Does a latent class underlie schizotypal personality disorder? Implications for schizophrenia.

Abstract

Despite growing enthusiasm for dimensional models of personality pathology, the taxonic versus dimensional status of schizotypal personality disorder (PD) remains a point of contention in modern psychiatry. The current study aimed to determine empirically the latent structure of schizotypal PD. We examined the latent structure of schizotypal PD in the Psychiatric Morbidity Survey in Great Britain and the second wave of the U.S.-based National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) survey. We analyzed composite indicators created from participant responses using the mean above minus mean below a cut (MAMBAC), Maximum Covariance (MAXCOV), and latent mode factor analysis (L-Mode) taxometric procedures. We also analyzed item-level responses using two latent variable mixture models--latent class analysis and latent class factor analysis. Taxometric and latent variable mixture analyses supported a dimensional, rather than taxonic, structure in both epidemiological samples. The dimensional model better predicted psychosis, intellectual functioning, disability, and treatment seeking than the categorical model based on DSM-IV diagnosis. People meeting criteria for schizotypal PD appear to exist on a spectrum of severity with the rest of the population. The possible dimensionality of schizotypal PD adds to growing support for a dimensional structure of PDs including other Cluster A disorders.

Schizotypy From a Developmental Perspective

“…However, unlike the so-called fully-dimensional perspective referred to above, these models consider that despite there being phenomenological continuity between traits and symptoms, the latent liability (eg the genetic susceptibility) is not continuously distributed in the population, which yields a group of liable individuals (a taxon) which is qualitatively different from the rest (ie structural discontinuity). The investigation of the structure of schizotypy with taxometric analyses is a convulse topic given its methodological complexity 16 and has raised mixed findings, with some studies supporting 17,18 and others not [19][20][21] the existence of a schizotypy or schizotypal personality disorder taxon.…”

The role of traits in describing, assessing, and understanding personality pathology.

“…Continuous measures of PD criteria account for variance in psychosocial functioning, disability, and treatment seeking beyond that explained by a categorical diagnosis of the same symptoms (Ahmed et al, 2013;Skodol et al, 2005), but the inverse is not true: Categorical diagnoses do not provide information about psychosocial functioning in excess of that provided by dimensional measures. In the assessment of criminality, dimensional measures have again been shown to be superior to categorical measures.…”

“…When the fits of continuous and discrete latent variable models are explicitly compared, continuous latent variable models are preferred in describing externalizing pathology, which includes antisocial personality pathology . Comparisons between continuous and discrete latent variable models have supported continuous latent variable models of schizotypy as well (Ahmed et al, 2013).…”

An event-related potential investigation of error monitoring in adults with a history of psychosis

“…The Interpersonal factor consists of subscales that reflect having no close friends/constricted affect and social anxiety (e.g., ''I find it hard to be emotionally close to other people.''). Items on the SPQ-BR are rated on a Likert scale consistent with the finding that schizotypal personality traits appear to be best represented on a continuum (Ahmed et al, 2013). The SPQ-BR was chosen as it assesses dimensional traits that have been demonstrated to be genetically and developmentally linked to psychosis (Raine, 2006) and may be sensitive to psychosis-proneness in individuals without a history of a clinical level of psychotic symptoms.…”