Margaret Sheehan considers herself lucky. An attorney from Washington, DC, Sheehan was diagnosed with Parkinson’s disease nearly eight years ago, when she was 44 — quite a young age to be diagnosed with the progressive neurological disorder.
Although the news hit her “like a ton of bricks,” she is grateful she didn’t have to go through years of examinations, misdiagnoses and uncertainty about what was happening to her body prior to having a definitive diagnosis, as so many people with Parkinson’s do.
“For me, most of the time between the first symptoms and diagnosis had to do with me being in denial,” Sheehan says. “There was a long process of not connecting dots, to the point where I handed my sister a plate of pancakes when we were on holiday and she said ‘That’s a pretty serious tremor, you might want to get that checked out.’ Even so, it was months before I saw a doctor, who literally took one look at me and said ‘You need an MRI immediately.’”
Once a brain tumor was ruled out by the MRI exam, Sheehan saw a neurologist a few days later and was diagnosed with Parkinson’s disease on the spot.
An Agonizing Road to Diagnosis
Particularly for people who experience early-onset Parkinson’s disease, Sheehan’s story is unusual. According to the National Parkinson Foundation, the typical person sees two to three physicians over a minimum of two years before receiving an accurate diagnosis. A key reason is that there is no definitive test, such as a blood test, that indicates Parkinson’s disease.
“People are commonly misdiagnosed with arthritis, neuropathy, shoulder pain — all kinds of things — before they are correctly diagnosed with Parkinson’s,” says Joyce Oberdorf, president and CEO of the National Parkinson Foundation (NPF). “They may even be told they’re imagining it. For many, this is an agonizing experience.”
Early-stage parkinsonism is difficult to spot because it manifests in many ways and affects many systems of the body, leading to signs and symptoms such as loss of sense of smell, impaired movement, rigidity, constipation and sleep problems. For relatively young patients, parkinsonism would not be in the top of a physician’s mind, and for older patients, these symptoms can be confused with the natural process of aging.
Following the US FDA’s January approval of GE Healthcare’s DaTscan, which detects receptors that diminish in the brains of patients with parkinsonian syndromes such as Parkinson’s disease, the experience of being in years-long “diagnostic limbo” for Americans with suspension of Parkinson’s could be coming to an end. Because it is a schedule II controlled radiopharmaceutical, prescription and use of DaTscan is limited to centers and physicians with the required DEA and radioactive licenses. Today, over 150 American imaging centers have access to DaTscan and are beginning to put it to use with patients.
DaTscan is a radiopharmaceutical imaging agent that works by binding to dopamine transporters (DaT) in the brain. A specific marker for DaT, DaTscan produces images that provide visual evidence of nigrostriatal degeneration based on a reduced density of dopamine transporters. This information can be used along with other diagnostic tests to help differentiate essential tremor from tremor due to parkinsonian syndromes. DaTscan was not designed to differentiate among different forms of PS. The effectiveness of DaTscan as a screening or confirmatory test and for monitoring disease progression of response to therapy has not been established.
The Importance of Early Diagnosis
Having a definitive medical test for Parkinson’s disease — or tools such as DaTscan that offer additional diagnostic evidence that can be used to help make diagnostic decisions — can lessen uncertainty and confusion for early-stage Parkinson’s patients. That alone is a breakthrough with important implications for patients. Clear and timely diagnosis paves the way for early intervention and disease management. New drugs are in development that may slow the progression of the disease, and patients can make lifestyle changes (e.g., stress reduction or exercise) to mitigate symptoms of Parkinson’s.
But there is an equally significant aspect to early diagnosis, from the standpoint of drug development. Todd Sherer, CEO of The Michael J. Fox Foundation, explains.
“Many trials investigating therapies for Parkinson’s disease recruit people at the earliest possible stage of the disease. Because of the subtlety of early-stage symptoms, some trials have found, after following the participants over a period of time, that 15-20 percent of them didn’t actually have Parkinson’s disease. When one-fifth of the patients you were testing didn’t even have the disease you were looking to treat, you have a significant problem in testing the effectiveness of a drug.”
To this point, The Michael J. Fox Foundation launched a large-scale clinical study last year that is using DaTscan — donated by GE Healthcare for use in the study — as a tool to help ensure that the participants do in fact have Parkinson’s disease. The study, called the Parkinson’s Progression Markers Initiative (PPMI), aims to define a set of biomarkers that indicate the progression of the disease, particularly in its early stages, to accelerate therapeutic development and ultimately improve patient care.
NPF’s Quality Improvement Initiative (QII) is a research project focused on determining which treatments produce the best outcomes over time. Currently, more than 4,000 patients are enrolled in QII in 19 NPF Centers of Excellence, making it the largest PD outcomes registry in the world. This gives NPF researchers the ability to study the impact of treatments in a real-world clinical setting.
