Image caption People over 65 are normally at the greatest risk of a stroke

More children and young adults in the US are having strokes - with unhealthy lifestyles being a likely cause, scientists have said.

Researchers at the US Centers for Disease Control and Prevention analysed hospital data on up to eight million patients a year between 1995 and 2008.

In Annals of Neurology, they say stroke rates in five to 44-year-olds rose by about a third in under 10 years.

Higher blood pressure, diabetes and obesity were common in stroke patients.

The researchers looked at figures for ischemic stroke, due to blood clots, and haemorrhagic stroke, which is caused by bleeding on the brain.

The rate of ischemic stroke increased by 31% in five to 14-year-olds, from 3.2 strokes per 10,000 hospital cases to 4.2 per 10,000.

There were increases of 30% for people aged 15 to 34 and 37% in patients between the ages of 35 and 44.

In all age groups the increase was greater in men than in women.

Figures for haemorrhagic stroke showed decreases in age groups except the five to 14-year-olds, but the researchers said: "The increase in ischemic stroke far outweighs the decreases."

Health initiatives

The report said the prevalence of hypertension, obesity and tobacco use had increased in stroke patients.

Stroke Symptoms The face can drop on one side - unable to smile or eye might droop

Unable to lift one or both arms

Slurred or garbled speech Source: NHS choices

More than half of 35 to 44-year-olds who had an ischemic stroke also had hypertension.

"Urgent public health initiatives are needed to reverse trends in modifiable risk factors associated with stroke in adolescents and young adults," the report concludes.

Dr Lorna Layward, from the Stroke Association in the UK, said: "People usually associate strokes with older people, but a quarter of all strokes happen to people of working age, and around 400 children have a stroke every year in the UK.

"We know that high blood pressure is the biggest risk factor for stroke, along with other factors such as obesity, diabetes, poor diet and smoking.

"This research emphasises the need for people to be aware that stroke can affect younger people, and for all of us, regardless of our age, to check our blood pressure and adopt a healthy lifestyle."