MADISON, N.J. (AP) _ Schering-Plough Corp. will pay $20 million to a research company to help develop new drugs for the treatment of Alzheimer's disease, the companies said.

The agreement allows a wholly owned subsidiary of Schering-Plough to receive the rights to any products and technology developed, the companies said Thursday.

Schering-Plough and Cephalon Inc. of West Chester, Pa., will work over five years on two approaches for treating Alzheimer's, Cephalon spokesman Jack Lief said.

Cephalon will study how the regulation of genes in the nervous system affects degenerative nerve diseases such as Alzheimer's.

In the second approach, researchers will try to inhibit a naturally occurring chemical that helps in the formation of amyloid plaques, a deposit found on the brains of Alzheimer's victims.

Symptoms of Alzheimer's, an irreversible neurological disorder, include gradual loss of memory, impairment of judgment and personality change. There is no known cure.