Patterns of anxiety symptoms in toddlers and preschool-age children: Evidence of early differentiation

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Abstract

The degree to which young children's anxiety symptoms differentiate according to diagnostic groupings is under-studied, especially in children below the age of 4 years. Theoretical (confirmatory factor analysis, CFA) and statistical (exploratory factor analysis, EFA) analytical methods were employed to test the hypothesis that anxiety symptoms among 2–3-year-old children from a non-clinical, representative sample would differentiate in a manner consistent with current diagnostic nosology. Anxiety symptom items were selected from two norm-referenced parent-report scales of child behavior. CFA and EFA results suggested that anxiety symptoms aggregate in a manner consistent with generalized anxiety, obsessive–compulsive symptoms, separation anxiety, and social phobia. Multi-dimensional models achieved good model fit and fit the data significantly better than undifferentiated models. Results from EFA and CFA methods were predominantly consistent and supported the grouping of early childhood anxiety symptoms into differentiated, diagnostic-specific categories.

Highlights

► We model anxiety symptoms in toddlers to test if they differentiate. ► Confirmatory factor analysis (CFA) supports a four-factor model. ► Factors include social, generalized, separation, and obsessive–compulsive anxiety. ► Exploratory factor analysis largely supports our theoretical (CFA) approach. ► Symptoms in toddlers differentiate similarly to how they do in older children.

Introduction

Anxiety disorders are among the most frequently occurring childhood psychiatric disorders with prevalence estimates approaching 10% among preschool children (Egger & Angold, 2006). Advances in early childhood assessment, albeit still largely dependent on parental reports, now make it feasible to study anxiety symptoms in young children1 (Carter et al., 2004, Carter et al., 2010a), and evidence of anxiety symptoms is present in children as young as 1 and 2 years of age (Carter et al., 2003, Egger and Angold, 2006). Supporting the need to be sensitive to development, one study of preschool children (Spence, Rapee, McDonald, & Ingram, 2001) found that 3-year-olds were significantly more anxious than 4- or 5-year-olds. Moreover, early emerging elevations in anxiety and general internalizing symptoms persist within the preschool period (Briggs-Gowan, Carter, Bosson-Heenan, Guyer, & Horwitz, 2006) and into the elementary school years (Mian, Wainwright, Briggs-Gowan, & Carter, 2011). Among school-aged children, anxiety symptoms are not only associated with later anxiety disorders, but also with depression and externalizing disorders in adolescence (Bittner et al., 2007).

Yet, despite interest in examining differentiation in manifestations of anxiety across disorders in older children (Birmaher, Khetarpal, Brent, & Cully, 1997), little attention has been paid to empirically testing the manner in which early emerging anxiety symptoms aggregate or conform to clinical syndromes that align with diagnostic categories. Such research is needed to elucidate the developmental etiology of anxious emotion and to inform developmentally sensitive clinical taxonomy in children of all ages, from early childhood through adolescence. In the present study, these issues were examined in a representative sample of 2- and 3-year-old children by conducting factor analyses on parent-reported anxiety symptoms from two norm-referenced, developmentally appropriate measures.

The process of revising the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (American Psychiatric Association, 2000) has highlighted the challenges of improving diagnostic conceptualization and incorporating elements of dimensional and categorical systems relevant to both research and clinical practice (Brown & Barlow, 2005). An important aspect of this process is improving conceptualizations of developmental phenotypes to address how emotional syndromes and disorders reflect shared and distinct developmental pathways. Factor analytic research in school-age children suggests that the symptoms of different anxiety disorders represent diagnostically distinct groups of symptoms (Spence, 1997). However, it is unclear whether different anxiety disorders emerge as distinct entities or if anxiety disorders begin in an undifferentiated form and become increasingly distinct over time.

In a review of developmental trajectories of anxiety symptoms, Weems (2008) differentiates between primary and secondary features of anxious emotion. Primary features represent the underlying dysregulation of the emotional response system that likely accounts for general risk for anxiety disorder, including physiological (e.g., racing heart), cognitive (e.g., catastrophizing), and behavioral (e.g., avoidance) symptoms. Secondary features represent symptoms that are disorder-specific, such as fear of embarrassment in social anxiety disorder (SAD) or excessive worry in general anxiety disorder. Regrettably, Weems's model does not acknowledge developmental processes before age six, although it offers a theory that may be applicable to younger children. Accordingly, primary features may be relatively stable across development, while secondary features may be less stable, such that children with chronic dysregulation of the anxiety response system may meet criteria for different diagnoses at different stages of development (Costello, Egger, & Angold, 2004). Thus, it might follow that young children's symptom profiles reflect more general, primary features while older children may exhibit more secondary features, suggesting that anxiety symptoms become increasingly differentiated and disorder-specific over time. Despite a lack of evidence for anxiety as a uni-dimensional construct, research in young children often applies a highly undifferentiated approach, lumping all anxiety symptoms together, often with depressive symptoms, as “internalizing symptoms” (Bongers et al., 2003, Sterba et al., 2007b).

