Charlie Sykes points out this article on a new "disease" called "intermittent explosive disorder":

To you, that angry, horn-blasting tailgater is suffering from road rage. But doctors have another name for it — intermittent explosive disorder - and a new study suggests it is far more common than they realized, affecting up to 16 million Americans.
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Road rage, temper outbursts that involve throwing or breaking objects and even spousal abuse can sometimes be attributed to the disorder, though not everyone who does those things is afflicted.

Of course this isn't new.  We've known about this a very long time.  We've even had videos about it, dating back to 1950, when our good friend Goofy was featured in Motor Mania.  In it, he turns from a mild mannered executive named Mr. Walker to a Dr. Jekyll type named Mr. Wheeler whenever he gets behind the wheel.  Then magically, after stepping out of his car he returns back to Mr. Walker.  To this day, this is one of my favorite Walt Disney cartoons.

Even Disney knew about this in 1950!  And we're just writing studies about it now?  Talk about being behind the times.