Bipolar illness (or manic depression) is a neurobiological, hereditary chemical imbalance of the brain. Thirty percent of all children born to a couple where one parent has the illness also are born bipolar. If both parents suffer from it, there is a sixty percent chance that their children will inherit the illness.

Yes, children can develop bipolar disorder before they reach their teen years. This is a relatively recent discovery, and it's unfortunate that it's taken so long for many doctors to realize this. But now that psychiatrists and doctors are recognizing that bipolar can show up in even young children, it's important to know what to look for.

Symptoms of depression include long periods of sadness and perhaps even crying spells that may or may not have an obvious cause to them. They may sleep too much or have trouble with falling asleep or staying asleep. They may seem to be very tired all the time. They may have low energy, which may or may not be because of their sleep problems. They may show increased agitation and irritability. They may be withdrawn, and no longer show interest in activities they normally enjoyed. There may be an observable and significant change in their appetite.

Most children and adolescents have moods that come and go, and this is  normal. Their feelings of sadness or elation are typical reactions to daily  occurrences in their lives, environmental or personal stress, or just hormones.