Major depressive disorder can affect a person's appetite, sleep, work performance, and relationships enough to severely disrupt activities of daily living. Learn what you can do to help your patient lead a healthier, happier life.

The leading cause of disability in the United States for people ages 15 to 44, major depressive disorder (MDD) affects approximately 14.8 million adults-6.7% of the U.S. population age 18 and older-every year, according to the National Institute of Mental Health (NIMH). It's also estimated that 2 million Americans over age 65 have a depressive disorder. MDD is more prevalent in women than men, although men are more likely to commit suicide. MDD can occur at any age, but according to the NIMH, the median age of onset is 32. As a nurse, you're likely to see patients in the primary care and inpatient settings with this common disorder.

In this article, I'll help you uncover MDD by learning how to recognize its symptoms and understanding which treatment options are best for your patient.

Not just feeling blue

MDD is distinguished from everyday feelings of sadness by its duration and severity. Characterized by at least 2 weeks of a depressed mood or loss of interest in pleasure or activities (anhedonia), the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Text Revision (DSM-IV TR) indicates a diagnosis of MDD if four or more of the following symptoms are present in addition to depressed mood or anhedonia:

* significant weight loss or gain

* difficulty sleeping (insomnia or hypersomnia)

* psychomotor agitation or retardation

* fatigue

* feelings of sadness, worthlessness, or guilt

* inability to concentrate

* recurrent thoughts of suicide.

There are several different types of MDD. The DSM-IV TR specifies the following subtypes:

* psychotic depression-a severe depressive illness accompanied by some form of psychosis, such as a break with reality, hallucinations, or delusions

* postpartum depression-diagnosed when a new mother develops a major depressive episode within 1 month after delivery

* seasonal affective disorder (SAD)-characterized by the onset of a depressive illness during the winter months when there's less natural sunlight; the depression generally lifts during the spring and summer.

Although the exact pathophysiology of MDD is unknown, there are several theories about its cause. These theories are linked to biochemical changes, genetics, and environment. One theory is that norepinephrine and serotonin are deficient in individuals with MDD (see Neurotransmitters out of balance). It's theorized that the lack of serotonin is related to a problem with serotonergic transmission. In addition, some individuals with depression have exhibited a reduction in both central and peripheral 5-hydroxytryptamine (also known as serotonin) reuptake sites. Postmortem and imaging studies also indicate that individuals with MDD have fewer serotonin transporter sites.

Disturbances in the function of the hypothalamic-pituitary-adrenal (HPA) axis may also play a critical role in depression. In people without depression, cortisol levels are usually flat from late afternoon to a few hours before dawn, when they begin to rise. In people experiencing depression, cortisol levels spike erratically throughout the day. Cortisol levels return to normal as depression resolves. In 40% of patients diagnosed with depression, hypersecretion of cortisol is resistance to feedback inhibition, indicating a dysfunction in the HPA axis. Other theories include hypothyroidism, which has been found in some individuals with depression (especially women); circadian rhythm changes, as evidenced by the abnormal sleep patterns of patients with MDD; and a defective gene on chromosome 4 (individuals with this defective gene are 26 times more likely to be hospitalized for severe depression and attempted suicide).

Another theory, known as kindling, points to environmental stressors that activate internal physiologic stress responses, which trigger the first episode of depression. This episode then creates electrophysiologic sensitivity to future episodes so that less stress is required to evoke another episode. And according to psychoanalytic theory, depression results from inward-directed anger and aggression over a significant loss. It has also been theorized that depression is a problem of negative cognitive patterns that develop over a period of time. Environmental factors, such as the recent loss of a family member through death, divorce, or separation; the lack of a social support system; or the diagnosis of a significant health problem, are also associated with MDD.

At risk

The exact cause of depression is unknown; however, researchers have linked certain risk factors to an increased incidence of developing depression. Risk factors for MDD include:

* family history (MDD is up to three times more common among first-degree biological relatives)

* stressful situations

* female gender

* prior episodes of depression

* onset before age 40

* medical comorbidity

* past suicide attempt

* lack of a support system

* history of physical or sexual abuse

* current substance abuse.

