People who have had "mini-strokes" -- aka transient ischemic attacks (TIAs)
- have a 50 percent chance of dying within nine years, a new study has found.

An Australian study published in Stroke: Journal of the American Heart Association compared mortality rates of people over 65 who had TIAs with others of the same age and gender who did not have TIAs. After nine years, about 50 percent of TIA patients died, compared to 30 percent of the control group.

Some 5 million people in the U.S. have had a TIA, according to the American Heart Association. Only half will report it to their doctors, the AHA says, and about 10 percent will go on to have a major stroke with 48 hours of the TIA.

Because the stroke-like effects of TIAs -- impeded movement, numbness, loss of speech -- are temporary and last just a few minutes or hours, it often isn't treated as a medical emergency.

Many don't realize the danger of TIAs, says study co-author John Worthington of Australia's University of New South Wales.

People who have had a TIA should go to the emergency room immediately and get a brain scan, he says. Patients will likely be started on aspirin therapy and other drugs to prevent blood clots.