On the other hand, some researchers propose that the diagnostic specificity found in older child and adult anxiety can also be found in young children (Egger and Angold, 2004, Warren et al., 2006), which suggests that even young children experience anxiety in a differentiated manner that may correspond with DSM-IV categories. If supported, this would demonstrate that secondary features (Weems, 2008) of anxiety disorders are present in young children, and may develop concurrently with more general, primary features. A differentiated diagnostic approach would also encourage the more refined study of genetic and ecological risk factors for narrower sets of disorder-specific symptoms (e.g., Hallett et al., 2009, Rapee and Spence, 2004). Although most empirical work on treatment efficacy for older children still lumps anxiety disorders (with the exception of panic disorder and obsessive compulsive disorder [OCD]), differentiating between diagnostic profiles has been integral to the development of empirically supported treatments for specific problems (i.e., Kendall, 2006). From a developmental perspective, one question then is at what point in development should anxiety be treated as differentiated?

Research documents differentiation in early anxiety and depressive symptom presentations (Briggs-Gowan and Carter, 1998, Carter et al., 2003, Egger et al., 1999) and patterns of risk (Marakovitz, Wagmiller, Mian, & Carter, 2011). Moreover, varied developmental and gender patterns are observed in young child trajectories of internalizing subscales that are masked when symptoms are viewed as an undifferentiated internalizing construct (Carter, Godoy, et al., 2010). However, few studies examine models of differentiation of internalizing symptoms among children below the age of 5, and especially below the age of 3 (Egger & Angold, 2006). Assessment challenges may contribute to the paucity of research on anxiety symptoms in very young children; yet prior research has demonstrated that parents are able to reliably identify and categorize their children's problem behaviors, including symptoms of anxiety (Achenbach and Rescorla, 2000, Carter et al., 1999, Carter et al., 2003). Given the limited research on clustering of anxiety symptoms in preschool- and toddler-age children, we review studies of anxiety symptoms among school-age children. There is substantial heterogeneity across studies regarding methods (e.g., items used, child vs. parent informant), samples (e.g., clinical vs. convenience), and analytical approaches used. However, research on the covariation of symptoms typically uses factor analysis, which is an ideal statistical approach for the task because it identifies the ways individual symptoms relate to one another or “hang together,” uncovering the latent groupings of symptoms that may represent meaningful clinical presentations. Results from relevant studies reviewed are summarized in Table 1.

Studies with school- and preschool-aged children have provided evidence of differentiation that closely maps onto DSM-IV categories despite employing wide age ranges, different item sets, and both clinical and non-clinical samples (see Table 1). The number of factors found among anxiety-related symptoms has ranged from three to six. Factors for symptoms related to separation anxiety disorder (SAD) and social phobia (SP) have been found consistently in reviewed studies that have included relevant items. OCD-related symptoms have also emerged relatively consistently, but to a lesser degree. The degree to which symptoms related to generalized anxiety disorder (GAD) are consistently found within a single factor is unclear, since these symptoms have been investigated as (1) a GAD syndrome, (2) a GAD/depression syndrome, or (3) a related syndrome comprising “general distress” or “physical symptoms”. The only study that found evidence for a uni-dimensional model resulted in poor model fit (Muris, Merckelbach, Schmidt, & Mayer, 1999).

A detailed investigation of studies with preschool children suggests that differentiation of anxiety symptoms according to diagnostic categories can be found in young children. Spence et al. (2001) found that a five-factor model, including SP, SAD, OCD, fears of physical injury and GAD, provided a good fit for the data and was superior to a one-factor model representing undifferentiated symptoms. Although symptoms related to GAD and SAD represented distinct factors, a high correlation between them (r = 0.87) suggested a significant association. Sterba, Egger, and Angold (2007) and Sterba, Prinstein, et al. (2007) used items from the Preschool Age Psychiatric Assessment (Egger & Angold, 2004), a semi-structured diagnostic parent interview, and found that a three-factor model including SAD, SP and combined generalized anxiety/depression fit the data better than either a uni-dimensional model or a more differentiated model of anxiety symptoms (Sterba, Egger, et al., 2007). In general, results of these studies suggest that use of assessment tools that capture a range of diagnostic presentations enables the identification of differentiated subtypes of anxiety in preschoolers. Finally, Eley et al. (2003) examined anxiety differentiation in a large, population-based sample of 4-year-old twin pairs whose mothers completed a short (16-item) checklist. The authors found that a five-factor model of anxiety, including general distress, SAD, fears, obsessive–compulsive behaviors, and shyness/inhibition was the best fit for the data (Eley et al., 2003). Thus, the limited research among preschool-aged children supports the notion that early childhood anxiety symptoms may cluster into diagnostic-specific groupings, similar to those found among older children.