* cerebrovascular accident

* cognitive impairment disorders (dementia)

* diabetes

* coronary artery disease

* cancer

* chronic fatigue syndrome

* AIDS.

* hormones (oral contraceptives and glucocorticoids)

* cardiovascular drugs (beta-blockers, calcium channel blockers, and thiazide diuretics)

* psychotropic medications (benzodiazepines and neuroleptics)

* anti-inflammatory and anti-infective drugs (nonsteroidal anti-inflammatory drugs and sulfonamides)

* antiulcer medications (cimetidine and ranitidine).

Many people experience depression but seek treatment for somatic complaints, such as:

* headache

* backache

* abdominal pain

* fatigue

* malaise

* anxiety

* decreased desire or problems with sexual functioning.

Assess for the following risk factors for suicide:

* previous suicide attempt

* organized plan

* alcohol or substance abuse

* presence of a thought disorder

* lack of a support system

* unmarried, divorced, or widowed

* presence of physical illness (especially a chronic condition).

Many medications are available for the treatment of MDD. Selective serotonin reuptake inhibitors (SSRIs) are often the first line of medication treatment. SSRIs work by inhibiting the reuptake of serotonin, decreasing symptoms with minimal adverse reactions (see The downside of SSRIs and SNRIS). Another commonly used class of drugs is the serotonin-norepinephrine reuptake inhibitors (SNRIs). SNRIs treat depression by increasing the availability of serotonin and norepinephrine. The norepinephrine-dopamine reuptake inhibitor bupropion, which increases norepinephrine and dopamine, or the noradrenergic and specific serotonergic antidepressant mirtazapine, which increases serotonin and aids in its delivery, may also be prescribed. Tricyclic antidepressants, which act by blocking the reuptake of serotonin and norepinephrine at the presynaptic neuron, and monoamine oxidase inhibitors, which inhibit the enzyme monoamine oxidase and increase the amount of serotonin and norepinephrine in the brain, aren't regularly used as a first-line treatment due to their adverse reactions. See Medications used to manage depression for adverse reactions and nursing considerations.

Nonpharmacologic methods used to treat MDD include psychotherapy (cognitive-behavior, psychodynamic, and group therapy), electroconvulsive therapy (ECT), and ultraviolet light therapy for patients with SAD.

Psychotherapy, either alone or in combination with medication, is considered to be an important component of treatment. The goals of cognitive-behavior therapy are to identify and challenge the accuracy of the patient's negative thinking, reinforce more accurate perceptions, and encourage behaviors that are designed to counteract the depressive symptoms. Psychodynamic therapy is based on the belief that unconscious conflicts, childhood trauma, and painful feelings take a toll on mental well-being. The therapist helps the patient explore how past events and trauma affect different aspects of his life. Group therapy allows patients to meet with others who are experiencing similar symptoms to share suggestions on dealing with everyday events and gain strength from knowing they're not alone.

Although ECT has been associated with negative publicity, the procedure is relatively safe and may benefit patients with severe, pharmacologically resistant MDD, especially older patients or those with severe adverse reactions to psychotropic drugs. Delivered in three treatments per week for up to 4 weeks, ECT may be indicated for patients who are severely incapacitated by depression or who have a strong suicide plan.

Table. Medications used to manage depression

The importance of following through

If your patient has been diagnosed with MDD, teach him about the disorder, including the nature of the illness, symptom identification and management (including signs and symptoms of relapse), treatment recommendations, information about prescribed medication and its expected effects, and long-term self-management. Make sure he understands that taking medication as prescribed is important and that antidepressants may not have an immediate effect. It may take 2 to 4 weeks or longer for him to experience a noticeable improvement in his mood. Teach him the importance of continuing treatment and not to abruptly stop taking his medication, even if he feels better.

