Sadly, although the national background check system is set up for that, most states refuse to add people to the ban list, citing privacy concerns.
This is understandable. I'm sure everyone's heard about that awful newspaper in New York that published a list of handgun permit holders overlaid on google maps? Giving the addresses of all handgun owners in the state, simply to intimidate them?
Imagine you had a psychotic episode at the age of 22, and were committed by a court for involuntary treatment. Until you have your rights restored, you can no longer own a gun, and will be flagged as "denied" by the background check system.
But what happens when some asshole reporter FOIAs the system and reveals the names of everyone who has ever been involuntarily committed?
This is one reason why states are extremely reluctant to give the system this information.
Unfortunately almost all "gun control" legislation is written by people who are both ignorant and rabidly anti-gun--simply to push for banning more and more types of weapons, with the ultimate goal of turning us into England or Australia.
One of my favorite Oleg Volk propaganda pictures: