Depression could be called the black death of the twenty-first century due to its high prevalence (life time prevalence could be 10-15% or higher). It often occurs in people during their middle age, 30-50 years old, and costs much because of the medical resources used to treat it and the higher suicide and rate of recurrence. In addition, people with depression are often comorbid with anxiety disorders and lack of efficient treatment. Even for the patients with anxiety disorders, the most useful medications are antidepressants
