A correlation between genetic high blood pressure and early cognitive decline has been found by Australian researchers.

The research, published by University NSW scientists on Thursday, indicates "subtle but real" changes in cognition from younger patients experiencing high blood pressure compared to previous findings of patients later in life.

"This research is groundbreaking," lead author Matt Lennon said.

The study used data from 448,575 participants and measured genetic blood pressure risk by amount rather than a direct measurement of blood pressure itself.

Their findings suggest future strategies to combat hypertension could be more personalised based on an individual's genetic risk for high or low blood pressure, as well as their age and sex.

The research also found that for those in their 60s, marginally higher blood pressures may be optimal for maintaining cognitive ability, compared to those in their 40s and 50s.

"The relationship of blood pressure with brain function is complex. Those with a genetic predisposition to higher blood pressure had significantly better reaction time, particularly in males," Dr Lennon said.

"We know that high blood pressure is remarkably common in the community, especially among males, and part of this may be explained by the fact that there are some genetic advantages to this in reaction time.

"Measuring how quickly an individual responds to a stimulus, although ones that come at the long-term costs of poorer cognitive health and greater risks of heart attacks and strokes."

High blood pressure is understood to affect one billion people worldwide and is the single most prevalent risk factor for cognitive decline.

"It is critical we understand the complexities of this modifiable risk factor for dementia, particularly in people in their 40s and 50s, to develop strategies of earlier intervention and prevention of cognitive decline and dementia," co-author Perminder Sachdev said.