Key Questions Remain

Williamson also knows the results won’t come without controversy or questions.

For example, while high blood pressure in midlife clearly raises your odds of having dementia, several studies have found that high blood pressure may not be as bad for the brains of people who get it at older ages.

Aggressive management of blood pressure in the elderly may also make side effects like falls more likely.

Williamson says his findings challenged previous research. About 28% of patients in the study were over age 75 when the study started. They saw the same reduction in risk as younger patients, he says.

He says previous studies were observational and may have mischaracterized the risks and benefits to older adults.

“Until you test, you don’t really know. Observation is not causation,” he says. “So now we can say in a randomized trial, the highest form of evidence, this benefits older people and younger people,” he says.