At first glance, distinguishing depression from ADHD in a child would seem to be an easy task. In fact, most depressed children present with dysthymia, a subacute, often agitated depression, with external symptoms that can be very similar to those of AD/HD.
The diagnostic criteria for Dysthymia as listed in the DSM-IV:
Presence, while depressed, of two (or more) of the following:
1. Poor appetite or overeating
2. Insomnia or hypersomnia
3. Low energy or fatigue
4. Low self-esteem
5. Poor concentration or difficulty making decisions
6. Feelings of hopelessness
Items 1, 2, 4, and 5 are also common in children with ADHD, and often only a very experienced clinician can elicit the subtle differences between these two quite distinct disorders. Many children who meet the diagnostic criteria for ADHD but do not respond well to stimulants are depressed in addition to (or sometimes instead of) having ADHD.
Bipolar disorder may present during childhood with symptoms very similar to ADHD. These children frequently present at a very young age, and are intensively active. In addition they often exhibit severe sleep disturbance, grandiosity (seem to want to direct the activity of others around them to an unusual degree) and hypersexuality as exhibited by sexually explicitly comments or inappropriate touching. They often exhibit "melt downs" which are prolonged and intense.
The clinician should ask about any family history of manic-depressive illness as part of the initial evaluation for ADHD, and should be aware that bipolar disorder can also be a cause of suboptimal or paradoxical responses to stimulants in hyperactive children.
Consultation with a behavioral health provider is indicated for children who have behaviors suggestive of bipolar or mood disorders.