Publications by authors named "Katherine L Narr"

The Global ECT MRI Research Collaboration (GEMRIC) has collected clinical and neuroimaging data of patients treated with electroconvulsive therapy (ECT) from around the world. Results to date have focused on neuroimaging correlates of antidepressant response. GEMRIC sites have also collected longitudinal cognitive data.

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Schizophrenia spectrum disorders (SSDs) are characterized by substantial clinical and genetic heterogeneity. Multiple recurrent copy number variants (CNVs) increase risk for SSDs; however, how known risk CNVs and broader genome-wide CNVs influence clinical variability is unclear. The current study examined associations between borderline intellectual functioning or childhood-onset psychosis, known risk CNVs, and burden of deletions affecting genes in 18 previously validated neurodevelopmental gene-sets in 618 SSD individuals.

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Background: Children who are HIV-exposed and uninfected (HEU) are at risk for early neurodevelopmental impairment. Smaller basal ganglia nuclei have been reported in neonates who are HEU compared to HIV-unexposed (HU); however, neuroimaging studies outside infancy are scarce. We examined subcortical brain structures and associations with neurocognition in children who are HEU.

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By measuring the molecular diffusion of water molecules in brain tissue, diffusion MRI (dMRI) provides unique insight into the microstructure and structural connections of the brain in living subjects. Since its inception, the application of dMRI in clinical research has expanded our understanding of the possible biological bases of psychiatric disorders and successful responses to different therapeutic interventions. Here, we review the past decade of diffusion imaging-based investigations with a specific focus on studies examining the mechanisms and predictors of therapeutic response in people with mood disorders.

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Introduction: Major depressive disorder (MDD) is associated with dysfunctional reward processing, which involves functional circuitry of the habenula (Hb) and nucleus accumbens (NAc). Since ketamine elicits rapid antidepressant and antianhedonic effects in MDD, this study sought to investigate how serial ketamine infusion (SKI) treatment modulates static and dynamic functional connectivity (FC) in Hb and NAc functional networks.

Methods: MDD participants (n = 58, mean age = 40.

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Background: The study aim was to determine whether associations of antenatal maternal anaemia with smaller corpus callosum, putamen, and caudate nucleus volumes previously described in children at age 2-3 years persist to age 6-7 years in the Drakenstein Child Health Study (DCHS).

Methods: This neuroimaging sub-study was nested within the DCHS, a South African population-based birth cohort. Pregnant women were enrolled (2012-2015) and mother-child dyads were followed prospectively.

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Article Synopsis
  • A study was conducted to explore the brain structure of children who were exposed to HIV in utero but did not get infected (HEU) compared to those who were not exposed (HU), particularly focusing on the prefrontal cortex.
  • Using MRI scans from 162 children, researchers found that HEU children had thicker cortices in certain prefrontal areas than HU children, specifically in the medial orbitofrontal cortex.
  • However, HEU children performed worse in language development compared to HU children, linking lower language scores to the structural differences in their brain's prefrontal cortex.
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Dysfunctional reward processing in major depressive disorder (MDD) involves functional circuitry of the habenula (Hb) and nucleus accumbens (NAc). Ketamine elicits rapid antidepressant and alleviates anhedonia in MDD. To clarify how ketamine perturbs reward circuitry in MDD, we examined how serial ketamine infusions (SKI) modulate static and dynamic functional connectivity (FC) in Hb and NAc networks.

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Objectives: Geriatric depression (GD) is associated with cognitive impairment and brain atrophy. Tai-Chi-Chih (TCC) is a promising adjunct treatment to antidepressants. We previously found beneficial effects of TCC on resting state connectivity in GD.

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Neurostimulation is a mainstream treatment option for major depression. Neuromodulation techniques apply repetitive magnetic or electrical stimulation to some neural target but significantly differ in their invasiveness, spatial selectivity, mechanism of action, and efficacy. Despite these differences, recent analyses of transcranial magnetic stimulation (TMS) and deep brain stimulation (DBS)-treated individuals converged on a common neural network that might have a causal role in treatment response.

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Introduction: Subanesthetic ketamine is a rapidly acting antidepressant that has also been found to improve neurocognitive performance in adult patients with treatment resistant depression (TRD). Provisional evidence suggests that ketamine may induce change in hippocampal volume and that larger pre-treatment volumes might be related to positive clinical outcomes. Here, we examine the effects of serial ketamine treatment on hippocampal subfield volumes and relationships between pre-treatment subfield volumes and changes in depressive symptoms and neurocognitive performance.

