There are a great diversity of childhood disorder forms and causes. Some of these disorders are primarily disorders of the brain, while others are more behavioral in nature. Brain-based disorders are caused by neurochemical problems or structural abnormalities of the brain. They can be innate (i.e., appearing at or shortly after birth); or they may result from a physical stress such as illness or injury, or an emotional stress, such as trauma or loss. Behavioral problems, on the other hand, are outward signs of difficulty displayed at home, at school, or among friends in an otherwise physically healthy child. Like brain-based problems, behavioral problems may also result from physical or emotional stress. Note that the division between brain-based and behavioral disorders is somewhat arbitrary in many cases. Brain-based disorders such as ADHD clearly impact a child's behavior in school and at home, and vice versa, many disorders previously thought to be primarily behavioral in nature have turned out to have a biological component to them.
Some of the childhood disorders we will discuss in this article can be cured or otherwise resolved, while others end up becoming chronic (long-term) problems that resist the best state-of-the-art interventions. The disorders we will discuss also vary in terms of prevalence and severity. Prevalence refers to a ratio, or percentage, of how often a disease or disorder occurs within a group of people in a population at a given time. Recently, the American Psychological Association has noted an increase in the prevalence of childhood mental illnesses as a whole. Estimates of the current prevalence suggest that between 17.6% and 22% of children have symptoms of one or more childhood disorders; and that 15% of American children suffer from a mental illness that is severe enough to cause some level of functional impairment.
Despite how common they may be, childhood disorders are not part of the normal developmental process that children are expected to go through. The diagnostic criteria for childhood mental disorders requires that children's behavior and/or development deviates from normal age-appropriate behavior and/or development, so understanding normal child development is important. For this reason, you might want to read over our extensive material concerning normal childhood development. Understanding normal developmental milestones for different ages puts you in a better position to understand why disordered behavior is considered abnormal.
Common childhood mental illnesses and developmental disorders include Depression, Bipolar Disorder and Anxiety Disorders, Autism and similar Pervasive Developmental Disorders, Attention Deficit and Hyperactivity Disorder, Learning Disabilities, Adjustment Disorders, Oppositional Defiant Disorder, and Conduct Disorder. The first three of these disorders are not strictly childhood disorders, but instead, affect both children and adults. Since we've already discussed these disorders in detail elsewhere, we will not go into much detail about them here.
- Major Depression is not strictly a childhood disorder, but children do become depressed. Major depression is diagnosed in children of all ages, but appears to increase significantly throughout adolescence. By age 18, prevalence rates appear to be 20%, with depression found in girls more often than boys. For more information about Depression, please click here.
- Bipolar Disorder involves alternating periods of depression and mania (high energy levels that result in a decreased need for sleep, talkativeness, impulsivity, excessive pleasure-seeking behaviors, etc.). As is the case with Major Depression, bipolar disorder is not exclusively a childhood disorder. Though both adults and children may be diagnosed with Bipolar, children display a somewhat different set of symptoms than do adults. For example, in children, mania often looks more like an extreme temper tantrum or severe irritability than the euphoric, hyperactive condition characteristic of adults. The Bipolar diagnosis as applied to children is currently considered controversial, because Bipolar disorder is often difficult to distinguish from other disorders that can occur in children, and may often be misdiagnosed as something else. Children may experience varying degrees of symptom severity, timing between mood fluctuations, et cetera. Some studies have indicated prevalence rates of Bipolar Disorder among children as high as 1% (e.g., meaning that one in every hundred children may display some signs of bipolar disorder)! For more information about Bipolar Disorder, please click here.
- Anxiety Disorders, described in our Anxiety Disorders topic center, are the most common mental illnesses among youngsters today, with prevalence rates ranging between 10% and 20%. Children with anxiety disorders are more likely to develop (or to continue experiencing) anxiety disorders in adulthood, and have an increased risk of developing major depression, attempting suicide, and being hospitalized for mental illnesses. One particular type of anxiety disorder, Obsessive-Compulsive Disorder (a combination of obsessions, or intrusive, repetitive, unwanted thoughts; and compulsions, or anxiety-reducing behavior such as repeated checking or counting) is found in about .5% to 2% of children and adolescents.