Maria has been feeling depressed for at least two and a half years. About three years ago, her husband of 20 years left her for another woman. Devastated, she became despondent and tearful almost daily.

Eventually, her depression got worse associated with inability to function. Her appetite, energy, concentration, and sleep became impaired. She also felt hopeless and suicidal. Her psychiatrist put her on a starting dose of antidepressant. She responded initially but after a few days, she felt just like before taking the medication.

For the past two years, Maria has tried four types of antidepressants. She has taken the usual adult doses of these drugs. Although she somewhat improves, she has virtually remained the same