Publications by authors named "Henk Temmingh"

Background: Personality disorders (PDs) are estimated to occur in 6.8% of South Africans and in 45% to 80% of clinical populations. Mental health practitioners often harbour negative attitudes and lack confidence in working with such patients.

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Multivariate techniques better fit the anatomy of complex neuropsychiatric disorders which are characterized not by alterations in a single region, but rather by variations across distributed brain networks. Here, we used principal component analysis (PCA) to identify patterns of covariance across brain regions and relate them to clinical and demographic variables in a large generalizable dataset of individuals with bipolar disorders and controls. We then compared performance of PCA and clustering on identical sample to identify which methodology was better in capturing links between brain and clinical measures.

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Article Synopsis
  • Schizophrenia is characterized by significant changes in brain structure, but it's not clear if these changes relate to the brain's network organization.
  • Researchers analyzed MRI scans from nearly 2,500 people with schizophrenia alongside healthy controls to see how structural changes connect to brain networks.
  • The study found that certain regions in the brain that are crucial for connectivity are more affected in schizophrenia, indicating a link between brain network vulnerability and the disease's impact, with some similarities to bipolar disorder but not major depressive disorder.
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Background: Patients with multi-episode bipolar and psychotic disorders have a high prevalence of substance use disorders, with negative consequences. A brief, easily administered screening test such as the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) is needed to identify those at risk in order to intervene appropriately. However, the ASSIST has not yet been validated in this population.

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Converging evidence suggests that schizophrenia (SZ) with primary, enduring negative symptoms (i.e., Deficit SZ (DSZ)) represents a distinct entity within the SZ spectrum while the neurobiological underpinnings remain undetermined.

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Article Synopsis
  • The study looked at how the brain's left and right sides might differ in people with schizophrenia compared to those without it, using brain scans from over 5,000 patients and 6,000 control subjects.
  • Researchers found that people with schizophrenia had slightly thinner areas in the left side of their brains, especially in certain regions, compared to those without the disorder.
  • The differences in brain structure might be linked to how schizophrenia affects brain functions, like language, but more research is needed to understand why they happen.
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Background: Obesity is highly prevalent and disabling, especially in individuals with severe mental illness including bipolar disorders (BD). The brain is a target organ for both obesity and BD. Yet, we do not understand how cortical brain alterations in BD and obesity interact.

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Article Synopsis
  • This international guideline suggests enhancing clozapine package inserts by implementing ancestry-based dosing and titration to reduce adverse drug reactions (ADRs).
  • Clozapine, a powerful medication, has a narrow therapeutic range and is highly associated with toxicity, especially in certain populations; it is especially risky due to its high rates of pneumonia-related mortality.
  • The guideline outlines six personalized dosing schedules based on ancestry and metabolic activity, recommending varying daily doses of clozapine tailored to individual patient profiles to minimize the risk of ADRs.
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Aims: Rates of obesity have reached epidemic proportions, especially among people with psychiatric disorders. While the effects of obesity on the brain are of major interest in medicine, they remain markedly under-researched in psychiatry.

Methods: We obtained body mass index (BMI) and magnetic resonance imaging-derived regional cortical thickness, surface area from 836 bipolar disorders (BD) and 1600 control individuals from 14 sites within the ENIGMA-BD Working Group.

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Schizophrenia is associated with widespread alterations in subcortical brain structure. While analytic methods have enabled more detailed morphometric characterization, findings are often equivocal. In this meta-analysis, we employed the harmonized ENIGMA shape analysis protocols to collaboratively investigate subcortical brain structure shape differences between individuals with schizophrenia and healthy control participants.

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Background: The aim of the current study was to explore the effect of gender, age at onset, and duration on the long-term course of schizophrenia.

Methods: Twenty-nine centers from 25 countries representing all continents participated in the study that included 2358 patients aged 37.21 ± 11.

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Individuals with bipolar disorders (BD) frequently suffer from obesity, which is often associated with neurostructural alterations. Yet, the effects of obesity on brain structure in BD are under-researched. We obtained MRI-derived brain subcortical volumes and body mass index (BMI) from 1134 BD and 1601 control individuals from 17 independent research sites within the ENIGMA-BD Working Group.

