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Mental Disorders

Disruptive or Externalizing Behavior Disorders, Emotional or Internalizing Disorders, Other Disorders

Children's mental health problems have emerged from a long history of misunderstanding and neglect to become the central concern of an active group of researchers and practitioners. The last few decades of the twentieth century witnessed an explosion of knowledge about the nature of disorders that affect children, their frequency of occurrence, their developmental course, and the effectiveness of treatments.

In both children and adults, mental disorders typically are defined in one of two ways: as a category or along a dimension. Categorical approaches are typified by the American Psychiatric Association's diagnostic criteria, as published in the Diagnostic and Statistical Manual of Mental Disorders: DSM-IV. The definitions of mental disorders in theDSM-IV are characterized predominantly by symptom criteria for diagnoses, as well as by taking into account impairment and, for some disorders, age of onset. For this approach, clinical interviews are the typical measurement.

In contrast to categorical approaches, dimensional approaches emphasize symptoms along a continuum from none or few symptoms to clinically significant levels of symptoms. The dimensional approach is typically measured by reliable and valid questionnaires administered to parents, teachers, or the children under study, with lists of behaviors that the respondent indicates as being characteristic of the child, sometimes or somewhat characteristic, or not characteristic of the child. Children are assigned a score along the continuum or are indicated as exceeding, or not, an empirically established cutoff for clinically significant levels of behavior problems or, at the next lower level, of borderline significance.

The mental disorders that children can develop are commonly divided into two groups: disruptive or externalizing behavior disorders (e.g., attention-deficit hyperactivity disorder, conduct problems) and emotional or internalizing behavior disorders (e.g., anxiety, depression). In addition, children also can develop other disorders that do not fit into this classification system, such as autism, schizophrenia, and eating disorders.

An important perspective within which to understand children's mental disorders is development. By its nature, children's behavior fluctuates over time. One of the biggest challenges for parents and practitioners is to distinguish between normal developmental changes and the emergence of a disorder (atypical changes). Development is also an important consideration in determining whether early signs of a disorder will emerge as a full-blown disorder, develop into a different disorder, or resolve into healthy functioning.

The disruptive or externalizing disorders consist of attention deficit hyperactivity disorder (ADHD), conduct disorder, and oppositional defiant disorder. Because the latter two are both considered disruptive behavior disorders, they are typically considered together.

Attention Deficit Hyperactivity Disorder

ADHD has as its primary symptoms inattention, impulsivity, and hyperactivity. Research has shown that inattention symptoms tend to cluster apart from symptoms of impulsivity and hyperactivity, while the latter two tend to cluster together. The DSM-IV maintains this distinction by including two sets of symptoms. In order to meet diagnostic criteria for ADHD, the child's parents or teachers must report the presence of at least six symptoms of inattention (e.g., is often easily distracted by extraneous stimuli) or six symptoms of hyperactivity-impulsivity (e.g., often fidgets with hands or feet or squirms in seat). In both cases, the symptoms must: (1) have been present and been causing impairment before age seven years; (2) have been present for six months or more; and (3) cause clinically significant impairment in terms of interpersonal or academic functioning in two or more settings and must differ from normal developmental expectations. Alternatively, behavior rating scales, on which respondents rate individual symptoms of ADHD, provide a dimensional, age-sensitive, quantitative assessment of ADHD-related problems, along with an indication of the level at which the scores are considered to be indicative of clinically significant problems.

Although reports vary depending on the criteria used, with DSM-IV based criteria the estimates of the incidence of ADHD are about 3 percent to 5 percent of the general population of children. As with the other externalizing disorders, it occurs much more frequently in boys than in girls, with a typical ratio of six to one in samples attained from treatment settings and three to one in community samples.

Although some children show signs of ADHD as early as infancy, for most children the first signs of behavior that differs from developmental expectations emerge between the ages of three and four years. Another common time for children to be first identified is at school entry.

No one knows exactly what causes ADHD. Biological factors are likely to include genetic transmission and pregnancy and birth complications, and may also include brain injury or lead exposure. Researchers have found strong evidence for the influence of genetics (although accounting for only 10 percent to 15 percent of the variance in ADHD symptoms) and neurobiological factors (with more support found for irregularities in brain structures than for neuro-chemical imbalances). The notion that sugar and other dietary factors cause ADHD has received little support. Family factors have not been found to play a clear role in causing ADHD, although family influences are known to be important in the developmental course and emergence of associated symptoms.

