Depression can describe both a mood and an illness.
Major depressive disorder is a clinical syndrome involving mood, neurovegetative functions, cognition, and behavior.
Affects 5% to 10% of patients in the primary care setting.
Risk factors include prior depression and a family history of depression. Recent bereavement, stress, or medical illness may contribute.
For screening and diagnosis, self-rating forms are helpful, but clinical diagnosis is essential. Positive screening should trigger full history, mental status exam, treatment, and follow-up.
Most patients respond well to treatment with medication, talk therapy, or a combination of both.
Suicidal ideation can occur before and peak during treatment, so early and careful follow-up is advised.
Depressive disorders are typically characterized by persistent low mood, loss of interest and enjoyment, neurovegetative disturbance, and reduced energy, causing varying levels of social and occupational dysfunction. Depressive symptoms include depressed mood, anhedonia, weight changes, libido changes, sleep disturbance, psychomotor problems, low energy, excessive guilt, poor concentration, and suicidal ideation. In some cases the mood is not sad, but anxious or irritable or flat.
Major depressive disorder is characterized by the presence of at least five symptoms and can be classified along a spectrum of mild to severe. Severe episodes may include psychotic symptoms such as paranoia, hallucinations, or functional incapacitation.
Subthreshold (minor) depression is not defined in DSM-5, but has sometimes been applied to diagnose a patient with two to four depressive symptoms, including depressed mood or anhedonia, lasting longer than 2 weeks.
Persistent depressive disorder (previously known as dysthymic disorder) is characterized by at least 2 years of a major depressive syndrome or subthreshold major depression with three or four depressive symptoms (including hopelessness, which is not a core major depressive symptom) for more days than not.
History and exam
Key diagnostic factors
- depressed mood
- functional impairment
Other diagnostic factors
- weight change
- libido changes
- sleep disturbance
- changes in movement
- low energy
- excessive guilt
- poor concentration
- suicidal ideation
- bipolar disorder excluded
- substance abuse/medication side effects excluded
- medical illness excluded
- schizophrenia excluded
- postpartum status
- personal or family history of depressive disorder or suicide
- oral contraceptives
- coexisting medical conditions
- comorbid substance use
- personality disorders
- gene-environment interaction
1st investigations to order
- clinical diagnosis
- metabolic panel
- thyroid function tests
- Patient Health Questionnaire-2 (PHQ-2)
- Patient Health Questionnaire-9 (PHQ-9)
- Edinburgh Postnatal Depression Scale
- Geriatric Depression Scale
- Cornell Scale for Depression in Dementia
Investigations to consider
- 24-hour free cortisol
- vitamin B12
- folic acid
severe depression, nonpregnant: psychotic, suicidal, severe psychomotor retardation impeding activities of daily living, catatonia, or severe agitation
moderate depression, nonpregnant: severe symptoms, significant impairment but no psychotic symptoms, no suicidal ideation, and no severe psychomotor retardation or agitation
mild depression, nonpregnant: low to moderate severity symptoms, partial impairment, no psychotic symptoms, no suicidal ideation, and no psychomotor retardation or agitation
Dean F. MacKinnon, MD
Psychiatry and Behavioral Sciences
The Johns Hopkins Hospital
DFM declares that he has no competing interests.
Dr Dean F. MacKinnon would like to gratefully acknowledge Dr Roger S. McIntyre, Dr Tonya Fancher, and Dr Richard Kravitz, the previous contributors to this topic.
RSM has received research funds from Stanley Medical Research Institute and National Alliance for Research on Schizophrenia and Depression (NARSAD). RSM is on the advisory board for AstraZeneca, Bristol-Myers Squibb, France Foundation, GlaxoSmithKline, Janssen-Ortho, Solvay/Wyeth, Eli Lilly, Organon, Lundbeck, Biovail, Pfizer, Shire, and Schering-Plough. RSM is on the Speakers Bureau for Janssen-Ortho, AstraZeneca, Eli Lilly, Lundbeck, Biovail, and Wyeth. RSM has received research grants from Eli Lilly, Janssen-Ortho, Shire, and AstraZeneca. RSM has received travel funds from Bristol-Myers Squibb. TF declares that she has no competing interests. RK has received research grants from Pfizer on non-depression-related topics.
Scott McAfee, MD
St Vincent's Hospital
SM declares that he has no competing interests.
Dietmar Winkler, MD
Department of Psychiatry and Psychotherapy
Medical University of Vienna
DW has received lecture fees from CSC Pharmaceuticals, GlaxoSmithKline, and Pfizer, and has served as a consultant for GlaxoSmithKline.
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