Risk Factors Raise the Chance of Non-Communicable Disease

1. A risk factor is something linked to an increased rate of a disease.
2. Being exposed to a risk factor does not guarantee the disease, but it raises the chance; a smoker is not certain to get lung cancer but is far more likely to than a non-smoker.
3. Risk factors can be aspects of a person's lifestyle, such as diet, alcohol or smoking.
4. They can also be substances in the body or environment, such as air pollution, asbestos or ionising radiation.
5. The more risk factors a person has, the greater their chance of developing a disease.

Correlation Is Not the Same as Cause

1. Data often shows a correlation between a risk factor and a disease, meaning the two change together.
2. A correlation on its own does not prove that the factor causes the disease.
3. Another explanation, or a third factor affecting both, could be behind the pattern.

A Causal Mechanism Proves the Link

1. To show a factor really causes a disease, scientists must find a causal mechanism, a biological process explaining how it does so.
2. A causal mechanism has been proven for some risk factors, but not for others.
3. For example, there is a proven causal link between smoking and lung cancer, because carcinogens in the smoke damage the DNA of lung cells.

Lifestyle Risk Factors and How They Harm the Body

1. Diet and cardiovascular disease
   1. A diet high in saturated fat raises blood cholesterol, which builds up as fatty deposits that narrow the coronary arteries and cause coronary heart disease.
2. Lack of exercise
   1. It contributes to obesity and high blood pressure, further raising the risk of cardiovascular disease.
3. Smoking
   1. Chemicals such as nicotine, carbon monoxide and tar damage the arteries and the alveoli, raising the risk of cardiovascular disease, lung disease and lung cancer.
4. Obesity
   1. Excess body fat, caused by a poor diet, reduces the body's sensitivity to insulin and is a major risk factor for type 2 diabetes.
5. Alcohol
   1. The liver breaks alcohol down into substances that are toxic to liver cells in high amounts, damaging the liver; alcohol also damages the neurones of the brain, reducing brain function.

Effects on Unborn Babies and the Role of Carcinogens

1. Smoking during pregnancy is harmful because carbon monoxide reduces the oxygen carried to the developing fetus, which can cause premature birth, low birth weight or stillbirth.
2. Drinking alcohol during pregnancy can damage the development of the fetus's brain.
3. Carcinogens, including ionising radiation such as X-rays and UV light, and chemicals in tobacco tar, damage DNA and cause the mutations that lead to cancer.

The Human and Financial Cost

1. Non-communicable diseases have a large human cost: a person may have a lower quality of life, be unable to work, and suffer poor mental health.
2. There is a financial cost too, as treatment is expensive for the individual and for healthcare providers such as the NHS.
3. Locally, communities support people who are ill; nationally, a sick workforce earns less and strains the economy.
4. Globally, non-communicable diseases cause more deaths than communicable ones, so their overall cost is the greatest.