A major limitation of the current literature is the considerable variation across studies regarding how anxiety symptoms are conceptualized and measured, leading to challenges in interpreting and comparing findings. Most studies have investigated the factor structure of anxiety symptoms in children in the context of symptom measure validation. Hence, only one measure is used in the analysis, and what is tested is how well the data fit the item construction of this particular measure. Because different measures have been designed to assess specific dimensions of anxiety and may not cover all related disorders, different factor profiles may reflect differences in domain coverage. Aggregating more general measures of child behavior that were not specifically designed to test differentiation according to diagnostic profiles may help mitigate the influence of a particular research group's conceptualization. This approach also allows for beginning analyses with a large pool of previously validated items. Variation across studies also reflects inconsistency regarding which disorders are included in analyses. Some studies investigate anxiety symptoms alone while others include depressive symptoms; others investigate anxiety “behaviors” rather than symptoms. Investigations of the broad internalizing domain are important, but focusing on anxiety symptoms exclusively provides a more precise picture of early anxiety. Another limitation is that most studies have employed either clinical or convenience samples, which may not reflect the way in which anxiety symptoms differentiate for children not represented. Since we know that a large number of young children with social-emotional problems do not receive clinical services (Kataoka, Zhang, & Wells, 2002), it is important to expand research to include epidemiological, or representative, community samples. Finally, further investigations with younger children are necessary to elucidate the manner in which latent symptom structures reflect developmental trajectories of anxious emotion (Weems, 2008).

The present investigation employed confirmatory factor analysis to investigate the underlying structure of anxiety symptoms among children 2–3-years-old as measured by anxiety items selected from two parent-report scales of child behavior. Following confirmatory modeling we sought to determine if findings would be supported by exploratory factor analysis. This analytic approach has been recommended for studies of latent symptom patterns (Brown & Barlow, 2005); it provides a way to “check” that findings are statistically sound while also prioritizing theory-driven hypothesis testing. The following hypotheses were made: (1) parent reports of selected child behaviors/symptoms will load onto four correlated factors that represent diagnostic categories: GAD, SAD, SP, and OCD; (2) a multi-dimensional model will explain observed patterns better than a uni-dimensional or undifferentiated model in which all symptoms load on a single factor; (3) theoretically derived, confirmatory models that impose relations between items and diagnostic categories will be corroborated by statistical methods that derive relations between items and latent categories (i.e., exploratory factor analysis).

Section snippets

Participants

The current work represents secondary analysis of data collected within a longitudinal study of an age- and sex-stratified random population sample, initially ascertained from birth records provided by the State of Connecticut for children born from July 1995 to September 1997 at Yale New Haven Hospital (for greater detail, see Carter, Wagmiller, et al., 2010). Based on birth record data, children at risk for developmental delays because of prematurity, low birth weight, low APGAR scores, birth

Theoretically derived confirmatory factor analysis

A large pool of 75 items, thought to be potentially related to anxiety symptoms, was considered (31 from the CBCL, 44 from the ITSEA). Before conducting CFA, the item pool was narrowed by inter-rater consensus for items deemed the strongest candidates for capturing symptoms related to DSM-IV anxiety disorders. This resulted in a hypothesized model with 36 total items (12 CBCL items and 24 ITSEA items) loading on four factors representing GAD, SAD, SP, and OCD. Correlated errors based on

Discussion

The purpose of this study was to investigate whether anxiety symptoms present in 2–3-year-old children from a representative sample cluster in a manner consistent with current diagnostic nosology. The hypothesis that symptoms would differentiate in a manner consistent with current diagnostic DSM-IV nosology was generally supported. Anxiety symptoms aggregated in a manner consistent with current understanding of GAD, OCD, SAD, and SP. The differentiated model performed better than the

Acknowledgements

Support for this research came from a grant to the fourth author from the National Institute of Mental Health (R01MH55278). We also wish to thank Matthew Idzik and Meagan Hilton, as well as all the children and families who participated in this project.

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