An examination of direct, indirect and reciprocal relationships between perfectionism, eating disorder symptoms, anxiety, and depression in children and adolescents with eating disorders

Eating Behaviors 32 (2019) 53–59

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An examination of direct, indirect and reciprocal relationships between perfectionism, eating disorder symptoms, anxiety, and depression in children and adolescents with eating disorders

T

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Haans Drieberga, Peter M. McEvoya,b, Kimberley J. Hoilesc, , Chloe Y. Shuc, Sarah J. Egana a

School of Psychology, Curtin University, Perth, Australia Centre for Clinical Interventions, Perth, Australia c Eating Disorders Program, Child and Adolescent Health Service, Perth, Australia b

A R T I C LE I N FO

A B S T R A C T

Keywords: Perfectionism Eating disorders Children Adolescents HOPE Project

Objective: Perfectionism is a transdiagnostic factor across eating disorders, anxiety, and depression. Previous research has shown anxiety mediates the relationship between perfectionism and eating disorders in adults. The aim of this study was to investigate the relationships between anxiety/depression, perfectionism and eating disorder symptoms in children and adolescents with eating disorders. Method: Structural equation modeling was used to investigate three models in a clinical sample of children and adolescents (N = 231, M age = 14.5, 100% female): (1) anxiety and depression as mediators of the relationship between perfectionism and eating disorder symptoms, (2) eating disorder symptoms as a mediator of the relationship between perfectionism and anxiety and/or depression, and (3) perfectionism as a mediator of the relationship between anxiety/depression and eating disorders. Results: Results indicated that both models 1 and 2 fit the data well, while model 3 provided a poor fit. These findings suggest that in clinical populations of children and adolescents, anxiety and depression mediate the relationship between perfectionism and eating disorder symptoms, and there is also a reciprocal relationship whereby eating disorders mediate the association between perfectionism, and anxiety and/or depression. Discussion: The results highlight the importance of further research to determine whether targeting perfectionism is helpful in the treatment of eating disorders and comorbid anxiety and depression in young people. It would be useful for clinicians to consider assessing for and treating perfectionism directly when it is elevated in children and adolescents with eating disorders.

1. Introduction Adolescence is a period associated with an elevated risk of developing an eating disorder (Ferreiro, Wichstrøm, Seoane, & Senra, 2014; Torstveit, Aagedal-Mortensen, & Stea, 2015). It is well established that individuals with eating disorders have a high prevalence of comorbid anxiety and depression (Arlt et al., 2016; Hughes et al., 2013; Koutek, Kocourkova, & Dudova, 2016; Pallister & Waller, 2008). In children and adolescents with eating disorders, perfectionism has been found to be associated with higher anxiety, depression (Morgan-Lowes et al., in preparation), eating disorder symptoms and lower remission (Johnston et al., 2018). Perfectionism has been proposed to be a transdiagnostic process elevated across eating disorders, anxiety, and depression (Egan, Wade, & Shafran, 2011), which has been supported by a recent meta-analysis

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(Limburg, Watson, Hagger, & Egan, 2017). While all aspects of perfectionism measures have been found to be related to eating disorders (Limburg et al., 2017), several studies have found that a subscale of the Multidimensional Perfectionism Scale (Frost, Marten, Lahart, & Rosenblate, 1990), concern over mistakes, is particularly strongly associated with eating disorder symptoms (e.g., Bulik et al., 2003; Wade et al., 2008). Clinical perfectionism, where self-worth is based on achievement despite adverse consequences (Shafran, Cooper, & Fairburn, 2002), is a key maintaining mechanism in the transdiagnostic model of eating disorders (Fairburn, Cooper, & Shafran, 2003). Despite robust evidence for a relationship between eating disorders and perfectionism, the nature of this association is not well understood (Bardone-Cone et al., 2007) and a deeper understanding, particularly of the indirect factors that may mediate this relationship, is required. In an examination of mediating variables, Egan et al. (2013) found

Corresponding author at: Eating Disorders Program, Child and Adolescent Health Service, Perth Children's Hospital, Locked Bag 2010, Nedlands 6909, Australia. E-mail address: [email protected] (K.J. Hoiles).

https://doi.org/10.1016/j.eatbeh.2018.12.002 Received 2 July 2018; Received in revised form 14 December 2018; Accepted 14 December 2018 Available online 19 December 2018 1471-0153/ © 2018 Elsevier Ltd. All rights reserved.

