For most preschoolers, life is about laughing, playing, and having fun. But even the smallest tykes feel down sometimes.
Child psychiatrist Dr. Joan Luby has been studying depression in preschool children for more than 20 years.
"Children as young as age 3 can get clinical depression," said Luby.
In a recent imaging study, Luby found depressed preschoolers had elevated activity in an area of the brain called the amygdala.
"You can see changes in the structure and volume of several key brain regions that are known to be involved in emotion processing," said Luby.
The study was the first to show these changes in children so young.
"We believe that the earlier you can identify the disorder, that you can treat the disorder more effectively," said Luby.
Researchers believe as many as one in every 33 children may have depression. Children with depression are often withdrawn, highly sensitive, have a difficult time dealing with negative emotions and are preoccupied with feelings of guilt. The symptoms often go unnoticed.
"Most people don't pick up on depression in their young children. Mostly parents pick up on what we call 'disruptive symptoms' in children," said Luby.
But if you do spot the symptoms, getting help could make all the difference.
In very young children, Luby says a behavioral therapy, in which the parent serves as an "emotional coach" for their depressed child, can be effective.
Antidepressants are considered generally safe for kids ages 7 and older, but the FDA has placed a "black box" warning on these drugs because of the increased risk of suicidal thinking.