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Date: Wed, 18 May 94 09:58:44 EDT Message-Id: <[log in to unmask]> From: "Bill Moore" <[log in to unmask]> Reply-To: "Bill Moore" <[log in to unmask]> To: [log in to unmask] Subject: Brain Imaging Offers Early Diagnosis, etc of PD 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. ------------------------------ ------ Bill Moore [log in to unmask] NSWCDD Code G24 Dahlgren, VA 22448 703.663.8851