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service, and a Diagnostic and Statistical Manual (DSM-5; American Psychiatric Association, 2013) eating disorder diagnosis. Ethical approval was granted by the Child and Adolescent Health Services Human Research Ethics Committee (2042/EP), and Curtin University Human Research Ethics Committee (HRE2017-0148).

in a sample of adults that anxiety partially mediated the relationship between perfectionism and eating disorders. The absence of full mediation suggested that additional variables play a role in accounting for this relationship. Given that depression is also strongly associated with eating disorders and perfectionism (Egan et al., 2011; Limburg et al., 2017), it is appropriate to investigate whether depression plays a similar mediating role to anxiety. For example, it would be useful to examine in children and adolescents if eating disorder symptoms arise out of an initial depressive or anxious state, and likewise the reverse relationship. In adolescents there is evidence of a link between perfectionism and eating disorder symptoms (e.g., Boone, Soenens, & Luyten, 2014), as well between depression, anxiety and perfectionism (e.g., Affrunti & Woodruff-Borden, 2014; Mitchell, Newall, Broeren, & Hudson, 2013). Research in adolescents has also demonstrated a link between eating disorders and anxiety/depression (e.g., Holm-Denoma, Hankin, & Young, 2014). Despite these associations, there has been no examination to date of whether anxiety and depression mediate the relationship between perfectionism and eating disorders in a clinical sample of children and adolescents with eating disorders. There is also literature suggesting that the relationship between eating disorders and depression and/or anxiety may be bi-directional (Micali et al., 2015; Puccio, Fuller-Tyszkiewicz, Ong, & Krug, 2016). There is emerging evidence that eating disorders and anxiety/depression are genetically correlated, with evidence for shared genetic components between these disorders (e.g., Brainstorm Consortium et al., 2018; Dellava, Kendler, & Neale, 2011). Hence it would be useful to further examine the relationships between symptoms of eating disorders, anxiety and depression and their relationship with perfectionism. Furthermore, given research which has found perfectionism to be a mediator of various psychopathologies (Egan et al., 2011), there is also a rationale for investigating if perfectionism is a mediator between anxiety/depression and eating disorders. The aim of this study was to examine the relationships between perfectionism, anxiety, depression, and eating disorder symptoms in children and adolescents with eating disorders. Given the findings of Egan et al. (2013), which demonstrated the indirect effect of anxiety on the relationship between perfectionism and eating disorder pathology in adults, we predicted a similar indirect effect in children and adolescents. Specifically, we hypothesised an indirect effects model where perfectionism predicts eating disorder symptoms through anxiety and depression. The direct effect between perfectionism and eating disorder symptoms was freed within Model 1 (Fig. 1, top). For the alternative Model 2 (Fig. 1, middle), based on the findings of Micali et al. (2015), we hypothesised an indirect effects model where perfectionism predicts anxiety and depression via eating disorder symptoms would also provide an adequate fit to the data. Direct effects from perfectionism to anxiety and depression were also freed within the model. Finally, we also investigated a final alternate model (Model 3, Fig. 1, bottom) where it was hypothesised that anxiety and depression would predict eating disorder symptoms through perfectionism.

