WASHINGTON – Drinking a milkshake-style medicine at breakfast seems to feed brain cells starved from Alzheimer’s damage, researchers reported Monday. It’s one of four promising experimental drugs poised for large-scale testing against the brain-destroying disease.

The milkshake drug, called Ketasyn, is a dramatically different way to approach dementia. It hinges on recent research suggesting diabetic-like changes in brain cells’ ability to use sugar for energy play a role in at least some forms of Alzheimer’s.

Special fatty acids in Ketasyn offer an alternate food source to rev up those hungry neurons, researchers told an international Alzheimer’s meeting here Monday. In a study of 150 patients, adding Ketasyn to their regular medicines produced a small but important boost in mental functioning, but only in people who don’t carry an Alzheimer’s gene called ApoE4. Still, that’s about half of all patients.

“We see this as a co-therapy,” not a way to stop Alzheimer’s, cautioned Dr. Lauren Constantini, a former Harvard scientist now with Accera Inc., the company that is developing the drug.

The drug Ketasyn follows the principle that when someone fasts, the body lives off stored fat. Ketasyn contains fatty acids that the liver metabolizes into substances called ketones, similar to what’s produced during a fast. Brain cells can use ketones in place of sugar for energy.

That’s also similar to the high-fat, low-protein ketogenic diet sometimes used for children with severe epilepsy. Manufacturer Accera is currently hunting funding for a Phase III study, and exploring different formulations for epilepsy and other brain disorders.

To stop Alzheimer’s brain decay, most scientists have their hopes pinned on drugs that promise to prevent a sticky goo called beta-amyloid from clogging up patients’ brains. And Monday brought frustrating news on that front: The first of those amyloid blockers to make it to large-scale, Phase III testing has hit a hurdle, and scientists will have to wait until at least month’s end to learn if the much-anticipated drug Alzhemed really works.

The problem is statistical, said lead researcher Dr. Paul Aisen of Georgetown University. Hospital-to-hospital differences in other medication use among the study’s 1,000 participants prevent an immediate clear comparison of Alzhemed’s role. Working with the Food and Drug Administration, researchers are adjusting for those variations, Aisen told the Alzheimer’s Association’s dementia prevention meeting.

Stay tuned, he said: There are some hints that Alzhemed-treated patients fared better.

Eli Lilly & Co. hopes to halt beta-amyloid formation by blocking an enzyme called gamma secretase involved in its creation.

Among 51 patients given the still-unnamed drug, those who took the highest dose had a 65 percent reduction of beta-amyloid in their blood. The study didn’t last long enough to tell if their symptoms improved, too, but the drop was so big that Lilly will begin a Phase III trial early next year to try prove the approach.

“This is a robust effect,” said Lilly researcher Dr. Eric Siemers. “How could you not do a Phase III study?”

Also next year, scientists will begin a U.S. study of an old Russian antihistamine against Alzheimer’s. A study of 180 Russian patients found the drug Dimebon improved mental functioning, patients’ ability to care for themselves and some other measures, said Dr. Rachelle Doody of the Baylor College of Medicine.

After a year of treatment, patients’ mental functioning hadn’t gotten any worse than when they started. Scientists think Dimebon may have some capacity to save neurons from death, said Dr. David Hung, chief executive of manufacturer Medication Inc.