Another piece of the puzzle

Penn scientists have found a biological indicator for Alzheimer's disease that may allow them to predict and track the degenerative neurological disorder. According to the University of Pennsylvania study, the presence of the molecule isoprostane in the urine of Alzheimer's patients is directly correlated with an increase in unstable compounds called "free radicals," which are linked to the disease. "What is in the urine is a mirror of what is happening in the brain," said Domenico Pratico, the lead researcher and a professor of pharmacology at the University. "That is the big excitement with us." The study, supported by federal funding, was published in the November issue of the Annals of Neurology. Pratico led a team of researchers at Penn's Alzheimer's Disease Center in comparing the levels of isoprostane in the urine of 35 Alzheimer's patients with the levels of 25 healthy volunteers. The researchers found that the amount of isoprostane was higher in the Alzheimer's patients. Scientists were already aware of an Alzheimer's indicator, called a tau protein, but it could only be measured using fluid from a spinal tap -- a painful and invasive procedure. Penn researchers showed a correlation between tau and isoprostane levels, allowing doctors to avoid administering the spinal tap. "The tau protein is not a predictor," Pratico said. "When you have tau, the disease is already advanced." Alzheimer's attacks cells in the brain, slowly impairing the ability of those afflicted to control their emotions, recognize errors, coordinate movements and remember information. The patient eventually loses all memory and mental functioning. "Basically, they present some good preliminary data," said Bruce Reed, associate director of the associate director of the Alzheimer's Disease Center at the University of California at Davis. "They clearly separated the Alzheimer's group and a clinical control." But Reed also said the study sample was too small to produce definitive results. The new test is not yet available in most laboratories because of the complicated equipment involved, but Pratico said the test could be a useful tool to help doctors measure the evolution of the disease and develop better therapies. Pratico and his researchers are starting a follow-up study on patients who exhibit mild cognitive impairment, but who have not been diagnosed with Alzheimer's. "We know that 45 percent of [patients with mild cognitive impairment] turn into Alzheimer's patients," said Virginia Lee, co-director of Penn's Center for Neurodegenerative Diseases and a collaborator in the study. "If the marker is predictive of Alzheimer's disease... it is an early predictor of someone who would get the disease." "The test is extremely useful for clinical trials... but it won't be a key diagnostic test," said Greg Cole, associate director of the Alzheimer's Center at the University of California at Los Angeles. Scientists are uncertain of the precise role of free radicals in the brain of Alzheimer's patients, but Pratico hopes that his work will provoke further research in this area. "We do not have the proof that free radicals are responsible for the disease, but we know that it is occurring," Pratico said. "The novelty of the study is that we are now sure that the damage of the free radicals is increased." "How specific is this process to Alzheimer's?" Reed asked. "[Research] needs to show that it doesn't happen in other things." In a related study published in the same issue, Pratico and his co-workers found that isoprostane could also be used as a marker for free radical damage in people suffering from Down Syndrome.

Please note All comments are eligible for publication in The Daily Pennsylvanian.