2.2. Measures 2.2.1. Eating Disorder Inventory, version 3 – Perfectionism (EDI-P; Garner, 2004) The EDI-P is a six-item self-reported scale of the EDI-3 designed to assess trait perfectionism. Items are scored from 1 to 6 with higher scores corresponded with higher levels of perfectionism. Despite initially being developed as a unidimensional measure of perfectionism, there is evidence that it consists of two factors, self-oriented and sociallyprescribed perfectionism (Lampard, Byrne, McLean, & Fursland, 2012; Sherry, Hewitt, Besser, McGee, & Flett, 2004). The EDI-P is the most frequently used measure of perfectionism in eating disorder samples (Bardone-Cone et al., 2007), has good validity (Friborg, Clausen, & Rosenvinge, 2013), and in the current study had good internal consistency (α = 0.80). 2.2.2. Adapted version of The Eating Disorder Examination (EDE; Fairburn & Cooper, 1993) The EDE is a semi-structured interview that generates a global eating disorder symptoms score, as well as four subscales: Restraint, Eating Concern, Shape Concern and Weight Concern. The adapted measure for children and adolescents is similar but not identical to the ChEDE (Bryant-Waugh, Cooper, Taylor, & Lask, 1996) and was used as the service pre-dated ChEDE publication. The adapted version of the EDE has acceptable reliability and validity (O'Brien et al., 2016). The current sample had acceptable internal consistency (restraint α = 0.79, eating concern α = 0.80, shape concern α = 0.92, weight concern α = 0.88, global α = 0.95).

2.1. Participants

2.2.3. Multidimensional Anxiety Scale for Children 2 (MASC 2; March, 2012) The MASC 2 is a widely used self-report measure of anxiety across four factors: physical symptoms, harm avoidance, social anxiety, and separation/panic. Because components of the harm avoidance subscale measure characteristics of perfectionism (March, Parker, Sullivan, Stallings, & Conners, 1997) it was excluded as an indicator of anxiety in the current study. The MASC 2 had excellent internal consistency in the current sample (α = 0.92). The MASC 2 has also demonstrated divergent validity by discriminating between depression and anxiety in an adolescent clinical sample (March, 2012). Norms for the MASC have been reported in children and adolescents with eating disorders (Watson, Egan, Limburg, & Hoiles, 2014b). Two-thirds (66%) of the current sample was assessed using the MASC (March et al., 1997) which was employed prior to changing to the MASC 2. Comparing the MASC to the MASC 2, subscales relevant to the current study are comprised of identical items, therefore maintaining consistency in the current sample.

Participants were 231 females aged 11.0 to 17.8 (M = 14.5, SD = 1.24). Data were derived from the Helping to Outline Paediatric Eating Disorders (HOPE) Poject registry. The registry comprises a sequential cross-sectional sample collected from 1996 to the present at the Child and Adolescent Health Services Eating Disorders Program, located at Perth Children's Hospital. Data originated from routine intake assessments and was entered into the registry after informed consent was obtained. Our sample comprised patients who were included in the HOPE database since 2012, when the collection of the key measure, Eating Disorder Inventory version 3 (EDI-3; Garner, 2004) commenced. Inclusion criteria were: females, first presentation at the

2.2.4. Children's Depression Inventory 2 (CDI 2; Kovacs, 2011) The CDI 2 is a 27-item self-reported scale that assesses depressive symptoms across four subscales: negative mood/physical symptoms, ineffectiveness, negative self-esteem, and interpersonal problems. The scale had excellent internal consistency in this sample (α = 0.94). Norms for the CDI have been reported in children and adolescents with eating disorders (Watson, Egan, Limburg, & Hoiles, 2014a). Prior to 2014, the HOPE database employed the CDI (Kovacs, 1985). For the current study, all CDI values have been converted to CDI 2 values in accordance with the conversion protocol recommended by Kovacs (2011).

2. Method

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Anxiety Eating Disorder Symptoms

Perfectionism Depression

Anxiety Perfectionism

Eating Disorder Symptoms

Depression

Anxiety Perfectionism

Eating Disorder Symptoms

Depression

Fig. 1. Structural equation model 1 (top), model 2 (middle), and model 3 (bottom). Direct and indirect pathways between perfectionism, anxiety, depression, and eating disorder symptoms.

