A New Enzyme found for Alzheimer's disease

Scientists say they have identified a long-sought enzyme suspected of playing a key role in Alzheimer's disease.

In Alzheimer's disease, the brain develops deposits that are thought to kill brain cells. These deposits are created when a long, string-like protein is cut in two specific places.

Scientists have long theorized the existence of a chemical scissors that makes one of these cuts. They called it gamma secretase, but they had never actually identified it.

In the journal Nature, scientists at Merck Research Laboratories in West Point, Pa., reported that they have found strong evidence that gamma secretase is actually presenilin 1.

Presenilin 1 had already been linked to a rare inherited form of Alzheimer's that strikes people in their 30s and 40s. The new work suggests it also plays a role in the more common, noninherited variety.

These obervations provides drug companies a potential target to create drugs that block the action of the enzyme.

However, the cause of Alzheimer's is still not known, and effective drugs for humans are still a long way off.