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Delineating the association of age and cortical thickness in healthy individuals is critical given the association of cortical thickness with cognition and behavior. Previous research has shown that robust estimates of the association between age and brain morphometry require large-scale studies. In response, we used cross-sectional data from 17,075 individuals aged 3-90 years from the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to infer age-related changes in cortical thickness.

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Age has a major effect on brain volume. However, the normative studies available are constrained by small sample sizes, restricted age coverage and significant methodological variability. These limitations introduce inconsistencies and may obscure or distort the lifespan trajectories of brain morphometry.

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The hippocampus consists of anatomically and functionally distinct subfields that may be differentially involved in the pathophysiology of bipolar disorder (BD). Here we, the Enhancing NeuroImaging Genetics through Meta-Analysis Bipolar Disorder workinggroup, study hippocampal subfield volumetry in BD. T1-weighted magnetic resonance imaging scans from 4,698 individuals (BD = 1,472, healthy controls [HC] = 3,226) from 23 sites worldwide were processed with FreeSurfer.

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For many traits, males show greater variability than females, with possible implications for understanding sex differences in health and disease. Here, the ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) Consortium presents the largest-ever mega-analysis of sex differences in variability of brain structure, based on international data spanning nine decades of life. Subcortical volumes, cortical surface area and cortical thickness were assessed in MRI data of 16,683 healthy individuals 1-90 years old (47% females).

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Article Synopsis
  • - Large-scale neuroimaging studies show differences in cortical thickness in various psychiatric disorders, but the biological reasons for these differences are not fully understood.
  • - The study aimed to identify neurobiological correlates of cortical thickness variations between affected individuals and controls across six disorders: ADHD, ASD, BD, MDD, OCD, and schizophrenia.
  • - Using data from 145 cohorts and advanced imaging techniques, the analysis revealed distinct patterns of cortical thickness associated with specific gene expressions in disorders, involving a total of over 28,000 participants.
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Background: Substance use disorders (SUDs) occur frequently in patients with psychotic disorders and have been associated with various demographic and clinical correlates. There is an absence of research on the prevalence and clinical correlates of SUDs in psychotic disorders in low-and-middle-income countries (LMICs).

Aim: We aimed to determine the prevalence and correlates of SUDs in psychotic disorders.

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Purpose: To determine the prevalence of substance use disorders (SUDs) in patients with schizophrenia in a sample from South Africa and compare the clinical and demographic correlates in those with and without co-occurring SUDs.

Methods: Patients with schizophrenia were interviewed using the Xhosa version SCID-I for DSM-IV. We used logistic regression to determine the predictors of SUDs.

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Article Synopsis
  • The ENIGMA Consortium aims to enhance neuroimaging studies by combining data from various institutions, tackling the issue of small sample sizes but facing challenges due to diverse scanning devices.
  • This study tested the effectiveness of the ComBat batch adjustment method to reduce site-related differences and improve statistical outcomes in comparing brain structure between individuals with schizophrenia and healthy controls.
  • Results showed that using ComBat significantly boosted statistical significance and power in analyses, making it a recommended tool for ENIGMA and other multi-site neuroimaging projects, with user-friendly R functions available for implementation.
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Major depressive disorder (MDD) is associated with an increased risk of brain atrophy, aging-related diseases, and mortality. We examined potential advanced brain aging in adult MDD patients, and whether this process is associated with clinical characteristics in a large multicenter international dataset. We performed a mega-analysis by pooling brain measures derived from T1-weighted MRI scans from 19 samples worldwide.

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Background: The aim of the current study was to explore the changing interrelationships among clinical variables through the stages of schizophrenia in order to assemble a comprehensive and meaningful disease model.

Methods: Twenty-nine centers from 25 countries participated and included 2358 patients aged 37.21 ± 11.

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Extrapyramidal side-effects (EPSE) are frequent in patients treated with antipsychotics and comorbid substance use disorders (SUDs). Methamphetamine has been shown to act as a dopaminergic neurotoxin. We aimed to determine whether EPSE occur more often in patients with psychotic disorders and co-occurring methamphetamine (MA) use disorders, and we examined the relationship between MA use, antipsychotic type, dose and EPSE.

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