After nearly a decade of use, Zero to Three recognized the need to incorporate new knowledge from clinical research and clinical experience in the DC:0-3 diagnostic system. The process of revision began in 2002. The revision was undertaken with the explicit aims of increasing the reliability of the diagnostic classification and facilitating epidemiologic and clinical research on the validity of the criteria. DC:0-3R, the revised edition, was published in August of 2005.
DC:0-3R reflects an integration of current empirical evidence on mental health disorders in infants, toddlers, and preschoolers and the clinical observations of mental health clinicians across the world. Inputs to the work of the revision task force included: 1) an initial survey of users of DC:0-3, 2) a detailed review of the literature, including RDC-PA, 3) a second survey of users to comment on a preliminary draft of DC:0-3R, 4) further comments from individuals and identified clinical groups working in areas where the task force had found particular uncertainty or differences of perspective, and 5) a final set of critical reviews of a penultimate revision document by a panel of expert infant mental health clinicians and researchers.
The evolution of nosology: Examples of changes in DC:0-3R from the first version
While we cannot enumerate all of the changes made in DC:0-3R, we will highlight some key revisions as illustrations of how a diagnostic classification system changes in response to emerging empirical evidence and the need to establish whether the classification system is psychometrically sound, valid, and clinically useful. We will describe the reasons why changes were made, as well as the real-world compromises that were made in the revision process.
What’s in a name?
At first glance, the change in the name of DC:0-3 Axis 1 from “primary diagnosis” to “clinical disorder” in DC:0-3R seems trivial. However, this change reflects two points of clarification in the revised edition. First, the fact that DC:0-3R and DSM Axis I now share the same name acknowledges the interrelationship between the two diagnostic classifications. The DC:0-3 diagnostic system is intended to supplement, not replace the DSM/ICD systems. The revised edition explicitly states that if a child meets criteria for a DSM disorder, that disorder should be coded on DC:0-3R Axis I, referencing both a DC:0-3R 800 code with the appropriate DSM code in parentheses. Thus, disorders such as attention deficit hyperactivity disorder, oppositional defiant disorder or obsessive compulsive disorder, which are not covered in the DC:0-3 classification, should be recorded as DC:0-3 clinical disorders on Axis 1. Second, the previous DC:0-3 Axis 1 label of “primary diagnosis” gave many clinicians the impression that they should only make one diagnosis, rather than identify all of the disorders for which the child met criteria. The appendix entitled “Guidelines to Selecting the
(italics added) Appropriate Diagnosis” in the first version of DC:0-3 reinforced the idea that there was a hierarchy of disorders and a proscription against identifying multiple disorders. By naming Axis I “clinical disorders” (and adding explicit text about comorbidity to the revised manual), the DC: 0-3R clarifies that infants, toddlers, and preschoolers may meet criteria for more than one psychiatric disorder and that the co-occurrence of disorders is often an indicator of illness severity and impairment (Angold, Costello, & Erkanli, 1999
; Egger & Angold, 2006b
Presuming health: crafting criteria to decrease the chance of false positives
The work group also grappled with the concern that DC: 0-3 criteria would identify disorders in healthy children. The anxiety disorders provide an example of this potential problem because it is challenging to distinguish between developmentally normative anxiety (e.g., stranger anxiety), variations in temperament that do not meet the level of clinical significance, and clinically significant anxiety in young children (Egger & Angold, 2006a
). Based on the current empirical evidence, DC:0-3R added specific criteria for symptoms, types and sub-types in the anxiety disorders section. However, to minimize the risk of false positives (i.e. children identified with a disorder who are actually healthy), the DC: 0-3R anxiety disorders section specifies broad characteristics of clinically significant anxiety that must be present before a diagnosis of any of the anxiety sub-types should be considered. Anxiety symptoms must: (1) cause the child distress, or lead to avoidance of activities or settings associated with the anxiety or fear, (2) occur during two or more everyday activities, or within two or more relationships, (3) be uncontrollable, at least some of the time, (4) persist for at least 2 weeks (note that for some disorders the duration is longer than 2 weeks), and (5) impair the child’s or the family’s functioning, and/or the child’s expected development.