Patients with MDD require monitoring and follow-up. A referral to a specialist may be required in certain situations, including coexistence of a psychiatric disorder, the presence of suicidal behavior, or when a patient is at risk for noncompliance or he doesn't have a support system.

Teach the patient's family the following:

* Don't attempt to cheer up a depressed person; rather, be accepting of his current mood.

* Be supportive by reassuring him that his mood will improve with treatment.

* Encourage him to maintain regular activity and rest patterns, with a balance of both.

* Take talk about suicide seriously; contact the healthcare provider if this occurs.

A helping hand

MDD is a serious condition that can affect a patient's mental, emotional, and physical health across the life span. As a nurse, you may be the first person to screen a patient for depression. And now you're better prepared to identify the symptoms of MDD and help your patient receive the most effective treatment.

Neurotransmitters out of balance

Forming the basic structure of the nervous system, neurons generate electrochemical impulses and transmit information. Neurotransmitters are the chemical vehicles that allow neurons to transmit these impulses smoothly (see illustration below).

The neurotransmitters serotonin, norepinephrine, dopamine, and gamma-aminobutyric acid are produced in neurons and stored in the synaptic vesicles until release. After release, any neurotransmitter not used during impulse transmission is sent back to storage through a reuptake mechanism. In depression, levels of serotonin or dopamine are inadequate, causing symptoms of sadness and a feeling of emptiness.

Assessing patients with depression

The following are questions you can ask your patient who has been diagnosed with depression:

* Can you describe what your depression feels like to you? How long have you felt this way?

* How would you rate your feeling of depression on a scale of 1 to 10, with 10 being the worst depression?

* What activities or things in your life give you pleasure?

* Do you sleep excessively or have difficulty sleeping?

* Have you lost weight recently or do you have a poor appetite?

* Have you experienced any losses or changes in your life?

* Are you experiencing thoughts of suicide? Do you have a specific suicide plan?

The downside of SSRIs and SNRIs

Although considered relatively safe, SSRIs and SNRIs do pose these risks:

* Discontinuation syndrome. The patient may develop such signs and symptoms as dizziness, headache, diarrhea, insomnia, irritability, nausea, and lowered mood if he abruptly stops taking the medication.

* Drug interactions. Taking an SSRI with warfarin, an anticoagulant, or certain medications used to treat cardiac disorders or diabetes can increase one medication level and decrease the other. For this reason, the patient needs close monitoring to make sure he's receiving safe and therapeutic doses of each drug in his regimen.

* Serotonin syndrome. This potentially fatal reaction to medications that elevate serotonin levels can cause tremor, diarrhea, hyperthermia, agitation, tachycardia, labile BP, changes in mental status, and diaphoresis. A patient with severe serotonin syndrome can develop seizures, respiratory failure, and coma. Immediately stop all medications and treat the signs and symptoms to prevent death.

* Suicide. When a patient starts an antidepressant, close monitoring for suicidal thoughts is important because mood elevation due to therapy can increase his energy to complete the act.

Characteristics of MDD: cheat sheet

On the Web

These online resources may be helpful to your patients and their families:

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th ed (text revision). Arlington, VA: American Psychiatric Publishing, Inc; 2000.

Isaacs A. Lippincott's Review Series: Mental Health and Psychiatric Nursing. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:102-115.

Murphy K. Shedding the burden of depression and anxiety. Nursing2008. 2008;38(4):34-41.

Parsey RV, Hastings RS, Oquendo MA, et al. Lower serotonin transporter binding potential in the human brain during major depressive episodes. Am J Psych. 2006;163 (1):52-58.

Porth CM. Pathophysiology: Concepts of Altered Health States. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:1277-1280.

Sadock BJ, Sadock VA. Kaplan & Sadock's Concise Textbook of Clinical Psychiatry. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2004:173-210.

Smeltzer SC, Bare BG, Hinkle JL, Cheever KH. Brunner & Suddharth's Textbook of Medical-Surgical Nursing. 11th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:118-120.