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Difficult Child Temperament and Attention-Deficit/Hyperactivity Disorder in Preschool Children

Bussing, Regina MD, MSHS; Lehninger, Frank MD; Eyberg, Sheila PhD

Editor(s): WOLRAICH, MARK L.

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Abstract

ATTENTION-DEFICIT/HYPERACTIVITY DISORDER (ADHD) is a common neurobehavioral disorder that has become the focus of considerable controversy (Stubbe, 2000), prompting a Consensus Conference by the National Institutes of Health in 1998 (National Institute of Mental Health, 1998). It is not a “benign” disorder; it persists over many years and is associated with increasing impairments, especially when accompanied by disruptive behavior disorders (Hechtman, 1999). Despite its onset in early childhood, the evidence base for treatments of preschoolers with ADHD is remarkably underdeveloped, both for psychosocial and for psychopharmacological interventions. Yet, preschoolers are increasingly referred to mental health professionals for ADHD evaluations, accompanied by an upsurge of medication usage in this age group (Zito et al., 2000).

At such young ages the diagnostic process is more challenging than that occurring in later years, especially when a preschooler has temperament qualities resembling ADHD symptoms, such as high-activity level and low persistence. Clinicians then face the task of differentiating between temperament variations and ADHD in need of intervention. A brief reflection on the relation between temperament, personality, and psychopathology in adulthood serves to illustrate some unique challenges in childhood mental disorder classification. Temperament characteristics of infants and children are viewed as the foundation onto which personality is developed over time (Merenda, 1999). Adult personality structure is assumed to develop from the interaction of temperament and social experiences (Strelau, 1987). For adults, personality disorders can be diagnosed and classified as a psychopathological condition coded on Axis 2; such disorders may occur concurrently with other psychiatric disorders captured on Axis 1 (American Psychiatric Association, 1994). For children, though, no corresponding concept of “temperament disorder” exists. Instead, developmental research and clinical child research have proceeded along separate lines in examinations of temperament and psychopathology, with little effort at integration. Hinting at the possibility of temperament disorder, the construct of “difficult temperament” has straddled the interdisciplinary fence, utilized both by developmental theorists and by practicing clinicians, but without the benefit of a clear or a shared definition. This article provides a brief overview of contemporary theories of temperament and the construct of difficult temperament to offer a framework for approaching the clinical assessment and treatment of preschoolers with highly active behavior.

PRESCHOOLERS WITH HIGH ACTIVITY LEVEL: TEMPERAMENT OR THE ADHD?

Many parents of children with ADHD recall that their child was extremely active as an infant and toddler, raising the question of how to differentiate the contributions of temperament from ADHD. Because measurement of temperament has generally fallen into the realm of developmental psychology, only few clinical guidelines for assessing temperament or differentiating extremes of temperament have been developed. Examples are the practice parameters for the assessment of infants and toddlers by the American Academy of Child & Adolescent Psychiatry (Thomas et al., 1997), and the pediatric guidance model proposed by Carey (Carey, 1985, 1998). At the same time, clinicians seeing preschoolers find themselves in a veritable no-man's land with respect to applicable diagnostic classification systems, diagnostic instruments, or practice guidelines for ADHD. Adequate diagnostic classification systems exist for children aged 3 years and younger and for children at elementary school age and older, with a looming gap during the critical preschool years.

ADHD is defined in the Diagnostic and Statistical Manual of Mental Disorder—Version IV (DSM-IV) as “a persistent pattern of inattention and/or hyperactivity-impulsivity that is more frequent and severe than is typically observed in individuals at a comparable level of development” (American Psychiatric Association, 1994, p. 78), with onset of some symptoms before age 7. The DSM-IV does not make specific suggestions for developmental adjustments in diagnosing ADHD in preschoolers. Yet, from a developmental perspective these young children, who are much more active and impulsive than older peers, are not expected to “give close attention to details” or “organize tasks and activities.” Nevertheless, preschoolers must also demonstrate at least 6 of 9 inattentive and/or hyperactive/impulsive symptoms to meet the diagnostic criteria. The DSM-IV specifies that the symptoms must not be better accounted for by another mental disorder and must not occur in the context of pervasive developmental disorders, but it neglects to address the context of the child's temperament characteristics. For example, the temperament domain of activity level relates conceptually to symptoms of hyperactivity, whereas symptoms of inattention may relate to the temperament domains of effortful control or persistence.

Because the DSM-IV is poorly suited as a diagnostic framework for young children, alternative classification schemes have been developed. The Diagnostic Classification: 0 to 3 (DC:0–3) (Zero to Three/National Center for Clinical Infant Programs, 1994) resembles the DSM-IV in its multiaxial approach, but offers a different set of diagnostic entities on Axis 1 (differentiating disorders in areas of traumatic stress, affect, adjustment, regulation, sleep, eating, relating, and communicating) and uses Axis 2 to classify relationships and attachments. Noteworthy is the absence of specific references to attention deficit or hyperactivity in the DC:0–3.

