Depressive disorders and bipolar and related disorders comprise new categories in the DSM-5 and have been divided into separate sections in the newest edition. Several new diagnoses have been included in each chapter to aid with diagnostic clarity and assist in limiting overdiagnosis of some conditions, such as bipolar disorder in children.

Major depressive disorder (MDD) requires a minimum of 2 weeks of symptoms including either depressed mood or loss of interest or pleasure in nearly all activities. Four additional symptoms must also be present ( Table 18.1 ). In children and adolescents, a new onset of irritability and/or restlessness may be present instead of depressed mood. Furthermore, many children/adolescents complain of pervasive boredom. A change in appetite (usually decreased but can be increased) with carbohydrate craving, with or without accompanying weight changes, and sleep disturbance along with somatic complaints (fatigue, vague aches and pains) may also be present. Furthermore, a key indicator in children may be declining performance in school. Psychotic symptoms, seen in severe cases of MDD, are generally mood-congruent (e.g., derogatory auditory hallucinations, guilt associated delusional thinking). Suicidal thoughts and attempts are common and should be evaluated. A prior history of suicidal thoughts/attempts and prominent feelings of hopelessness are risk factors that should be closely monitored.

Previously a bereavement exclusion existed in making a diagnosis of MDD. Current evidence suggests that although most people experience bereavement following a significant loss (e.g., loss of a loved one, financial ruin, etc.) without developing depression, many do, in fact, experience depressive symptoms related to depression. As such, evidence suggests that treatments for MDD and MDD with bereavement are often likely to help with the remittance of symptoms.

The prevalence of MDD in prepubertal children is approximately 2% with a 1 : 1 female-to-male ratio. In adolescence the prevalence is approximately 5% with a female-to-male ratio of 2 : 1 (similar to adults). If untreated, major depression can become chronic in 10% of patients.

Genetic predisposition for MDD is present with twin studies showing 40-65% heritability. Additionally, family studies show a twofold to fourfold increased risk for depression in offspring of depressed parents. Other potential responsible factors for depression include dysregulation of central serotonergic and/or noradrenergic systems, hypothalamic-pituitary-adrenal axis dysfunction, and the influence of pubertal sex hormones. Stressful life events such as abuse and neglect have also been found to precipitate MDD, especially in young children.

Anxiety-related disorders (up to 80% prevalence), substance-related disorders (up to 30% prevalence), and conduct/disruptive disorders (up to 20% prevalence) frequently present as co-morbid with MDD. Onset of MDD in childhood is also more likely to be related to bipolar symptoms versus adult-onset bipolar disorder. This is especially true when a family history of bipolar disorder is present.

Differential diagnoses for MDD are diverse. It is always prudent to rule out mood disorder due to another medical condition or substance-related mood disorders before considering MDD. Dysphoria and concentration concerns related to untreated attention-deficit/hyperactivity disorder (ADHD) may also be mistakenly diagnosed as depression. Medically, conditions such as hypothyroidism, anemia, diabetes, and folate and B ₁₂ vitamin deficiencies need to be ruled out.

Persistent depressive disorder (formerly dysthymia and chronic MDD) (prevalence rate 0.5-2.0%) is a chronic form of depression characterized by a depressed or irritable mood (subjectively or described by others) present for at least 1 year. Two of the following symptoms are also required: changes in appetite, sleep difficulty, fatigue, low self-esteem, poor concentration or difficulty making decisions, and feelings of hopelessness. Approximately 70% of children and adolescents with persistent depressive disorder eventually develop major depression.

Disruptive mood dysregulation disorder (DMDD) has been added to DSM-5 and includes children ages 6-18 years who present with a chronic (12 or more months) pattern of severe irritability and behavioral dysregulation. The prevalence rate of DMDD is not known; however, estimates based upon the core feature of chronic irritability suggest a rate between 2% and 5%. DMDD typically first presents in school-age children and is more common among males. In distinguishing bipolar disorder in children from DMDD, particular attention should be given to the course of symptoms (with DMDD being chronic and persistent and bipolar disorder presenting with episodic mood changes). Co-morbidities with DMDD are relatively high, and conditions such as conduct, impulse-control, and disruptive behavior disorders should be assessed. Furthermore, children and adolescents with DMDD may also present with other mood concerns, anxiety, and/or autism spectrum disorder symptoms and diagnoses.

