Type A and Type B personality theory

Interestingly the entry doesn't mention that the original finding was linked to an observation about the worn out chairs in the doctor's reception.

The cardio patients (type A's) wore out the front edges of the chairs because they were sitting on the edge all the time.

Also of interest is Type D personality which has been correlated with cardiovascular issues and poor medication adherence: https://en.wikipedia.org/wiki/Type_D_personality

Type A here...