© PARaised levels of alcohol and drug consumption increase the risk of stroke.
Stroke deaths in England have halved in the past 10 years thanks to better treatment, research suggests.
The number of strokes has fallen among older people, who have been the target of medical interventions to control their blood pressure, such as prescription of statins. But those younger than 55 are having more strokes, probably as a result of obesity and type 2 diabetes.
One of the authors of the work, Olena Seminog, of the Nuffield department of population health at Oxford University, said reducing deaths was good but preventing strokes would be better still.
"This is very good news but we should still appreciate the importance of prevention because people who have a stroke do have a high chance of surviving now, but many survivors will still [have] a lot of disability," she said. "That can be sometimes severe. It will have an impact on their lives and their families' lives."
© Getty3D illustration of the of the blood vessels in the human brain and cerebrovascular disease or hemorrhagic stroke and causes of a brain stroke.
The study, published in the British Medical Journal, shows that the overall number of strokes fell by 20% between 2001 and 2010. After adjusting for age and other potential factors, stroke deaths decreased by 55% during the study period.
Most strokes are in older people, often in their 80s, which is where most of the prevention effort has been. Of 425,000 strokes in the first decade of the 21st century, about 33,000 were in people under the age of 55.
The increase was seen in the 35-54 age group, with no change observed in those younger than that. "A lot of this increase is down to increasing rates of obesity and type 2 diabetes," said Seminog. "It is a worrying situation. It shows how obesity affects major conditions like stroke." Obesity is linked to raised blood pressure.
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In that age group there were raised levels of alcohol and drug consumption, which increase people's risk. Smoking doubles the risk of stroke, but rates have been declining. Salt consumption, which raises blood pressure, has also come down, although experts say it needs to be lower still.
Older people tend to have their blood pressure monitored by the GP and will be advised to take medication to bring it down and statins to reduce the cholesterol deposits that can clog the arteries.
The data came from hospital and mortality records for all residents of England aged 20 and older who were admitted to hospital with stroke or died from stroke between 2001 and 2010. They included both kinds of stroke - those caused by clots obstructing blood flow to the brain and also bleeds in the brain.
The team based their findings on 947,497 stroke events in 795,869 people, including 337,085 stroke deaths. The average age at onset of stroke was 72 for men and 76 for women, and the average age of those who died from stroke was 79 for men and 83 for women.
Most of the decline - 78% in men and 66% in women - occurred because better treatment meant people did not die. There have been campaigns to make people aware of the symptoms of stroke so that they get medical attention and, where appropriate, clot-busting drugs quickly.
The remaining 22% in men and 34% in women was found to be due to a reduction in stroke event rates, which decreased by 20% overall.
The authors pointed out that the NHS was spending about 5% of its budget on caring for people who have been affected by stroke. "By focusing on prevention and reducing the occurrence of stroke, major resources can be conserved," they said.