Strokes are becoming more common at a younger age, with about one in five victims now below the age of 55, a new study has found. 

The study followed 1.3 million people in a US region and found 19 per cent of those experiencing a stroke in 2005 were in this age group, up from 13 per cent in 1993. "The reasons for this trend could be a rise in risk factors such as diabetes, obesity and high cholesterol," said study author Brett Kissela from University of Cincinnati College of Medicine in Ohio. 

"Other factors, such as improved diagnosis through the increased use of MRI imaging may also be contributing. Regardless, the rising trend found in our study is of great concern for public health because strokes in younger people translate to greater lifetime disability," said Kissela in a statement. 

Researchers looked at occurrences of strokes in people between the ages 20 and 54 in the Greater  Cincinnati/Northern Kentucky area during three separate, one year-long periods between July of 1993 and June of 1994, and the calendar years of 1999 and 2005.

Only first ever strokes were included in the analysis. The study found that the average age of people who
experienced stroke fell from 71 years in 1993 and 1994 to 69 years in 2005. The study found that strokes among people under 55 made up a greater percentage of all strokes over time, growing from about 13  per cent in 1993-94 to 19 percent in 2005.

"The good news is that some of the possible contributing factors to these strokes can be modified with lifestyle changes, such as diet and exercise. "However, given the increase in stroke among those
younger than 55, younger adults should see a doctor regularly to monitor their overall health and risk for  stroke and heart disease," said Kissela. 

The study was published in the medical journal of the American Academy of Neurology.