Studies out of the Mayo Clinic last week reveal promising advances in the early detection and diagnosis of Alzheimer's disease and other forms of dementia.

One Mayo-led study found a way to analyze brain scans that differentiates two forms of dementia from Alzheimer's. Another determined a more accurate method for predicting memory loss or cognitive impairment in otherwise healthy seniors.

The discoveries, presented at a global Alzheimer's conference in Vienna, were met with a mix of hope and caution -- hope because of the need for advances in the care of dementia, which is becoming more prevalent in the aging United States, and caution because a better diagnosis doesn't necessarily mean better outcomes, given the limited medications and dementia treatments available.

Dr. Ronald Petersen, a Mayo neurologist, acknowledged that an accurate diagnosis might not change the course of treatment for now. But with nearly 100 drugs for dementia under development, he said, researchers can't wait to also develop better tests.

"This is a public health crisis that we have to do something about," he said. "We can't wait to start this line of research until the drug is out, because it would take years for us to catch up."

Petersen led the prediction study, which followed 1,291 seniors over 10 years and found that a combination of clinical exams and memory tests could accurately predict their dementia risks.

The imaging study reviewed MRI scans from 90 people who had died and found unique patterns in their brains to determine whether they suffered from Alzheimer's or two other forms of dementia: frontotemporal lobar degeneration and Lewy body disease. The study raises the potential to diagnose Alzheimer's definitively while people are alive. Currently, only an autopsy can be so precise.

The high cost of imaging scans such as MRIs or CTs has prompted some insurance companies to restrict or limit their use in questionable cases -- particularly for low back pain. Those limits haven't been applied as much to scans for dementia, though.

Most doctors can learn all they need to know about someone's level of dementia and treatment needs through a review of medical history, a complete exam and cognitive tests, said Dr. Thomas von Sternberg, assistant medical director for geriatrics at Bloomington-based HealthPartners. However, many still order brain scans just to be certain and to show patients they have tried everything.

"If you present with memory loss to a neurologist, to a primary care doctor or to a 7-11," he said, "you're going to get (an imaging) scan."

At the same time, von Sternberg and others agree imaging can play a meaningful role in certain complex cases and in preparing people with dementia and their families for what may come.

Identifying the frontotemporal version of dementia early is helpful to individuals and families because that form of dementia is much more likely to cause behavior problems, said Michelle Barclay of the Alzheimer's Association of Minnesota-North Dakota.

"Early detection is extremely important," she said, "whether we have new drugs or not."

One concern over testing for the risk or early signs of dementia is burdening people with information they can't control. Boston researchers reported this week that people tested for APOE-4 -- a gene that increases the risk of Alzheimer's -- suffered no higher rates of depression or anxiety than those who didn't receive this information about their risk levels.

But two University of Minnesota experts -- doctors Rosalie and Robert Kane -- said the testing could have a psychological impact and isn't ready for broad use.

"Societal benefit seems unlikely, given that it is not possible to prevent Alzheimer's disease, and available treatments have at best a modest effect on disease progression," they wrote in an editorial accompanying the study in the New England Journal of Medicine.

"Societal harm from testing remains possible, given that Alzheimer's disease is widely regarded as being singularly horrific."

Mayo's Petersen said doctors must scrutinize the value of any tests or imaging scans for patients with dementia. However, he said, there is value in diagnostic results beyond being able to prescribe specific drugs.

While there are many sham puzzles and books that claim to prevent dementia, Petersen said, plenty of research shows people can make "lifestyle modifications" to reduce their risks.

"Maybe (a test result) serves to motivate people by telling them, 'You do have a risk profile; now here's something you might be able to do about it,' " he said. To see more of the Pioneer Press, or to subscribe to the newspaper, go to http://www.twincities.com. Copyright (c) 2009, Pioneer Press, St. Paul, Minn. Distributed by McClatchy-Tribune Information Services. For reprints, email tmsreprints@permissionsgroup.com, call 800-374-7985 or 847-635-6550, send a fax to 847-635-6968, or write to The Permissions Group Inc., 1247 Milwaukee Ave., Suite 303, Glenview, IL 60025, USA.