Despite significant improvements in the empirical basis for diagnostic categorization across the years, one area where there have been few changes is the integration of developmental changes into the diagnostic criteria. The diagnostic criteria for common childhood disorders often involve the application of adult criteria to children. Although the Diagnostic and Statistical Manual (5th ed.; DSM-5) (American Psychiatric Association [APA], 2013) includes descriptions of child manifestation of symptoms for some disorders, few disorders include guidance on how symptoms may manifest differently across children and adolescents of different ages. Thus, therapists are left to use their clinical judgment to apply DSM criteria in a developmentally sensitive manner.

The lack of attention to developmental variations in symptoms in the DSM and its application is consistent with a common misconception in psychopathology, the developmental uniformity myth (Kendall, Lerner, & Craighead, 1984), which holds that disorders manifest the same no matter the age of the individual. In fact, research indicates that psychological symptoms vary quite a bit across developmental stages.

For example, there are developmental differences in the frequency of specific anxiety disorders at different ages, with separation anxiety disorder more common in young children (ages 6 to 9) and social phobia more frequent in adolescents (Weems & Costa, 2005; Weems, Hammond-Laurence, Silverman, & Ginsburg, 1998). This may be related to physical developmental changes occurring during these ages, such as that young children learn individuation and independence from parents at ages 6 to 11 and experience fears related to loss or separation from parents (Weems & Costa, 2005) and adolescents emphasize peer relationships and social interactions (Warren & Sroufe, 2004; Westenberg, van Strien, & Drewes, 2001) and therefore more often experience anxiety related to social situations.

There are also differences in the rates of depression across childhood and adolescence, with low rates in children (less than 2%) and a dramatic increase in prevalence in adolescence (4%–8%) (Hankin et al., 1998), especially in females (Silberg et al., 1999). Bipolar disorder is also rare in young children but increases in prevalence around puberty, with 15 to 19 years of age as the typical age of onset (for a review, see Kim & Miklowitz, 2002).

There are also developmental differences in depressive symptoms over the long term. For example, children who have their first depressive episode before adolescence tend to have more severe, recurrent, and treatment-resistant major depressive disorder, and as many as 40% of children who have a depressive episode will have a second episode within 5 years (Kovacs et al., 1984). Childhood-onset bipolar disorder is also typically more chronic and treatment resistant than later-onset bipolar disorder (for a review see Kim & Miklowitz, 2002). Children are less likely to see their symptoms as causing functional impairment than are their parents or other reporters (APA, 1994; Langley, Bergman, & Piacentini, 2002). As such, it is essential for assessors to be sensitive to these developmental patterns in symptoms and to rely on multiple reporters in assessing child and adolescent psychopathology.

Despite the necessity of involving multiple reporters in the assessment of child and adolescent psychopathology, there is rarely agreement on symptoms (Achenbach, McConaughy, & Howell, 1987; Comer & Kendall, 2004; Grills & Ollendick, 2002; Rapee, Barrett, Dadds, & Evans, 1994). Parent–child agreement ranges from kappas of .09 for depressive symptoms to .32 for anxiety symptoms and .29 for symptoms of attention-deficit/hyperactivity disorder (Grills & Ollendick, 2002; Rapee et al., 1994). Children often report anxiety symptoms at higher rates and intensity than their parents (Bird, Gould, & Staghezza, 1992; Edelbrock, Costello, Dulcan, Conover, & Kala, 1986; Herjanic & Reich, 1997; Hodges, Gordon, & Lennon, 1990; Kolko & Kazdin, 1993; Lagattuta, Sayfan, & Bamford, 2012); however, it is unclear which report of child anxiety is more accurate or the weight that should be given to each reporter.

Some have suggested that the age of the child should influence the degree to which assessors rely on parent versus child report. For example, it has been suggested that parental report should be relied on in assessing children below the age of 11 because such young children experience difficulties in self-report of behavior or mood problems (Achenbach et al., 1987; Ollendick & Hersen, 1993) most likely due to their limited verbal ability and insight. Further, self-report questionnaires are not commonly recommended for children under the age of 8 because children of that age typically are unable to complete such measures without assistance (Beidel & Stanley, 1993). Others have suggested that children are not always able to respond to self-report measures appropriately; for instance, they are likely to respond to questions on questionnaires based on their emotional reaction to a statement rather than based on the frequency of the event (King & Gullone, 1990; McCathie & Spence, 1991). However, the format of assessment also may influence children’s ability to complete a self-report questionnaire. Questionnaires with only three anchors are the most reliable and valid way to use such measures with children (Beidel, Turner, & Morris, 1995; Ollendick, 1983). Additionally, new information indicates that children as young as 4 can report on their daily emotional states when assessed using a pictorial Likert scale and simplified wording read to them by an assessor (Lagattuta et al., 2012). Thus the most important aspect of assessment of young children’s self-report may be the use of developmentally sensitive tools and techniques.

