radioligand followed by imaging using a standard single photon emission computed tomography (SPECT) scanner. DaTscan provides visualization of the dopamine transporter (DaT) distribution within the striata (i.e., striatal uptake, or striatal signal) by SPECT imaging in patients presenting with symptoms or signs suggestive of dopaminergic neurodegeneration.

Most DaTscan studies published to date have been conducted in centers outside of the US. DaTscan has not been studied in the syndrome of MCI, and minimally in corticobasal degeneration (CBD). Very little normative data exists in the aged population either.

The FDA-approved indication is to assist in the evaluation of adult patients with suspected Parkinsonian syndromes (PS). In these patients, DaTscan may be used to help differentiate essential tremor from tremor due to Parkinsonian syndromes (such as idiopathic Parkinson's disease, multiple system atrophy and progressive supranuclear palsy). DaTscan will be used as an adjunct to other diagnostic evaluations. Identifying dopaminergic dysfunction is also important in other settings such as those with cognitive impairment with or without parkinsonism, and in subjects with REM sleep behavior disorder. The findings on DaTscan in subjects with these various disorders will be correlated with clinical diagnoses and other multimodal imaging studies (e.g., MRI, MRS, FDG-PET, and amyloid-PET) to enhance our understanding of neurodegenerative diseases. A subset of subjects will undergo a 2nd DaTscan at least 1 year after the initial scan was performed to determine if changes over time provide any prognostic information.

Inclusion Criteria:

• Diagnosis of one of the syndromes of interest using established criteria
• Age 40-90 inclusive
• MMSE score above 10
• No active medical disorder that could preclude participation
• Stable medication regimen over previous four weeks
• Absence of certain medications that could significantly impact the DaTscan findings
• For those with dementia, caregiver that is with the patient at least 4 hours/day for at least 5 days per week
• For those with dementia, or severe parkinsonism, patient and caregiver willing and able to participate in all study-related procedures
• Patient is capable of giving informed consent, or if appropriate, has caregiver capable of giving consent on the subject's behalf.

Exclusion Criteria:

• Does not fulfill criteria for any of the desired diagnoses

• Age <40 or >90

• Women with intact uterus and not post-menopausal unless pregnancy test performed at screening is negative

• Women who are pregnant or are breast-feeding an infant

• MMSE score <10

• Active medical disorder that could preclude participation in this protocol

  • Hypersensitivity to the radioligand, cocaine, or iodine (including seafood allergy)
  • Myocardial infarction or cerebral infarct over preceding year, stable or unstable angina, known symptomatic coronary artery disease
  • Renal or liver disease viewed by the physician to be too severe to warrant DaTscan infusion/imaging
  • History of significant alcohol or drug abuse
  • Any other medical disorder considered by the study physicians as inappropriate for this protocol

• Patient or caregiver unwilling or unable to participate in all study-related procedures

• Caregiver is not with a patient with dementia or severe parkinsonism at least 4 hours/day for at least 5 days/week

• Patient or caregiver unwilling or unable to provide informed consent