What research participation involves
In this page you will find answers to some frequently asked questions about clinical research and what might you expect from research participation
Please note that the information given here describes general rules and common practices in clinical research. Individual research studies will have their own unique design, set-up and procedures. Before you decide whether or not to join any research project you should discuss the specifics of that study with the members of research team.
Have we missed anything? If there is any additional information you think is missing from this page please let us know at: movementdisorders@ucl.ac.uk
FAQ for clinical research participation
What is the meaning of the different phases of clinical trials?
What does it mean that a clinical trial is “blind” or “double-blind"?
Will I be able to get access to new study drugs after the end of the clinical trial?
Will I have to stop taking my usual medication if I participate in a clinical trial?
Can I participate in more than one clinical trial or clinical study?
How do I get invited to participate in clinical research? What is the consent process?
What will clinical research participation require from me? What will happen during the trial?
What are the different types of clinical research? What is the difference between a clinical trial and a study?
There are two general categories of clinical research: clinical trials and clinical studies.
Clinical trials are sometimes also called interventional trials, drug-trials or treatment-trials. Clinical trials of this kind will involve the testing of some type of intervention (be it a new drug, surgery, therapy or any other treatment) that would not otherwise be part of routine and standard care program for the participants. The goal of clinical trials is to understand the benefits and harm of a new treatment and to measure if it is more effective than standard treatment. Clinical trials are often staged in “phases”, depending on the extent and type of tests the investigational drug or treatment have already completed (see: What is the meaning of the different phases of clinical trials?)
Observational clinical trials are sometimes also called non-drug trials or simply clinical research studies. These studies do not involve any type of intervention delivered by researchers which is designed to affect their physical or mental health. The aim of these studies is to observe a group of people to understand more about their biology, behaviour, health or experience of events. This can involve gathering of information from questionnaires, cognitive tests and biological samples.
What is the meaning of the different phases of clinical trials?
The different “stages” of clinical trials are a general indication to the level of investigation the study drug or treatment have already completed and to the general goals of the trial. As a general rule, all new drugs and treatments are required to successfully complete each trial phase in sequence before moving on to the next phase of testing and finally apply for general regulatory approval.
Phase 1 (I): A phase 1 trial is usually the first investigation of a new drug or treatment in people. Phase 1 trials are performed after the new treatment has shown therapeutic potential in laboratory experiments, often after its safety was tested and verified in laboratory animals. Phase 1 are usually small trials that recruit a small number of people to find out:
The side effects of the new potential treatment.
How the body reacts to the new treatment.
What dose of the drug or frequency of intervention is safe.
Phase I trials usually do not directly estimate the effectiveness of the drug in treating the medical condition (e.g., Parkinson’s or other movement disorders) but they may collect anecdotal evidence for treatment efficacy.
Phase 1 trials often test the new drugs/treatments first on healthy volunteers (phase 1a) before moving on to tests in small groups of patients (phase 1b). Phase 1 trials are often not placebo-controlled and may include treatment with different and potentially varying doses of a study drug.
Phase 2 (II): At this phase, the drug is tested in a larger group of people (usually less than 100) with the relevant condition to understand more about the safety, side effects and potentially the therapeutic effect of the new drug or treatment. Volunteers are randomised into either the treatment group or the standard treatment. If the results show that the new treatment is as effective (or better) than the standard treatment then it moves into phase 3.
Phase 3 (III): This phase tests the drug in a much larger group of people (usually over 100 up to thousands) with the relevant condition. Phase 3 studies are usually placebo-controlled so that some participants receive the new treatment while others receive a dummy treatment (see What is a “placebo-controlled” trial?).
Phase 4 (IV): Phase 4 trials are usually done after the drug has been approved by the drug regulatory authorities and received its license. Trials are run at this stage to understand more about how the drug works, its cost effectiveness, long-term effects and to gather information about effectiveness in a wider population.
What is the research registry?
The UCK MDC research registry is a database of people who have expressed an interest in movement disorders research, and it is managed by the UCL Movement Disorders Centre. By signing up to the registry you are giving us your permission to review your medical records and contact you to tell about research opportunities which are potentially suitable for you.
More information on the research registry and how to register can be found at our research registries webpage. If you are treated at University College London Hospital (UCLH) or the Royal Free Hospital you can also ask your hospital consultant or specialist nurse for more information.
What is a “placebo-controlled” trial?
