The study here shows that given a population of individuals with hypertension, those who manage to control their high blood pressure go on to suffer lesser degrees of cognitive decline. Numerous mechanisms may link hypertension to structural damage in the brain: degeneration of the blood-brain barrier, allowing inappropriate molecules and cells into the brain, leading to neuroinflammation and other effects; rupture of capillaries causing microbleeds, effectively tiny strokes; outright pressure damage in tissue very close to small vessels that directly harms brain cells; and so forth. This damage adds up, but note that it is a set of physical issues that stem from increased pressure rather than the biochemistry that causes that increased pressure. Therefore these downstream issues can be suppressed by any method that reduces blood pressure consistently, even though that will leave the underlying damaged biochemistry to continue to cause other issues.
High blood pressure appears to accelerate cognitive decline among middle-aged and older adults, but treating high blood pressure may slow this down, according to a preliminary study. According to the American Heart Association's 2017 Hypertension Guidelines, high blood pressure affects approximately 80 million U.S. adults and one billion people globally. Moreover, the relationship between brain health and high blood pressure is a growing interest as researchers examine how elevated blood pressure affects the brain's blood vessels, which in turn, may impact memory, language, and thinking skills.
In this observational study, the researchers analyzed data collected on nearly 11,000 adults from the China Health and Retirement Longitudinal Study (CHARLS) between 2011-2015, to assess how high blood pressure and its treatment may influence cognitive decline. High blood pressure was defined as having a systolic blood pressure of 140 mmHg or higher and a diastolic blood pressure of 90 mmHg or higher, and/or taking antihypertensive treatment. According to guidelines of the American Heart Association, high blood pressure is defined as 130 mmHg or higher or a diastolic reading of 80 mmH or higher.
Researchers interviewed study participants at home about their high blood pressure treatment, education level, and noted if they lived in a rural or urban environment. They were also asked to perform cognitive tests, such as immediately recalling words as part of a memory quiz. Among the study's findings: (a) Overall cognition scores declined over the four-year study; (b) Participants ages 55 and older who had high blood pressure showed a more rapid rate of cognitive decline compared with participants who were being treated for high blood pressure and those who did not have high blood pressure; (c) The rate of cognitive decline was similar between those taking high blood pressure treatment and those who did not have high blood pressure.