That driver riding your bumper on Highway 9 this morning has a reason for the madness. He's not late for work or intoxicated. He has a mental disorder that often manifests itself when he gets behind the wheel.

That's the findings of a new study that suggests up to 16 million Americans suffer from "intermittent explosive disorder," a chemical imbalance that causes outbursts that are way out of proportion to the situation at hand. That's usually the case with road rage. How many seconds does someone gain by such behavior and what are the potential dangers to others?

The Associated Press reports road rage, temper outbursts that involve throwing or breaking objects and even spousal abuse can sometimes be attributed to the disorder. The study, funded by the National Institute of Mental Health, suggests five to seven percent of the population suffers from IED.

The average number of lifetime attacks is 43 with a property damage bill of $1,359 per person. The study involved face-to-face interviews with more than 9,000 adults who answered questionnaires in 2001-2003.

Treatments range from behavior therapy, much like that of anger management and anti-depressants that target serotonin receptors in the brain are often helpful. There's another one that works just as well: Take away their drivers' licenses.

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