Internal structure of the Community Assessment of Psychic Experiences—Positive (CAPE-P15) scale: Evidence for a general factor

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Abstract

Background

Psychotic-like experiences (PLEs) are prevalent in the general population and are associated with poor mental health and a higher risk of psychiatric disorders. The Community Assessment of Psychic Experiences—Positive (CAPE-P15) scale is a self-screening questionnaire to address subclinical positive psychotic symptoms (PPEs) in community contexts. Although its psychometric properties seem to be adequate to screen PLEs, further research is needed to evaluate certain validity aspects, particularly its internal structure and its functioning in different populations.

Aim

To uncover the optimal factor structure of the CAPE-P15 scale in adolescents aged 13 to 18 years using factorial analysis methods suitable to manage categorical variables.

Method

A sample of 727 students from six secondary public schools and 245 university students completed the CAPE-P15. The dimensionality of the CAPE-P15 was tested through exploratory structural equation models (ESEMs). Based on the ESEM results, we conducted a confirmatory factor analysis (CFA) to contrast two factorial structures that potentially underlie the symptoms described by the scale: a) three correlated factors and b) a hierarchical model composed of a general PLE factor plus three specific factors (persecutory ideation, bizarre experiences, and perceptual abnormalities).

Results

The underlying structure of PLEs assessed by the CAPE-P15 is consistent with both multidimensional and hierarchical solutions. However, the latter show the best fit. Our findings reveal the existence of a strong general factor underlying scale scores. Compared with the specific factors, the general factor explains most of the common variance observed in subjects' responses.

Conclusions

The findings suggest that the factor structure of subthreshold psychotic experiences addressed by the CAPE-P15 can be adequately represented by a general factor and three separable specific traits, supporting the hypothesis according to which there might be a common source underlying PLEs.

Introduction

Psychotic-like experiences (PLEs) are common in the general population (Scott et al., 2008), particularly during childhood and adolescence (Laurens et al., 2012), with a rapid decline in prevalence with age (Rössler et al., 2007). The median prevalence of PLEs is 17% in children aged 9 to 12 and 7.5% in adolescents aged 13 to 18 years (Kelleher et al., 2012a, Kelleher et al., 2012b), but marked variations across countries have been found (Nuevo et al., 2010). PLEs are regarded as risk factors for future psychotic disorders (Hanssen et al., 2005, Kelleher et al., 2012a) and have been proposed as important markers to identify at-risk subjects (Kelleher and Cannon, 2011). However, not all individuals experiencing PLEs will develop clinical psychosis (Kline et al., 2014), and these experiences may represent normal aspects of the growth process (Wigman et al., 2011a, Wigman et al., 2011b). The risk of later psychotic outcomes may increase when PLEs are persistent over time (Cougnard et al., 2007, Domínguez et al., 2011), when they interact with additional risk factors, and/or when protective factors are absent (Mackie et al., 2011, Wigman et al., 2011a). However, it has been posited that PLEs may not be pathognomonic for psychotic disorders (Fisher et al., 2013), although they are associated with poor mental health (Nuevo et al., 2010), higher sensitivity to daily life stress (Collip et al., 2013), cannabis use (Stefanis et al., 2004), depressive symptoms (Barragan et al., 2011), distress, depression and poor functioning (Armando et al., 2010), and risk of suicide attempts in both general adolescent samples (Kelleher et al., 2013, Saha et al., 2011) and help-seeking adolescent subjects (Kelleher et al., 2014, Nishida et al., 2014).

Based on previous findings demonstrating strong associations between PLEs and psychiatric disorders, and given the evidence showing the potential role of PLEs as predictors of psychosis onset in adolescents and young adults, there is increasing interest in elucidating their underlying structure, which remains debated (Therman et al., 2014). According to the multidimensional perspective, PLEs are heterogeneous and differentially associated with mental health problems (Armando et al., 2010, Barragan et al., 2011). However, it has also been posited that these experiences could be represented by a unidimensional construct, as Laurens et al. (2012) observed in a large sample of children aged 9–11 years, which parallels recent findings showing the existence of a general psychosis dimension in both early psychosis and enduring psychosis (Reininghaus et al., 2013).

