I believe there are a variety of causes of anxiety. I truly believe there is a very large component being genetic. On my mom's side there is anxiety disorders back through my Grandmother's brother. He was a hypochondriac. My mom's mom definitely had some issues as well. My mom, well, yep. My youngest sister does and so do I. I also think there is a large correlation of environment/nurture. My mother had an awful upbringing. Other than my father dying at 46 (I was 15), I had a darn good childhood. My mom is much, much more affected with anxiety issues than I am. I also believe there are just miswirings in the brain, not necessarily genetic but congenital. Then you have the folks who have chemical imbalance issues, perhaps not as simple as being a chemical imbalance that's why some meds aren't helpful for one but are for others. I believe, too, some folks just have a 'personality' tendency toward it. I also think that you can have any combo of all of the above reasons that cause anxiety. If a person has anxiety due to a purely environmental reason, then managing anxiety will be very different than managing a person who's brain make-up is the soul reason. That's why I think anxiety, like cancer, will be hard to really find the 'cure' to. We just don't have all of the answers. We may not for a very long time.
I also think that anxiety is worse nowadays (not to say it wasn't prevalent 50yrs ago) because we have so much information at our fingertips. Everybody today has more health anxiety. Everytime you turn on the tv or read a magazine, you are being bombarded by some medication or some news report about the ravages of breast cancer or heart diesease. If we weren't told practically every minute of everyday to watch out for this pain or that, we wouldn't be so darned concerned about small aches and pains being caused by a heart attack. Should we know the signs, of course. But when hearing that chest pain is a sign of heart attack, it should be followed by a decripition of how intense and how long does it lasts etc. We don't get that level of information so we end up thinking that heartburn is actually a heart attack. Today, too, we are always in a hurry. We lead high stress lives, pure and simple. Hardly a minute goes by that we aren't going and doing; pushing for that better job, taking care of kids; paying for mounting bills. The list can go on and on.
And like shrub and abeja say, it is up to the individual to deal with his/her own issues. He/She needs to recognize it in themeslves.