High Blood Pressure
High blood pressure is also known as hypertension. Blood pressure is the amount of force exerted against the walls of the arteries as blood flows through them.

In the United States, approximately 85 million people have high blood pressure - about 1 in every 3 adults over 20, according to the American Heart Association (AHA).

The National Institutes of Health (NIH) estimate that about two-thirds of people over the age of 65 in the U.S. have high blood pressure.

If left untreated or uncontrolled, high blood pressure can cause many health problems. These conditions include heart failure, vision loss, stroke, and kidney disease.
Chapter 1. Causes

The heart is a muscle that pumps blood around the body. Blood that has low oxygen levels is pumped towards the lungs, where oxygen supplies are replenished. The oxygen rich blood is then pumped by the heart around the body to supply our muscles and cells. The pumping of blood creates pressure.

If a person has high blood pressure, it means that the walls of the arteries are receiving too much pressure on a constant basis. The causes of high blood pressure are divided into two categories:

Essential high blood pressure: This has no established cause.

Secondary high blood pressure: There is an underlying cause.
Chapter 2. Even though there is no identifiable cause for essential high blood pressure, there is strong evidence linking some risk factors to the likelihood of developing the condition.

Most of the causes below are risk factors for essential high blood pressure. There are also examples of secondary high blood pressure:
1) Age. The older you are the higher your risk of having high blood pressure.
2) Family history. If you have close family members with hypertension, your chances of developing it are significantly higher. An international scientific study identified eight common genetic differences that may increase the risk of high blood pressure.
Chapter 3.
3) Temperature. A study that monitored 8,801 participants over the age of 65 found that systolic and diastolic blood pressure values differed significantly across the year and according to the distribution of outdoor temperature. Blood pressure was lower when it got warmer, and rose when it got colder.
4) Ethnic background. Evidence indicates that people with African or South Asian ancestry have a higher risk of developing hypertension, compared to people with predominantly Caucasian or Amerindian (indigenous of the Americas) ancestries.

Chapter 4. 5) Obesity and overweight. Both overweight and obese people are more likely to develop high blood pressure, compared to people of normal weight.

6) Some aspects of gender. In general, high blood pressure is more common among adult men than adult women. However, after the age of 60 years both men and women are equally susceptible.
7) Physical inactivity. Lack of exercise, as well as having a sedentary lifestyle, raises the risk of hypertension.
Chapter 5. 8) Smoking. Smoking causes the blood vessels to narrow, resulting in higher blood pressure. Smoking also reduces the blood's oxygen content so the heart has to pump faster in order to compensate, causing a rise in blood pressure.

9) Alcohol intake. People who drink regularly have higher systolic blood pressure than people who do not, according to researchers. They found that systolic blood pressure levels are about 7 millimeters of mercury (mmHg) higher in people who drink frequently than in people who do not drink.

Other ones: 10) High salt intake. 11) High fat diet. 12) Mental stress. 13) Diabetes. 14) Psoriasis. 15) Pregnancy.
Chapter 6. Signs and symptoms

Most people with high blood pressure will not experience any symptoms. It is often known as the "silent killer" for this reason. However, once blood pressure reaches about 180/110 mmHg, it is considered a medical emergency known as a hypertensive crisis. At this stage, symptoms will show, including:

Headache – nausea – vomiting – dizziness - blurred or double vision - nosebleeds - palpitations, or irregular or forceful beating of the heart - breathlessness