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, restlessness, or boredom may be seen instead of depressed mood. A sudden drop in grades is often present. 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. Psychotic symptoms, seen in severe cases of major depression, are generally mood-congruent (e.g., derogatory auditory hallucinations, guilt associated delusional thinking). Suicidal thoughts and attempts are common and should be evaluated.
The prevalence of MDD in prepubertal children is 2% with 1:1 female-to-male ratio; in adolescents the prevalence is 6% to 8%, with a female-to-male ratio of 2:1 (similar to adults). If untreated, major depression can become chronic in 10% of patients.
Depression has a clear genetic predisposition, with familyhistory as the strongest single factor for developing MDD.Twin studies show 40% to 65% heritability for depression.Family studies show a twofold to fourfold increased risk fordepression 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 theinfluence of pubertal sex hormones. The stress-diathesismodel relates to the interaction of genes and environment;for example, a less functional genetic variant of the serotonin receptor in presence of stressful life events could contribute to depression.
Criteria for Diagnosis of a Major Depressive Episode
A. Five or more of the following symptoms present during the same 2-week period and represent a change from previous functioning; at least one of the symptoms is either (1) depressed mood or (2) loss of interest or pleasure. Note: Do not include symptoms that are clearly due to a general medical condition or mood-incongruent delusions or hallucinations 1.
Depressed mood most of the day, nearly every day, as indicated by either subjective report (e.g., feels sad or empty) or observation made by others (e.g., appears tearful). Note: In children and adolescents, mood can be irritable.
2.
Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day (as indicated by subjective account or observation by others) 3.
Significant weight loss when not dieting or weight gain or decrease or increase in appetite nearly every day. Note: In children, consider failure to make expected weight gains 4.
5.
6.
Fatigue or loss of energy nearly every day 7.
Feelings of worthlessness or excessive or inappropriate guilt (which may be delusional) nearly every day (not self-reproach or guilt about being sick) 8.
Diminished ability to think, concentrate, or be decisive nearly every day (subjective account or as observed by others) 9.
Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, a suicide attempt or a specific plan for committing suicide
B. The symptoms do not meet criteria for a mixed manic episode.
C. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
D. The symptoms are not due to the direct physiologic effects of a drug or abuse, a medication, or a general medical condition (e.g., hypothyroidism).