First,, on the FBI's bureau of crime statistics, gun violence is way down, it is just highly publicized because it makes for dramatic news. People with anxiety disorders would be much more likely to freeze up in a gun confrontation, something that happens to people that are disorder free all to often.
People aren't getting more crazy. We just are calling more people crazy. Someone who used to be called eccentric is now suffering OCD. A collector is now a hoarder. We are creating anxiety disorders just to give people an excuse to act odd. There are some anxiety disorders that do require management, but no more than 50 years ago. Gun violence is increasing because we are giving more people a reason to claim they are crazy.
While I think some people with anxiety disorders commit gun crime due to it I think it's very tough to tell if it's causing an increase in gun violence, I think any increase in gun violence is largely tied to economic and political factors in the country at a current time period.
No, I do not believe that anxiety disorders are part of the reason that gun violence has increased, because there is no evidence that anyone who is violent with a gun is more likely to have an anxiety disorder. To the contrary, people with anxiety disorders are more likely to be timid and shy away from guns.
No, I do not believe anxiety disorders are a part of the reason gun violence has increased. Anxiety disorders have many natural and environmental reasons for affecting people. Gun violence is typically caused by criminals and people who should not have guns. I would think that people who are being treated for an anxiety disorder would not be allowed to own a gun.