Having a mini-stroke can reduce a person's life expectancy by up to 20 per cent, a new study suggests.

In a mini-stroke — known in the medical world as a transient ischemic attack (TIA) — the blood flow to part of the brain is temporarily blocked or reduced.

With a mini-stroke, the initial symptoms of blurred vision, numbness, sudden headache, and difficulty speaking or walking (similar to stroke symptoms) soon disappear. In a stroke, the brain incurs permanent damage because the blood flow stays blocked.

Having a history of TIA has long been known as a risk factor for strokes. This new study suggests there are also serious impacts on life expectancy. 

Researchers identified more than 22,000 people hospitalized in Australia because of a mini-stroke between 2000 and 2007 and tracked their medical records for at least two years. Using death registry data from 2009, they then compared this population to those in the general population. Their findings were startling.

'The risks faced by TIA patients go well beyond their early stroke risk' —Melina Gattellari, study author

For those patients who'd had a mini-stroke in 2000, their survival rate nine years later was 20 per cent lower than the population as a whole.

Survival rates at the one-year and five year marks were also lower. A year after a mini-stroke, 91.5 per cent of the TIA patients were still alive, versus 95 per cent survival among the general population. Five years after a mini-stroke, 67.2 per cent of the TIA group was alive, compared to 77.4 per cent of the general population. 

The statistical analysis drives home that adults with a history of TIA need to look after their health or risk a dramatically shortened lifespan.

"Our findings suggest that patients and doctors should be careful to intensely manage lifestyle and medical risk factors for years after a transient ischemic attack," said Melina Gattellari at the University of New South Wales' School of Public Health and Community Medicine.

Further data analysis showed that patients who'd had a mini-stroke before the age of 50 did not show a markedly greater risk of death than the general population. But for those who had a TIA after age 65 faced "significantly reduced" life expectancy.  

"We thought the reverse may be true — that survival rates in older TIA patents would be more like other older people, who, although not affected by TIA, are affected by other conditions that may influence their survival," Gattellari said. "But even a distant history of TIA is a major determinant of prognosis."

"Certainly, the risks faced by TIA patients go well beyond their early stroke risk," she said.

The researchers say their study was the first to "comprehensively quantify the impact of hospital-diagnosed TIA on life expectancy."

The study was published in Stroke: Journal of the American Heart Association.