There are many factors that could influence a person’s medical condition and cause disease symptoms to wax and wane over time. The goal of a clinical trial is to identify whether a new drug or treatment have a unique, direct and reliable effect on symptoms, regardless of any other factors that might influence disease course in a specific individual. This is why clinical trials compare clinical outcomes between groups of people who have taken the study drug and people who did not take the new treatment. Both groups might be influenced by many unknown factors but if the treated group shows a clear and consistent improvement in symptoms we can be fairly certain that this improvement is the result of the investigational treatment.
Clinical trials today use “placebo” treatments for the untreated study group. A placebo or “dummy treatment” is set to look like the active treatment but without actually including the active component. So, for example, in drug trials, participants in the placebo group might take drug tablets that look just like the treatment drug but do not actually contain any active ingredient (in the past these were sometimes called “sugar tablets”).
The important thing to note is that if you are joining a placebo controlled clinical trial you have no way of knowing whether or not you will be receiving the investigational treatment. This means you will undergo all the tests and procedures the trial requires but may not gain any of the potential benefits the study drug entails. Both researchers and study participants have no way of knowing or deciding which participant will be assigned to which treatment group (see What does it mean that a trial is “randomized”?). Some placebo-controlled trials offer all participants the opportunity to take the active treatment, either through a crossover design or an open label extension (see respective links for more information).
You should discuss the trial’s design and potential post-trial access to investigational treatment with the research team before you decide whether to join a trial.
What does it mean that a clinical trial is “randomized"?
Randomization is the process through which research participants are allocated to either the active treatment or the placebo (dummy treatment) research group. Study participants are randomly assigned to either group, usually by a computer program. The computer-guided randomization tries to ensure a level of similarity between the active treatment and placebo groups. For example, randomization may try to ensure that both groups have the same number of male and female participants, that participants in both groups are of similar ages, have a similar disease history, etc. Most importantly, the researchers themselves do not control in any way the randomization/group allocation process and have no way of knowing or deciding which participant will be assigned to which group.
What does it mean that a clinical trial is “blind” or “double-blind"?
“Blinding” refers to the lack of knowledge about which research participant belongs to the active treatment or the placebo group. In "single blind" trials, the researchers know the treatment the participants will receive but the participants do not know if they are taking the active treatment or placebo. In a "double blind" trial, both researchers and participants do not know what treatment is allocated until the end of trial.
Every “blinded” clinical trial will have well-defined procedures in place that allow revealing whether a particular participant is taking active treatment or placebo (this is called un-blinding) in case of an emergency.
What is an “open label” clinical trial?
An open label trial is a type of clinical trial in which both the researchers and participants know which treatment is being administered. Open labels trials might be early phase trials, trials which compare two different types of treatment or even randomized placebo-controlled trials. The main point is that you as the participant would know what treatment you are receiving (and so will the researchers).
What is a “crossover” study design?
A crossover study design is a trial in which all participants get access to the investigational treatment, but they might do so at different time points. In a typical crossover study, participants start up in the active or placebo group for a period of time and subsequently switch (“cross-over”) to the other treatment group for an additional and comparable period of time. Usually participants will not know when they are receiving the active or placebo treatment, although they typically do know at what time the treatment was switch. A crossover design allows researcher to directly compare clinical outcomes in the same participants with and without the investigational treatment.
What is an open label extension?
Some clinical trials offer trial participants to enroll into an open label extension after the completion of the formal part of the study. In an open label extension, trial participants are given the opportunity to continue taking the investigational treatment after the trial finished (or to start taking it, if they were on the placebo group during the trial). The extension is completely voluntary and participants can stop taking the investigational drug at any time or not join the extension at all.
You should discuss the trial’s design and potential post-trial access to investigational treatment with the research team before you decide whether or not to join a trial.
Will I be able to get access to new study drugs after the end of the clinical trial?
By definition, treatments offered as part of clinical trials have not been formally approved and are therefore not available for general use once a trial has finished. This is particularly relevant for treatments undergoing early stage testing (phase 1 and 2 trials), which, even if successful, can take many years to achieve final regulatory and marketing approval. Some trials (usually phase 3 studies, but not exclusively) might offer post-trial access to the investigational drug or treatment – see What is an open label extension?.
It might be a frustrating experience to be denied access to potential treatment, especially if you have taken part in a trial and felt an improvement in your condition. If you feel this might be a concern you should discuss this with the research team before making a decision about research participation.
Will I have to stop taking my usual medication if I participate in a clinical trial?
Generally speaking, clinical research studies and trials for Parkinson’s and other movement disorders will not require that you stop or change your normal medication. However, it is crucial that the research team is made fully aware of all medications and food supplements you are taking or have taken in the months preceding the trial or study. This is to ensure your health and safety during the research. In some clinical trials any changes to your medication during the trial’s treatment period might actually be used as an indication to the efficacy of the investigational treatment.
Please note that some investigational procedures (for example, certain types of neurosurgery or certain neuroimaging techniques) will require that you temporarily stop or change some of the medications you might be taking. You should have a detailed and open discussion with the research team about all procedures involved in the research and how they might interact with your current clinical care and medications before you decide whether or not to join a trial or study.
Can I participate in more than one clinical trial or clinical study?
Generally yes, with "observational" studies being more flexible than interventional trials, but it depends on the specific requirements and eligibility criteria of each individual research project.
Many clinical trials require that participants not have taken any other investigational treatment within a particular time frame prior to enrolment into the new trial (this time period will be different for different trials). However, typically there is no explicit restriction on participation in a clinical trial after or during participation in any “observational” clinical study (i.e., studies that did not involve any investigational drug or treatment). You should let the trial's research team know about all research studies you are participating in, especially studies which included medical tests or procedures, to ensure your helth and safety throughout.
Enrolment into any observational clinical study should not preclude you from joining a clinical trial. However, if you are enrolled in a study which includes repeated assessments over time (follow-up study) researchers would greatly appreciate it if you notify them on any trial participation, as these may influence measurements collected for the study.
There is absolutely no restrictions on the number of research studies (observational studies) you can take part in. However, upon enrolment into a new study it is good to let researchers know of any studies you previously participated in. Some studies have a legal right to share information (with your consent) and can thus avoid performing superfluous procedures and collecting the same information multiple times.
How do I get invited to participate in clinical research? What is the consent process?
There are many ways in which you could find clinical studies and trials which are potentially suitable for you. There are a few local and national research registries which you can register for, thus giving your permission for researchers to review your medical information and contact you to invite you to participate in studies and trials which might be suitable for you. Some charities operate research networks through which they share information about clinical research opportunities (e.g., Parkinson’s UK research involvement webpage, Parkinson’s Movement research involvement webpage). Finally, your consultant and specialist nurse will be able to tell you about clinical research opportunities happening at your local hospital.
If you are invited to participate in research you will be approached by your clinician or a member of the research team. You will be given an information sheet with full details of what the study is about, what you will be asked to do and what we expect to find. You can take as much time as needed to read and decide if you would like to participate. There will be plenty of opportunities to ask questions and discuss the study with a member of the research team. At this stage the study team might also ask you for some information about your health, your condition and your medical history to ascertain your suitability for the trial/study.
If you decide to join the study the first thing you will be asked to do is to provide written informed consent. This will a form you will be asked to read and sign, thus confirming you understand that your participation is voluntary; you agree for the team to collect information about you and have access to your medical notes; all data collected will remain confidential and anonymous and you can withdraw from the study at any time. A member of the study team will be available to help you go through the information, answer any questions and complete the consent forms.
What will clinical research participation require from me? What will happen during the trial?
Research participation will invariably require you to spend some time completing study-related assessments and procedures. Most trials and studies will require visits to the hospital where the research is conducted, often beyond visits required for your regular clinical care. Some research studies may require one or more overnight stays at the hospital. Trials and studies often have to follow a relatively strict schedule of appointments, dictating at what time intervals visits need to take place. Some research studies use on-line web portals that allow you to complete some or all of the research tasks and assessments remotely from home. Before you enrol into a study it is vitally important that you make sure you know and understand how many research visits will be required, when (or at what time intervals) they will take place and how long each visit will last.
Researchers used a wide range of methods to collect different types of information about you and your health. Research might involve things like completing questionnaires, performing certain tasks, undergoing medical procedures and more. When you are invited to take part in research the research team will describe and explain all research-related procedures and will answer any of your questions. You can see our research methodology below to learn more about some of the common tools and procedures used in movement disorders clinical research.
How will my personal information be kept confidential and secured? Will the company who sponsors the clinical trial have access to my personal information?
Researchers will take every measure to ensure your personal information is kept confidential and secure at all times. If you join a clinical trial the company sponsoring the trial will not know your identity or have access to your personal identifiable information.