The weight of the evidence: revision of DC:0-3 diagnoses not included in the DSM system
Another challenge for the work group was revision of diagnostic categories unique to the DC:0-3 nosology. We will describe two examples of how the relative lack or relative abundance of empirical evidence differentially shaped the revision of two diagnostic categories unique to the DC:0-3 system: regulatory disorders and disorders of relating and communicating.
The DC:0-3 presented a new category of disorders call “regulatory disorders.” In the revised edition, the name of the category was changed to “regulation disorders of sensory processing” to emphasize that difficulties processing sensory information (i.e., from senses (visual, auditory, touch, olfaction, taste) or from movement) are the core symptoms of these disorders. Here again, a change in name reflects an attempt to provide greater specificity to these criteria. The name change also reflected a revised definition of these disorders as “difficulties in regulating emotions and behaviors, as well as motor abilities, in response to sensory stimulation that lead to impairment in development and functioning” (p. 28, (Zero to Three, 2005
). The work group sought input from occupational therapists who evaluate young children with sensory and motor dysregulation (Miller, Robinson, & Moulton, 2004
). Despite clinical enthusiasm for this category of disorders (regulatory disorders were the most common disorder diagnosed in the user survey (Zero to Three, 2005
)), data supporting sensory and motor dysregulation syndromes as distinct and valid disorders are scant. The lack of consensus among experts and the lack of empirical data led the task force members to conclude that there was insufficient evidence to support the inclusion of detailed symptom criteria for each of the subtypes. Instead, descriptive information was provided with the hope that future research will lead to more specific criteria.
Changes in the “disorders of relating and communicating” section of DC:0-3R reflects an opposite situation than the one described above for regulatory disorders; there has been substantial advances made in our understanding of the presentation and treatment of autistic spectrum disorders since the publication of DC: 0-3 (Volkmar, Lord, Bailey, Schultz, & Klin, 2004
). Based on the current and growing strength of empirical support for the DSM-IV criteria for pervasive developmental disorders, the DC:0-3R states that when a child’s symptoms meet the DSM-IV-TR criteria for any of the pervasive developmental disorders (including pervasive developmental disorder, not otherwise specified), the DSM diagnosis should be recorded on Axis I, referencing both a DC:0-3R 800 code and the appropriate DSM code. It was difficult for the workgroup to reach a consensus about multisystem developmental disorder (MSDD), a DC:0-3 disorder that does not require the full appearance of the relationship and communication difficulties observed in children with autistic disorder. Disagreement about MSDD’s inclusion in DC:0-3R led to a compromise: the classification of MSDD was retained, but it was designated as an option to be applied only
for children under two years of age, since agreement about the diagnosis of DSM PDDs in children younger than two has not yet been achieved.
Changes to Axis II
Axis II is intended to be used to assess the child’s relationships with all of the child’s primary caregivers including biological, foster or adoptive parents, grandparents, and other adults. In the DC:0-3R, two tools for evaluating and classifying the child’s relationships with his or her primary caregivers are includes as appendices: The Parent-Infant Relationship Global Assessment of Functioning (PIR-GAS), and the Relationship Problems Checklist. The workgroup made minor scaling changes and re-wordings of the PIR-GAS, a 0–100 scale that is meant to reflect degrees of disturbance in the parent-child relationships. Psychometric data on the PIR-GAS are not included in the original or revised DC:0-3 manual. Because of a lack of empirical support for the relationship disorders specified in the original DC:0-3, the symptoms of these putative disorders were turned into a Relationship Problems Checklist which is meant to guide the clinician in assessing whether and in what way the child’s caregiving relationships are dysfunctional.
Changes to Axis III
Axis III is unchanged in the revised DC:0-3. Axis III is for recording medical and developmental disorders (e.g., language disorders) and mental retardation using other established diagnostic systems. As noted above, Axis I DSM disorders including PDDs are coded on Axis 1.
