What is the cause of high blood pressure and normal high pressure?

The normal systolic blood pressure (high pressure) in humans is 90-140 mmHg and the normal diastolic blood pressure (low pressure) is 60-90 mmHg. If the diastolic blood pressure is ≥90 mmHg and the systolic blood pressure is normal, we call it pure diastolic hypertension. Simple diastolic hypertension occurs most often in young and middle-aged people, who have relatively good elasticity and normal blood storage in their large arteries, and are therefore prone to having a simple elevated diastolic blood pressure with a normal systolic blood pressure.