It is common practice in clinical research to assign every study participant with a unique code used in all study documentation. All research related-information thus relies on codes, leaving your personal identity confidential (this process is called “anonymisation”). Written records linking participants’ study codes with personal identifiable information (i.e., participants' names, addresses, NHS numbers, etc.) are stored securely in locked filing cabinets at the local clinical site. Any personal information kept on computerized databases is protected using the highest standards (using certified and secured computer storage and access tools). Your name and contact details will be known to the local research and clinical teams so that they can monitor your health and arrange research-related visits and procedure.
Will clinical research participation affect my medical care? What if I have a medical emergency while taking part in a clinical trial or study?
Your decision on whether or not to participate in research will have absolutely no effect on your current or future medical care.
If you decide to take part in research then typically the study team will inform your general practitioner (GP) and your main hospital clinician about your involvement. Your GP and hospital consultant will not routinely receive information or results of tests performed during the study. However, in some cases they may be notified if any research tests uncover previously unknown health conditions that require medical attention. Policies for disclosure of medical information may vary between different research studies so you should discuss this with the research team before you make a decision about joining a trial or study.
If you join an interventional clinical trial you will be given an information card which you should carry with you at all times and use in cases of medical emergency. This card can be used to contact and notify the research team in case you start feeling unwell or have a medical emergency while taking an experimental medication. This is to ensure the research team are made aware of any problems in case they may be related to the investigational drug or treatment. If you feel unwell while taking part in a clinical trial and have to receive medical attention you should let the clinical care team know about your research involvement. This is to ensure the care team could give you the best medical care and can consult the research team if needed.
Will I be paid for my participation in clinical research? Will I be able to be reimbursed for expenses related to my research participation?
Pharmaceutical companies who perform clinical trials are strictly forbidden to offer any kind of payment for trial participants. However, most clinical trials and studies will offer reimbursement for travel expanses for any medical or hospital visits associated with the study. If the study requires an overnight stay at the hospital your food and board costs will be covered by the researchers. Expenses for an accompanying carer or family member might also be covered or reimbursed under some circumstances.
Trials and studies will often have restrictions on the type of expanses that are eligible for reimbursement, caps for maximal costs and requirements for documentation you need to provide to be reimbursed (e.g., train tickets, parking stubs, etc.). Before you join a trial or study you should discuss with the research team what, if any, costs will be reimbursed and what are the specifics of the reimbursement process.
Can I withdraw from a clinical trial? What if I want to discontinue a clinical trial or clinical study?
Every participant in a clinical trial or study has the right to withdraw at any time without providing any explanation. Furthermore, your decision to discontinue your research participation will have absolutely no effect on your current or future medical care.
Are there independent sources where I can seek general advice about taking part in clinical research?
Yes, there are many national and local organizations that could give you more information and opportunities to discuss research participation with professionals and other research participants. Here are a few example of such organizations:
National Institute of Health Research (NIHR) clinical research networks (www.crn.nihr.ac.uk).
INVOLVE (www.invo.org.uk).
Parkinson’s Movement (https://www.parkinsonsmovement.com/).
Parkinson’s UK research support network (www.parkinsons.org.uk/research/get-involved-research).
Methods dictionary
In this section you will find descriptions and explanations about some of the more common procedures used in movement disorders clinical research
The information provided in this page describes common practices and general rules regarding tests and procedures used in clinical research. If you are considering taking part in a research study or trial a member of the respective research team will provide you with detailed information about the specifics of the study and answer any questions.
Have we missed anything? If you would like to suggest additional research methods that should be covered in this page please write to us: movementdisorders@ucl.ac.uk
Biological samples (or Biosamples)
Biological samples might include blood, urine, stool, saliva, skin, cerebral-spinal fluid or even brain tissue which can be collected and used for clinical diagnosis and for research. Biological samples enable clinicians and researchers to perform an in-depth investigation of the collected tissue to get a better understanding of genetics, physiological changes and biological processes which might be related to disease. If needed for research purposes, biological samples will be collected by qualified and experienced personnel who will adhere to strict collection procedures to ensure the safety of research participant and the integrety of the collected samples.