Various self-report screening questionnaires have been developed to measure PLEs in the general population (Kline et al., 2012). The use of these questionnaires, combined with additional instruments that address general psychopathology, may facilitate the identification of adolescents who need clinical evaluation and/or intervention (Kelleher et al., 2011). A widely used self-report instrument to address PLEs is the Community Assessment of Psychic Experiences (CAPE). Its original version (42 items, three subscales: positive, depressive and negative symptoms) (Stefanis et al., 2002) has high internal reliability and construct and discriminant validity (Konings et al., 2006, Brenner et al., 2007). The CAPE is regarded as an appropriate tool to detect individuals at an increased risk of developing psychosis in clinical and help-seeking populations (Mossaheb et al., 2012). Prior studies using the 20-item positive subscale (CAPE-P) have found a similar and stable structure with 3–5 factors, revealing that specific subtypes of PPEs are differentially related to distress, depression and poor functioning (Armando et al., 2010, Barragan et al., 2011, Wigman et al., 2012). A recent study investigated the internal structure of the CAPE-P and found that a three-factor model yielded the best fit when items addressing magical thinking, grandiosity, and paranormal beliefs were omitted (Capra et al., 2013). The proposed factors were bizarre experiences (BEs), persecutory ideation (PI) and perceptual abnormalities (PAs), which resulted in a new 15-item version of the questionnaire (CAPE-P15). This factorial solution solves problems detected by prior research, mainly those related to the excluded items (misinterpretation, cross-loading and unclear associability with psychopathology) and fits well with previous findings showing strong associations between the proposed factors and mental health problems (Yung et al., 2009, Wigman et al., 2011a, Wigman et al., 2011b).

The purpose of the present study is two-fold. First, we seek to provide further evidence on the internal structure of the CAPE-P15 by conducting exploratory and confirmatory analyses to contrast two possible factor solutions. Second, we attempt to expand the scope of the research on and use of the CAPE-P15 from the population studied by Capra et al. (2013) (English-speaking university students, mostly females) to a broader population of Spanish-speaking adolescents aged 13–18.

We believe that the results of this study yield new insights into the underlying positive features of PLEs and enhance the range of application of the instrument.

Section snippets

Participants

A cross-sectional study was conducted with 727 high school students (adolescents) (women = 50.7%) aged 13 to 18 years (mean = 15.4, ±1.33), recruited between April and July 2014 in six secondary schools of the city of Talca, Chile. Only 2 subjects rejected to participate in the study, and then, nearly 100% of the subjects attending to each school were recruited. We observed that 3.9% of subjects have one or more missing values, with a distribution completely at random (MCAR, Little's test sig. = 

ESEM analysis to test a set of interpretable models

The goodness-of-fit level was unacceptable for the unidimensional model (A), moderate for the two-factor model (B) and good for the three-factor model (C) (Supplementary Table 2). The moderate to high correlations observed among the factors of model C suggest a possible superior order structure. Consequently, we fitted a hierarchical ESEM model (D) with three specific factors and a general factor, which yielded an excellent fit (CFI = 0.99, TLI = 0.99, RMSEA = 0.025) (range of G factor loadings:

Discussion

We examined the internal structure of positive psychotic experiences addressed by the CAPE-P15 (Capra et al., 2013) in a sample of non-help-seeking adolescents aged 13–18 years. The comparison of different competing models yielded two latent structures with acceptable fit levels: a three-correlated-factor model (persecutory ideation, bizarre experiences and perceptual abnormalities) and a hierarchical model (one general PLE factor and three specific factors). Our initial analyses replicated the

Role of funding source

This work was supported by the Dirección de Investigación, Universidad de Talca (I002981).

Contributors

Daniel Nunez designed the study and directed its implementation, did the literature searches, and wrote the manuscript.

Victor Arias performed the statistical analyses, and wrote the manuscript.

Edgar Vogel and Gómez reviewed the manuscript and revised critically for intellectual content.

Conflict of interest

None of the authors have any conflicts of interest.

Acknowledgments

The authors would like to thank all the students for their participation.

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