The study, published in Neurology, involved nearly 31,000 people with Alzheimer's disease seen at Alzheimer's Disease Centers nationwide. Of the participants, 81 percent were white, 12 percent were African-American, 4 percent were Latino, 1.5 percent were Asian and .5 percent were American Indian.

Study author Kala Mehta of the University of California, San Francisco, found Latino study participants lived an average of about 40 percent longer than the white participants. African-American participants lived an average of 15 percent longer than whites.

Asian and American Indian participants lived about as long with the disease as the white participants did.

"It's not clear why Latinos and African-Americans have an advantage when it comes to living longer with Alzheimer's disease," Mehta said in a statement. "Possible explanations may be underlying genetic or cultural factors.

"Determining the underlying factors behind this difference could lead to longer survival for everyone with Alzheimer's disease," Mehta said.