A third diagnostic classification system developed specifically for children and adolescents, and aimed at primary care providers, is the Diagnostic and Statistical Manual for Primary Care (DSM-PC) (American Academy of Pediatrics, 1996). This is a developmentally based classification system that provides categories for “normal variations” and “problems” as downward extensions of the child-relevant DSM-IV disorders. For ADHD, the DSM-PC provides examples of normal developmental variations of both hyperactive/impulsive behaviors and inattention for preschoolers, school-aged children, and teenagers. However, it also does not offer adjusted criteria for the diagnosis of ADHD in young children.

The research on the ADHD has largely been clinically driven. Two professional groups have developed practice guidelines for assessment and treatment of ADHD, the American Academy of Pediatrics (American Academy of Pediatrics, 2000, 2001) and the American Academy of Child & Adolescent Psychiatry (Dulcan & Work Group on Quality Issues, 1997; Greenhill et al., 2002). These guidelines vary in the intensity of recommended assessment approaches, but neither is particularly suited for evaluating preschoolers. Alternatively, the practice parameters of the American Academy of Child & Adolescent Psychiatry for the psychiatric assessment of infants and toddlers, while not specifically intended for ADHD, provide a useful framework for clinicians seeing preschoolers with hyperactive behavior, asserting that “it is axiomatic that the infant or toddler must be understood, evaluated, and treated within the context of the family” and advocating for a developmental, relational, multidimensional, and multidisciplinary perspective during the assessment process (Thomas et al., 1997). The recommended assessment approach also mentions the assessment of child temperament through standardized scales, such as the Infant Behavior Questionnaire (Rothbart, 1986) or the Toddler Behavior Assessment Questionnaire (Goldsmith, 1996). In this practice parameter, temperament is viewed as a dimension distinct from diagnosis, one that is important to assess in order to understand potential areas for preventive intervention via parental education and guidance.

TEMPERAMENT

Temperament is typically defined as heritable, physiologically based behavioral tendencies that are first evident in infancy and relatively consistent across development (Frick, 2004). Pioneering work on temperament was conducted by Thomas and associates who, based on their observations in the New York Longitudinal Study, proposed 9 dimensions of temperament (Thomas, Chess, & Birch, 1968). The dimensions include physical activity level, physiologic rhythmicity, approach/withdrawal from new stimuli, adaptability, intensity of mood expression, quality of mood, persistence/attention span, distractibility, and sensory threshold (Thomas et al., 1968). They inferred 3 specific higher order profiles, supported by factor analysis (Thomas et al., 1968). The first and most common category, the easy child (about 40% of the sample), was defined as one who usually displays a happy mood, easily approaches new stimuli, and has regular body functions. The second category was called the slow-to-warm-up child (about 15% of the sample), who initially withdraws from new stimuli and does not easily adapt to change. Their third category, labeled the difficult child (about 10% of the sample), had the combined temperament qualities of negative mood, low rhythmicity, low approach, low adaptability, and high intensity. Of note, this original categorization of difficult temperament does not include reference to the child's activity level or attention span. The difficult child was the one most likely to experience adjustment problems during childhood (Thomas & Chess, 1977) and to have difficulty coping with stress in adulthood (Thomas & Chess, 1984). Thomas and Chess also emphasized that the “goodness of fit” between the child's temperament and environmental demands, mostly operationalized as parental demands, may influence the child's future ability to adapt (Thomas et al., 1968) (Table 1).

Table 1
Table 1:
Contemporary models of temperament

Developmental researchers have sought to refine our understanding of the core elements of child temperament further (Goldsmith et al., 1987), with recent authoritative reviews addressing conceptualization and measurement of temperament (Rothbart & Bates, 1998) as well as its relation to social development (Sanson, Hemphill, & Smart, 2004) and to parenting (Sanson, 1995). Concerns about conceptual overlap among the 9 temperament dimensions in the Thomas and Chess model stimulated both empirical and theoretical refinements, and, increasingly, agreement has been reached that the most important dimensions of temperament include emotional processing, self-regulation, and activity level (Frick, 2004), a more parsimonious approach than the many dimensions suggested by Thomas and Chess. One leading group of theorists, Rothbart and Bates, have defined temperament as a constitutionally based individual difference in reactivity and self-regulation in the domains of affect, activity, and attention, with reactivity denoting responsiveness to change in the internal and external environments, and self-regulation referring to processes that modulate reactivity, including attention, approach, withdrawal, attack, inhibition, and self-soothing (Rothbart & Bates, 1998). They noted that temperament describes dispositions that are not continuously expressed but occur in response to eliciting stimuli, and cautioned that early views on temperament as unchanging and stable have been replaced by more dynamic views of developmental change in temperament.

