Holding Off Alzheimer's Disease

Patients with mild cognitive impairment -- a neurological condition that is often a precursor to Alzheimer's disease -- can be temporarily protected against Alzheimer's if they take a currently approved medicine called donepezil, researchers announced yesterday.

This is the first time any drug has been shown to slow the progression from mild cognitive impairment to Alzheimer's, researchers said.

The results were announced during an international conference on Alzheimer's disease in Philadelphia. The study was funded by the National Institute on Aging with Pfizer Inc. and Eisai Inc., the makers of donepezil. The drug is sold under the brand name Aricept.

Mild cognitive impairment, according to the National Institute on Aging, is more severe than aging-related memory problems such as forgetting to pick up something at a store. But it is not as severe as Alzheimer's disease, which is characterized by forgetfulness and dementia -- disorientation and confusion. Yet four in 10 people with mild cognitive impairment go on to develop Alzheimer's within three years.

The study found that donepezil slowed progression to Alzheimer's in the first 18 months of a three-year study; thereafter, there was no difference between the drug and sugar pills. On average, researchers said, the medicine slowed the disease by about six months.

Scientists advised caution in interpreting the results, which are considered preliminary. A June report in the medical journal the Lancet suggested donepezil did little to help Alzheimer's patients and was not cost-effective; the drug's makers countered that a number of studies had found it was effective.

-- Shankar Vedantam

Some Fishy Red Snapper

Fish lovers, beware: The fish you bought at the grocery store may be an impostor, according to new research.

To teach his students about genetic testing, Peter B. Marko, an assistant professor of marine sciences at the University of North Carolina at Chapel Hill, had his students test 22 fish sold as red snapper at nine stores in Delaware, Florida, Illinois, Massachusetts, New York, North Carolina, South Carolina and Wisconsin.

To their surprise, Marko and his students discovered that 77 percent of the fish tested turned out to be some other, less desirable, usually less expensive species of fish. Some of the fish were other types of snapper found in the western Atlantic, while others were relatively rare. Some came from as far away as the western Pacific.

"Substitutions among closely related fish species are difficult to detect, because most distinguishable features are lost during processing," Marko and his colleagues wrote in reporting their findings last week in the journal Nature.

In addition to passing off less expensive, and typically less tasty, fish as red snapper, the practice is disturbing because regulators keep track of the fish species that fishermen catch and sell, to make sure certain species are not being threatened by overfishing.

"Mislabeling to this extent not only defrauds consumers but could also adversely affect estimates of stock size if it influences the reporting of catch data that are used in fisheries management," the researchers wrote.

-- Rob Stein

Ocean 'Sink' May Be Filling Up

After nearly 15 years of study, a group of scientists have concluded that the ocean, which has soaked up half of human-generated carbon emissions over the past 200 years, may be losing some of its capacity to act as a pollution "sink."

In two articles published Friday in Science magazine, the scientists examined the impact of "anthropogenic" carbon dioxide, which is generated by burning of fossil fuels or deforestation. While they said experts are just beginning to track this phenomenon, "the delicate balance of marine planktonic species could undergo significant shifts in the future as humankind continues along the path of [carbon pollution] in the surface oceans."

Millions of years of sedimentation have produced organisms with calcium carbonate shells that can absorb carbon dioxide, but Richard A. Feely, a marine chemist at the National Oceanic and Atmospheric Administration, said "the slowing down of the formation of these calcium carbonate shells will have an effect on the ecosystem of which we have little understanding."

Feely added that lab scientists have seen changes in the structure of algae, for example, but they have not been able to track such phenomena in the open ocean.

-- Juliet Eilperin

When Peter B. Marko and students tested fish sold as red snapper, they found that 77 percent of the fish tested were some less desirable species of fish.