During the 20th century, the burden of disease shifted quite significantly to be one from changes in our lifestyle. During the 1900's, pneumonia and tuberculosis were the leading causes of death, but during the 2010, the cause shifted to heart diseases, cancer, etc.

We all learn in school that the heart is constantly responding to orders sent by the brain in the form of neural signals. The heart signals have a effect on brain function like influencing emotional processing as well as higher cognitive faculties like attention.