Usually paired with reduced knowledge about the dangers of chain smoking.
But isn't that a good thing? Obviously, being a healthy, fully realized adult means a certain amount of self-awareness. Knowledge of who you are, how you affect other people, and all that -- nobody wants to be that douche in the Camaro who blithely cuts people off in traffic and then assumes all the honking is them letting him know his Camaro is awesome (which he ignores, because dude, he already knows). But it appears that too much self-awareness is literally fatal. This is referred to as the self-absorption paradox.
Psychologists think this is because there are two ways you can dwell on your life: self-reflection (analyzing your thoughts, feelings, and actions to learn how to get better) and self-rumination (endlessly focusing on all the ways you suck). The former makes you healthier and happier (and more popular with others), while the latter makes you miserable, to the point where you hate the hypothetical happy person above for not joining you in the abyss. If you're asking how you do one without falling into the other, well, let us know if you figure it out. Or go write a self-help book and become a millionaire. At the moment, most people can't regulate their self-hatred without some kind of chemical assistance.
It appears (from our unscientific examination of the problem) that part of the problem is ...