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Early Alzheimer’s Detection Still Elusive
Early diagnosis of Alzheimer's disease can give patients and their families better care and treatment options. Although companies aggressively market screening tests for Alzheimer's, an expert says a complete physical and neurological exam is the best test for the disease.
Although there is no known cure for Alzheimer's disease, early detection and treatment can improve cognitive function and quality of life for many patients.
Dr. James Burke, director of the clinical corps of the Joseph and Kathleen Bryan Alzheimer's Disease Research Center at Duke University Medical Center, says genetic testing can measure risk and susceptibility to the condition, but the presence of the ApoE4 (Alzheimer's disease) gene doesn't indicate whether the disease is actually present.
"It's a susceptibility gene," explains Burke. "It's somewhat analogous to cigarette smoking and lung cancer. If you smoke, you have an increased risk of lung cancer. If you have the ApoE4 gene, you have an increased risk for Alzheimer's disease. But, as with lung cancer, you could smoke and not get lung cancer, or you could have lung cancer and not smoke. Similarly with ApoE4, you could have Alzheimer's without inheriting the ApoE4 gene from a parent."
Burke, an associate professor of neurology at Duke, says marketing claims have led many patients and their loved ones to believe there is a simple screening test to detect early Alzheimer's.
"Despite the fact that there are a number of companies selling tests measuring markers in the blood or spinal fluid, the best test is still a history, a physical examination and a brief neuropsychological test. This has the best ability to distinguish what's normal aging from what's pathologic aging. It also has the ability to look for other factors, such as depression or stroke."
There has been some promising research indicating that gradual shrinkage of the hippocampus, a tiny region in the brain, could be a key to early detection.
"This has been a Holy Grail for many years," notes Burke. "When Alzheimer initially described Alzheimer's disease, one of the features he noted was that the brains of patients with Alzheimer's were shrunken. We've become much more sophisticated, and today we know that in the early stages, the part of the brain that shrinks the most is the hippocampus.
"It's a very small region, smaller than the size of your pinkie, located deep in the temporal lobe of the brain. But it's the gateway for memory. Measuring shrinkage of the hippocampus with an MRI scan can be a very sensitive tool, but its small size and irregular shape make it extremely difficult to measure accurately. There's been a lot of very promising work recently measuring rates of change of the hippocampus. But it's still more of a research tool than a practical measure."
Burke emphasizes that families can help by reporting signs of age-related cognitive problems, and that early detection can improve care options. "As a memory problem progresses, it's likely that there is ongoing nerve loss. So if we can intervene early, that would be the opportunity when we have the best chance of functional recovery."
Like many specialists in senior health, Burke believes there should be more widespread testing for signs of early-onset Alzheimer's.
"I think this kind of screening should be a routine part of medical care now. Alzheimer's is a disease that is age-dependent. Ninety percent of patients who have it are over the age of 60. I think that, just like measuring someone's blood pressure, there should be some questions about cognitive status when you go to see your physician regularly. Unfortunately, with people who have Alzheimer's disease, since their memory is affected, they're often not as aware of cognitive problems as family members are. Family members have to be encouraged to contact physicians about concerns."
He adds that staying mentally and physically active can help in the fight against Alzheimer's.
"There's very strong evidence that simple things – physical exercise, keeping mentally active – can actually stave off the progression of Alzheimer's disease. We often look for these very technical fixes to problems. But in fact, if we all lost a little weight, kept our blood pressure down, kept our sugar under control, we'd probably be able to live longer and healthier lives."
About This Article
Published: Aug. 5, 2005
Updated: Aug. 13, 2005
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