Depression is more than just a feeling of being sad for a short period. Among teens, depression can cause a persistent feeling of sadness and loss of interest in activities and it can control thoughts and behaviour.

According to Johns Hopkins All Children's Hospital, around one in 20 teenagers around the world suffer depression. Suicide, the most serious risk in depression, is one of the leading causes of deaths in people aged 15-24, it said.

Depression can occur at any time in life but its symptoms in teens may be different than those seen in adults.

The signs and symptoms include feeling hopeless, being irritable, conflict with family and friends, low self-esteem, feelings of worthlessness or guilt, fixation on past failures or exaggerated self-blame or self-criticism, extreme sensitivity to rejection or failure, the need for excessive reassurance, academic problems and frequent thoughts of death, dying or suicide.

It also has some behavioural impact such as tiredness, insomnia or oversleeping, changes in appetite, use of alcohol or drugs, slowed thinking, speaking or body movements, frequent complaints of unexplained body aches and headaches.

Depression symptoms likely won't get better on their own. For most teens, depression symptoms ease with treatment.

Many factors may play a role in depression like genetics, biology and chemistry, hormones and stressful childhood events such as trauma, death of a loved one, bullying, and abuse.

Several factors increase the risk of developing or triggering teen depression that include having issues that negatively impact self-esteem, such as obesity, peer problems, long-term bullying or academic problems; having been the victim or witness of violence, such as physical or sexual abuse; having mental health conditions such as bipolar disorder, an anxiety disorder, a personality disorder, anorexia or bulimia, and having a learning disability or attention-deficit/hyperactivity disorder (ADHD).

Family history may also increase teenagers' risk of depression, such as having a parent, grandparent or other blood relatives with depression, bipolar disorder or alcohol use problems, having a family member who died by suicide, having a dysfunctional family and family conflict.

There's no sure way to prevent depression. But some strategies may help such as spending quality time with teen children, listening to them with love and respect, encouraging healthy behaviour and forming positive relationships.

If a teen is depressed, parents and family may experience a number of negative emotions. But keep in mind the child is not deliberately being difficult. He or she is actually suffering. So, parents must be more patient to help their child.