Brain aneurysms can rupture and cause a serious form of haemorrhagic stroke called subarachnoid haemorrhage.

An abrupt interruption of blood flow in the brain causes an ischaemic stroke, while a bleed within the brain causes a haemorrhagic stroke. The former is the most common type of stroke, making up 80 per cent to 85 per cent of all strokes here.

Brain aneurysm-related stroke or subarachnoid haemorrhage is one of two types of haemorrhagic stroke. It is uncommon, comprising only 6 per cent of stroke cases, said Dr Teo Kejia, an associate consultant in the Division of Neurosurgery at National University Hospital.

A number of factors can increase one's risk of developing a brain aneurysm, a weak bulging spot in a blood vessel in the brain. Smoking is one of them.

Uncontrolled high blood pressure can also place increased pressure on the walls of the blood vessels inside the brain, thus increasing a person's chances of developing an aneurysm, said Dr Teo.

Having a first-degree relative, such as a parent, brother or sister, with a history of a brain aneurysm also puts you at risk of developing one compared with someone with no such family history. "However, this increased risk is small," Dr Teo said.

Smoking and high blood pressure are also risk factors for all types of stroke, the fourth most common cause of death in Singapore, accounting for 10 per cent of all deaths.

Indeed, the leading modifiable risk factor for stroke is high blood pressure, said Associate Professor Deidre Anne De Silva, a senior consultant at National Neuroscience Institute's department of neurology.

"Stress can be a factor for high blood pressure and thus, high stress may lead to poor blood pressure control. In addition, stress can indirectly lead to poor lifestyle practices such as unhealthy diet and lack of exercise, which in turn can increase stroke risk."

Apart from smoking, other modifiable risk factors are high cholesterol, diabetes, obesity and a sedentary lifestyle, said Prof De Silva, who is also president of the Singapore National Stroke Association.

Joyce Teo