Well depending on the severity of the anxiety disorder, he might not be able to completely overcome it per say...so focusing on how to handle it might be a more useful direction to go. Aside from medication there are relaxation techniques and such that can sort of help which could probably be taught to him....also though just helping him through anxiety/panic can help like if he's having a panic attack like comfort him and try and make him feel safe and know that nothing bad will happen. Also its very possible certian environmental stimuli can trigger anxiety so perhaps attempting to find out some of the things that set off his anxiety or make it worse and maybe solutions for those or ways to work around it. Like if he gets more anxious after a long day of being out and about...maybe he needs more rest time, or if a lot of noise/chaos stresses him out maybe he needs more quiet time. Lol I by no means have all the answers or anything, but I've had anxiety issues since I was a kid and it seems coping is more realistic then totally overcoming it....though with treatment and learning some coping skills early on there is a good chance his anxiety could improve and become much less severe to the point he wouldn't qualify for a diagnoses of an anxiety disorder anymore but it could still persist its hard to say.