New PET Tricks for Old-Age Disease

Doctors of the future may have an additional tool when it comes to detecting Alzheimer's disease.

Researchers from the University of California, Los Angeles may have devised a new way of looking at patients' brains where they can see the damage that leads to Alzheimer's disease at the molecular level.

Using a positron emission tomography (PET) scanner, they were able to peek at the brain and look at the proteins -- the materials that cause the problems -- linked to memory deterioration.

A small study of 83 volunteers published today in the New England Journal of Medicine found that using a PET scan to look for certain proteins associated with Alzheimer's can help differentiate those with Alzheimer's disease from those with mild cognitive impairment.

Unlike with Alzheimer's, the memory and thinking problems associated with mild cognitive impairment are not severe enough to interfere with daily activities.

The authors of the study suggest that this new technique might be helpful in diagnosing Alzheimer's -- which affects an estimated 4.5 million Americans -- and for developing drugs that target the proteins that cause the disease.

Alzheimer's disease is expected to affect as many as 16 million Americans by 2050, as the baby boomers reach the age at which they're most at risk.

Imaging Could Be an Important Step in Treatment

"This study will give us an important tool we've been lacking in our search for better understanding and treatment of Alzheimer's," said David Harper, assistant professor of psychology in the psychiatry department at Harvard Medical School. "It could be useful in tracking the effectiveness of several new drugs that directly attack the Alzheimer's disease lesions."

The study also may give doctors a way to see the proteins implicated in the disease.

"This is the first study that claims to 'see' both plaques and tangles," said Dr. Sam Gandy, chair of the Alzheimer's Association's Medical and Scientific Advisory Council and director of the Farber Institute for Neurosciences at Thomas Jefferson University in Philadelphia.

"This will be a useful addition to the tools we have," Gandy said.

More Evidence May Be Needed

According to other Alzheimer's observers, however, the study is limited and doesn't add much to what is already known.

"We can diagnose Alzheimer's disease already with 90 percent certainty on a clinical basis without such a procedure," said Dr. Myron Weiner, chair in brain science and Alzheimer's disease research at the University of Texas Southwestern Medical Center in Dallas.

"All this study tells us is that the protein formations in mild cognitive impairment is in between what it is for those without any problems and those with Alzheimer's disease," Weiner said. "We already knew that."

Others said that while it would be helpful, the technology currently had its limitations.

"We need to be cautious in overinterpreting its significance," said Dr. Ronald Petersen, director of the Alzheimer's research center and neurology professor at the Mayo Clinic. "It is another molecular tracer, but its technical qualities are inferior to what is available currently. It has a much more limited use."

Some have taken an even stronger position, arguing that the study's authors are inventors of the new materials used in the scan and that they may have a vested interest in the results.

Based on these concerns, detractors of the study argued that technology must not be oversold, especially at such an early stage. They say that in order for such technology to be useful, more follow-up studies would be needed to see if there is a strong enough relationship between the PET findings and progression to Alzheimer's disease.

"For now, the data in this study may prove useful in research, but it is not a definitive test that is ready for public or clinical use," said Dr. William Thies, vice president of medical and scientific relations at the Alzheimer's Association. "We need testing in larger populations."

A Routine Test for the Future?

But while clinical implications may be years away, it is not hard to imagine the technology going into widespread use.

"One envisioned scenario is that brain scans such as this might join prostate tests, mammography and colonoscopy as surveillance tools after you reach a particular age," said Gandy.

"This study is a small window into a much bigger story," said Thies. "Advanced imaging technologies -- including PET, MRI and others -- have great potential to improve early detection."

And with early detection comes the potential for preventing the disease from taking its toll.