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Schizophr Res. 2013 Oct;150(1):197-204. doi: 10.1016/j.schres.2013.07.042. Epub 2013 Aug 9.

Deconstructing sub-clinical psychosis into latent-state and trait variables over a 30-year time span.

Author information

1
Department of General and Social Psychiatry, Psychiatric University Hospital, University of Zurich, Zurich, Switzerland; Collegium Helveticum, a Joint Research Institute between the University of Zurich & ETH Zurich, Switzerland. Electronic address: roessler@dgsp.uzh.ch.

Abstract

BACKGROUND:

Our aim was to deconstruct the variance underlying the expression of sub-clinical psychosis symptoms into portions associated with latent time-dependent states and time-invariant traits.

METHODS:

We analyzed data of 335 subjects from the general population of Zurich, Switzerland, who had been repeatedly measured between 1979 (age 20/21) and 2008 (age 49/50). We applied two measures of sub-clinical psychosis derived from the SCL-90-R, namely schizotypal signs (STS) and schizophrenia nuclear symptoms (SNS). Variance was decomposed with latent state-trait analysis and associations with covariates were examined with generalized linear models.

RESULTS:

At ages 19/20 and 49/50, the latent states underlying STS accounted for 48% and 51% of variance, whereas for SNS those estimates were 62% and 50%. Between those age classes, however, expression of sub-clinical psychosis was strongly associated with stable traits (75% and 89% of total variance in STS and SNS, respectively, at age 27/28). Latent states underlying variance in STS and SNS were particularly related to partnership problems over almost the entire observation period. STS was additionally related to employment problems, whereas drug-use was a strong predictor of states underlying both syndromes at age 19/20. The latent trait underlying expression of STS and SNS was particularly related to low sense of mastery and self-esteem and to high depressiveness.

CONCLUSIONS:

Although most psychosis symptoms are transient and episodic in nature, the variability in their expression is predominantly caused by stable traits. Those time-invariant and rather consistent effects are particularly influential around age 30, whereas the occasion-specific states appear to be particularly influential at ages 20 and 50.

KEYWORDS:

Cannabis; Epidemiology; Latent state–trait model; Schizotypal personality; Schizotypy; Sub-clinical psychosis; Substance use

PMID:
23932663
DOI:
10.1016/j.schres.2013.07.042
[Indexed for MEDLINE]

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