Non-communicable Diseases and their Causes

Diseases of the heart and blood vessels, including coronary heart disease, where the arteries that supply the heart become narrowed, as well as strokes and high blood pressure.

Many forms of cancer, such as lung cancer, bowel cancer, breast cancer and skin cancer, caused by uncontrolled cell division.

Lung diseases include emphysema and chronic bronchitis, which are often caused by smoking. Liver diseases include cirrhosis, which is often caused by alcohol.

Obesity and type 2 diabetes, which can be caused by eating too much, and deficiency diseases, which are caused by a lack of a nutrient, such as scurvy, which is caused by a lack of vitamin C.

You inherit alleles that make some diseases more likely, for example a tendency to a high level of cholesterol in the blood.

What you eat and drink, how much you exercise, and whether you smoke or drink alcohol have large effects.

Air pollution, radiation, workplace chemicals such as asbestos and the amount of sun that you get can all raise the risk.

The risk of most diseases rises with age. Being obese raises the risk of heart disease, type 2 diabetes and cancer.

A risk factor is something that increases the chance of getting a disease. It does not mean that a person will definitely get it, and a person with no risk factors can still become ill.

The risk factors can multiply each other. A person who smokes and has high blood pressure has a much higher risk of a heart attack than the effect of each factor added together.

A correlation is a link between two variables. A scatter diagram can show a positive correlation, where both rise together, a negative correlation, where one rises as the other falls, or no correlation.

Two things can rise together without one causing the other. For example, ice cream sales and sunburn both rise in summer, because of the weather.

A cause is more likely if the correlation is found in many large studies, if the effect is bigger with a greater dose, and if there is a scientific explanation of how the factor could cause the disease.

Larger samples, which are chosen at random, give more reliable results than small ones.

Rates of disease can differ between areas of a town, because of differences in income, access to fresh food and places to exercise, and the number of people who smoke.

These diseases cost a country a great deal. In the UK the NHS spends billions of pounds each year on treating diabetes, heart disease and cancer. Governments try to reduce the risk by laws, such as the ban on smoking in public places, and by campaigns.

Non-communicable diseases are rising fastest in low and middle income countries, as diets change to include more processed food, and as more people smoke and live in cities.