Another contemporary typology of temperament is Buss and Plomin's (1984) 3-factor model of emotionality, activity, and sociability (EAS). Building on the EAS model, Graham and Stevenson (1987) have proposed a 3-factor structure of temperament and behavior problems, such that emotional disorders, hyperactivity, and antisocial disorder may be viewed as extreme manifestations of ordinary, nonpathological temperaments. Cloninger and colleagues have developed a psychobiological model of personality development that includes both dimensions of temperament (novelty seeking, harm avoidance, reward dependence, and persistence) and character (self-directedness, cooperativeness, fantasy, and spirituality) (Cloninger, Svrakic, & Przybeck, 1993). They propose that temperament is heritable, while character depends on experience and conscious decision making. Goldsmith et al. (1987) characterizes temperament as “individual differences in the expression of primary emotions,” including anger, sadness, fear, joy, pleasure, disgust, interest, and surprise. Kagan (2002) instead proposes temperament categories labeled inhibited and uninhibited to the unfamiliar. His research focuses on behavioral inhibition as a type of temperament characterized by avoidance and withdrawal from novel situations and with identifiable physiological responses (Kagan & Snidman, 1999). This brief account points to one of the challenges of temperament research, namely, the multiple co-existing models of temperament with variations in the dimensions that are included and even some differences in the labels given to comparable dimensions. Of importance, nearly all of the contemporary models include activity level, a domain that is at least conceptually related to hyperactivity.

LINKING TEMPERAMENT AND ADHD

Different research groups view the relations between temperament and psychopathology from very different perspectives. Some propose that temperament constellations serve as risk factors for developing particular psychiatric disorders, whereas other groups consider the distinction between temperament and psychopathology as artificial, with mental disorders best understood as extremes of temperament. Studies exploring temperament qualities as potential risk factor for ADHD have found that children who are inattentive and have difficulty delaying responses at age 2, exhibit hyperactivity, inattention, and aggression at age 4 (Silverman & Ragusa, 1992). Children with behavioral disinhibition are found significantly more likely than nondisinhibited children to have ADHD and comorbid mood and disruptive behavior disorders (Hirshfeld-Becker et al., 2002). Children with poor attention, oppositional, aggressive, and destructive behaviors before age 3½ are found to have higher risk for comorbid ADHD and disruptive behavior disorders at age 5½ (Shaw, Owens, Giovannelli, & Winslow, 2001). Graham and Stevenson (1987) have conceptualized the extremes of the temperament domains of emotionality, activity, and sociability as risk factors for specific disorders, such that high emotionality serves as a precursor for later affective disorders, high-activity levels for hyperactivity syndromes, such as ADHD, and low sociability for later antisocial behavior. Partial support for this hypothesis has been provided (Bussing et al., 2003; Gjone & Stevenson, 1997; Rende, 1993), but as discussed by Rutter (1989), developmental pathways from temperament to behavior disorder likely differ by disorder type. For example, significant genetic influence has been found for the covariance between emotionality and attention, but not between emotionality and anxious/depressed behavior, in a longitudinal twin study of temperament and behavior problems (Gjone & Stevenson, 1997). Based on findings from the Australian Temperament Project, Sanson and colleagues proposed that hyperactivity unassociated with aggression emerges in later years from poor self-regulation when the child faces societal, especially school, demands, whereas aggression emerges when a difficult-temperament infant interacts with a stressed environment (Sanson, Smart, Prior, & Oberklaid, 1993). Another research group (McIntosh, 1996) has examined temperament characteristics as risk factors for ADHD in a cross-sectional design comparing boys on ADHD medication with those of healthy boys. Using parent and teacher ratings of temperament, they found that boys in the ADHD group had lower scores on persistence and higher scores on activity level and distractibility domains of temperament, all of which are characteristics that constitute diagnostic criteria for ADHD. In a similar cross-sectional study, associations between ADHD and the temperament domains of poor focus, low-inhibitory control, and activity level were found in a data set carefully cleaned of measurement confounding (Lemery, Essex, & Smider, 2002), suggesting that ADHD symptoms are not identical with key temperament domains (Nigg, Goldsmith, & Sachek, 2004).

Different positions on the relationship between temperament and psychopathology mostly reflect disciplinary boundaries between developmental and clinical researchers. A recent set of publications sought integration of the 2 fields (Frick, 2004), and ADHD was among the disorders targeted in this review (Nigg et al., 2004). Nigg and colleagues suggested association but not identity between ADHD and key temperament domains of attention, inhibitory control, and activity level, and emphasized that to understand ADHD in terms of temperament, it it is necessary to distinguish between potential accompanying anxiety and antisocial behaviors (Nigg et al., 2004). They offered a heuristic developmental heterogeneity model of multiple temperament-related developmental pathways and ADHD subtypes that may arise from these pathways (eg, primary combined subtype ADHD with and without secondary conduct disorder; secondary combined subtype ADHD with primary conduct disorder, primary combined subtype ADHD with anxiety) (Nigg et al., 2004). The temperament qualities labeled negative approach and anger proneness were proposed as precursors to subsequent oppositional or conduct disorder comorbidities (Nigg et al., 2004), presentations of ADHD associated with the worst outcomes (Hechtman, 1999) and associated with high caregiver stress and parental perception that the child is difficult (Bussing et al., 2003; Podolski & Nigg, 2001).

