I'm not sure if its possible for a child to all of a sudden develop adhd. I know that my son was possibly born with add. then he had all the vaccines that have the chemicals that they were experimenting with. Its difficult to know when he developed it because he came out of the womb not sleeping well. But all of his health issues aside, I know one thing for sure, and that is if a child does not have a.d.d. or a.d.h.d symptoms when they start out and then they start acting "a.d.h.d". it is from their diet. Or possibly a vaccine. Food coloring such as red 40 will cause anyone to start acting out of whack. food coloring is not only a dye too brighten it to make it look all so pretty and waiting to be eaten, it is a preservative. making the food keep its color. as well as food allergies: that alone is a "big one". Certain foods have preservatives in them that will disturb the brain's neurotransmitters. They also have hormonal poisoning in them such as dairy foods. Its the chemicals that are put into the food that the animals eat as well as the chemicals put into them, so they can produce more milk, eggs and so on. so a child can be allergic to certain foods, but if it seems like something that is happening that didn't start at birth, I'm willing to bet major bucks on the food they eat, as well as the mixture of puberty. That's enough to send anyone off a cliff. Remember us moms, when we seemed like normal kids then we hit our teens and around 12 -13 and it seemed like we were becoming schizophrenic? It can be anything from the ground up; whats going into the animals, to whats being put into their systems, whats done during the process of the foods, grains being bleached, to the changing of the kids hormones. Males as well as females start acting out; i.e, too much testosterone in the blood, they can act like they are on a emotional roller coaster, like a menstrual cycle. Their hormones are very similar. Boys can get too much estrogen in their system at one time as well. And peer pressure, seems a lot like a.d.h.d. But I would really look back on their behavior from infants, like sleeping patterns , what foods they might have not taken to, vaccines and any intro to chemicals that were put into their system in childhood. sometimes it can have an outbreak or reaction to the changing in their hormones now. It's a memory of that allergic reaction. Their chemical's system or immunity remembers that they once were allergic to that, and the changing of their hormones pick it up like a forgotten hitch-hiker.