Changes to Axis IV
Axis IV provides a framework for evaluating psychosocial and environmental stressors. A checklist of stressors is included as an appendix in the DC:0-3R. The stressor checklist does not encompass the universe of possible stressors; clinicians are encouraged to list all stressors affecting the child and family being evaluated. The impact of any given stressor on a child is affected by the child’s developmental level, by the availability of caregivers to buffer, protect and help the child understand and cope, and by the severity, duration, and number of stressors. The checklist provides spaces to indicate age of onset, duration, severity and context of each stressor so as to encourage a comprehensive assessment of all aspects of these risk factors.
Changes to Axis V
Whereas Axis V in the DSM system codes global functioning, Axis V in DC:0-3R, as in the first edition, provides an opportunity for the clinician to assess and rate the child’s capacities for developmentally-appropriate emotional and social functioning. This difference represents a shift from the DSM focus on “incapacity” and “impairment” to an exploration of an infant, toddler, or preschooler’s functional capacities for and competence in social and emotional domains. The DC:0-3 perspective provides the opportunity to identify the child’s functional coping capacities, not only the child’s incapacities. The revision attempted to clarify the descriptions in this section. Like the regulatory disorders, the capacities in Axis V are clearly very important in understanding mental health and developmental problems in young children, but more empirical evidence is needed to help us to define and measure these capacities and integrate these findings into an overall mental health assessment.
Crosswalk between DC:0-3R and the DSM
We have described above cross-classification between the DSM and the DC:0-3R. Cross-classification is different than a “cross-walk” between the two systems. A number of states have supported the use of DC:0-3R-DSM “crosswalks” to facilitate the use of DC:0-3 in clinical settings. The need for a “crosswalk” has arisen because ICD-10 codes are required for reimbursement (e.g., for Medicaid coverage) and ICD-10 codes are usually based on their corollary DSM codes. Thus, a crosswalk serves an administrative, not a clinical, purpose. On one hand, the development of a crosswalk between the DSM/ICD and DC:0-3 systems reflects increasing recognition of the need for a developmentally appropriate nosology of early childhood mental health problems and the need to provide young children with mental health assessments and interventions. On the other hand, the crosswalk may give the impression that the empirical support both for specific DC:0-3 disorders and for their relationships with the DSM/ICD criteria is much stronger than it is.
Diagnostic Classification and Clinical Formulation
Guidelines for the assessment and clinical formulation were also revised in DC:0-3R. The inclusion of these guidelines in the DC:0-3 diagnostic manual acknowledges the relationships between nosology, assessment, and clinical formulation. Clinical formulation emerges as the clinician pulls together a wide range of information from multiple sources and contexts, and across many domains. From this information the clinician identifies a meaningful pattern that can be used to define the child’s mental health needs and plan treatments or interventions to address these needs. It is beyond the scope of this paper to address the components of comprehensive mental health assessments of young children and their families or the process of clinical formulation (an excellent resource is (Zeanah, 2009)). However, below we explore three key points about the interplay between nosology, assessment, and clinical formulation.
First, the DC:0-3 system is multi-axial. A comprehensive mental health assessment must attempt to understand the child across all five axes. For example, the child’s present emotional or behavioral symptoms must be understood within the child’s current level of functioning across multiple developmental domains (e.g., cognitive functioning, expressive and receptive language, gross and fine motor skills, and social-emotional skills). Moreover, because children three and under (and in some states five and under) are eligible for early intervention services for developmental delays, as well as for medical disorders, it is critical that clinicians who are assessing young children identify any delays and medical disorders on Axis III so as to provide appropriate referrals for developmental assessments (e.g., by speech therapists, occupational therapists). Collaboration with other pediatric health providers, including the child’s pediatrician, is essential to ensure that underlying medical, developmental, or genetic conditions are considered in the differential diagnosis. Because the pervasiveness of the child’s symptoms across settings may vary, assessment of the context of symptoms is also essential. Assessment must include the quality of the child’s relationships with caregivers and others (Axis II), the child’s environment and stressors (Axis IV), as well as the quality and context of the child’s capacities for social and emotional functioning (Axis V). A comprehensive assessment will include multiple sessions, multiple informants, multidisciplinary and multi-cultural perspectives, and multiple modes of assessment (Zeanah, Jr., 2000
). Lastly, assessment of young children requires training in and clinical expertise in infant mental health. On one hand, a diagnostic classification must show acceptable reliability and validity to be clinical useful; on the other hand, the value of these systems in clinical practice will only be as good as the systems of care and individual clinicians who apply them.
