2024-05-14
081_ The influence of protective and risk factors on psychotic-like experiences in healthy individuals and psychotic symptoms in patients with schizophrenia
Research Question and Aims
State oft the art:
The assumption of a temporal and phenomenological continuum of psychosis has led to the investigation of "psychotic-like
experiences" (PLEs) in the general population in recent years (1). With a prevalence of 7.2% in the general population, PLEs
represent a significant phenomenon (2) and increase the risk of developing psychosis, other mental and physical illnesses, suicidality
and lead to a reduced subjective quality of life (3, 4, 5, 6). At the end of the psychosis continuum is schizophrenia, which is less
common, with a prevalence of about 1.4%, but is associated with substantial impact on life (7, 8). Various factors have been
identified as influencing both PLEs and schizophrenia. There is evidence that certain personality traits may both influence the
occurrence of PLEs and psychotic symptoms. In particular, higher levels of neuroticism appear to be directly related to the
occurrence of psychotic symptoms, as do higher levels of openness and lower levels of extraversion (9). In addition, cannabis and
tobacco use have been reported in the literature as independent predictors of PLEs (10, 11, 12). There is also an interaction between
the Polygenic Risk Score for Schizophrenia (PRS-Sz) and PLEs in healthy individuals (13). Childhood trauma and a family history of
psychiatric illness play a role in the development of psychosis (7, 14, 15). The 2021 discovered "polygenic resilience score" may also
be of interest in this context and will be investigated in the analysis of factors influencing both PLEs and schizophrenia (16). There is
currently no analysis comparing these factors for both PLEs in healthy controls and psychotic symptoms schizophrenia in a statistical
model.
Objective:
We aim to investigate whether and to what extent potential influencing factors such as personality traits, cannabis and tobacco
consumption, as well as PRS-Sz, PRS Resilience, noticeable family history, and childhood trauma influence PLEs (measured by the
Comprehensive Assessment of Psychotic Experiences (CAPE-42)) in healthy individuals and psychotic symptoms in patients with
schizophrenia (measured by the Positive and Negative Syndrome Scale (PANSS)). The PsyCourse dataset provides a unique
opportunity to analyze and compare the effects of all these factors together in one single model. A better understanding of the
factors that influence psychotic symptoms at the beginning and end of the psychosis continuum could improve both prevention and
early recognition of psychosis.
Analytic Plan
Research Question 1:
We want to explore the influence of protective factors (PRS Resilience, inconspicuous family history) and risk
factors (tobacco use, cannabis use, childhood trauma (cut-off total), Big Five openness and neuroticism, PRS Schizophrenia) on PLEs
(CAPE-42) in a group of healthy controls.
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Research Question 2:
We want to explore the influence of protective factors (PRS Resilience, inconspicuous family history) and risk
factors (tobacco use, cannabis use, trauma (cut-off total), Big Five Openness and Neuroticism, PRS Schizophrenia) on psychotic
symptoms differs (PANSS) in a group of patients with schizophrenia.
Research Question 3:
We want to investigate the influence of protective factors (PRS Resilience, unremarkable family history) and risk factors (tobacco use,
cannabis use, trauma (total cut-off), Big Five Openness and Neuroticism, PRS Schizophrenia) on the status (clinical vs. control) within
the PsyCourse Study sample.
Data from healthy individuals (Control Group) and patients with Schizophrenia from the PsyCourse who have completed the CAPE-
42 or the PANSS will be included in this study.
Analytic methods for Research Question 1: Method:
multiple linear regression with standardized variables, comparison of effect sizes
Dependent variables: psychotic experiences measured with CAPE-42 (positive, negative and affective subscale)
Independent Variable: personality traits, cannabis use, tobacco use, Childhood Trauma (CTS) and PRS for schizophrenia, PRS for
resilience, family history
<>Covariate: age, sex, ancestry principal components
First, we will calculate a multiple linear regression baseline model without PRS. Second, we add the PRS for resilience and separately
the PRS for schizophrenia. By adding the PRSs to the models, we aim to reduce the residuals.
Analytic methods for Research Question 2:
Method: multiple linear regression with standardized variables, comparison of effect sizes
Dependent variables: Psychotic symptoms in schizophrenia patients with PANSS (positive, negative and general subscale)
Independent Variable: personality traits, cannabis use, tobacco use, Childhood Trauma (CTS) and PRS for schizophrenia, PRS for
resilience, family history
Covariate: age, sex, ancestry principal components, medication
First, we will calculate a multiple linear regression baseline model without PRS. Second, we add the PRS for resilience and separately
the PRS for schizophrenia. By adding the PRSs to the models, we aim to reduce the residuals.
Analytic methods for Research Question 3:
Comparison of the model performance (by the coefficients of determination), comparison of parameters (estimated standardized
regression coefficients) from Research Question 1 and 2, Multigroup structural equation modeling
Resources needed
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