Researchers measured the blood pressure of more 4,000 adults in middle age (around age 50) and again in older age (around age 76). When the adults reached age 76, MRIs were used to assess blood vessel damage in the brain, and tests designed to gauge memory and thinking ability were administered. The results: older adults who’d had high blood pressure in midlife had smaller brains, less gray matter, and lower thinking and memory scores. Blood vessels are needed to deliver blood and nutrients to the brain, and high blood pressure creates stress that can weaken the vessels over time, says study co-author Lenore J. Launer, Ph.D. “High blood pressure may eventually lead to the brain getting less blood, which leads to tissue damage and tissue loss.”  Even older adults who’d managed to lower high midlife blood pressure were still shown to have brain lesions that could affect cognitive function. “Low blood pressure in old age is mainly due to the fact that there’s already been stiffening and changes in arteries,” says Launer. When the brain doesn’t get enough blood, that leads to tissue damage and tissue loss. In other words, if the early damage is serious enough, it may not be reversible.  All of this means one thing: To help your brain stay healthy, it’s best to keep your blood pressure from ever getting too high in the first place, says Launer. For tips and tricks to stay below the healthy 120/80 threshold, check out these proven ways to lower blood pressure naturally. More from Prevention: The Smoothie Cure For High Blood Pressure