Publications by authors named "Julia-Katharina Pfarr"

6 Publications

  • Page 1 of 1

Effects of polygenic risk for major mental disorders and cross-disorder on cortical complexity.

Psychol Med 2021 Apr 8:1-12. Epub 2021 Apr 8.

Department of Psychiatry and Psychotherapy, Philipps-Universität Marburg, Rudolf-Bultmann-Str. 8, 35039Marburg, Germany.

Background: MRI-derived cortical folding measures are an indicator of largely genetically driven early developmental processes. However, the effects of genetic risk for major mental disorders on early brain development are not well understood.

Methods: We extracted cortical complexity values from structural MRI data of 580 healthy participants using the CAT12 toolbox. Polygenic risk scores (PRS) for schizophrenia, bipolar disorder, major depression, and cross-disorder (incorporating cumulative genetic risk for depression, schizophrenia, bipolar disorder, autism spectrum disorder, and attention-deficit hyperactivity disorder) were computed and used in separate general linear models with cortical complexity as the regressand. In brain regions that showed a significant association between polygenic risk for mental disorders and cortical complexity, volume of interest (VOI)/region of interest (ROI) analyses were conducted to investigate additional changes in their volume and cortical thickness.

Results: The PRS for depression was associated with cortical complexity in the right orbitofrontal cortex (right hemisphere: p = 0.006). A subsequent VOI/ROI analysis showed no association between polygenic risk for depression and either grey matter volume or cortical thickness. We found no associations between cortical complexity and polygenic risk for either schizophrenia, bipolar disorder or psychiatric cross-disorder when correcting for multiple testing.

Conclusions: Changes in cortical complexity associated with polygenic risk for depression might facilitate well-established volume changes in orbitofrontal cortices in depression. Despite the absence of psychopathology, changed cortical complexity that parallels polygenic risk for depression might also change reward systems, which are also structurally affected in patients with depressive syndrome.
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http://dx.doi.org/10.1017/S0033291721001082DOI Listing
April 2021

Subclinical schizotypal vs. autistic traits show overlapping and diametrically opposed facets in a non-clinical population.

Schizophr Res 2021 Mar 18;231:32-41. Epub 2021 Mar 18.

Cognitive Neuropsychiatry Lab, Department of Psychiatry and Psychotherapy, Philipps Universität Marburg, Marburg, Germany; Center for Mind, Brain, and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany; Marburg University Hospital - UKGM, Marburg, Germany.

Background: The overlap of autism spectrum disorder (ASD) and psychosis or schizophrenia spectrum disorders (SSD) has exposed problems central to conceptualising and understanding co-morbidity in psychiatric disorders.

Methods: In the present study, we demonstrate that a deep phenotyping approach aids clarification of both overlapping and diametrically opposed features of ASD and SSD on the level of trait facets.

Results: We first show overlap of negative and disorganised (but not positive) features of schizotypy with autistic traits in a sample of n = 376 German non-clinical subjects using multiple psychometric measures of schizotypy (MSS multidimensional schizotypy scale, OLIFE Oxford-Liverpool Inventory of Feelings and Experiences, and SPQ-B schizotypal personality questionnaire - brief) and the AQ autism spectrum quotient, with control measures for affective spectrum pathology (BDI). Findings were then replicated in a French-Swiss sample (n = 264) using MSS, OLIFE, AQ, and in addition the Community Assessment of Psychic Experiences (CAPE). Additional principal component analysis confirmed our finding of the co-existence of both overlapping (loss of function, social communication deficit, and negative schizotypy) as well as diametrically opposed features (AQ attention to detail, positive schizotypy) across the two spectra. Results were validated with Horn's parallel analyses, affirming two component solutions, and PCA using sample-specific, factor-analysis-derived schizotypy scores.

Conclusions: Providing a framework for multi-dimensional transdiagnostic characterisation of ASD vs. SSD phenotypes we point out overlapping vs. discriminating facets. In addition to the use of novel multidimensional schizotypy scales, it also shows transcultural consistency of findings, and highlights a particular role for the attention to detail AQ subscale.
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http://dx.doi.org/10.1016/j.schres.2021.02.018DOI Listing
March 2021

Associations of subclinical autistic-like traits with brain structural variation using DTI and VBM.

Eur Psychiatry 2021 Mar 3:1-38. Epub 2021 Mar 3.

Cognitive Neuropsychiatry Lab, Department of Psychiatry and Psychotherapy, Philipps-University Marburg / Marburg University Hospital - UKGM, Marburg, Germany.

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http://dx.doi.org/10.1192/j.eurpsy.2021.15DOI Listing
March 2021

Distress severity in perceptual anomalies moderates the relationship between prefrontal brain structure and psychosis proneness in nonclinical individuals.

Eur Arch Psychiatry Clin Neurosci 2021 Feb 2. Epub 2021 Feb 2.

Cognitive Neuropsychiatry Lab, Department of Psychiatry and Psychotherapy, Philipps-Universität Marburg, Rudolf-Bultmann-Str. 8, 35039, Marburg, Germany.

