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Upon completion of the chapter, the reader will be able to:

  1. Explain the etiology and pathophysiology of major depressive disorder (MDD).

  2. Identify the signs and symptoms of MDD.

  3. Outline the treatment goals for a patient with MDD.

  4. Recommend pharmacotherapy given a specific patient with MDD.

  5. Develop a monitoring plan for a specific patient with MDD that includes the assessment of efficacy as well as adverse effects.

  6. Predict, prevent, identify, and resolve potential drug-related problems.

  7. Educate patients and caregivers on the proper use of antidepressant therapy.


Major depression is a common, seriously disabling disorder nonresponsive to volitional efforts to feel better. Individuals with major depressive disorder (MDD) experience pervasive symptoms affecting mood, thinking, physical health, work, and relationships. Inadequately treated MDD increases the risk of suicide.1

Although antidepressants and agents used adjunctively in depression account for 16 of the top 200 prescription drugs dispensed in the United States, inadequate treatment remains a serious concern.2,3

Patient Encounter Part 1

A 35-year-old man presents to the psychiatry clinic with his brother. He complains of increased sleep and increased appetite although he still feels fatigued when he wakes up. He states that he has gained 12 lb (5.4 kg) in the last month. With prompting from his brother, he admits that he has lost interest in hunting, which is his favorite activity, especially now that it is deer hunting season. He has been going through a difficult divorce, and his wife has custody of his two children. He has been having difficulty waking up to go to work in the morning. He states that he has thoughts about driving his car across the interstate into oncoming traffic, but he would not do that because it is against his religion.

What symptoms of MDD does the patient have?

What medical or psychiatric issues could be contributing to the symptoms?

What additional information do you need to know before creating a treatment plan for this patient?


At least 17.3 million adults over the age of 18 experience at least one episode of depression, and 8.1% of individuals over 20 years of age in the United States experienced depression in any given 2-week period.4 Women are twice as likely to experience MDD.4,5 According to the World Health Organization (WHO), depression is the leading cause of disability worldwide and a major contributor to the overall global burden of disease.6


The cause of MDD is probably multifactorial. Multiple theories abound, and practitioners suggest that development of depression likely involves a complex interaction of genetic predisposition, psychological stressors, and underlying pathophysiology. There are no currently accepted unifying theories to adequately explain the pathophysiology of depression.7



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