Premenstrual dysphoric disorder (PDD) was also added to DSM-5 and is marked by repeated irritability, anxiety, and mood lability that presents during the premenstrual cycle and remits near the onset of menses. Approximately 1.8-5.8% of adult women are thought to experience PDD with adolescent rates thought to be at a similar level. At least five physical (e.g., sleep disturbance, breast tenderness, joint/muscle pain, fatigue, appetite changes) and/or behavioral symptoms (e.g., affective lability, irritability, depressed mood, anxiety) must be present. Symptoms typically peak near the onset of menses. PDD differs from premenstrual syndrome in the number of symptoms present and in regard to the affective symptoms that are present. MDD is the most commonly presenting co-morbidity. However, other conditions such as anxiety disorders, allergies, migraine headaches, eating disorders, and substance abuse disorders may worsen during the premenstrual period.

Unspecified depressive disorder is a diagnosis used when patients have functionally impairing depressive symptoms that do not meet criteria for another condition.

Numerous specifiers for depressive disorders may also be identified. These include methods of noting additional struggles with anxious distress, mixed features (including elevated mood/hypomanic symptoms), melancholic features (loss of pleasure/lack of reactivity to pleasurable stimuli), psychotic features, and seasonal patterns (most common in northern or extreme southern latitudes, in which depressive symptoms occur in the late fall and early winter when the hours of daylight are shortening).

Treatment of depression involves psychopharmacological approaches and/or psychotherapy. Regardless of the treatment approach chosen, a thorough diagnostic interview and screening measures should be completed. There are a variety of screening tools such as Kovacs Children’s Depression Inventory (CDI) that may be helpful. First-line pharmacological treatment involves selective serotonin reuptake inhibitors (SSRIs) that have demonstrated response rates of 50-70% despite high-placebo response rates. Fluoxetine is the only medication approved by the U.S. Food and Drug Administration (FDA) for treatment in youth 8 years and older. However, many other “off label” medications such as citalopram, escitalopram, paroxetine, and venlafaxine have positive clinical trial results as well. An antidepressant should be given an adequate trial (6 weeks at therapeutic doses) before switching or discontinuing unless there are serious side effects. For a first episode of depression in children and adolescents, treatment for 6-9 months after remission of symptoms is recommended. Patients with recurrent or persistent depression may need to take antidepressants for extended periods (years or even a lifetime). If a patient does not respond to adequate trials of two or more antidepressants, a child psychiatrist should be consulted. Following a thorough evaluation, the psychiatrist may use augmentation strategies that include other medications such as lithium, thyroid hormone, lamotrigine, or bupropion.

For acute depression, more frequent office visits are indicated, and the risks of medication (including suicidal and self-destructive behaviors) should always be discussed with caregivers and the patient. Higher frequency of monitoring should include regular telephone calls and/or collaborative care with a psychotherapist. Psychoeducation about the illness and a discussion about calling immediately if new symptoms occur should be held with the family. Notable side effects are thoughts of suicide, increased agitation, or restlessness. Other side effects include headache, dizziness, gastrointestinal symptoms, sleep cycle disturbance, sexual dysfunction, akathisia, serotonin syndrome, and risk of increased bruising (due to platelet inhibition).

In 2004, the FDA issued warnings regarding the potential for increased suicidal thoughts and/or behaviors when using an antidepressant. The data suggest that antidepressants pose a 4% risk, versus a 2% risk in placebo. An increase in suicides in children and adolescents since that year has many experts believing that it might be related to lowered prescription rates of antidepressants and resultant untreated depression. Substance use, concomitant conduct problems, and impulsivity increase the risk of suicide.

Psychotherapy appears to have good efficacy in mild to moderate depression. In moderate to severe depression, combined treatment with psychotherapy and medication has the greatest rate of response, although in severe cases, the efficacy was equivalent to medication alone. Cognitive-behavioral therapy (CBT) and interpersonal therapies have received the most empirical support. CBT involves a variety of behavioral techniques and skills-building to mitigate cognitive distortions and maladaptive processing. Interpersonal therapy focuses on collaborative decisions between the therapist and patient and is based on the exploration and recognition of precipitants of depression. Family therapy is often used as an adjunct to other treatments for depression. Light therapy has been shown to be beneficial for seasonal variants of MDD. Electroconvulsive therapy (ECT) is also used in refractory and life-threatening depression.

Suicide is a fatal complication of MDD and surpasses motor vehicle accidents as a cause of death in adolescents. It has high prevalence among high school students with 20% having contemplated suicide and 8% having attempted suicide each year. While the risk of suicide during an MDD episode is high, it can be paradoxically higher during start of treatment, as energy and motivation improve with cognitive recovery from depression.

Treatment is targeted toward decreasing morbidity and suicide. Along with treatments mentioned previously, modalities such as hospitalization, partial hospitalization, therapeutic after-school programs, or group therapies may be needed.