Young people who use cocaine and amphetamines were warned yesterday that they may be putting themselves at increased risk of a brain haemorrhage.

Young people who use cocaine and amphetamines were warned yesterday that they may be putting themselves at increased risk of a brain haemorrhage.

Doctors from the National Hospital for Neurology and Neurosurgery in London said the growing pandemic of cocaine use in Western society is overshadowing the traditional risk factors for brain haemorrhage - or stroke - such as high blood pressure. Over a period of seven months, the research team treated 13 patients with an average age of 31 who had suffered strokes after taking the drugs. Strokes are normally very rare in this age group.

To their surprise, they found that nine out of the 10 patients fit enough to have a brain examination had an abnormality of the blood vessels in the brain, including six with a cerebral aneurysm (a balloon-like swelling in a blood vessel).

Cocaine and amphetamines are thought to cause brain haemorrhage as a result of a surge in blood pressure triggered by their ingestion. People with abnormal blood vessels in their brain, such as a cerebral aneurysm, are at the greatest risk. However, it is also possible that the drug taking caused the deformed blood vessels, said Andrew McEvoy, who led the research, published in the British Medical Journal. .

"These drugs may be leading to abnormalities in the brain that are giving rise to strokes. It is otherwise extremely unusual for patients of this age to [have] brain haemorrhages," he said.

The warning came as ministers announced a £2.4m research programme to develop strategies to tackle drug misuse. A total of 14 projects have been commissioned, including a study of the the impact of drug misuse on young people's psycho-social development.

Gisela Stuart, a Health minister, said: "Drug problems cause immense harm to individuals and to society. The Government is committed to a 10 year strategy for tackling drugs misuse and there is a pressing need for high-quality research to support the objectives of the strategy."

Dr McEvoy and colleagues say in the BMJ that doctors should be aware of the link between illegal drug use and stroke and investigate patients accordingly. They should try to find out if they had been using illegal drugs and, if they had, refer them for an angiogram to discover if they had an abnormality of blood vessels in the brain.

Despite the widespread use of ecstasy, there seem to be few neurological complications associated with the drug, though the authors urge caution anyway. Amphetamine use has been recognised as a cause of stroke since 1945 and evidence has grown in recent years that cocaine has a similar effect.

One study in Connecticut found 59 per cent of people who died from stroke and had a post mortem examination had been taking cocaine.

The British authors write: "A history of severe headache immediately after using amphetamine, ecstasy or cocaine should alert doctors to the possibility of intracerebral haemorrhage. [A brain scan] should always be performed when severe headache or altered consciousness, or both, occur in relation to use of these compounds."

Clubbers have been warned to beware of the dangers of a drug known as GBH (ganmma hydroxybutyrate), also called "liquid ecstasy," especially when mixed with alcohol. The drug has become popular because it is not illegal to possess and is relatively cheap. Overdoses are common because the difference between an effective dose and an overdose is slight. It can cause convulsions and coma.