Power estimates for structural equation modeling (SEM) are complex and depend on a range of factors, including the magnitude of parameter estimates, sample size, missing data, bias in parameter estimates, and solution propriety (convergence), which renders ‘recommended’ sample size guidelines problematic (Wolf, Harrington, Clark, & Miller, 2013). Given the difficult to access sample used in this study, and resultant fixed sample size, we estimated the power of structural parameters in our model post hoc using Monte Carlo simulations with 10,000 replications. These simulation provided estimates of coverage (proportion of replications for which the 95% confidence intervals contained the true parameter value; values should be > 0.90, Wolf et al., 2013) and power for each structural parameter (the proportion of replications for which the null hypothesis that a parameter is equal to zero is rejected for each parameter at α = 0.05). If power fell below 0.80 on any structural parameter, we also increased the sample size within these simulations to 500 and 1000 to determine the required sample size to achieve 0.80 power.

2.3. Statistical analysis Descriptive analyses were conducted with SPSS version 21. Structural models using robust maximum likelihood estimation were run using Mplus version 8.1 with Full Information Maximum Likelihood used to account for missing data (Muthén & Muthén, 2017). EDI-P items were used as indicators of perfectionism, with items 1 (Only outstanding performance is good enough in my family) and 4 (My parents have expected excellence of me) freed to covary because they assess family expectations. Three models were tested. Model 1 tested direct and indirect effects from perfectionism to eating disorder symptoms via anxiety and depression. Model 2 tested an alternative model whereby perfectionism led to eating disorder symptoms, which then led to anxiety and depression. Model 3 tested direct and indirect effects from anxiety and depression to perfectionism, which, in turn, led to eating disorder symptoms. Anxiety and depression were free to covary in all models. Bootstrapped 95% confidence intervals from 1000 resamples were calculated around all direct and indirect effects parameters. Goodness-of-fit between the observed data and the two hypothesised models was assessed using the χ2 test, Comparative Fit Index (CFI), Tucker-Lewis Index (TLI), Root Mean Square Error of Approximation (RMSEA), and the Standardized Root Mean Square Residual (SRMR). Model fit indices were adopted from Hu and Bentler (1999). The Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) were used to compare non-nested models, with differences of 10 or more providing very strong evidence supporting the model with the smallest value (Fabozzi, Focardi, Rachev, & Arshanapalli, 2014).

3. Results Table 1 shows the clinical characteristics and demographics of the sample, which primarily comprised anorexia nervosa-type presentations. All correlations (Table 2) were statistically significant, (p < .01), supporting the viability of the indirect effects models. Fit statistics for Model 1 indicated acceptable but not excellent fit across multiple indices (see Model 1 in Table 3, Fig. 2). Model 2 provided a similar fit to 55

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considered further. AIC and BIC did not distinguish between Models 1 and 2, but Model 3 provided the worst fit. For Model 1 (Fig. 2), the indirect pathway between perfectionism and eating disorder symptoms via depression was significant (0.21, p = .03). However, the indirect pathway between perfectionism and eating disorder symptoms via anxiety was non-significant (0.11, p = .22). This model explained a significant proportion of variance in anxiety (17%, p = .01), depression (16%, p = .01) and eating disorder symptoms (71%, p < .001). For Model 2 (Fig. 3), the indirect pathway between perfectionism and anxiety via eating disorder symptoms was significant (0.36, p < .001). In addition, the indirect pathway between perfectionism and depression was significant (0.37, p < .001). This model explained a significant proportion of variance in anxiety (66%, p < .001), depression (69%, p < .001) and eating disorder symptoms (19%, p = .003). Models 1 and 2 were re-run controlling for Body Mass Index (BMI) as a proxy for starvation state on eating disorder symptoms only, and then on all intermediate and outcome variables. BMI was a significant predictor of anxiety, depression, and eating disorder symptoms in Model 1, but only eating disorder symptoms (not anxiety and depression) in Model 2. Importantly, the pattern of significant relationships among the primary constructs of interest did not change at all for any model, so only the models without BMI are reported. Finally, we ran Monte Carlo simulations on Models 1 and 2. For Model 1, coverage was ≥0.94 for all structural parameters. Power ranged between 0.25 (anxiety predicting eating disorder symptoms) to 0.99 (anxiety and depression predicting perfectionism). Increasing the sample size to 500 increased power for the anxiety-eating disorder pathway to 0.55, and a sample of 1000 increased power to 0.84 (0.83 for the indirect effect of perfectionism-anxiety-eating disorder symptoms). For Model 2, coverage was ≥0.94 and power was 1.00 for all structural parameters.