Second, the aim of a nosology is to classify problems as disorders, not to classify children as problems (Rutter & Gould, 1985
). Resistance to categorical diagnosis sometimes arises from a misperception that making diagnoses reduces individuals to “labels” and thereby minimizes the complexity of the child and his or her relationships. The goal of a mental health assessment is to make sense of a child’s mental health symptoms and the associated factors including the parent-child relationship, the environmental context, the child’s physical and developmental status, acute and chronic stressors, and biological features. Understanding the interplay between these factors may begin with a nosological framework, but the domain of classification must be integrated with within-person, relationship-based, and environmental (including family, neighborhood, culture) approaches to understanding the risk for, emergence of, and persistence of impairing emotional, behavioral, and developmental symptoms and disorders in early childhood.
Third, standardized nosologies facilitate the development of dimensional and diagnostic measurement tools (Angold & Costello, 2009
). A comprehensive mental health assessment of a young child must use multiple modes of assessment including adult reports, observational assessments, structured or unstructured play/interactions with the child, and standardized cognitive, motor, language, and social/emotional assessments. When possible, empirically tested measures with demonstrated reliability and validity should be used. There are a number of psychometrically sound scalar measures for assessing mental health symptoms in young children beginning at about 12 months. Types of measures include broad symptom checklist measures (e.g., the Infant Toddler Social Emotional Assessment (ITSEA) for children 12–36 months old (Briggs-Gowan, 1996
; Briggs-Gowan, 1998
; Carter, Briggs-Gowan, Margaret, Jones, &, Little, 2003
)), DSM-referenced rating scales (e.g., the Early Childhood Inventory-4 (ECI) (ages 3–6 years old)(Gadow & Sprafkin, 1997
; Gadow et al., 2001
; Sprafkin & Gadow, 1996
))), or checklist measures of specific symptom clusters (e.g., the ADHD Rating Scale (DuPaul, Power, Anastopoulos, & Reid, 1998
; Gimpel & Kuhn, 2000
In the future, structured diagnostic interviews for assessing early childhood psychiatric symptoms and disorders will enable clinicians to reliably assess the full range of early childhood mental health symptoms and disorders. The Preschool Age Psychiatric Assessment (PAPA) is currently the only comprehensive parent-report psychiatric interview with demonstrated test-retest reliability and validity for assessing psychiatric symptoms and disorders in children ages 2–5, but the PAPA is not currently feasible for use in most clinical settings (Egger et al., 2006
). Observational assessments also play an important role in infant and early childhood mental health assessments. Currently, there is only one diagnostic assessment protocol for young children that combines results of parent-report and observational structured assessments to make a diagnosis in clinical settings: the Autism Diagnostic Interview Schedule (ADI-R), which when conducted in conjunction with the Autism Diagnostic Observational Assessment (ADOS), is considered the “gold standard” assessment for autism (Lord, Rutter, DiLavore, & Risi, 2003
; Rutter, LeCouteur, & Lord, 2003
). In the future, psychometrically sound and valid descriptive and observational measures, as well as genetic, metabolic, and neuroimaging methods which are rapidly being developed, will change our characterizations of disorders and be integrated into future nosologies and assessment approaches (Angold & Costello, 2009
The development of the ADI-R, the ADOS, and the PAPA illustrate the iterative relationship between nosology and measurement: each of these measures has advanced the quality of research on early childhood psychopathology which then leads to refinement of the current classification systems. Standardized and psychometrically validated tools, whether scalar or diagnostic, are still not widely used in clinical infant mental health settings. This gap between research and clinical practice is also present in mental health practice in later childhood (Angold, 2009
). Access to measures, availability of training in their application and interpretation, and feasibility of use within time and budget constraints must be addressed so that the infant mental health field can bring evidence-based assessments and interventions to young children and their families.
