Gina Kolata / New York Times News Service

When Awilda Jimenez started forgetting things last year, her husband, Edwin, felt a shiver of dread. Her mother had developed Alzheimer’s in her 50s. Could his wife, 61, have it, too?

He learned there was a new brain scan to diagnose the disease and nervously agreed to get her one, secretly hoping it would lay his fears to rest.

“The scan was floridly positive,” said her doctor, Adam Fleisher, director of brain imaging at the Banner Alzheimer’s Institute in Phoenix.

The Jimenezes have struggled ever since to deal with this devastating news. They are confronting a problem of the new era of Alzheimer’s research: The ability to detect the disease has leapt far ahead of treatments.

There are none that can stop or even significantly slow the inexorable progression to dementia and death.

Families like the Jimenezes, with no good options, can only ask: Should they live their lives differently, get their affairs in order, join a clinical trial of an experimental drug?

“I was hoping the scan would be negative,” Edwin Jimenez said. “When I found out it was positive, my heart sank.”

The new brain scan technology, which went on the market in June, is spreading fast. There are already more than 300 hospitals and imaging centers, located in most major metropolitan areas, that are ready to perform the scans, according to Eli Lilly, which sells the tracer used to mark plaque for the scan.

The scans show plaques in the brain — barnaclelike clumps of protein, beta amyloid — that, together with dementia, are the defining feature of Alzheimer’s disease. Those who have dementia but do not have excessive plaques do not have Alzheimer’s. It is no longer necessary to wait until the person dies and has an autopsy to learn if the brain was studded with plaques.

Many insurers, including Medicare, will not yet pay for the new scans, which cost several thousand dollars. And getting one comes with serious risks. While federal law prevents insurers and employers from discriminating based on genetic tests, it does not apply to scans. People with brain plaques can be denied insurance.

The Food and Drug Administration, worried about interpretations of the scans, has required something new: Doctors must take a test showing they can read them accurately before they begin doing them. So far, 700 doctors have qualified, according to Eli Lilly. Other kinds of diagnostic scans have no such requirement.

In another unusual feature, the FDA requires that radiologists not be told anything about the patient. They are generally trained to incorporate clinical information into their interpretation of other types of scans, said Dr. R. Dwaine Rieves, director of the drug agency’s Division of Medical Imaging Products.

But in this case, clinical information may lead radiologists to inadvertently shade their reports to coincide with what doctors suspect is the underlying disease. With Alzheimer’s, Rieves said, “clinical impressions have been misleading.”

“This is a big change in the world of image interpretation,” he said.

Like some other Alzheimer’s experts, Fleisher used the amyloid scan for several years as part of a research study that led to its FDA approval. Subjects were not told what the scans showed. Now, with the scan on the market, the rules have changed.

Desperate to slow the progression of his wife’s disease, Edwin Jimenez is now giving her remedies he found on the Internet. There is no good evidence they work. But, he says: “What am I going to do? People feel so helpless with this disease that they are willing to try anything.”