DIFFICULT TEMPERAMENT

The concept of the “difficult child” has been widely used since originally coined by Thomas and Chess (Thomas et al., 1968). Of significance, their definition of difficult did not include hyperactivity or poor attention span, 2 of their 9 dimensions of temperament. Subsequent algorithms for assigning children to the difficult and easy temperament categories defined by Thomas and Chess have been developed by Carey and colleagues (Carey & McDevitt, 1978; Fullard, McDevitt, & Carey, 1984). The difficult child has been a clinically useful concept for anticipatory guidance in pediatric settings (Carey, 1985, 1998) and a helpful term generally for use in discussion with parents about children's behavior problems. Among temperament researchers, however, the various temperament constellations labeled difficult temperament have become problematic (Rothbart, 1982, 2004; Vaughn, Taraldson, & Cuchton, 2002).

During a roundtable discussion among leading temperament researchers, Thomas and Chess commented: “[some researchers] have expanded the term [“difficult temperament”] to include any child who is difficult for the parent because of one or another temperamental attribute” (Goldsmith et al., 1987, p. 521). Differences in the operationalization of difficult temperament make comparisons of results across studies difficult (Rothbart, 2004). Furthermore, temperament characteristics considered difficult may change with age, prompting some researchers to use different definitions of difficult temperament at different stages of child development, even within the same study (Hyde, Else-Quest, Goldsmith, & Biesanz, 2004). Of note, researchers have also demonstrated that the definitions of difficult temperament vary by cultural background and sociodemographic factors (Oberklaid, Prior, Sanson, Sewell, & Kyrios, 1990), further illustrating the relativity of the construct.

In research on the difficult temperament construct, another concern has been that it is measured almost exclusively by parent report. As noted by Bates (1980, 1983), the construct may therefore reflect parent characteristics or parent perceptions of child characteristics more than a child's true characteristics. For example, his research has shown that although mothers generally regard fussy, hard-to-soothe, labile infants as difficult, extraverted mothers tend to rate such infants as easy (Bates, Freeland, & Lounsbury, 1979). In his classic review of antecedents, accompaniments, and consequences of the difficult temperament label in developmental research, Bates (1980) concluded that the difficult temperament construct should be considered a reflection of social perceptions. He further noted that parents' subjective perceptions of their child's temperament may be more important than the objective factors in shaping their child's social development.

In the 1987 roundtable discussion, only 2 of the 4 participating temperament research groups (Thomas & Chess and Buss & Plomin) continued to support the concept of difficult temperament (Goldsmith et al., 1987). Rothbart argued for an alternative to the difficulty construct, by viewing social costs and benefits associated with different temperament characteristics rather than relying on a classification based on what parents find difficult to handle. In that discussion, Goldsmith asserted there was “little value in equating difficulty with any particular set of temperamental characteristics without an assessment of the context relevant to the individuals involved” (Goldsmith et al., 1987, p. 521). Despite the confusion and controversy surrounding the concept of difficult temperament, it is likely to remain in use. Of particular note, many research studies exploring the relation between various temperament constellations and the development of ADHD refer to difficult temperament characteristics. For this reason, it is essential to examine the definition and the approach used to measure difficult temperament in any given study, to place the information into context.

DIFFERENTIATING TEMPERAMENT FROM ADHD IN REFERRED PRESCHOOLERS

Although researchers have made significant strides in integrating findings from studies of temperament and psychopathology, clinicians must still rely on their own skills and experiences, guided by a sound assessment strategy, to formulate diagnostic impressions of preschoolers referred for hyperactivity. It has been suggested that “the solution to the confusion about what is temperament and what is not, at least for the clinician, is to use multiple sources of information to allow for some convergence to occur or not occur around the child's observable behavior and the perceptions of the child by adults in his or her world” (Garrison, 1990, p. 207). We conclude that preschoolers whose disruptive behaviors cause concern require a multidimensional approach to evaluation and planning for appropriate intervention. Even if it were possible to separate extremes of temperament from ADHD in a meaningful way, it would still be necessary to determine appropriate treatments—assigning a label of difficult temperament provides neither reassurance nor license to engage simply in watchful waiting.

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          Keywords:

          attention-deficit/hyperactivity disorder; preschoolers; temperament

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