There are also clinical trials that test new ways to stop a disease from recurring (coming back) or reduce the side effects of treatment.

They say it will allow them to study how and why Alzheimer's disease progresses, to devise precise ways of diagnosing it and to test ways to stop its onslaught on the brain without conducting long experiments with human subjects that can be difficult to interpret.

Levels Termed Low Officials of the agency said most of the drug residue levels found in the milk were low and did not pose any health hazards, but a senior official said the agency was stepping up its milk testing to stop the illegal use of the drug in dairy cattle.