If levels of the chemicals serotonin and norepinephrine are too low, a person's mood, feelings and thinking can be affected. Antidepressants can help by raising these levels and bringing sufferers back to a more balanced state of mind.
For mild to moderate depression, Dr. Saltz says psychotherapy can be incredibly helpful. "You don't necessarily need medication," she says. However, most people who are moderately or severely depressed should consider antidepressants, she says.
What's the most successful treatment for depression? "Most studies show that it's a combination of medication plus psychotherapy that is really the most effective," she says.