Depression is more prevalent in women than men and is especially common among adolescents.
　　Mild depression comes and goes and is characterized by downheartedness, sadness, and dejection. Short-term episodes of depression or other mood changes can occur with hormone changes, including those that accompany pregnancy, premenstrual syndrome (PMS), or shortly after the birth of a baby (postpartum depression).
　　 Noticeably disturbed thought processes, poor communication and socialization, and sensory dysfunction indicate moderate depression.
　　People with severe depression are withdrawn, without expression, indifferent toward their surroundings, and may show signs of delusional thinking and limited physical activity.