They said residents of one Texas county who lived in neighbourhoods with the highest number of fast-food restaurants had a 13 per cent higher risk of experiencing a stroke than those in neighbourhoods with the fewest such restaurants.

The study, presented at the American Stroke Association's International Stroke Conference, does not prove living near fast-food restaurants raises the risk of stroke, but it does suggest the two are linked in some way.

"The data show a true association," Dr Lewis Morgenstern of the University of Michigan's stroke program, who led the study, said in a statement.

But he said it is not clear whether being surrounded by fast-food means you eat more of it, or that it is simply a sign of an unhealthy neighbourhood.

"We need to start unravelling why these particular communities have higher stroke risks," Morgenstern said. "Is it direct consumption of fast food? Is it the lack of more healthy options? Is there something completely different in these neighbourhoods that is associated with poor health?" he asked.

For the study, Morgenstern and colleagues examined stroke data on residents of Nueces County, Texas, between January 1, 2000 and June 2003.

During that time, county residents suffered a total of 1,247 ischemic strokes, the most common type caused by a blocked artery that chokes off bloodflow to the brain.

They used US Census Bureau demographic and socioeconomic data to determine the number of fast-food restaurants in each neighbourhood. And they compared neighbourhoods with the lowest number of fast-food restaurants – fewer than 12 – to those with the highest number – more than 33.

They found the relative stroke risk rose one per cent for each fast-food restaurant in a neighbourhood.

Morgenstern said public health experts should consider fast-food dense neighbourhoods as prime areas for stroke prevention programs.

"We need to consider targeting communities that have a lot of fast-food restaurants as places where we can improve health," Morgenstern said.

Prior studies have found a link between fast-food restaurants, heart risks and obesity, leading consumer groups to push for laws such as July's moratorium on new fast-food restaurants in certain Los Angeles neighbourhoods.

The food industry often maintains that a lack of exercise is more to blame.