Scientists have successfully used magnetic resonance imaging (MRI) to identify the destructive brain legions that cause Alzheimers disease in mice. If the results can be replicated in people, they could point to a diagnostic test for an ailment that currently afflicts nearly 4.5 million Americans.

The amyloid plaques that are a hallmark of Alzheimers disease can currently be identified only during an autopsy, although patients are diagnosed with the disease on the basis of behavioral observations. Joseph Poduslo of the Mayo Clinic School of Medicine and his colleagues manufactured a novel molecular probe that targets plaques in the brains of laboratory mice and allows them to show up on a standard MRI scan. "A simple MRI evaluation for Alzheimers disease would ease the suffering of so many families and, hopefully, vastly improve patient-care options," Poduslo remarks. The probe--a molecule that is derived from the protein that causes the plaques in humans--was able to cross the blood-brain barrier and attach to the amyloid plaques in the brains of mice. Most important, it also provided enough visual contrast to produce high-resolution MRI images while the animals were alive. The findings were published online on Friday by the journal Biochemistry.

The researchers also tested the new probe on tissue donated by patients who had succumbed to Alzheimers. Although the molecule behaved differently in human brains than it did in those of mice, the probe successfully labeled the plaques. Further research is needed to determine whether the approach will work for human patients, but the authors note that their results could allow for early diagnosis and offer a way to monitor the disease's progression as well as the efficacy of current therapies.