Cognitive Tests
"Cognition" is a general term for a person's abilities to think, remember things, pay attention, solve problems, etc. Changes in things like memory, attention and other cognitive abilities can sometimes occur in people with Parkinson’s and other movement disorders. Doctors and researchers use standard methods to measure cognition using Neuropsychological tests, which can help identify changes or problems in cognitive abilities over time. Standard cognitive tests will typically require you to answer a series of simple questions and complete a few simple tasks, some in writing and some verbally. As part of these tests you may be asked to do things such as: name objects, memorize and repeat short texts or word lists, count or do other simple numerical tasks, draw simple objects, etc.
DAT Scan (Dopamine Active Transfer scan)
See single photon emission computed tomography imaging using DaT scan.
Deep Brain Stimulation (DBS)
Some people with Parkinson’s are suitable for surgery to help treat and manage their symptoms. DBS is a surgical procedure which involves implanting electrodes into your brain which are connected to a pulse generator. High frequency stimulation are generated and stimulate the target area of the brain. Current research studies aim to improve DBS techniques and its outcome in treating Parkinson’s.
Functional Magnetic Resonance Imaging (fMRI)
fMRI scans are widely used to explore not only the structure but the function of the brain. This method allows us to see what parts of the brain are most active during a specific activity, emotion or behaviour. The methods relies on measuring blood and oxygen levels in the brain to give indications of the levels of activity of different brain region. In movememt disorders research this method can be used to assess functional changes that may occur in the brain as a result of the disease.
The procedure: MRI and fMRI scanner are large cylindrical scanner that you are asked to lie in. You will be asked to remove all jewellery and metal items since these might react with the strong magnetic fields produced during a scan. You wouldn't feel anything during the scan, but you will be asked to lie still and the machine might make some loud noises. Some people who find it hard to be motionless for extended periods of time or people suffering from claustrophobia (feeling unconfortable in small spaces) might find the process uncomfortable. fMRI scans are usually longer than MRI scans, lasting 30-60 minutes or more. You might be asked to perform certain tasks during the scan to evaluate the changes in brain function that are specifically related to the task.
Lumbar puncture - CSF sample collection
A lumbar puncture collects a small amount of Cerebral Spinal Fluid (CSF) from the spine. CSF is a unique fluid found only in the central nervous system, i.e., in the brain and spinal cord. Substances found in CSF can be a direct indication to biological processes that happen in the brain and may be related to disease. CSF is often used to detect biomarkers, which are different biological substances that can be used as an indication of diagnosis, disease severity, disease stage and more. In clinical trials, CSF might be collected to check whether the drug being tested actually reaches the brain and interacts with its therapeutic targets. Some clinical trials use a lumbar puncture procedure in order to inject the study drug into the Cerebral Spinal Fluid. This route of administration is used to ensure that drugs have a better chance of reaching their therapeutic targets in the brain.
The lumbar puncture procedure might be performed in a sitting or lying position. Local anasthetics and special thin needles are used to minize pain during the injection. You will be monitored following the procedure but typically will be free to get up and move around within minutes or up to one hour following the procedure. A lumbar puncture is considered a generally safe procedure and most common side effects are headaches and/or some local swelling where the needle was inserted.
Magnetic Resonance Imaging (MRI) - structural and connectivity imaging
An MRI is a type of scan that uses strong magnetic fields to produce images of the inside of the body. An MRI can be used to scan any part of the body, but in movement disorders research it is usually used to visualize the structure of the brain. MRI can be used to indicate whether there is any change or abnormality to the structure of the brain, helping to visualize specific parts of the brain which may be affected. A reletively new type of MRI scan is called a "connectivity MRI", which can create images of the connections between different parts of the brain.
The procedure: An MRI machine is a large cylindrical scanner that you are asked to lie in. You will be asked to remove all jewellery and metal items since these might react with the strong magnetic fields produced during a scan. You wouldn't feel anything during the scan, but you will be asked to lie still and the machine might make some loud noises. Some people who find it hard to be motionless for extended periods of time or people suffering from claustrophobia (feeling unconfortable in small spaces) might find the process uncomfortable. Connectivity MRI scans are typically longer than the standard structural MRI, and can take up to one hour.