Limitations of Current Classifications and Future Research
Despite its title and intent, the DC:0-3 system does not yet provide fully adequate diagnostic criteria for the identification of mental health disorders in infants. We need clinically-focused longitudinal studies of infants that use much more refined measures of the specifics of symptomatology as it emerges from birth to 24 months. Most likely, infancy syndromes will be defined by patterns of dysregulation across multiple domains. We need measures that will enable us to describe normative variation and patterns of dysregulation in crying, sleeping, eating, motor activity, sensory sensitivity and disturbances in social relatedness (e.g., not simply presence of dysregulation but the intensity, frequency, duration, onset, and environmental and relational context of the symptom). We will need to determine empirically the boundaries between normative and clinically significant presentations just as we have done with psychiatric symptomatology in preschoolers (Egger & Angold, 2006b
). Integration of early temperament approaches, which cover many of the domains described above, with those of developmental psychopathology will most likely provide an avenue for moving forward in our understanding of very early-onset psychopathology (Angold & Costello, 2009
). Developing an empirically based nosology of mental health symptoms and disorders for infant and toddlers is one of the most important needs facing the infant mental health field.
Current mental health classifications are imperfect. This is true across the lifespan, but particularly true in early childhood. Just as the DSM and ICD systems have undergone multiple iterations (DSM-V is slated for publication in 2012), the DC:0-3R will change, and, we hope, will eventually become part of a nosology of psychopathology that reflects a truly developmental approach to mental health disorders across the life span.
The current classifications of psychopathology, for adults as well as children, are based on clinical observations of clusters of specific behaviors and emotional states. The high rates of comorbidity among psychiatric disorders in adults and children, including preschoolers (Angold et al., 1999
; Egger & Angold, 2006b
), suggest that our current nosologies may be identifying syndromes that are, in fact, not distinct disorders, but varied presentations of an underlying syndrome that cannot be characterized adequately by our current descriptive criteria. As we get closer to understanding the underlying mechanisms that cause and sustain the clusters of behavioral and emotional symptoms that we call mental health disorders, we would expect to have greater, but not complete, delineation of the boundaries between different disorders. Ongoing research in cognitive and affective neuroscience, developmental psychology, genetics, and epidemiology has the potential to reshape our understanding of the neurobiological foundations and mechanisms of mental disorders. As we understand more about the relationship between multiple biological systems and behaviors, we should be able to develop a clinically and biologically meaningful nosology that enables us to find better ways to identify and alleviate the suffering of young children.
The infant mental health field has insights important to the diagnostic process throughout the lifespan. The inclusion of (1) the characteristic and quality of primary caregiving relationships and (2) the developmental and environmental contexts in the diagnostic process should not be seen as barriers to the development of a scientifically and clinically meaningful nosology in early childhood. Rather, they should be seen as important components of all classifications of psychopathology from early childhood to late life. For example, the challenge of characterizing depressed mood in toddlers with limited expressive language is also faced with older children who have very low IQs, as well as with demented seniors. Moreover, understanding how problematic behaviors and emotions change within the context of relationships is not only informative for understanding disorders in early childhood, but is a key perspective for understanding and treating mental disorder throughout the lifespan, as family-behavioral therapies demonstrate so clearly. As the infant mental field makes progress in developing a valid classification system of disorders for itself, it may well be able to inform and re-shape our approaches to classification of psychopathology at other ages. We may then reach a point where we have a shared nosology of mental disorders that is developmentally sensitive and relevant from infancy to old age.