Symptoms:

• Acting-out behavior (missing curfews, unusual defiance)
• Appetite changes (usually a loss of appetite but sometimes an increase)
• Criminal behavior (such as shoplifting)
• Depressed or irritable mood
• Difficulty concentrating
• Difficulty making decisions
• Episodes of memory loss
• Excessive sleeping or daytime sleepiness
• Excessively irresponsible behavior pattern
• Excessive or inappropriate feelings of guilt
• Failing relations with family and friends
• Faltering school performance
• Fatigue
• Feelings of worthlessness, sadness, or self-hatred
• Loss of interest in activities
• Persistent difficulty falling asleep or staying asleep (insomnia)
• Plans to commit suicide or actual suicide attempt
• Preoccupation with self
• Reduced pleasure in daily activities
• Substance abuse
• Temper (agitation)
• Thoughts about suicide or obsessive fears or worries about death
• Weight change (unintentional weight loss or gain)

If these symptoms last for at least 2 weeks and cause significant distress or difficulty functioning, get treatment.

Signs and tests:

True depression in teens is often difficult to diagnose, because normal adolescents have both up and down moods. These moods may alternate over a period of hours or days.

The health care provider will perform a physical examination and order blood tests to rule out medical causes for the symptoms. The doctor will also evaluate for signs of substance abuse. Heavy drinking, frequent marijuana (pot) smoking, and other drug use can be caused by, or occur because of depression.

A psychiatric evaluation will also be done to document the teen's history of sadness, irritability, and loss of interest and pleasure in normal activities. The doctor will look for signs of potentially coexisting psychiatric disorders such as anxiety, mania, or schizophrenia. A careful assessement will help determine suicidal/homicidal risks -- that is, if the teen is a danger to him or herself or others.

Information from family members or school personnel can often help identify depression in teenagers.