A non-communicable disease (NCD) is a disease that is not transmissible directly from one person to another. NCDs include Parkinson's disease, autoimmune diseases, strokes, heart diseases, cancers, diabetes, chronic kidney disease, osteoarthritis, osteoporosis, Alzheimer's disease, cataracts, and others. NCDs may be chronic or acute. Most are non-infectious, although there are some non-communicable infectious diseases, such as parasitic diseases in which the parasite's life cycle does not include direct host-to-host transmission. The four main NCDs that are the leading causes of death globally are cardiovascular disease, cancer, chronic respiratory diseases, and diabetes. NCDs account for seven out of the ten leading causes of death worldwide. Figures given for 2021 are at least 43 million deaths due to NCDs, equivalent to 75% of non-pandemic-related deaths globally. Of these, at least 19 million were due to cardiovascular diseases; 10 million to cancers; 4 million to chronic respiratory diseases; and over 2 million to diabetes, including kidney disease deaths caused by diabetes. Risk factors such as a person's background, lifestyle and environment increase the likelihood of certain NCDs. Every year, at least 5 million people die because of tobacco use and about 2.8 million die from being overweight. High cholesterol accounts for roughly 2.6 million deaths and 7.5 million die because of high blood pressure.
Risk factors Risk factors such as a person's background; lifestyle and environment are known to increase the likelihood of certain non-communicable diseases. They include age, gender, genetics, exposure to air pollution, and behaviors such as smoking, unhealthy diet and physical inactivity which can lead to hypertension and obesity, in turn leading to increased risk of many NCDs. Most NCDs are considered preventable because they are caused by modifiable risk factors. The WHO's World Health Report 2002 identified five important risk factors for non-communicable disease in the top ten leading risks to health. These are raised blood pressure, raised cholesterol, tobacco use, alcohol consumption, and being overweight. The other factors associated with higher risk of NCDs include a person's economic and social conditions, also known as the social determinants of health. It has been estimated that if the primary risk factors were eliminated, 80% of the cases of heart disease, stroke and type 2 diabetes and 40% of cancers could be prevented. Interventions targeting the main risk factors could have a significant impact on reducing the burden of disease worldwide. Efforts focused on better diet and increased physical activity have been shown to control the prevalence of NCDs .
Environmental diseases NCDs include many environmental diseases covering a broad category of avoidable and unavoidable human health conditions caused by external factors, such as sunlight, nutrition, pollution, and lifestyle choices. The diseases of affluence are non-infectious diseases with environmental causes. Examples include:
Many types of cardiovascular disease (CVD) Chronic respiratory diseases (such as asthma and chronic obstructive pulmonary disease Diabetes mellitus type 2 Noise-induced hearing loss Lower back pain caused by too little exercise Malnutrition caused by too little food, or eating the wrong kinds of food (e.g. scurvy from lack of Vitamin C) Skin cancer caused by radiation from the sun Obesity
Inherited diseases
Genetic disorders are caused by errors in genetic information that produce diseases in the affected people. The origin of these genetic errors can be:
Spontaneous errors or mutations to the genome: A change in chromosome numbers, such as Down syndrome. A defect in a gene caused by mutation, such as Cystic fibrosis. An increase in the amount of genetic information, such as Chimerism or Heterochromia. Cystic fibrosis is an example of an inherited disease that is caused by a mutation on a gene. The faulty gene impairs the normal movement of sodium chloride in and out of cells, which causes the mucus-secreting organs to produce abnormally thick mucus. The gene is recessive, meaning that a person must have two copies of the faulty gene for them to develop the disease. Cystic fibrosis affects the respiratory, digestive and reproductive systems, as well as the sweat glands. The mucus secreted is very thick and blocks passageways in the lungs and digestive tracts. This mucus causes problems with breathing and with the digestion and absorption of nutrients.
Inherited genetic errors from parents: Dominant genetic diseases, such as Huntingtons, require the inheritance of one erroneous gene to be expressed. Recessive genetic diseases require the inheritance of erroneous genes to be expressed and this is one reason they work together.
Global health
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![Non-communicable disease: Total disease burden from non-communicable diseases, measured in DALYs (disability-adjusted life years) per year (data: IHME, Global Burden of Disease)[3]](https://upload.wikimedia.org/wikipedia/commons/thumb/4/42/Disease_burden_from_non-communicable_diseases%2C_OWID.svg/500px-Disease_burden_from_non-communicable_diseases%2C_OWID.svg.png?utm_source=en.wikipedia.org&utm_campaign=parser&utm_content=thumbnail)