In the general population, psychosis risk phenotypes occur independently of attenuated prodromal syndromes. Neurobiological correlates of vulnerability could help to understand their meaningfulness. Interactions between the occurrence of psychotic-like experiences (PLE) and other psychological factors e.g., distress related to PLE, may distinguish psychosis-prone individuals from those without risk of future psychotic disorder. We aimed to investigate whether (a) correlates of total PLE and distress, and (b) symptom dimension-specific moderation effects exist at the brain structural level in non-help-seeking adults reporting PLE below and above the screening criterion for clinical high-risk (CHR). We obtained T1-weighted whole-brain MRI scans from 104 healthy adults from the community without psychosis CHR states for voxel-based morphometry (VBM). Brain structural associations with PLE and PLE distress were analysed with multiple linear regression models. Moderation of PLE by distress severity of two types of positive symptoms from the Prodromal Questionnaire (PQ-16) screening inventory was explored in regions-of-interest after VBM. Total PQ-16 score was positively associated with grey matter volume (GMV) in prefrontal regions, occipital fusiform and lingual gyri (p < 0.05, FDR peak-level corrected). Overall distress severity and GMV were not associated. Examination of distress severity on the positive symptom dimensions as moderators showed reduced strength of the association between PLE and rSFG volume with increased distress severity for perceptual PLE. In this study, brain structural variation was related to PLE level, but not distress severity, suggesting specificity. In healthy individuals, positive relationships between PLE and prefrontal volumes may indicate protective features, which supports the insufficiency of PLE for the prediction of CHR. Additional indicators of vulnerability, such as distress associated with perceptual PLE, change the positive brain structure relationship. Brain structural findings may strengthen clinical objectives through disentanglement of innocuous and risk-related PLE.
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http://dx.doi.org/10.1007/s00406-020-01229-5DOI Listing
February 2021

Anterior vs Posterior Hippocampal Subfields in an Extended Psychosis Phenotype of Multidimensional Schizotypy in a Nonclinical Sample.

Schizophr Bull 2021 Jan;47(1):207-218

Cognitive Neuropsychiatry Lab, Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany.

Numerous studies have implicated involvement of the hippocampus in the etiology and expression of schizophrenia-spectrum psychopathology, and reduced hippocampal volume is one of the most robust brain abnormalities reported in schizophrenia. Recent studies indicate that early stages of schizophrenia are specifically characterized by reductions in anterior hippocampal volume; however, studies have not examined hippocampal volume reductions in subclinical schizotypy. The present study was the first to examine the associations of positive, negative, and disorganized schizotypy dimensions with hippocampal subfield volumes in a large sample (n = 195) of nonclinically ascertained young adults, phenotyped using the Multidimensional Schizotypy Scale (MSS). Hippocampal subfields were analyzed from high-resolution 3 Tesla structural magnetic resonance imaging scans testing anatomical models, including anterior vs posterior regions and the cornu ammonis (CA), dentate gyrus (DG), and subiculum subfields separately for the left and right hemispheres. We demonstrate differential spatial effects across anterior vs posterior hippocampus segments across different dimensions of the schizotypy risk phenotype. The interaction of negative and disorganized schizotypy robustly predicted left hemisphere volumetric reductions for the anterior and total hippocampus, and anterior CA and DG, and the largest reductions were seen in participants high in negative and disorganized schizotypy. These findings extend previous early psychosis studies and together with behavioral studies of hippocampal-related memory impairments provide the basis for a dimensional neurobiological hippocampal model of schizophrenia risk. Subtle hippocampal subfield volume reductions may be prevalent prior to the onset of detectable prodromal clinical symptoms of psychosis and play a role in the etiology and development of such conditions.
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http://dx.doi.org/10.1093/schbul/sbaa099DOI Listing
January 2021

A multimodal imaging study of brain structural correlates of schizotypy dimensions using the MSS.

Psychiatry Res Neuroimaging 2020 08 25;302:111104. Epub 2020 May 25.

Cognitive Neuropsychiatry lab, Department of Psychiatry and Psychotherapy, Philipps Universität Marburg, Marburg, Germany; Center for Mind, Brain, and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Germany; Marburg University Hospital - UKGM, Marburg, Germany. Electronic address:

Schizotypy is a multidimensional construct of subclinical schizophrenia-like behavioural traits and cognition. The recently developed multidimensional schizotypy scale (MSS) provides an improved psychometric assessment of the three main dimensions (positive, negative, and disorganised). We tested the hypothesis that the three dimensions are related to brain structural variation in the precuneus and fronto-thalamo-striatal system in a new non-clinical healthy cohort to support a dimensional model of the psychosis spectrum. We analysed data from 104 subjects with Multidimensional Schizotypy Scale (MSS) phenotyping and 3 Tesla magnetic resonance images using voxel-based morphometry (VBM) applying CAT12 software, and diffusion-tensor imaging (DTI) with TBSS in FSL to test for correlations with MSS scores. MSS subscales and total score were negatively associated with GMV in brain areas including the medial prefrontal cortex, anterior cingulate cortex, and lateral prefrontal and orbital cortex. MSS schizotypy was associated with white matter integrity in anterior thalamic radiation, uncinate fasciculus, and superior longitudinal fasciculus. Our findings provide first direct evidence for an association of schizotypy (as a psychosis risk phenotype) and the fronto-thalamo-striatal system, in both grey and white matter with regionally diverging effects across single dimensions. This provides new evidence arguing for the fronto-striatal system (rather than precuneus) in schizotypy.
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http://dx.doi.org/10.1016/j.pscychresns.2020.111104DOI Listing
August 2020