People with high blood pressure that is left untreated may have an increased risk of developing a bleed on the brain, a new study has found.

High blood pressure, also known as hypertension, is a major cause of heart attack, stroke, kidney failure and premature death. However, it rarely carries any signs or symptoms. In fact, a person can look and feel well even if they have it.

A study of over 4,600 patients has found that if left untreated, high blood pressure can significantly increase the risk of a intracerebral haemorrhage, which is a type of stroke caused by a weakened blood vessel that ruptures and then bleeds into the tissue of the brain.

The US researchers found that compared to people without high blood pressure, those with untreated high blood pressure were between nine and 11 times more likely to suffer a brain bleed.

For those with high blood pressure, those with untreated high blood pressure were between 3.7 and 5.5 times more likely to suffer a brain bleed.

Overall, the risk was higher among racial minorities than white people, but it was unclear why this was the case and poorer access to medical care was suggested as a possible reason.

"It's important to be aware of having high blood pressure in the first place, and once diagnosed, to have it treated appropriately," commented the study's lead author, Dr Kyle Walsh, of the University of Cincinnati.

The only way to know if you have high blood pressure is to have it checked by a doctor or pharmacist.

Details of these findings were presented at the American Stroke Association's International Stroke Conference 2016 in Los Angeles.