Schizophrenia Bulletin doi:10.1093/schbul/sbz005 Downloaded from https://academic.oup.com/schizophreniabulletin/advance-article-abstract/doi/10.1093/schbul/sbz005/5310427 by [email protected] on 27 August 2019 Common Taxonomy of Traits and Symptoms: Linking Schizophrenia Symptoms, Schizotypy, and Normal Personality David C. Cicero*,1, Katherine G. Jonas2, , Kaiqiao Li2, Greg Perlman2, and Roman Kotov2 1Department of Psychology, University of Hawaii at Manoa, Honolulu, HI; 2Department of Psychiatry, Stony Brook University, Stony Brook, NY *To whom correspondence should be addressed; tel: 808-956-3695, fax: 808-956-4700, e-mail: [email protected] The associations among normal personality and many Introduction mental disorders are well established, but it remains Trait-based paradigms, which have treated psychopa- unclear whether and how symptoms of schizophrenia and thology as fully dimensional, have been useful in under- schizotypal traits align with the personality taxonomy. standing psychopathology, particularly internalizing and This study examined the joint factor structure of nor- externalizing disorders.1–3 The Hierarchical Taxonomy mal personality, schizotypy, and schizophrenia symptoms of Psychopathology (HiTOP) seeks to improve on tra- in people with psychotic disorders (n = 288) and never- ditional diagnostic systems, such as the Diagnostic and psychotic adults (n = 257) in the Suffolk County Mental Statistical Manual of Mental Disorders (DSM) and Health Project. First, we evaluated the structure of International Classification of Diseases (ICD), and con- schizotypal (positive schizotypy, negative schizotypy, and ceptualize psychopathology dimensionally.4 A major mistrust) and normal traits. In both the psychotic-disor- dimension within HiTOP is the psychotic spectrum, der and never-psychotic groups, the best-fitting model had which ranges from normal personality to schizotypal 5 factors: neuroticism, extraversion, conscientiousness, traits to frank psychosis. Schizotypy also reflects a liabil- agreeableness, and psychoticism. The schizotypy traits ity for the development of schizophrenia.5–8 The dimen- were placed on different dimensions: negative schizotypy sional conceptualization is supported by evidence that went on (low) extraversion, whereas positive schizotypy psychotic disorders form a continuum with schizotypal and mistrust went on psychoticism. Next, we added symp- traits,9–15 and schizotypal traits fit well in the personal- toms to the model. Numerous alternatives were compared, ity taxonomy alongside normal traits.16,17 An alternative and the 5-factor model remained best-fitting. Reality dis- view of schizotypy is that it is quasi-dimensional, and tortion (hallucinations and delusions) and disorganiza- previous work has not definitely resolved this issue.9,13 tion symptoms were placed on psychoticism, and negative Some research has demonstrated that psychosis exists on symptoms were placed on extraversion. Models that sepa- a continuum with normal perceptual experiences whether rated symptom dimensions from trait dimensions did not examined with latent variable mixture models18 or taxo- fit well, arguing that taxonomies of symptoms and traits metric methods.19,20 This study aims to identify where are aligned. This is the first study to show that symptoms schizotypy fits within other spectra of psychopathology of psychosis, schizotypy, and normal personality reflect regardless of whether the underlying construct is dimen- the same underlying dimensions. Specifically, (low) extra- sional or categorical. Previous research strongly supports version, negative schizotypy, and negative symptoms form that other psychopathology spectra included in HiTOP one spectrum, whereas psychoticism, positive schizotypy, parallel dimensions of normal personality and extend and positive and disorganized symptoms form another. into maladaptive extremes2,3,21–23 (although some recent This framework helps to understand the heterogeneity research suggests that normal personality characteris- of psychosis and comorbidity patterns found in psychotic tics are separate from personality disorders on a genetic disorders. It also underscores the importance of traits to level24). Recent theorists have noted that personality understanding these disorders. pathology is often neglected in schizophrenia research,25 and unlike other spectra, the psychotic spectrum has not Key words: psychoticism/mistrust/detachment/positive been comprehensively studied vis-à-vis the taxonomy of symptoms/negative symptoms normal personality. © The Author(s) 2019. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: [email protected] Page 1 of 13 Psychosis and Personality This mapping is especially complicated because psychotic model or form additional dimensions. This study sought to symptoms are multidimensional, with structural studies address this issue by performing the first-factor analysis of finding at least 2 factors of positive and negative symp- all relevant dimensions. First, we examined the joint struc- Downloaded from https://academic.oup.com/schizophreniabulletin/advance-article-abstract/doi/10.1093/schbul/sbz005/5310427 by [email protected] on 27 August 2019 toms.26–28 The positive symptom factor includes reality dis- ture of schizotypy and normal personality traits in psy- tortion (delusions and hallucinations) and disorganization chotic-disorders and never-psychotic samples. We tested (bizarre behavior and formal thought disorder), and the alternative models that reflect organizations suggested in negative symptom factor includes inexpressivity (flat affect the literature. Next, in the psychotic-disorders sample, we and alogia) and avolition (avolition and asociality).29–32 added symptoms of schizophrenia, again comparing all Maladaptive personality traits relevant to psychosis organizations suggested in the literature. These analyses typically are labeled schizotypy and are also multidi- were designed to determine whether schizophrenia symp- mensional. This domain includes an array of perspec- toms, schizotypy, and normal personality fall along the tives including risk factors,5,6,33–36 prodromal signs and same major spectra, and help to understand heterogeneity symptoms,37–41 maladaptive traits,42–45 and personality within psychotic disorders from the perspective of traits. disorders.10,46,47 Across perspectives, schizotypy includes at least 2 dimensions, positive (anomalous perceptions Methods and beliefs) and negative (anhedonia and social with- drawal).48,49 These dimensions also have been labeled Participants psychoticism and detachment.4,36 Some studies observed Data came from the Suffolk County Mental Health Project, additional factors,50–54 among which the placement of a longitudinal epidemiologic study of first-admission mistrust—sometimes termed suspiciousness or para- patients with psychosis.84–86 The psychotic-disorders group noia—has been inconsistent. Models have grouped was recruited from 12 psychiatric inpatient units of Suffolk mistrust with positive schizotypy,51,55,56 negative schizo- County, NY, between 1989 and 1995. Inclusion criteria were typy,52,57 antagonism/disagreeableness,58,59 or found a sep- first admission within 6 months, psychosis, ages 15–60, intel- arate factor,53,60–62 including large multinational studies.63 ligence quotient >70, proficiency with English, resident of Multiple models have been proposed to organize per- Suffolk County, and no apparent medical etiology for psy- sonality, and the most studied includes 5 traits: neu- chotic symptoms. Patients were followed over 2 decades, and roticism, extraversion, conscientiousness, agreeableness, 288 completed the personality assessment at the 20-year time and openness.64 Some theorists have hypothesized a link point. The never-psychotic group (N = 257) was recruited between maladaptive openness and psychoticism/positive using random digit dialing to zip codes where the psy- schizotypy,65 but observed correlations are weak and often chotic disorder group resided (for sampling procedure see nonsignificant.66–69 Openness is largely unrelated to other Velthorst et al87). The study was approved annually by the forms of psychopathology,23 and neuroticism, extraver- institutional review boards of Stony Brook University and sion, conscientiousness, and agreeableness have emerged as participating hospitals. All participants provided written in- the normal personality characteristics relevant to mental formed consent. See table 1 for the demographic character- disorders. Schizotypy does not fit fully into this taxonomy. istics of the samples. Socioeconomic status was measured Detachment typically maps onto low extraversion53,70,71 or with the Hollingshead Index of Socioeconomic Status.88 forms a distinct dimension.51,55 In contrast, psychoticism/ Four participants in the never-psychotic group were positive schizotypy has been consistently found to form a excluded due to excessive missing data. Demographic in- dimension distinct from normal personality.66–68,72–75 formation was available for 373 participants in the psy- It is less clear how schizophrenia relates to normal per- chotic-disorders group at 20-year wave, 85 of whom did sonality because few investigations assessed both relatively not provide information necessary for present analyses and rare psychotic disorders and normal personality. A meta- were excluded. These participants did not significantly