Diseases do not just happen. Every disease has a cause, and once this cause is known, prevention is often the next most reasonable and cost-effective step. –Anon.
The United States is in the midst of enormous epidemics of chronic debilitating diseases, the most important of which are cardiovascular diseases, type-2 diabetes, mental disorders, and cancer. Attack rates of these diseases began increasing in the mid-20th century and have grown steadily since that time. They are major causes of death in older adults, and, in recent years, their numbers have been rising in younger age groups. Overall, these diseases are, by far, the major causes of disability and death in the United States.