Depression, an overview

Overview of depression – Summary of relevant conditions | BMJ Best Practice
Depression is a mental state characterised by persistent low mood, loss of interest and enjoyment in everyday activities, neurovegetative disturbance, and reduced energy, causing varying levels of social and occupational dysfunction. Depressive disorders are common in people of all ages and may be classified depending on the duration, severity, and number of symptoms, and the degree of functional impairment.[1][2] In bipolar disorder, a manic episode may have been preceded by and may be followed by hypomanic or major depressive episodes.

Relevant conditions
Depression in adultsSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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Major depressive disorder is characterised by at least 5 symptoms and can be classified along a spectrum of mild to severe. 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.[2]

Depression in childrenSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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One of the most common paediatric psychiatric disorders, especially among girls during adolescence. It may be characterised more by irritability than sadness, and it often occurs in association with other conditions such as anxiety.[3]

Disruptive mood dysregulation disorder
Disruptive mood dysregulation disorder is a category of depressive disorders first diagnosed at 6 to 18 years of age, with age of onset before 10 years. It is characterised by the Diagnostic and Statistical Manual of Mental Disorders, fifth edition, text revision (DSM-5-TR) as severe and recurrent temper outbursts on average 3 or more times per week for at least 1 year, and a persistent irritable or angry mood for most of the day nearly every day between temper outbursts.[2]

Persistent depressive disorderSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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Includes common forms of depression, but lasting longer than acute major depressive disorder. The DSM-5-TR modified its classification system to include all chronic forms of depression under the single category persistent depressive disorder, which includes both chronic major depressive disorder and the previous category of dysthymic disorder (dysthymia), or chronic low-grade depression. The DSM-5-TR includes specifiers to identify different pathways to the diagnosis of persistent depressive disorder and various presentations based on severity and clinical characteristics.[2]

Postnatal depressionSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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Postnatal depression is not recognised by current classification systems as a condition in its own right, but the onset of a depressive episode within 4 weeks of childbirth can be recorded via the perinatal-onset specifier in the DSM-5-TR.[2] In common usage, depressive episodes occurring within 6 to 12 months of delivery may be considered to be postnatal depression.

Characteristics of postnatal depression may include guilt about the depressive symptoms, ambivalent feelings toward the infant, impaired bonding, and obsessive ruminations, including intrusive thoughts about harming the infant. Postnatal depression should be distinguished from a minor mood disturbance (postnatal blues or ‘baby blues’), in which the symptoms generally resolve within 2 weeks.

Premenstrual syndrome and dysphoric disorderSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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Premenstrual syndrome (PMS) is characterised by cyclical, physical, and behavioural symptoms occurring in the luteal phase of the normal menstrual cycle (the period between ovulation and onset of menstruation). Premenstrual dysphoric disorder (PMDD) is a more severe variant that includes at least one affective symptom. Depression may coexist with PMS or PMDD in up to 50% of cases. A diagnosis of PMS or PMDD may predate a diagnosis of depression.[4]

Seasonal affective disorderSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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Seasonal affective disorder (SAD) is a subtype of major depression and bipolar disorder, occurring with seasonal change over at least a 2-year period. Most commonly presents with onset of depression in the autumn or winter, and full remission of symptoms over the spring or summer. Lifetime estimates for depressive and bipolar disorders with a seasonal pattern average between 0.4% and 2.9% in US, Canadian, and UK community studies.[5][6][7] Some estimates may be as high 9.7%.[8] However, these differences are probably due to differences in the sampling and diagnostic criteria used.

Bipolar disorder in adultsSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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A recurrent and often chronic mental illness, bipolar disorder is marked by episodes of hypomania or mania and depression, associated with a change or impairment in functioning. The long-term course of illness is characterised by a predominance of depression, although a history of at least one manic, hypomanic, or mixed episode is required to make the diagnosis of a bipolar disorder.

Bipolar I disorder: at least one manic episode.

Bipolar II disorder: has never had a full manic episode; at least one hypomanic episode and at least one major depressive episode.[2]

Bipolar disorder in children
Bipolar disorder is an uncommon condition in children that becomes more frequent in teens, approaching the rate of frequency seen in adults.[9][10] The adult criteria describe a disorder of fluctuating mood cycles, consisting of episodes of elevated mood and increased activity or energy (mania) lasting at least 1 week, and episodes of lowered mood and activity (depression); an episode of mania is necessary for a diagnosis to be made. The diagnosis can be controversial, as criteria overlap with other childhood conditions such as ADHD and comorbid oppositional defiant disorder.

Suicide risk mitigationSigns & symptomsInvestigationsDifferentialsTreatment algorithm
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Suicide is an important cause of death globally and a significant public health concern. An estimated 800,000 people die by suicide each year; it is the second leading cause of death among people aged 15 to 29 years.[11] Originally called suicide risk management, suicide risk mitigation aims to be a more realistic and compassionate approach.[12][13][14] It refers to the identification, assessment, intervention, and treatment of a person at risk of suicide. It is an ongoing process whether due to a mental illness or a life crisis.

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