CHICAGO, Illinois (AP) -- One parent with Alzheimer's disease is tough enough, but imagine the memory-robbing illness striking both parents -- and knowing chances are high you'll get it, too.  A study of more than 100 families for the first time gauges the size of that risk

"I'm scared," said Jackie Lustig, 52, of Sudbury, Massachusetts, whose father died of Alzheimer's and shose mother is living it. "I'm hoping to heck that the pharmaceutical companies come up with something better than there is now. It's not a nice way to go."

The study, appearing in March's Archives of Neurology, found more than 22 percent of the adult children of 111 couples with Alzheimer's had the disease themselves.  Risk grew with age.  Among offspring older than 60, more than 30 percent were affected.  In those older than 70, nearly 42 percent had the disease.

Prior studies have found a 6 to 13 percent prevalence of the disease in the U.S. population older than 65.

At age 62, Gayle Dorman worries every time she misplaces her car keys. "Is this the day I'm going to start losing it?" she wonders.

The suburban Tacoma, Washington, woman spent eight years caring for her parents, who died of Alzheimer's, and in a cruel coincidence, her husband's mother, who also died of the illness.

She said she was surprised to learn "a lot of other people have a double whammy like I do." No one knows how many people have two afficted parents, but experts say that as baby boomers age, there are likely to be more.

For now, there's no cure for the more than 26 million people worldwide estimated to have Alzheimer's, which gradually destroys memory and other mental abilities.

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