The frequent co-occurrence of other conditions and the extent to which ADHD symptoms cause problems in multiple settings (e.g. home, school) complicate treatment of ADHD. These characteristics contribute to the lack of consensus on the best treatment for ADHD as well as the understanding that no one approach works for all children and that many children with ADHD will benefit from a multifaceted treatment program. In addition, there is consensus that treatments must be ongoing and must be sensitive to children's developmental level and other strengths and needs of the child and the family. Stimulant medications, the most frequently used treatment, lead to dramatic improvements in symptoms in about 80 percent of children with ADHD. To treat the problems often associated with ADHD (e.g., conduct problems, depression), which have not been found to benefit from stimulant medications, parent management training (PMT) is an effective approach. Although there are many variations on PMT, standard features typically include providing parents with an understanding of the disorder and techniques for managing their child's behavior problems. Treatment approaches that combine stimulant medication with PMT have shown the greatest effectiveness. Although many other interventions are available, the evidence for their effectiveness is limited. At the beginning of the twenty-first century, a large study funded by the National Institute of Mental Health was underway and was evaluating the effectiveness of an intensive intervention combining medication, PMT, and classroom interventions. This study offered great promise for providing information on the best treatments for children with ADHD.

Conduct Problems (Disruptive Behavior)

The primary behaviors that fall into this category are aggression, noncompliance, defiance, and aversive interpersonal behavior. The DSM-IV categorizes children with the less severe form of disruptive behavior disorders as having oppositional defiant disorder (ODD). Symptoms of ODD include a pattern of negativistic, defiant, noncompliant, and argumentative behavior, lasting for at least six months and causing significant impairment in social or academic functioning. In contrast, aggression and violation of rules characterize conduct disorder (CD). The fifteen symptom-based criteria are clustered into four groups: (1) aggression to people and animals, (2) destruction of property, (3) deceitfulness or theft, and (4) serious violation of rules. From the dimensional perspective, ODD and CD are considered externalizing behavior problems, further distinguished as two subtypes: delinquent and aggressive.

Estimates of the frequency of occurrence among school-age children of ODD range from 5 percent to 25 percent and of CD from 5 percent to 20 percent. As with ADHD, both ODD and CD are more frequently diagnosed in boys than in girls. ODD is twice as common in males than females, although only before puberty; rates are about even in postpubertal males and females. The male to female ratio for CD is between two to one and three to one.

Children may be first diagnosed with ODD or CD at any point in childhood. ODD may be present as early as three years of age and is usually diagnosed by the early school years. Some researchers consider ODD to be a milder, earlier version of CD, although the matter is controversial. Only about 25 percent of children with ODD progress to the more severe CD. On the other hand, most children who meet the criteria for CD were previously diagnosed with ODD and had persisting ODD symptoms. Children with childhood-onset (i.e., before age ten years) of CD, who are more likely to be boys, have been found to be more likely to persist in antisocial behaviors over time. In a 1996 research report, Terri Moffitt and her colleagues delineated two alternative developmental pathways for children with conduct problems. The researchers described one group of these children, those with early onset and problems that persist, as following the life-course-persistent path, whereas those whose conduct problems first emerged later in adolescence and were typically limited to the teen years were described as following the adolescent-limited path.

The development of ODD or CD is likely to have origins in multiple factors associated with diverse pathways. Researchers have found evidence that several factors are related to the development of ODD, CD, or both: genetically based, early temperament difficulties (e.g., having lower frustration tolerance), neurobiological factors (e.g., low psychophysiological arousal), social-cognitive factors (e.g., cognitive distortions), family patterns of interaction (e.g., inadequate monitoring of the child's behavior), and family environmental stress and adversity (e.g., marital discord).

