Definition and clinical presentation

Depression is a mood disorder characterized by persistent feelings of sadness, despair, and loss of interest or pleasure in most activities. Patients may also report somatic symptoms such as changes in appetite, sleep disturbances (insomnia or hypersomnia), psychomotor agitation or retardation, fatigue, and decreased concentration. Suicidal ideation or thoughts of self-harm may occur. Major depressive episodes last for at least 2 weeks and significantly impair social, occupational, or other important areas of functioning. It must be differentiated from transient mood changes or “the blues,” which are less severe and brief.

Epidemiology

Major depression affects about 9.5% of the U.S. population annually, with higher prevalence in women (12%) compared to men (7%) and adolescents (4%). It crosses all racial, ethnic, and socioeconomic groups and is a leading cause of disability worldwide.

Pathophysiology and mechanisms

Depression arises from a complex interplay of genetic, neurochemical, hormonal, and psychosocial factors, including:

• Genetic predisposition and family history of mood disorders.

• Neurotransmitter imbalances (serotonin, norepinephrine, dopamine).

• Medical illnesses (e.g., hypothyroidism, diabetes).

• Psychiatric comorbidities such as anxiety or bipolar disorder.

• Substance abuse, including alcohol and certain medications.

• Postpartum hormonal changes and psychosocial stressors.

Clinical assessment and history

1. Mood and thoughts

   • Assess the patient’s subjective feelings, changes in mood, self-esteem, hopelessness, and suicidal ideation.

   • Explore plans, dreams, and satisfaction with life achievements.

2. Behavior and social function

   • Changes in social interactions, withdrawal, or isolation.

   • Alterations in sleep, appetite, daily activities, and concentration.

   • Substance use and coping strategies.

3. Family and environment

   • Family history of depression or psychiatric illness.

   • Impact of recent losses, trauma, or lifestyle changes.

   • Social support and community resources.

4. Suicide risk evaluation

   • Look for verbal and behavioral clues (talking about death, giving away possessions).

   • Assess the presence and specificity of suicide plans and support networks.

Emergency diagnostic and therapeutic considerations

1. Suicide risk management

   • Determine suicide potential: low, moderate, or high based on hopelessness, plan, and support.

   • Remove access to means of self-harm (medications, sharp objects).

   • Close monitoring, possibly one-to-one observation, and ensuring safety.

   • Urgent psychiatric referral and hospitalization if indicated.

2. Medical evaluation

   • Physical and psychiatric examination to exclude organic causes.

   • Ordered diagnostic tests (e.g., thyroid function, CBC, metabolic panel).

3. Treatment initiation

   • Supportive care: adequate nutrition, rest, stress reduction.

   • Pharmacotherapy: antidepressants according to clinical guidelines.

   • Psychotherapy and counseling referrals.

Medical causes and contributing factors

Special populations and situational considerations

Adolescents

Emotional lability may mask depression. Clues include poor school performance, somatic complaints, substance abuse, and risky sexual behavior. Family or group therapy may be effective; antidepressants used cautiously.

Elderly

May present with physical complaints, cognitive changes, or agitation rather than overt sadness. Higher suicide risk in those over 85, with low self-esteem or desire for control.

Cultural considerations

Language barriers may hinder communication; use professional interpreters to facilitate accurate expression of feelings.

Patient counseling and prognosis

• Educate patients about depression’s nature and treatability.

• Encourage expression of feelings and engagement in enjoyable activities.

• Stress adherence to prescribed medications and discuss potential side effects.

• Reinforce the importance of follow-up and ongoing support.

• Warn patients and families about signs of worsening depression or suicidal behavior.

References

1. Maunder RJ, Pierson DJ, Hudson LD. Subcutaneous and mediastinal emphysema: pathophysiology, diagnosis, and management. Arch Intern Med. 1984;144(7):1447–53.

2. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 5th Edition. 2013.

3. Kuehner C. Why is depression more common among women than among men? Lancet Psychiatry. 2017;4(2):146–58.

4. O'Hara MW, Swain AM. Rates and risk of postpartum depression—a meta-analysis. Int Rev Psychiatry. 1996;8(1):37-54.

5. Nock MK, et al. Suicide and suicidal behavior. Epidemiol Rev. 2008;30:133-54.