Could anxiety disorders be treated?

Absolutely. Exercise is a great way to relieve stress. Your body releases endorphins during exercise, which can help you feel calm. If you exercise 30 - 60 minutes a day, your stress levels can improve. When stressed, take 5 slow, deep breaths with your eyes closed, then roll your shoulders forward 5 times, then back 5 times. This will slow your heart rate and release tension in your neck and shoulders.
Managing anxiety: The most effective treatment for anxiety is relaxation training coupled with cognitive therapy that helps you modify the thoughts, perceptions and beliefs that trigger the anxiety. Learning to calm your body and your mind is the key. You can learn these skills on your own, but having a mental health professional "coach" you is quicker and more effective. Entrenched anxiety may require meds.
Yes. Treatments for anxiety disorders include psychotherapy and medication. The most common medications which are used for these conditions are also used for depression.