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Research Frontiers: Mind Block
Since the late Dr. Andreas Rett first identified the syndrome that bears his name more than 50 years ago, doctors have learned to treat the seizures, reflux and other symptoms of the disorder but they have not yet learned to alleviate the neurological impairment it causes. Researchers at Kennedy Krieger will begin a new drug trial this summer that represents an important step toward achieving that goal.
Rett syndrome is caused by a genetic mutation that results in abnormal development predominantly in girls, affecting approximately 1 in 10,000 to 1 in 22,000 in the United States. The syndrome manifests itself around six months of age, hindering such developmental milestones as crawling, standing and early language development. Between 18 months and five years, girls with Rett syndrome begin to develop hand wringing behaviors, gastrointestinal problems, including severe reflux and failure to thrive, and respiratory difficulties such as hyperventilation, air swallowing and cyanotic spells. Approximately half of Rett syndrome patients also experience seizures.
Rett syndrome also results in severe intellectual disabilities. Researchers have confirmed that girls with Rett syndrome have abnormally high levels of receptors for the amino acid glutamate in both the gray matter and prefrontal cortex areas of the brain, as well as in their spinal fluid. They have also confirmed that such high levels of receptors correspond with the primary periods of neurological decline, which plateaus around age 15. This promising new research trial hopes to show that the brain injury caused by excessive glutamate can be suppressed by using a common drug known to block glutamate receptors. "We aren't trying to cure' Rett syndrome by this approach," says Dr. Sakkubai Naidu, principal investigator of the study, which is funded by the National Institute of Child Health and Human Development. "But we are hoping to identify a way to halt the on-going brain injury caused by the disorder."
Dr. Naidu and her colleagues will recruit 90 patients with Rett syndrome between the ages of five and 15 years who, over the course of a six month period, will receive varied doses of the drug compound, which is known to be safe and effective in blocking the glutamate receptors. During an initial three-day inpatient stay, the patients will undergo neurological examinations, EEG, respiratory monitoring, behavioral evaluations, cognitive assessment, blood work, electrocardiograms, gait analysis, physical, occupational and speech evaluations, hearing tests, bone density assessment and gastrointestinal evaluations. Follow-up assessments will be performed at two weeks, one month and three months after the initial evaluation. After six months the girls will return for a follow-up inpatient evaluation. Following this second evaluation, researchers will interpret the test results to determine whether the patients' abilities and conditions improved or stabilized while they were taking the drug and, if so, which dosage was most effective.
If successful, this study could signal the beginning of effective therapeutic interventions to ease the devastating neurological conditions associated with Rett. "We believe we can modify certain fundamental changes that the brain undergoes due to this genetic defect," says Dr. Naidu. "The promise for effective treatment for those with Rett syndrome seems much brighter as basic science unravels the neurobiological basis of this disorder." To make an appointment with Dr. Naidu, call Kennedy Krieger Care Management at 443-923-9400. For more information about the study, phone 443-923-2778.