In children and adolescents 8 years of age and older, it is common to include the child’s self-report; however, the degree to which the child’s report is relied on may vary by the type of symptoms being assessed. Some have suggested that child report is most accurate in cases of internalizing symptoms (Jensen, Xenakis, Davis, & Degroot, 1988) versus externalizing or behavior symptoms, which are more reliably observed by parents and teachers (Kendall, 2006).

When assessing children, it can be difficult to know when and how to ask about behaviors such as sexual involvement, use of drugs or alcohol, and suicidal and homicidal ideations. The consumption of alcohol is common in late adolescents, with 4 out of 5 twelfth graders reporting that they have drunk alcohol, 50% to 62% of sixth graders reporting that they have tasted alcohol, and only 29% reporting that they have had more than a sip (Johnston, O’Malley, Bachman, & Schulenberg, 2002). This is an increase from fourth graders, where only 10% of children have had more than a sip of alcohol. Given this information and the increased rates of substance abuse in those who began drinking at age 11 and 12 (DeWit, Adlaf, Offord, & Ogborne, 2000), assessors should not assume that because a child is well below the drinking age he or she is not drinking. Therefore, while most children will not have consumed alcohol in large quantities, asking is likely recommended with children after the age of 11.

With regard to nicotine or illicit drugs, a similar pattern emerges. Sixty percent of high school seniors have smoked cigarettes; one third of them did so during the previous month. Further, 50% of high school seniors have used illicit drugs (drugs other than alcohol and nicotine) at some time in their lives (Johnston et al., 2002). Given that use of these substances is somewhat common in adolescents, assessors should be sure to ask about drug use, particularly given the association between drug use and psychological struggles (Deas & Brown, 2006; Kandel et al., 1999). Further, 7.8% of adolescents 12 to 17 years of age struggle with diagnosable substance abuse disorders; therefore, questions concerning these topics should be asked of children starting as early as late childhood (Kendall, 2006).

Other risky behaviors that should be assessed beginning in adolescence include sexual behaviors and the use of contraception. Twenty-one percent of adolescent males reported that they had sex by the age of 15 (Albert, Brown, & Flanigan, 2003; Sonenstein, Pleck, & Leighton, 1991) and 7.2% to 10% by the age of 13 (Albert et al., 2003; Kann et al., 1998). Similar rates were found in female adolescents (Albert et al., 2003). Close to 50% of high school students have had sex by the time that they graduate (Kann et al., 1998), with significantly higher rates among African American high school students (89% of males and 70% of females) (Kann et al., 1995). African American and Latino teens also report higher rates of sexual behaviors at earlier ages than Caucasians (Kann et al., 1998).

Although 57% to 74% of adolescents reported that they used contraception at their first sexual experience (Albert et al., 2003), only 10% to 20% of adolescents who are having sex use condoms consistently (DiClemente et al., 1992; Kann et al., 1995), a number that is lower in adolescents of diverse ethnicities (Airhihenbuwa, DiClemente, Wingood, & Lowe, 1992). Additionally, many adolescents have sex during monogamous relationships that are short term and therefore have multiple sexual partners over short periods of time (Overby & Kegeles, 1994). For that reason, it is important that assessment of adolescents includes assessment of sexual behaviors and the use of contraception in order to identify risky behaviors that adolescents may be engaging in as well as symptoms of psychological disorders that may be the target of treatment.

Developmental sensitivity is equally important in therapy as it is in assessment. Although various types of child and adolescent therapy exist, as with adults, one of the most well-validated treatment options for children and adolescents is cognitive behavioral therapy (CBT) (Durlak, Fuhrman, & Lampman, 1991). CBT has been used with children and adolescents between the ages of 4 and 18, with the techniques included varying with the age and developmental level of the child.