Evidence for the effectiveness of treatment of children with serious conduct problems is not promising. Although families are likely to be offered a range of treatment options, none of them has been shown to be strongly effective. As with ADHD, the treatments that are most likely to be effective include a combination of treatments targeting not only the child but also the family, school, and neighborhood. The most effective treatments also take into consideration the developmental status of the child and the developmental trajectory of conduct problems for the child, with the children most difficult to treat being those who are farther along in the trajectory. Three approaches to treatment that have at least some empirical support are parent management training (focused on teaching parents new skills for managing their child's behavior); cognitive problem-solving skills training (focused on changing children's perceptions and appraisals of interpersonal events); and multisystemic treatment (focused on the context within which the child functions, including family, school, neighborhood, and the legal system).

Some children develop depression and anxiety, disorders that involve not only maladaptive thoughts and emotions but also maladaptive behaviors. It is important to distinguish these disorders from common depressed mood or childhood worries and fears. Knowledge of normal development of emotions and cognitions is helpful in making these distinctions.


Anxiety disorders in children are most likely to fall into the DSM-IV diagnostic categories of generalized anxiety disorder, simple phobia, separation anxiety disorder, obsessive-compulsive disorder, or posttraumatic stress disorder. Children diagnosed with generalized anxiety disorder have a consistent pattern, lasting six months or more, of uncontrollable and excessive anxiety or worry, with the concerns covering a broad range of events or activities. In addition to worry, symptoms include irritability, restlessness, fatigue, difficulty in concentrating, muscle tension, and sleep disturbances. Deborah Beidel found that this disorder commonly begins at around age ten, is persistent, frequently co-occurs with depression, and is often accompanied by a number of physical symptoms such as sweating, suffering from chills, feeling faint, and having a racing pulse.

In contrast to generalized anxiety disorder, children with the other anxiety disorders have a much more narrow focus of their concerns. Simple phobia is typically focused on a specific situation or object. With separation anxiety, children display excessive fear and worry about becoming separated from their primary attachment figures. This disorder is often expressed as school refusal or school phobia. Obsessive-compulsive disorder consists of specific obsessions (abnormal thoughts, images, or impulses) or compulsions (repetitive acts). Posttraumatic stress disorder symptoms develop in reaction to having experienced or witnessed a particularly harrowing event. Symptoms include sleep disturbances, irritability, attention problems, exaggerated startle responses, and hypervigilance.

For phobias and separation anxiety disorder, it is particularly necessary to determine if a child's fears reflect typical concerns of the age group or are clinically significant. Onset of a fear at a time that is different from children's age-typical fears is often an important indication of clinical significance. Other important indications of clinical significance include fear reactions that are strong, persistent, and intense and that interfere with school, family, or peer relationships. Similarly, it is essential to distinguish symptoms of obsessive-compulsive disorder from typical childhood rituals and routines.

Although generalized anxiety disorder and specific phobias are among the most common disorders in children, the other anxiety disorders are rare. Diagnosis of anxiety disorders is particularly difficult because it is so dependent on self-reports from the children. Children may not recognize that their fears are excessive and typically do not complain about them, although they will go out of their way to avoid situations that evoke the anxiety.

The anxiety disorders are typically viewed as having their origins in learning experiences. Children may learn fears through imitation, instruction, or direct reinforcement. Similarly, compulsive behavior can develop from a chance occurrence when a child felt positive reinforcement for engaging in a particular behavior because it was associated with reduced anxiety.

Anxiety disorders that begin in childhood often persist into adulthood. Thus it is particularly important to treat them early. Behavioral or cognitive therapies have been most successful. Treatment typically involves a combination of graduated exposure to the feared situation and teaching the child adaptive and coping self-statements. The effectiveness and safety of using medications was the subject of several studies at the beginning of the twenty-first century; some early findings showed promising results from the use of antidepressants.

Depression (Mood Disorders)

Depression is another relatively common disorder that often first appears in childhood or adolescence. The DSM-IV includes the depression diagnoses of major depression and dysthymia. To be diagnosed with major depression, children must experience either depressed mood (or irritability) or Depression is a relatively common mood disorder that often first appears during childhood or adolescence. (Custom Medical Stock) loss of interest in their usual activities plus other symptoms such as sleep or appetite disturbance, loss of energy, or trouble concentrating. These symptoms must be present nearly every day for two weeks or more. For dysthymia, the symptoms are typically of a lower level of severity but persist for one year or more. For both disorders, the symptoms must cause impairment and must reflect a change from the child's usual level of functioning. Standardized questionnaires are also used to measure depression and determine whether a child's level of symptoms are in the nondepressed range or indicate mild, moderate, or severe levels of depression.