Table 1 Clinical characteristics and demographics of the sample (N = 231). Variable

n (%)

Age (years) Birthplace Australia Europe Africa Asia America NZ/Oceania Other Weight (kg) Height (metres) Body Mass Index (kg/m2) Currently taking psychiatric medication MASC 2 score CDI 2 score EDE global score (0–6) Restraint (0–6) Eating concern (0–6) Shape concern (0–6) Weight concern (0–6) EDI-P score DSM-5 eating disorder diagnosis: AN-R AN-BP BN OSFED: Aty-AN BN-LF/LD PD UFED

223 176 (78.9) 25 (11.2) 11 (4.9) 6 (2.7) 3 (1.3) 1 (0.4) 1 (0.4)

50 (21.6)

M, range

SD

14.5, 11.0–17.8

1.24

– – – – – – – 44.4, 1.62, 16.8, – 45.8, 25.0, 3.52, 3.76, 2.95, 3.96, 3.42, 22.9,

– – – – – – – 8.18 0.07 2.54 – 17.3 12.7 1.53 1.63 1.59 1.70 1.81 6.46

83 (35.9) 16 (6.9) 20 (8.7)

– – –

68 (29.4) 8 (3.5) 1 (0.4) 35 (15.2)

– – – –

24.6–80.0 1.35–1.82 11.8–27.3 0–81 0–52 0–5.95 0–6.00 0–5.80 0–6.00 0–6.00 6–36

– – – – – – – –

Note: MASC 2 = Multidimensional Anxiety Scale for Children score based on physical symptoms, social anxiety, and separation/panic subscales (March, 2012), CDI 2 = Child Depression Inventory score based on the Total CDI 2 (Kovacs, 2011), EDE = Eating Disorder Examination (Fairburn & Cooper, 1993), EDI-P = Eating Disorder Inventory – Perfectionism (Garner, 2004), DSM-5 = Diagnostic and Statistical Manual of Mental Disorders – Fifth Edition, AN-R = anorexia nervosa – restricting, AN-BP = anorexia nervosa – binge/ purge, BN = bulimia nervosa, OSFED = other specified feeding or eating disorders, Aty-AN = atypical anorexia nervosa, BN-LF/LD = bulimia nervosa – low frequency and/or limited duration, PD = purging disorder, UFED = unspecified feeding or eating disorders.

4. Discussion The aim of this study was to examine if anxiety and depression mediated the relationship between perfectionism and eating disorder symptoms in female children and adolescents diagnosed with an eating disorder. As hypothesised, a significant indirect relationship was found between perfectionism and eating disorder symptoms via depression, indicating that depression mediated the relationship. In addition, a significant direct relationship was found between perfectionism and eating disorders symptoms. These findings indicate that higher perfectionism is associated with more severe eating disorder symptoms directly, but also because of the association perfectionism has with depression. Contrary to our expectations, anxiety was not a significant mediator of the relationship between perfectionism and eating disorder symptoms. This result is inconsistent with Egan et al. (2013), who found that anxiety partially mediated this relationship in adults. While our finding may be due to differences in presentations of anxiety in children and adolescents, it may also be related to the sample size in our study. The weak indirect relationship between perfectionism and eating disorder symptoms via anxiety observed by Egan et al. (2013) was similar to the current study (0.11) yet the sample used by Egan et al. was considerably larger (N = 369 vs. N = 231). Comparability of the magnitudes of the indirect effect coefficients from these two studies is

Table 2 Correlations among scale scores (N = 231). Perfectionism

Anxiety

Depression

– 0.27* 0.32* 0.35*

– 0.76* 0.66*

– 0.77*

Perfectionism Anxiety Depression Eating disorder symptoms

Note: Perfectionism = EDI-P (Garner, 2004), Anxiety = MASC 2 (March, 2012) (based on physical symptoms, social anxiety, and separation/panic subscales), Depression = CDI 2 (Kovacs, 2011), Eating Disorder Symptoms = EDE global score (Fairburn & Cooper, 1993). * p < .01.

Model 1. Modification indices were observed for both models, but did not reveal areas of substantial model strain and freeing up more parameters in the model was not deemed to be theoretically defensible. Model 3 provided a poor fit to the data across all indices, so was not Table 3 Goodness of fit indices for structural equation models. Model

χ2 (df)

CFI

TLI

RMSEA (90% CI)

SRMR

AIC

BIC

Model 1 Model 2 Model 3

327.58 (112) 328.19 (114) 499.87 (114)

0.911 0.912 0.841

0.892 0.894 0.810

0.091 (0.080–0.103) 0.090 (0.079–0.102) 0.121 (0.110–0.132)

0.073 0.074 0.157

15,689 15,686 15,854

15,889 15,880 16,047

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MASC-PS

MASC-SA

.86**

MASC-SP

.74**

.42**

EDI1

EDI2

.80**

.27 (-.16, .70)

.47**

EDI3

EDE-R

Anxiety

.61** .42** (.25, .58)

.85**

.90** (.83, .97) .74**

Eating Disorder Symptoms

.11 (-.01, .22)

Perfectionism

.42**

EDE-S

EDI4 .74**

EDI5

EDE-E

.93**

.40** (.24, .55)

.54* (.13, .95)

.92**

Depression

.63**

EDE-W .74**

.84**

EDI6

.89**

CDI-NM

.89**

CDI-NSI

CDI-IE

CDI-P

Fig. 2. Standardised path coefficients for Model 1, with 95% confidence intervals in parentheses. EDI = Eating Disorder Inventory, CDI = Children's Depression Inventory 2 (subscales: NM = negative mood, NSI = negative self-esteem, IE = ineffectiveness, IP = interpersonal problems), EDE = Eating Disorder Examination (subscales: R = restraint, E = eating concern, S = shape concern, W = weight concern); MASC = Multidimensional Anxiety Scale for Children 2 (subscales: PS = physical symptoms, SA = social anxiety, SP = separation anxiety/panic), *p < .05; **p < .001.

MASC-PS

EDE-R

EDE-E

EDE-S

MASC-SA

.86**

EDE-W

MASC-SP

.74** .42**

EDI1 .80**

.85**

.93** .92**

EDI2

Anxiety

.61** .48**

EDI3

.44** (.29, .59) .74** .43**

Perfectionism

Eating Disorder Symptoms

.81** (.74, .88)

.74** (.59, .90)

.83** (.78, .88)

EDI4 .73**

EDI5

Depression

.63**

EDI6

.84** .89**

CDI-NM

CDI-NSI

.74** .89**

CDI-IE

CDI-P

Fig. 3. Standardised path coefficients for Model 2, with 95% confidence intervals in parentheses. EDI = Eating Disorder Inventory, CDI = Children's Depression Inventory 2 (subscales: NM = negative mood, NSI = negative self-esteem, IE = ineffectiveness, IP = interpersonal problems), EDE = Eating Disorder Examination (subscales: R = restraint, E = eating concern, S = shape concern, W = weight concern); MASC = Multidimensional Anxiety Scale for Children 2 (subscales: PS = physical symptoms, SA = social anxiety, SP = separation anxiety/panic), **p < .001.

proportions of variance. Model 1 where depression was a mediator between perfectionism and eating disorders, accounted for 74% of the variance in eating disorder symptoms, 18% of anxiety, and 17% of depression. Conversely, in Model 2, where eating disorder symptoms were a mediator between perfectionism and anxiety/depression, accounted for only 22% of the variance in eating disorder symptoms, but 69% of anxiety and 70% of depression. Model 3, where perfectionism was a mediator of the relationship between anxiety/depression and eating disorder symptoms, provided a poor fit for the data. Notwithstanding the cross-sectional data and need to be cautious making causal conclusions, if researchers are primarily concerned with predicting eating disorder symptoms, Model 1 may be preferred, whereas if

consistent with the notion that sample size was a factor in the statistically non-significant result for anxiety in the current study. Simulations suggested that we would have needed a sample size of almost 1000 for 80% power to detect this effect. The second model, where eating disorder symptoms mediated the relationship between perfectionism and anxiety/depression, had a similar goodness to fit to the first model. This suggests that the relationship between anxiety/depression and eating disorders is reciprocal in nature, consistent with previous research (e.g., Boujut & Gana, 2014; Ranta et al., 2017), and supports the notion of perfectionism as a transdiagnostic process (Egan et al., 2011; Limburg et al., 2017). However, the two models explained substantially different 57

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depression in children and adolescents. If perfectionism is elevated in a young person with an eating disorder, clinicians may consider including this factor as a relevant target in formulation and treatment.

predicting anxiety/depression is of interest, Model 2, would be superior. It is possible that the relationships between perfectionism, eating disorder symptoms, and anxiety and depression observed in our sample were symptomatic of a starvation state, and it's associated impacts on factors such as cognitive rigidity. However, controlling for BMI as a proxy for starvation state in the models did not alter the pattern of relationships in any of the models. These findings lend some support to the importance of perfectionism and its relationship with symptoms of eating disorders and anxiety and depression independent of BMI. The strength of the direct effects between perfectionism and symptoms suggest that, if these current findings were replicated in prospective and experimental studies, it would be useful to determine whether targeting perfectionism in youths with eating disorders is associated with a transdiagnostic effect in reducing eating disorder symptoms, as well as anxiety and depression. Likewise, given the bidirectional relationships, future research could examine whether treating anxiety and depression results in reductions in comorbid eating disorder pathology, and conversely, whether treating eating disorder symptoms reduces depression and anxiety. A recent meta-analysis by Linardon, Wade, de la Piedad Garcia, and Brennan (2017), which indicated that greater improvements in depressive symptoms during cognitive behaviour therapy (CBT) for bulimia nervosa may be explained by greater improvements in eating disorder symptoms in adults, provides some validation of the utility of such therapeutic directions. Similarly, evidence suggests that Cognitive-Behaviour Therapy-Enhanced (CBT-E; Fairburn, 2008), which targets perfectionism when elevated, has efficacy in the treatment of eating disorders in adolescents. Further, in addition to CBT for perfectionism having efficacy in the reduction of eating disorder symptoms in adults (Steele & Wade, 2008), a pilot study has indicated efficacy in reducing eating disorder symptoms in female adolescents with anorexia nervosa (Hurst & Zimmer-Gembeck, 2015). It would be valuable for future research to compare CBT for perfectionism with evidence-based disorder-specific treatments in children and adolescents to determine if CBT for perfectionism is able to treat the eating disorder equally effectively, but result in larger reductions in comorbid anxiety and depression, as seen in adult samples (Steele & Wade, 2008). There are several limitations of the study. First, temporal precedence (i.e., prospective data) is necessary (but not sufficient) to infer causality between variables, but the cross-sectional design of this study does not provide us with such information. Future studies should consider longitudinal and experimental designs to enable a clearer picture of whether perfectionism leads to anxiety and depression, which then causes some individuals to develop eating disorders, or whether perfectionism causes eating disorders, which then leads to anxiety and/or depression. A second limitation is generalisability of the findings, which are based on a treatment-seeking, female, clinical population, at a tertiary treatment setting. Future research accounting for a wider range of cultures/ethnicities, populations not in treatment, as well as males is warranted. Third, almost all of the hypothesised pathways were statistically significant, suggesting that power was not a critical concern. It is also noteworthy that Monte Carlo simulations suggested that a sample size of almost 1000 would have been required to achieve 0.80 power to detect a significant effect for the pathway with the lowest power (anxiety to eating disorder symptoms in Model 1). However, the confidence intervals for some parameters were wide, and the relatively weak pathways from anxiety to eating disorder symptoms, and from perfectionism to eating disorder symptoms, may have achieved statistical significance in a larger sample. Future research with more statistical power and thus potential for greater precision in estimates should investigate this possibility, along with the relative strengths of associations between the pathways. In conclusion, the study provides support for the transdiagnostic nature of perfectionism. This highlights the importance of further research to determine whether directly targeting perfectionism will be helpful in the treatment of eating disorders and comorbid anxiety and

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