“Parkinson’s disease can be managed, but treatment can be complex,” says Oberdorf. “Our ultimate aim is to create and share models of diagnosis, treatment and care to fulfill our mission of the best care for every patient.”
Channeling the Energies of All Stakeholders
The National Parkinson Foundation and The Michael J. Fox Foundation both engage with Parkinson’s patients, not only to feed information and services out to the community, but to encourage their contribution in the work towards a cure.
“It’s the Parkinson's patients, caregivers and loved ones who really know the disease,” Sherer says. “They know what the needs are, and they can make an important contribution in helping us to test and design new therapies. So one of the roles of The Michael J. Fox Foundation is getting patients into clinical research — people who carry the genes, carry the symptoms and know what is really happening with the disease.”
Margaret Sheehan, for her part, has been involved in two clinical trials and wants to help more people understand what it is like to live with Parkinson’s disease.
“Parkinson’s is a neurological disease, affecting both mind and muscle,” Sheehan says. “So there are symptoms you can’t see that are very real. My brain can do everything it could do before — but it takes more conscious thought. It’s not depression, but literally the way my brain works. I can feel it, and it’s different. I think there’s a lack of appreciation for the non-motor symptoms.”
The good news is that, according to Sherer, the Parkinson’s development pipeline is more robust than ever, with the highest number of therapies for Parkinson’s disease currently in testing. “There is no guarantee that these therapies will work,” he says, “but when I look at the scope of activity and the possibilities, I’m very optimistic.”
Important Risk and Safety Information about DaTscan (Ioflupane I 123 Injection)
INDICATIONS AND USAGE – DaTscan is a radiopharmaceutical indicated for striatal dopamine transporter visualization using single photon emission computed tomography (SPECT) brain imaging to assist in the evaluation of adult patients with suspected Parkinsonian syndromes (PS). DaTscan may be used to help differentiate essential tremor from tremor due to PS (idiopathic Parkinson’s disease, multiple system atrophy and progressive supranuclear palsy). DaTscan is an adjunct to other diagnostic evaluations. The effectiveness of DaTscan as a screening or confirmatory test and for monitoring disease progression or response to therapy has not been established. CONTRAINDICATIONS – DaTscan is contraindicated in patients with known hypersensitivity to the active substance, any of the excipients, or iodine. WARNINGS AND PRECAUTIONS – Hypersensitivity Reactions: Hypersensitivity reactions, generally consisting of skin erythema and pruritis, have been reported following DaTscan administration. Thyroid Accumulation: The DaTscan injection may contain up to 6% of free iodide (iodine 123 or I-123). To decrease thyroid accumulation of I-123, block the thyroid gland at least 1 hour before administration of DaTscan; failure to do so may increase the long-term risk for thyroid neoplasia. ADVERSE REACTIONS: In clinical trials, headache, nausea, vertigo, dry mouth or dizziness of mild to moderate severity were reported. In postmarketing experience, hypersensitivity reactions and injection site pain have been reported. DRUG INTERACTIONS: Drugs that bind to the dopamine transporter with high affinity may interfere with the DaTscan image. The impact of dopamine agonists and antagonists upon DaTscan imaging results has not been established. SPECIFIC POPULATIONS: Pregnancy – It is unknown whether DaTscan can cause fetal harm or increase risk of pregnancy loss in pregnant women. DaTscan should be given to pregnant women only if clearly needed. Like all radiopharmaceuticals, DaTscan may cause fetal harm depending on the stage of fetal development, and the magnitude of the radionuclide dose. Radioactive iodine products cross the placenta and can permanently impair fetal thyroid function. Nursing Mothers – It is not known whether DaTscan is excreted into human milk, however, I-123 is excreted into human milk. Because many drugs are excreted into human milk and because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to interrupt nursing after administration of DaTscan or not to administer DaTscan. Nursing women may consider interrupting nursing and pump and discard breast milk for 6 days after DaTscan administration to minimize risks to a nursing infant. Pediatric Use – The safety and efficacy of DaTscan have not been established in pediatric patients. Geriatric Use – There were no differences in responses between the elderly and younger patients that would require a dose adjustment. Renal and Hepatic Impairment – The effect of renal or hepatic impairment upon DaTscan imaging has not been established. The kidney excretes DaTscan; and patients with severe renal impairment may have increased radiation exposure and altered DaTscan images. DRUG ABUSE AND DEPENDENCE: Ioflupane I 123 Injection is a DEA Schedule II controlled substance. A DEA license is required for handling or administering this controlled substance. OVERDOSAGE: It is unknown whether or not ioflupane is dialyzable. The major risks of overdose relate to increased radiation exposure and long-term risk for neoplasia. In case of radioactivity overdosage, frequent urination and defecation should be encouraged to minimize radiation exposure to the patient. PROCEDURE – Radiation Safety: DaTscan emits radiation and must be handled with safety measures to minimize radiation exposure to clinical personnel and patients.
Prior to DaTscan administration, please read the Full Prescribing Information