Movement Disorders Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS)
The MDS-UPDRS is a commonly used scale to measure motor symptoms and disease severity in Parkinson’s disease. There are four parts to this rating scale which assess: motor function, motor symptoms, non-motor symptoms and motor complications (including medication wearing off symptoms and dyskinesia). The scale is given in the form of a questionnaire, partly to be completed by the researcher (or doctor/nurse) making the assessment and partly to be completed by the patient. The questionnaire asks about your experiences of daily living and you will be asked to assess the severity and frequency of different problems you may experience. The MDS-UPDRS also includes an assessment of motor function, for which the examiner will ask you to perform a few simple motor tasks, such as moving your hands and legs in certain ways, tapping your fingers, rising from a chair, walking a short distance, etc. The full MDS-UPDRS scale will take about 20-40 min to complete.
Neuroimaging
Neuroimaging is a widely used method which allows us to see the effect of Parkinson’s disease and other Movement Disorders on the brain. There are different neuroimaging techniques we use to gather information on the structure and/or function of the brain. A few commonly used neuroimaging techniques include: MRI, fMRI, PET, SPECT
Neurological examination
A neurological examination is performed by a trained clinician and designed to assess you reflexes, sensory and motor function. This assessment gives a first indication of the function of the nervous system, without a more detailed investigation (e.g., neuroimaging). A neurological examination can help with the clinical diagnoses process and if often used in research to review the presentation of symptoms and to assess the severity of disease. A neurological examination will include a review of your medical history and current symptoms as well as a physical examination. The examiner will ask you to answer some questions about yourself and your past and current symptoms as well as some general questions evaluating your mental state. The examiner will check your reflexes and ask you to perform some simple tasks such as tracking on abject with your eyes, moving your hands and legs in certain ways, tapping your fingers, standing up and walking a short distance, etc.
Non-motor symptoms scale
People with Parkinson’s might experience a range of non-motor symptoms, such as sleep problems, dizziness and falls, feelings of depression or anxiety, hallucinations, constipation, urinary and sexual problems, problems with memory or attention and more. There are a number of ways to measure these symptoms but one of the most commonly used is the Non-Motor Symptoms Scale (NMSS). This is a questionnaire in which the examiner will take you through a list of about 30 non-motor symptoms to check whether you have experienced any of them. You will be asked to evaluae the severity of each symptom and how often you have been experiencing it.
Positron Emission Tomography (PET)
PET scan is very similar to a SPECT scan: both imaging technoques involve the injection of a radioactive tracer and the use of specialized scanners to visualize structure and function of specific parts of the brain. There are a number of technical differences between PET and SPECT but the overall procedure and information gained from the test is generally similar.
You can watch this video outlining the PET procedure (courtesy of UCL/UCLH NIHR Biomedical Research Centre).
For more information on a type of PET specifically used to diagnose and study movement disorders please see single photon emission computed tomography imaging using DaT scan.
Single Photon Emission Computed Tomography (SPECT) imaging and DAT scans
Single photon emission computer tomography, commonly known as SPECT, is a type of neuroimaging which can give information on both the structure and the function of different parts of the brain. SPECT neuroimaging uses radioactive substances (called "tracers") which connect to specific cells or parts in the brain. A specialized camera detects the radioactive radiation the tracers emit and uses it to re-consutruct an image of the relevant brain region. Dopamine is a major brain chemical and the loss of brain cells responsible for producing dopamine is believed to be the main cause of Parkinson's disease. A special type of SPECT scan, called Dopamine Active Transfer scan (DAT scan) uses a tracer which labels dopamine-producing cells in the brain. This procedure can therefore be used to assess the number and activity levels of dopamine-producing brain cells. DAT scans can be used as part of the clinical diagnostic process for Parkinson's and may be used in research to look at disease-related changes over time and to assess the effects of new potential treatments.
The procedure: SPECT and DAT scans require the injection or infusion of a radioactive tracer. The test requires only a small amount of radiation which is not associated with any long-term health risks. Following the injection you will be asked to wait approximately 3-4 hours before the scan can start. For the scan itself you will be asked to lie perfectly still on your back for the duration of the scan, which is typically 30-60 min. The images are taken with specialized cameras which can rotate all around you but will not touch you and you will not be enclosed in a tunnel-like scanner. Most of the radioactive tracer leaves your body through your urine within a few hours after the scan and your body breaks down the remaining tracer over the next few days.
Some medications may affect the results of the DAT scan and you will be asked to stop taking them at least 2 days before the scan. Most anti-parkinsonian medications do not interfere with the test and can be taken regularly but others, including many anti-depressants, anti-anxiety and other medication will need to be stopped for a few days. In any case you should discuss your full list of medications with the doctor or researcher who referred you to the scan ahead of time.