What is depression?

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From the Guidelines

Depression is a serious mental health disorder characterized by persistent feelings of sadness, loss of interest in activities, and a range of emotional and physical problems that can significantly impact daily life, as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) 1.

Definition of Depression

Depression is a complex condition that affects how a person thinks, feels, and behaves, often leading to various emotional and physical issues. According to the American Psychiatric Association, a diagnosis of major depressive disorder requires the presence of 5 or more symptoms within the same 2-week period, including depressed mood, loss of interest or pleasure, significant weight loss or gain, insomnia or hypersomnia, psychomotor agitation or retardation, fatigue or loss of energy, feelings of worthlessness or guilt, diminished ability to think or concentrate, and recurrent thoughts of death or suicide 1.

Key Characteristics of Depression

Some key characteristics of depression include:

  • Persistent sad or empty feelings
  • Loss of interest in hobbies or activities once enjoyed
  • Fatigue or loss of energy
  • Difficulty concentrating or making decisions
  • Changes in sleep patterns or appetite
  • Feelings of worthlessness or guilt
  • Recurrent thoughts of death or suicide

Importance of Proper Diagnosis and Treatment

Depression is not a sign of weakness, but a serious medical condition that requires proper treatment. The severity of depressive disorders can be based on symptom count, intensity of symptoms, and/or level of impairment, and treatment usually involves psychotherapy, medications, or a combination of both 1. Lifestyle changes, including regular exercise, adequate sleep, stress reduction, and social connection, can also help manage symptoms. It is essential to seek professional help if symptoms of depression persist or worsen over time.

From the FDA Drug Label

A major depressive episode (DSM–IV) implies a prominent and relatively persistent (nearly every day for at least 2 weeks) depressed or dysphoric mood that usually interferes with daily functioning, and includes at least 5 of the following 9 symptoms: depressed mood, loss of interest in usual activities, significant change in weight and/or appetite, insomnia or hypersomnia, psychomotor agitation or retardation, increased fatigue, feelings of guilt or worthlessness, slowed thinking or impaired concentration, a suicide attempt or suicidal ideation. A major depressive episode implies a prominent and relatively persistent depressed or dysphoric mood that usually interferes with daily functioning (nearly every day for at least 2 weeks); it should include at least 4 of the following 8 symptoms: change in appetite, change in sleep, psychomotor agitation or retardation, loss of interest in usual activities or decrease in sexual drive, increased fatigue, feelings of guilt or worthlessness, slowed thinking or impaired concentration, and a suicide attempt or suicidal ideation.

Depression is defined as a major depressive episode that implies a prominent and relatively persistent depressed or dysphoric mood, usually interfering with daily functioning, and includes a combination of symptoms such as:

  • Depressed mood
  • Loss of interest in usual activities
  • Changes in appetite or sleep
  • Psychomotor agitation or retardation
  • Increased fatigue
  • Feelings of guilt or worthlessness
  • Slowed thinking or impaired concentration
  • Suicide attempt or suicidal ideation 2 3

From the Research

Definition of Depression

Depression is a highly prevalent and disabling condition associated with significant morbidity and mortality 4. It is defined as five or more of the following symptoms in the past 2 weeks, during which at least one is depressed mood or loss of interest or pleasure:

  • Depressed mood
  • Diminished interest or pleasure in activities
  • Significant weight loss or gain, or decreased or increased appetite
  • Insomnia or hypersomnia
  • Psychomotor agitation or retardation
  • Fatigue or loss of energy
  • Feelings of worthlessness or excessive or inappropriate guilt
  • Poor concentration or indecisiveness
  • Recurrent thoughts of death or suicidal ideation, plan, or attempt 5

Characteristics of Depression

Depression is a recurrent, often chronic, lifetime illness requiring long-term treatment 6. The range of symptoms and clinical syndromes subsumed under the rubric "depression" is remarkably large, covering transient sad feelings and devastating biological illness 7. Individual patients with depression present with unique symptom clusters, and the prevalence of persistent, unresolved symptoms contributes to patient functioning and disease progression 8.

Importance of Accurate Diagnosis and Treatment

Screening for depression is recommended in the general adult population when resources are available for diagnosis, management, and follow-up 5. Management of depression depends on its severity and may include psychotherapy, pharmacotherapy, or both 5. Accurate diagnosis and treatment are crucial, as severe mood disorders can be life-threatening medical illnesses 7.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Advances in the treatment of depression.

NeuroRx : the journal of the American Society for Experimental NeuroTherapeutics, 2006

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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