More than 350 million people of all ages suffer from depression worldwide, according to the World Health Organization.

WHO lists depression as the leading cause of disability and a major contributor to the global burden of diseases. The causes of depression are still unknown, but it is believed that genetics, illnesses including brain trauma, medications and life events can all contribute to the illness.

Studies suggest women are twice as likely to get depression, and that people in rich countries have a slightly higher risk of depression than those from low-to-mid-income countries.

Depression is characterized by sadness, loss of interest or pleasure, feelings of guilt or low self-esteem, disturbed sleep or diet patterns, tiredness and poor concentration.

Up to 60 to 70 percent of patients with depression suffer from chronic pain and other physical symptoms, which include headaches, pain in the back, muscles, joints and chest. Other symptoms include fatigue, sudden weight loss, dizziness, shortness of breath and sleeping disorders, such as insomnia and lengthy sleeping times.

If you, or someone around you, has experienced several of these symptoms for over two weeks, seek treatment as soon as possible.

Sources: WHO and Chen Lin from Beijing Huilongguan Hospital

Related: Plumbing the depths of despair

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