Research published online in Neurology, the medical journal of the American Academy of Neurology, has found that stroke is becoming more common among young people.
Study author Dr Brett Kissela explained it could be down to an increase in risk factors, such as obesity, diabetes and high cholesterol.
Scientists took into account the occurrences of stroke in candidates aged between 20 and 56 over three one-year long periods.
It found that the average age of stroke victims fell from 71 in 1994 to 69 in 2005, as well as the number strokes among under 55s accounting for the entire cases over the same time rising from 13 per cent to 19 per cent.
Although expanding waistbands may well be adding to this trend, Dr Kissela also pointed to technological advances that enable stroke to be identified sooner.
"Other factors, such as improved diagnosis through the increased use of MRI imaging may also be contributing."
Whichever the cause, and perhaps both, Dr Kissela reminded people that stroke risk can be cut by making healthy lifestyle choices in both diet and physical activity.
Figures from the NHS show that in England alone, more than 150,000 people suffer a stroke every year, making it the country's third biggest killer behind heart disease and cancer.
Although people over the age of 65 are at a greater risk of stroke, as many as a quarter of cases occur in people below this age.
Communications officer at the Stroke Association Dr Clare Walton described evidence of stroke increasing among young people as "alarming".
"This problem needs to be addressed now," she said. "In many cases a stroke can be prevented and everyone can reduce their risk by making a few simple healthy lifestyle changes."
Echoing the sentiments of Dr Kissela, Dr Walton directed people towards a balanced diet, frequent exercise and regular blood pressure checks to help reduce the threat of stroke.
