In most individuals, the systolic pressure increases sharply with age, whereas the diastolic pressure increases until about age 55 years and then declines. Older individuals with an elevated systolic pressure have a condition known as isolated systolic hypertension (ISH). When the systolic pressure is high, blood vessels become less flexible and stiffen, leading to cardiovascular disease and kidney damage. Research indicates that treating ISH saves lives and reduces illness. The treatment is the same for ISH as for other forms of hypertension.