The 2017 American College of Cardiology/American Heart Association hypertension guidelines eliminated “prehypertension” and defined high blood pressure as beginning at 130/80 mm Hg instead of 140/90 mm Hg. On this basis, it’s estimated that more than 45% of US adults 20 years and older have hypertension compared to 32% under the old guidelines.
The recommendations also called for earlier treatment with lifestyle changes and, in some patients, with medication. You can read more about these guidelines and recommendations here.
For research on the specific effects of hypertension on your brain, see: