Elsevier

Psychiatry Research

Volume 240, 30 June 2016, Pages 34-41
Psychiatry Research

The Five-Factor Model personality traits in schizophrenia: A meta-analysis

https://doi.org/10.1016/j.psychres.2016.04.004Get rights and content

Highlights

  • Schizophrenia and control subjects differed in all the personality traits measured by the NEO-FFI.

  • Schizophrenia patients scored a higher N and lower E, O, A and C than controls.

  • These effect sizes were not affected by gender distribution or mean age in each study, expect for gender effect for A.

  • TCI may be more suitable for detecting distinctive personality traits in schizophrenia than NEO-FFI.

Abstract

Personality is one of important factors in the pathogenesis of schizophrenia because it affects patients’ symptoms, cognition and social functioning. Several studies have reported specific personality traits in patients with schizophrenia compared with healthy subjects. However, the results were inconsistent among studies. The NEO Five-Factor Inventory (NEO-FFI) measures five personality traits: Neuroticism (N), Extraversion (E), Openness (O), Agreeableness (A) and Conscientiousness (C). Here, we performed a meta-analysis of these personality traits assessed by the NEO-FFI in 460 patients with schizophrenia and 486 healthy subjects from the published literature and investigated possible associations between schizophrenia and these traits. There was no publication bias for any traits. Because we found evidence of significant heterogeneity in all traits among the studies, we applied a random-effect model to perform the meta-analysis. Patients with schizophrenia showed a higher score for N and lower scores for E, O, A and C compared with healthy subjects. The effect sizes of these personality traits ranged from moderate to large. These differences were not affected by possible moderator factors, such as gender distribution and mean age in each study, expect for gender effect for A. These findings suggest that patients with schizophrenia have a different personality profile compared with healthy subjects.

Introduction

Schizophrenia is a complex psychiatric disorder that has positive and negative symptoms, cognitive impairment and poor social functioning. Historically, early psychopathologists such as Bleuler and Kraepelin observed a deterioration of personality in patients with schizophrenia. Personality is considered to be one of important factors for the pathogenesis of schizophrenia because it may influence patients' symptoms, cognition and social functioning (Compton et al., 2015, Gurrera et al., 2014). Furthermore, personality features predict the onset and course of the illness (Gleeson et al., 2005, Lonnqvist et al., 2009, Van Os and Jones, 2001).

The five major personality traits of the Five-Factor Model (FFM) are Neuroticism (N): vulnerability to emotional instability and self-consciousness; Extraversion (E): predisposition towards sociability, assertiveness and social interaction; Openness (O): cognitive disposition to creativity and aesthetics; Agreeableness (A): tendency towards being sympathetic, trusting and altruistic; and Conscientiousness (C): tendency towards dutifulness and competence (Costa and McCrae, 1992). The Revised NEO Personality Inventory (NEO-PI-R) and the NEO Five-Factor Inventory (NEO-FFI), the shorter version of the NEO-PI-R, are well-established self-report questionnaires that measure these five major personality traits. Personality trait analyses using the FFM have reported potential differences between patients with schizophrenia and healthy subjects (Akdag et al., 2003, Boyette et al., 2013, Brenner et al., 2009, Brenner et al., 2011, Gurrera et al., 2000, Gurrera et al., 2014, Herran et al., 2006, Kentros et al., 1997, Kirihara et al., 2012, Onitsuka et al., 2005, Pillmann et al., 2003, Suslow et al., 2014). Although not all of the results of these studies reached statistical significance, patients with schizophrenia tended to show higher scores on N and lower scores on E, O, A and C than healthy subjects. Particularly, high N and low E in patients with schizophrenia were relatively consistent among studies, although differences in the other personality traits were inconsistent among studies. Thus, several subsequent studies focused on only N and/or E on the basis of the relatively consistent findings among previous studies. These personality differences have been shown to be longitudinally stable, suggesting they are not due to acute state effects (Boyette et al., 2015). Premorbid personality traits of high N and low E were associated with a risk of the development of schizophrenia (Goodwin et al., 2003, Krabbendam et al., 2002, Lonnqvist et al., 2009, Malmberg et al., 1998, Van Os and Jones, 2001), and premorbid high E was associated with a risk of bipolar disorder (Lonnqvist et al., 2009). In addition, first-degree relatives of patients with schizophrenia and related disorders scored higher levels of N than healthy subjects (Boyette et al., 2013, Maier et al., 1994). Individuals with schizotypal personality disorder (SPD) scored higher levels of N and lower levels of E, A and C than those without SPD (Gurrera et al., 2005). Furthermore, N was positively and E and A were negatively related to schizotypal personality trait (schizotypy) scores in general population (Asai et al., 2011, Ross et al., 2002). These findings suggest that personality traits of schizophrenia are considered to span a continuum and a common genetic factor might confer a risk for schizophrenia, as well as for personality traits related to schizophrenia. Therefore, studying disorder-related personality traits may help to improve our understanding of schizophrenia. However, in addition to the N and E traits other traits (O, A and C) might also be meaningful in schizophrenia. The limited sample sizes in previous studies have made it difficult to reveal distinctive personality traits in schizophrenia. We need to solve two issues to obtain a definitive conclusion: low statistical power derived from small sample sizes and the impact of possible confounding factors, such as gender distribution and mean age in each study, on the outcome. To resolve these issues, we performed a meta-analysis to find differences in personality traits assessed by the Temperament and Character Inventory (TCI) between patients with schizophrenia and healthy subjects (Ohi et al., 2012), and this method could successfully detect distinctive personality traits in schizophrenia.

In this study, a meta-analysis was undertaken to determine whether patients with schizophrenia have a distinctive personality trait profile assessed by NEO compared with healthy subjects. In addition, we examined whether a between-studies effect of age or gender would indicate a moderating influence of these variables on the outcomes.

Section snippets

Meta-analysis of studies assessed by NEO between patients with schizophrenia and controls

We first searched for the studies that we used for our meta-analysis in the PubMed and PsycINFO databases, with the search terms “NEO”, “NEO-FFI”, “NEO-PI-R”, “Big five”, “Neuroticism”, “Extraversion”, “Openness”, “Agreeableness” or “Conscientiousness” and “schizophrenia”. Our search data encompassed all publications up to March 2016. Additionally, references cited in the publications that we obtained were searched to identify additional potentially relevant studies that might not be listed in

Results

We found 277 relevant articles in PubMed and PsycINFO using the search terms mentioned in the Methods section. Of these, a total of nine studies met the inclusion criteria (Supplementary Fig. S1) for our meta-analysis (with a total of 460 patients with schizophrenia and 486 healthy subjects) (Akdag et al., 2003, Boyette et al., 2013, Brenner et al., 2009, Camisa et al., 2005, Gurrera et al., 2000, Gurrera et al., 2014, Kirihara et al., 2012, Pillmann et al., 2003, Suslow et al., 2014).

Discussion

This is the first pooled study on comparisons of NEO FFM personality traits between patients with schizophrenia and healthy subjects. Although there was significant heterogeneity in all personality traits among studies, our results suggest that patients with schizophrenia have distinguishable personality traits compared with healthy subjects. Leave-one-out sensitivity analysis revealed that the differences other than A between patients and controls were not caused by each individual study.

Conflicts of interest

No conflicts of interest.

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