Miércoles 14 de Septiembre de 2005, Ip nº 126

Skull Scanner Reveals Alzheimer's
Por John Gartner

Technology that's now used to monitor patients in the operating room could become the first accurate way to diagnose Alzheimer's disease before death.

The only definitive way to diagnose Alzheimer's today is by performing an autopsy. But early test results indicate that a brain-wave analysis device can accurately detect the beginning stages of the deadly illness and even help to diagnose depression. The technology, developed by Aspect Medical Systems, converts the data from an electroencephalogram, or EEG, into a numerical value between 0 and 100 indicating the amount of electrical brain activity.

If the technology gains FDA approval for diagnosing Alzheimer's, doctors could gain new insight into how the disease begins, which could lead to earlier treatment and help researchers find a cure.

The technology, which is undergoing clinical trials, enables doctors "to intervene at a much earlier stage in the disease," according to Nassib Chamoun, Aspect Medical's president and CEO.

A monitor analyzes the EEG data collected by a sensor placed on the patient's forehead, Chamoun said. A software algorithm based on technology currently used in Aspect's Bispectral, or BIS, monitor (now used to monitor brain function during surgery) then converts the EEG data into a numerical score.

The most common method of identifying the disease currently is by interviewing patients and their families to determine memory loss.

Aspect conducted three trials correlating reduced brain-wave activity with an electroencephalogram showing early signs of Alzheimer's. The test results, which were presented in June at the Alzheimer's Association International Conference on Prevention of Dementia, evaluated 111 healthy subjects and 27 Alzheimer's patients.

One of the studies, performed at McLean Hospital and Harvard Medical School, found the device identified Alzheimer's patients with 81 percent accuracy. Aspect is performing another test in Cape Cod, Massachusetts, studying 150 senior citizens to confirm the preliminary results, Chamoun said.

Dr. James Olds, director of the Krasnow Institute at George Mason University, is skeptical that technology based on EEG, a relatively dated technology, can accurately identify the onset of Alzheimer's. "I have serious doubts whether an ancient technology -- even when used with advanced algorithms -- will get us there," he said.

EEG data is blind to the detailed areas of the brain such as the hippocampus that are often the first regions where brain cells die, according to Olds, who served on the Commonwealth of Virginia's Alzheimer's and Related Diseases Commission.

Olds said attempts to use three-dimensional brain-scanning technology, including positron emission tomography and functional magnetic resonance imaging, yield important clues but include too many false positives. "Even with the most sophisticated tests, we don't know enough," he said.

Aspect's original brain-scanning technology has become a staple in many operating rooms over the past two decades. Aspect's A-2000 BIS Monitor is used in 40 percent of U.S. operating rooms to guard against patients waking up during procedures -- a state known as intraoperative awareness. The A-2000 costs approximately $5,900, and the technology is also integrated into medical devices by companies including Philips and General Electric.

Anesthesiologist Dr. Donald Mathews, associate chairman for academic affairs at St. Vincent Catholic Medical Center in New York, has used the BIS monitor for six years to tailor his doses. The right amount of anesthesia can allow the patient to spend less time in or even skip the recovery room, he said.

Aspect Medical is also applying its technology to diagnose depression. The company presented research at the New Clinical Drug Evaluation Unit annual meeting (.pdf) indicating that the technology could analyze EEG data to show increased suicidal thoughts with 76 percent accuracy.

The company modified its algorithm to pinpoint changes in the dissociation between activity in the left and right sides of the brain, which is one of the indicators of depression. "We can measure subtle shifts between hemispheres," Chamoun said.

The technology can also detect if an antidepressant medication is working in just a week instead of up to two months, which is how long doctors typically wait to evaluate a patient after starting medication, Chamoun said. Patients with depression are often given several medications until the right treatment is found, and this technology could speed up the screening process.

"Instead of six months, four to six weeks is the target for remission," he said.

Earlier this year medical device maker Boston Scientific gave Aspect Medical $25 million to develop its Alzheimer's and depression technology, and Chamoun said the company will test several hundred patients during the next six months.

While Aspect Medical has not begun the FDA approval process for its depression technology, Chamoun said "there is a very high probability of the product going through the regulatory process."


  30/08/2005. Wired Magazine.