Relationship Between Symptoms, Retinal Morphology, and the Nigrostriatal Dopamine System in Parkinson's Disease

Study Overview
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Brief Summary
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The purpose of this study is to examine if a correlation exists between findings from brain imaging studies of the status of the dopamine system in the brain using DaTscan and SPECT imaging, clinical symptoms of Parkinson's disease, and changes in the structure of the retina as detected by optical coherence tomography (OCT) in recently diagnosed and more advanced Parkinson's disease patients.

Official Title
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Relationship Between Symptom Severity, Retinal Morphology, and the Nigrostriatal Dopamine System in the Brain in Parkinson's Disease

Conditions
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Parkinson's Disease

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Willing and able to give informed consent. Between the ages of 50-80 years old. Male or female with idiopathic PD who fulfill UK PD Society brain bank criteria for diagnosis of Parkinson's disease. Early stage subjects will need to have Unified Parkinson's Disease Rating Scale (UPDRS) motor scores of < 10, be within 3 years of diagnosis, and not requiring dopaminergic therapy Later stage subjects will need to have Unified Parkinson's Disease Rating Scale motor scores of > 20 and be > 5 years from diagnosis If female, one of the following three scenarios must apply: at least two years post-menopausal surgically sterile negative urine pregnancy test, and following a reliable method of birth control (oral contraceptive, intrauterine device, contraceptive implant, barrier, or abstinence) for at least two months prior to entry, and agreeing both to follow a reliable method of birth control, and (if relevant) to desist from breast feeding during, and for two weeks following tracer administration. Exclusion Criteria: Abrupt onset of Parkinsonism 'Other Parkinson-like syndromes (e.g. progressive supranuclear palsy, multiple system atrophy) Any condition that would preclude successful completion of SPECT scanning Use of anti-coagulant therapy Any clinically significant eye disease that would complicate interpretation of OCT data Use of any drugs that would alter or interfere with tracer binding for SPECT imaging studies (ex., cocaine, amphetamines, methylphenidate, ephedrine, phentermine, bupropion, fentanyl, selective serotonin reuptake inhibitors). Known sensitivity to the imaging agent or to Lugol's solution or to potassium perchlorate. History or presence of severe renal disease.

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Early Parkinson's disease patients<br>All subjects will undergo a complete neuro-ophthalmological examination, including assessment of best-corrected visual acuity, ocular motility, pupillary reflexes, slit-lamp biomicroscopy, intraocular pressure (IOP) measurement, and dilated fundus examination, followed by an optical coherence tomography study. Subjects will also have a DaTscan for striatal dopamine transporter visualization using single photon emission computed tomography (SPECT) brain imaging. A clinical examination will also be performed in order to document motor and cognitive functioning. | |
| Advanced Parkinson's disease patients<br>All subjects will undergo a complete neuro-ophthalmological examination, including assessment of best-corrected visual acuity, ocular motility, pupillary reflexes, slit-lamp biomicroscopy, intraocular pressure (IOP) measurement, and dilated fundus examination, followed by an optical coherence tomography study. Subjects will also have a DaTscan for striatal dopamine transporter visualization using single photon emission computed tomography (SPECT) brain imaging. A clinical examination will also be performed in order to document motor and cognitive functioning. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| OCT results | OCT measures including measurements of the thickness (microns) of specific retinal layers including RNFL, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, photoreceptors, and retinal pigment epithelium. | 1 day | 
| DaTscan results | Striatal binding ratios will be calculated for striatal regions of interest. | 1 day | 
| Clinical examination results | UPDRS motor score | 1 day |