Early life changes in brain activity and blood flow may be the reason why people tend to develop abnormally high blood pressure, or hypertension, researchers said.

High blood pressure is a condition in which the force of the blood against the artery walls is too high. It is also often called the silent killer because it typically has no symptoms until after it has done significant damage to the heart and the arteries.

In 90-95 per cent of people, high blood pressure has no identifiable cause, yet it is a risk factor for diseases of the brain, kidneys, heart, eyes, and other parts of the body, said a group of researchers at the Institute of Cytology and Genetics in Russia. 

For the study, published in Experimental Physiology, the team investigated physiological changes in a rat model called ISIAH, short for inherited stress-induced arterial hypertension.

These rats develop high blood pressure at four to six weeks of age, and this is sustained throughout their lifetime.The researchers compared the high blood pressure rats to a control group with normal blood pressure. 

As the mice in high blood pressure group grew older, changes in rates of blood flow in certain arteries were observed. In addition, changes were found in the brain activity, specifically a decrease in the prefrontal cortex -- the brain region associated with cognition, decision-making and working memory -- as well as an increase in the hypothalamus -- an area of the brain that controls mood and appetite.

"The study of early physiological changes may help clarify the cause of high blood pressure. Understanding this could help us prevent the disease early on," said led author Alisa Seryapina from the Institute of Cytology and Genetics.