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Last May, MedNews carried a story about early detection of Parkinson's using new technology. John Cottingham [log in to unmask] > Date: Sun, 15 May 94 08:24:31 MST > From: mednews (HICNet Medical News) > To: hicnews > Subject: Parkinson Disease: Brain Imaging Offers Early Diagnosis > Message-ID: <[log in to unmask]> > > *Parkinson Disease: Brain Imaging Offers Early Diagnosis* > > Parkinson disease, a progressive and debilitating disorder that > affects nearly 1 million Americans, is difficult to diagnose before > irreversible brain damage has occurred. In the hope of preventing > neuronal loss, researchers at Yale University School of Medicine > have developed a brain-imaging technique that promises to allow > earlier, possibly pre-symptomatic, identification of Parkinson > disease. "Earlier detection can lead to earlier treatment with > neuron-protecting drugs, many of which are now under evaluation," > says Dr. Kenneth L. Marek, director of the Movement Disorders > Center at Yale University. He and his colleagues evaluate patients > at the GCRC at Yale University. > > One of the most common neurological disorders, Parkinson disease is > believed to be caused by the destruction of brain cells that produce the > neurotransmitter dopamine. Subsequent deficits of dopamine in the > mid-brain lead to the tremors, rigidity, and other movement disorders > characteristic of the disease. These definitive clinical symptoms appear > after more than 80 percent of dopamine-producing cells have been > destroyed. "If we could intervene when patients still have 50 to 60 > percent of their neurons left, and not 20 to 30 percent, we might be > able to retard disease progression," says Dr. Marek. > > In a recent issue of the Proceedings of the National Academy of Sciences > (December 15, 1993, pp. 11965-11969), Dr. Marek and his colleagues report > that they can measure Parkinson-associated brain cell loss indirectly by > using an imaging technique known as single photon emission computed > tomography (SPECT). The scientists designed a radioactive marker known > as **[123I]CIT**, a chemical relative of cocaine that,like cocaine, > actively binds to cell membrane proteins known as dopamine > transporters. Found only on dopamine-producing cells, the > transporters provide a clue to the number of dopamine producing > cells in the brain. When labeled CIT binds to transporter > proteins, their quantity and locations can be determined via SPECT > imaging. > > Dr. Marek and his colleagues administered a solution of**[123I]CIT**to > five patients who had relatively mild Parkinson disease and to five > healthy age matched control subjects. SPECT imaging over a period of > 2 days showed that CIT concentrations were markedly reduced among > Parkinson patients. In fact, the patients appeared to have lost > more than 65 percent of their dopamine transporters. > > Because SPECT has proved useful for distinguishing Parkinson patients > from healthy subjects, Dr. Marek and his associates are now applying this > technique to several ongoing studies. The researchers plan to use SPECT > to monitor the brain's response to promising neuro-protective agents and to > evaluate graft survival following fetal brain implantation in Parkinson > patients. > > The scientists also hope to develop a simple screening strategy for early > and definitive diagnosis of Parkinson disease. They are evaluating common > features of Parkinson disease -- including dementia, depression, and > speech dysfunction-as potential early markers of disease. These > clinical signs might give advance warning of underlying Parkinson > disease, and SPECT analysis could be used to verify the diagnosis. > "I feel relatively confident that SPECT imaging may serve as a > confirmatory test for patients who are at greater risk for > developing Parkinson disease," says Dr. Marek. > > > > ------------------------------ > > .