Towards the end of his life, David McClelland helped drive the development of psychoneuroimmunology -- or the study of how psychology influences health, through the intermediation of neurochemistry. Mind over health, as it were.
David once had lunch at the Faculty Club at Harvard with a Nobel-prize-winning immunologist and said, "you know, I'm kind of getting into your field. I'm looking at how the mind affects the immune system." The Nobel laureate looked at him, and, without batting an eye, said "the mind doesn't affect the immune system." Needless to say, I'm going to disagree here!
I'm picking out various studies that may be of interest--the first, and probably the simplest, is the influence motive and cardiovascular health.
This study looked at the Power/Influence motive and blood pressure. There is a relationship, but it requires a little explanation.
We talk about "motive profiles" when you have a certain combination of shapes, for example "high power, low affiliation." The Leadership Motive Profile is high Power motive (above the median), low Affiliation motivation, and moderate Achievement motivation. For short, think of it is high Influence, everything else much lower. If this is combined with Activity Inhibition--the ability to channel motivational energy in a mature way, or to restrain your impulses--it leads to someone who can think about influencing people instead of pushing them around: a leader, not a bully.
This happens to be the best motive profile for managers and organizational leaders, for obvious reasons: these are mature people (emotionally speaking) enjoying influence and thinking of positive ways to influence others.
Unfortunately, it also correlates with higher levels of epinephrine and norepinephrine (AKA adrenaline and noradrenaline), which in turn correlates directly with higher blood pressure. In fact, the relationship is quite strong. (See McClelland, D. C. Inhibited power motivation and high blood pressure in men. Journal of Abnormal Psychology, 1979, 88, 182-190.)
What does this mean? It means that someone who thinks about influence but restrains themselves from impulsive action is more likely to have a cardiovascular incident if they don't take care of themselves! Especially men: I once heard the 50-50 rule: 50% of men with this profile have a cardiovascular incident by the time they are fifty years old. Yow!
Think about it this way: these are people sensitive to the people around them and very alert to how others treat them as well as how they treat others. To manage people means being patient, restrained, thoughtful--and holding in your temper. Whaddya know--your blood pressure goes up!
So are we killing off the best leaders? Well, that assumes you aren't doing something about it. The problem with the old "Type A" concept (besides the idea that it is a personality type invented by a cardiologist) is that a Type A person thinking about health would get just as obsessed about managing health as anything else! What knowing this means is that you can manage your health better. Or so one hopes...
I wonder, given that this is exactly the profile of most published writers I studied, whether writers are more prone to heart attacks, but of course writers also get to kill off people who annoy them in their books. Presumably this lowers tension considerably!
It's an empirical question, but not one answered, to my knowledge...