Can we regulate guns being sold to the "mentally ill?"

"Mentally ill" is a huge category and an incorrect term. Mental disorder is the proper term. . So which mental disorder? The agoraphobes? The anxiety ridden? The OCD? Personality disorders? The schizophrenics? The severely depressed? It's convenient to blame people with a mental disorder for our latest problem.  But the problem is easy access to guns by anyone sane or insane or for that matter just plain stupid . . .  Everyone has rights in this country and not just second amendment rights.