Atlas of pathophysiology, 2 Edition

Part II - Disorders

Neurologic disorders


Depression is a chronic and recurrent mood disorder. Although many people may feel depressed at one time or another, clinical depression is defined when the symptoms interfere with everyday life for an extended period. It affects 3% to 5% of the general population, but it's reported to be significantly underdiagnosed and usually inadequately treated.

Forms of depression include major depression, dysthymia, postpartum depression, premenstrual dysphoric disorder, and seasonal affective disorder.

Age Alert

The peak age of depression onset is between 20 and 40.


Some people may have a genetic predisposition to developing depression.

Possible contributing factors

·   Disappointment at home, work, or school

·   Death of a friend or relative

·   Prolonged pain or having a major illness

·   Medical conditions, such as hypothyroidism, cancer, or hepatitis

·   Drugs, such as sedatives and antihypertensives

·   Alcohol or drug abuse

·   Chronic stress

·   Abuse or neglect

·   Social isolation

·   Nutritional deficiencies (such as folate and omega-3 fatty acids)

·   Sleeping problems


An imbalance of the neurotransmitters is thought to be the underlying mechanism in depression. In a person with normal levels of neurotransmitters, serotonin and norepinephrine are released from one neuron and travel to another one, activating receptors. After the receptors are activated, the neurotransmitters are taken up by the presynaptic neuron. A patient with depression has inadequate levels of serotonin or norepinephrine, thus not allowing this smooth transmission of impulses.

Signs and symptoms

·   Persistent sad, anxious, or “empty” mood

·   Feelings of hopelessness and pessimism

·   Feelings of guilt, worthlessness, and helplessness

·   Loss of interest or pleasure in hobbies and activities that were once enjoyed

·   Loss of energy or fatigue

·   Unexplained pain

·   GI symptoms

·   Headache

·   Insomnia

·   Dizziness

·   Palpitations

·   Heartburn

·   Numbness

·   Loss of appetite

·   Premenstrual syndrome

Age Alert

In children, symptoms of depression include hyperactivity, poor school performance, somatic complaints, sleeping and eating disturbances, lack of playfulness, and suicidal ideation or actions.

Diagnostic test results

Several screening questionnaires are used to detect depressive symptoms. They include:

·   Beck Depression Inventory

·   Center for Epidemiological Studies Depression Scale

·   Zung Self-Rating Depression Scale.

Clinical Tip

To screen for depression, ask your patient these two questions:

·   Have you felt down, depressed, or hopeless for most of the past 2 weeks?

·   Have you felt little interest or pleasure in performing activities for most of the past 2 weeks?

If the patient answers yes to either question, further assessment is warranted.


·   Selective serotonin reuptake inhibitors, such as fluoxetine and sertraline

·   Tricyclic antidepressants, such as nortriptyline and desipramine

·   Venlafaxine

·   Nefazodone

·   Bupropion

·   Monoamine oxidase inhibitors

·   Psychotherapy

·   Electroconvulsive therapy

·   Exercise

·   Support groups

·   Self-help literature

·   Light therapy





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