I have a lot to say on this topic.

It's common for different psychiatric disorders to co-exists. There's research supporting the notion that Bipolar and ADHD like to hang together. After all, mental illness is dysfunction in the brain and neurochemistry is connected effecting different parts.

My pdoc told me something interesting after I questioned him on if I had Bipolar or ADHD with recurrent depression. He said ADHD is really a childhood disorder and an individual with it will outgrow the hyperactivity as an adult. The ADHD adult is left with ADD without hyperactivity. Therefore, those who are hyperactive are probably hypomanic and those who seem that way most of the time just run that way normally until a depression hits them. He also said many people with Bipolar are misdiagnosed with ADHD as children because the mood swings aren't so apparent at that age.

So your child with ADHD might have Bipolar that hasn't reared its ugly head yet.

Another note..

I strongly believe that ADHD is over-diagnosed in this country. I volunteered in my son's kindergarten class every Friday. 5 out of 20 kids in his class were diagnosed ADHD and they were all males. That's 1/4 which doesn't correlate with studies that show the percentage of the population with ADHD. Compared to the past, America loads children with more work earlier in age. They are forced to sit quietly for up to 8 hours in a day. Hundreds of years ago life was more physically active. Children helped parents with chores and farming. There was some education but a child wasn't forced to sit all day. They burned up their energy.

Our kids have too much energy and within the confinement they appear to be over-active. I read an interesting report that claims the ADHD mind isn't an illness; it's an innate way of thinking that benefited hunters in our primitive days. Those people who had a now labeled ADHD mind were the great warriors and hunters of their time. That would explain why ADHD kids get into so much stuff lol.