New Jersey adopted a "Silver Alert" system yesterday to notify the public about missing people believed to be suffering from dementia or other cognitive impairments, joining a growing list of states with similar measures.

Acting Gov. Richard J. Codey - Gov. Corzine was out of state - signed the bill in an afternoon ceremony at the Green Hill Nursing Home in West Orange.

The system is loosely based on the Amber Alerts used to help authorities find missing children.

"With the Amber Alert proving so effective in protecting some of our most vulnerable, our children, the Silver Alert is a smart next step in protecting another vulnerable segment of our population, the elderly and disabled," Codey said.

State Sen. John Girgenti (D., Passaic), a sponsor of the bill, said more than 400 people with dementia and other cognitive disorders are reported missing in New Jersey every year.

"Statistics show at least half of those with dementia who wander away suffer serious injury or death if not found within 24 hours," said Assemblyman Paul Moriarty (D., Gloucester), another sponsor of the bill, referring to nationwide figures.

About half of the states have adopted measures along similar lines, according to Matthew Gever, a policy specialist at the National Conference of State Legislatures, although the criteria for issuing such alerts vary.

New Jersey's system covers anyone believed to be suffering from cognitive disorders, without limitations based on age. It is to be used only in cases involving risk of serious injury or death.

Highway message signs may also be used to alert the public if the missing person is driving when he or she disappears and if accurate information about the vehicle is available.

In Pennsylvania, several Silver or senior-alert bills have been referred to legislative committees. New York Gov. George S. Pataki vetoed a Silver Alert bill in 2003 because he feared the alerts would become too frequent.

On the national level, the House passed a Silver Alert bill in February in a voice vote. The legislation has been referred to a Senate committee.

New Jersey's system would be a voluntary effort between state and local law enforcement agencies and the media. Broadcast media would be notified by state police and asked to relay information.

The law takes effect July 1.