Studies of community samples have found that from 2 percent to 5 percent of children have mood disorders. Rates increase with age. Although rates are about equal for boys and girls in childhood, beginning at puberty girls are twice as likely as boys to receive a depression diagnosis. Depression is a recurrent disorder, with each additional episode increasing the likelihood of a recurrence.

Early stages in the emergence of depression are often missed because children are not likely to recognize or report their distress. Once a depression disorder emerges, it is typically persistent and progresses from relatively mild symptoms to more severe symptoms.

Genetics contribute to the likelihood of a childhood depression occurring, as do neurobiological factors and stress. Children with particular patterns of thinking, such as blaming themselves for negative outcomes while not giving themselves credit for positive outcomes, may be more vulnerable to depression than others.

Treatments that have been found to be successful often involve intervention into the psychosocial components of the disorder. For example, treatment may involve helping the children identify and modify mal-adaptive beliefs and perceptions, develop social skills and problem-solving abilities, and broaden their resources for coping with stress. A particularly effective focus in treatment of adolescents with depression has been on interpersonal relationships, addressing the stage-salient concerns of adolescents. Although they are often prescribed, evidence for the effectiveness of antidepressant medication in children and adolescents has been mixed, possibly because of the methodological challenges of studying medications during periods of still rapid development.

The disorders included in this last category involve more extreme deviations from normal development than the externalizing and internalizing behavior disorders. Parents typically become extremely concerned when symptoms of these disorders emerge. Two of these disorders, autism and childhood schizophrenia, are considered pervasive developmental disorders in the DSM-IV, a term suggesting not only that the disorders emerge early but also that they affect all of the developing systems, including social, language, and cognitive-intellectual.


Autism is an extremely rare condition, occurring in fewer than 5 out of 10,000 individuals, possibly more common in males. Symptoms, which must emerge before the age of three years to meet DSM-IV diagnostic criteria, include impairment in social interaction (e.g., avoidance of eye contact) and communication (e.g., delayed or inadequate speech), as well as repetitive and stereotyped patterns of behavior, interests, or activities. Thus autism develops early and disrupts development in all key areas. The causes of autism are not known, but research findings center on genetic factors, including chromosome abnormalities, and brain injuries or anomalies in brain development. Research on treatment for autism has been controversial because parents understandably pursue a wide range of activities to help their children. Behavioral treatments of specific problematic behaviors have been shown to be successful and often involve teaching the parents the skills to manage their children's behavior. Evidence for the effectiveness of medications have been mixed but offer some promise.


Schizophrenia also is rarely diagnosed in children, probably occurring in fewer than 1 in 1,000 children, and the DSM-IV does not even include criteria for a specific category of childhood schizophrenia. In childhood, although not in adolescence, schizophrenia occurs more frequently in males than females. Symptoms include hallucinations and delusions, disorganized or incoherent speech, and disorganized behavior. Onset is typically in late childhood or adolescence following predominantly normal development. Once it emerges, the course of schizophrenia is characterized by episodes alternating with periods of improvement and relapse. The causes of schizophrenia are most likely genetic and other biological considerations. Treatment may involve the same antipsychotic medications that are used with adults. Research indicates that medications may be most effective when combined with a program of helping the family to manage the child's behavior and minimize stress levels.

Eating Disorders

The DSM-IV includes two eating disorders. Anorexia nervosa is characterized mainly by refusal to maintain even minimally normal body weight, symptoms of intense fear of gaining weight even though underweight, and disturbance in the perception or experience of one's body weight or shape. The second disorder, bulimia nervosa, is diagnosed when individuals engage repeatedly in binge eating alternating with inappropriate methods to prevent weight gain. Eating disorder symptoms and associated behaviors can also be measured with questionnaires. Eating disorders tend to be more prevalent in industrialized countries and are relatively rare, with prevalence estimates typically fewer than 2 percent, nearly all girls. Onset is typically around adolescence and may be associated with a stressful event. Causes are likely to include a combination of biological, family, and sociocultural factors as well as individual psychological characteristics of the child. Treatment, often resisted, requires coordination between medical attention and therapy, including behavioral intervention, training in self-monitoring, and the development of coping skills.


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Sherryl Hope Goodman

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