There is no exhaustive list of chronic diseases, but the most important ones are cardiovascular diseases, cancers, chronic respiratory diseases and diabetes. They are actually the leading global causes of death worldwide. Other chronic diseases, such as mental illnesses, consequences of injuries, osteoarthritis, neurological diseases, liver diseases and chronic kidney diseases contribute substantially to disability. Chronic diseases are a heterogeneous group, but many of them share the same underlying causes.

Many direct causes and risk factors for chronic disease, such as high blood pressure, diabetes and raised blood lipid levels are linked to lifestyle factors, such as smoking, unhealthy diet, lack of physical or alcohol consumption. Also environmental factors, such as air pollution and exposure to toxic substances and infectious diseases, such as hepatitis can play a role in the development of chronic diseases. The context only adds to the complexity: urbanisation, ageing process or globalisation (increasing interaction of people through the growth of the international flow of money, ideas, culture, but also e.g. of lifestyle habits) Globalisation has e.g contributed to the increasing smoking trend in developing countries, which is one of the reasons why also in these countries ever more people suffer from chronic diseases).

The terms “chronic diseases” and “non-communicable diseases” are often interchanged, but they are not synonyms since they are grounded in different classification systems:

• the difference between communicable (infectious) diseases and non-communicable diseases is based on the underlying causes
• chronic and acute conditions can be distinguished from one another by their effects.

In fact, certain non-communicable diseases are acute in nature, e.g. acute appendicitis and injuries. Chronic diseases, on the other hand, include certain communicable diseases, such as HIV/AIDS or chronic hepatitis. 

Highly cost effective interventions are available to prevent and control common chronic diseases. These usually consist both on population strategies such as tobacco control or population wide restriction of salt on one hand, and strategies focussing on specific target groups, such as treatment of people at high risk of cardiovascular disease on the other hand.

Life style changes are essential to address the epidemic of chronic diseases. Campaigns to motivate individuals to stop smoking, reduce alcohol consumption, practice more physical activity or promote healthy eating can largely contribute to reduce the development or progress of most chronic diseases. Also, societal factors often determine behaviours, e.g. the publicity for or the pricing of products, such as cigarettes, alcohol and fast food, or the high levels of saturated and trans-fats, sugars and salt hidden in processed foods. This is where policy makers can intervene.