Hi there. It's difficult to say because it varies by person. You probably won't know your son's limitations until he grows up. Myself, I am only 24 but have had Hydro since I was 11. Luckily I'm more fortunate than others; I had my last revision in 1999 and have been fine since.

The most important thing is identifying a malfunction. Some symptoms seem like warnings with some and no big deal for others (some live with headaches for their whole lives and for some headaches are abnormal, even a warning sign). But a few that should serve a REAL warning are "sundowning" (inability to keep eyes level or raises), blurriness of vision and especially extreme drowsiness. I had all the following on my last malfunction (which was the one I had in 99) and was aware of it.

My own limitations are thankfully not damaging to my intellect but my attention span and short-term memory are very poor. Physically there's no problem other than the obvious higher level of vulnerability than others; I studied martial arts before my diagnosis, but it wasn't long after fully recovering my neurologist ok'd my return (given the circumstances). I'm honestly not aware of many hydro patients that go on to accomplish physical fame of any kind but there are plenty who are successful.

Hope I helped some.