• depressed or irritable mood  
• temper, agitation  
• loss of interest in activities, apathy  
• reduced pleasure in daily activities  
• inability to enjoy activities which used to be sources of pleasure  
• change in appetite, usually a loss of appetite but sometimes an increase  
• change in weight (unintentional weight loss or unintentional weight gain)  
• persistent difficulty falling asleep or staying asleep (insomnia)  
• excessive daytime sleepiness  
• fatigue  
• difficulty concentrating  
• difficulty making decisions  
• memory loss (amnesia) episodes  
• preoccupation with self  
• feelings of worthlessness, sadness, or self-hatred  
• excessive or inappropriate feelings of guilt  
• acting-out behavior (missing curfews, unusual defiance)  
• thoughts about suicide or obssessive fears or worries about death  
• plans to commit suicide or actual suicide attempt  
• excessively irresponsible behavior pattern

 

If these symptoms persist for at least two weeks and cause significant distress or difficulty functioning, treatment should be sought.

Signs and tests

 
• physical examination and blood tests to rule out medical causes for the symptoms (for example: hypothyroidism, pregnancy, kidney disease).  
• evaluation for substance abuse - heavy drinking, frequent marijuana smoking, and other drug use can be both causes and consequences of depression. Past practice in addiction treatment was to assume depression was only a symptom of use, not a potential cause, and it was left untreated. Research now shows that this leads to increased risk of relapse. If a substance abuse problem is found, be sure that psychiatric evaluation doesn’t stop at diagnosing this, but continues to assess depression and other potential psychiatric problems.  
• psychiatric evaluation to assess history of persistent sad, empty, or irritable mood and loss of interest or pleasure in normal activities. Evaluation for other potentially co-existing psychiatric disorders (such as anxiety, mania, or schizophrenia).  
• assessment of suicidal/homicidal risks.  
• information from family members or school personnel is often helpful in identifying depression in teens.