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Article Synopsis
  • Alcohol and tobacco are teratogens that can affect neurodevelopment, but this study also considers lower exposure levels and socio-ecological factors like socioeconomic resources (SER) and adverse childhood experiences (ACEs).
  • The study involved 313 mother-child pairs and assessed various factors including maternal education, household income, PAE, and PTE, using both self-reports and neuroimaging techniques on children aged 8-11.
  • Results showed that higher SER correlated with fewer ACEs and that prenatal tobacco exposure partially mediated the impact of SER on ACEs; different brain volumes were also linked to SER and exposure levels to tobacco during pregnancy.
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Background: Yoga may be an ideal early intervention for those with modifiable risk factors for Alzheimer's disease (AD) development.

Objective: To examine the effects of Kundalini yoga (KY) training versus memory enhancement training (MET) on the resting-state connectivity of hippocampal subregions in women with subjective memory decline and cardiovascular risk factors for AD.

Methods: Participants comprised women with subjective memory decline and cardiovascular risk factors who participated in a parent randomized controlled trial (NCT03503669) of 12-weeks of KY versus MET and completed pre- and post-intervention resting-state magnetic resonance imaging scans (yoga: n = 11, age = 61.

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Background: Total sleep deprivation (TSD) transiently reverses depressive symptoms in a majority of patients with depression. How TSD modulates diffusion tensor imaging (DTI) measures of white matter (WM) microstructure, which may be linked with TSD's rapid antidepressant effects, remains uncharacterized.

Methods: Patients with depression ( = 48, mean age = 33, 26 women) completed diffusion-weighted imaging and Hamilton Depression Rating (HDRS) and rumination scales before and after >24 h of TSD.

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Article Synopsis
  • - The study investigates the links between brain structure (gray matter volume), depression, and resilience in older adults with major depressive disorder, highlighting the significance of resilience as a protective factor.
  • - Involving 49 adults over 60 years old, the research found that higher depression severity correlates with increased anxiety and apathy, but lower resilience; brain scans indicated that larger gray matter volume is associated with improved resilience and reduced anxiety/apathy.
  • - The findings suggest that enhanced gray matter in certain brain regions may serve as a marker for resilience in geriatric depression, indicating potential areas for therapeutic interventions aimed at alleviating depressive symptoms.
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Introduction: Ketamine treatment prompts a rapid antidepressant response in treatment-resistant depression (TRD). We performed an exploratory investigation of how ketamine treatment in TRD affects different cognitive domains and relates to antidepressant response.

Methods: Patients with TRD (N = 66; 30 M/35F; age = 39.

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  • Maternal perinatal depression can negatively impact child development and brain structure, particularly in low- and middle-income countries like South Africa.
  • This study assessed the effects of maternal depressive symptoms during pregnancy and after birth on the brains of children aged 2-3 years, using MRI to analyze brain structure.
  • Results showed that only postpartum depression, especially if persistent, was linked to smaller amygdala volumes in children, highlighting the need for early identification and support for mothers experiencing depression during the perinatal period.
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Maternal psychological distress during pregnancy has been linked to adverse outcomes in children with evidence of sex-specific effects on brain development. Here, we investigated whether in utero exposure to intimate partner violence (IPV), a particularly severe maternal stressor, is associated with brain structure in young infants from a South African birth cohort. Exposure to IPV during pregnancy was measured in 143 mothers at 28-32 weeks' gestation and infants underwent structural and diffusion magnetic resonance imaging (mean age 3 weeks).

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Ketamine produces fast-acting antidepressant effects in treatment resistant depression (TRD). Though prior studies report ketamine-related changes in brain activity in TRD, understanding of ketamine's effect on white matter (WM) microstructure remains limited. We thus sought to examine WM neuroplasticity and associated clinical improvements following serial ketamine infusion (SKI) in TRD.

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The current small study utilised prospective data collection of patterns of prenatal alcohol and tobacco exposure (PAE and PTE) to examine associations with structural brain outcomes in 6-year-olds and served as a pilot to determine the value of prospective data describing community-level patterns of PAE and PTE in a non-clinical sample of children. Participants from the Safe Passage Study in pregnancy were approached when their child was ∼6 years old and completed structural brain magnetic resonance imaging to examine with archived PAE and PTE data ( = 51 children-mother dyads). Linear regression was used to conduct whole-brain structural analyses, with false-discovery rate (FDR) correction, to examine: (a) main effects of PAE, PTE and their interaction; and (b) predictive potential of data that reflect of PAE and PTE (e.

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Background: Electroconvulsive therapy (ECT) is effective for treatment-resistant depression and leads to short-term structural brain changes and decreases in the inflammatory response. However, little is known about how brain structure and inflammation relate to the heterogeneity of treatment response in the months following an index ECT course.

Methods: A naturalistic six-month study following an index ECT course included 20 subjects with treatment-resistant depression.

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