Publications by authors named "Silvin Knight"

Background: Orthostatic hypotension (OH) is a prevalent condition among older adults, characterised by a sudden drop in blood pressure upon standing, often leading to dizziness and increased risk of falls, morbidity and mortality. The skeletal muscle pump is thought to be important in maintaining venous return and stabilising blood pressure during postural changes, especially during the performance of physical counterpressure manoeuvres (PCMs). This study investigated the temporal relationships between thigh muscle activation, thigh haemoglobin concentration and cardiovascular parameters (heart rate [HR], stroke volume [SV] and total peripheral resistance [TPR]) to understand the muscle pump's role in haemodynamic regulation while performing supine and standing PCMs.

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Introduction: There is a critical link between vascular disease and the progression to dementia. The hippocampus has been implicated in memory and cognitive decline. In this study, we investigate the independent and moderating effects of increased arterial stiffness (AS) and reduced cerebral blood flow (CBF) on hippocampal volume (HV) in a large MRI sample of community-dwelling older adults from the Irish Longitudinal Study on Ageing (TILDA).

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Objective: Research indicates that complex occupations may enhance cognition in older adults, potentially serving as a proxy for cognitive reserve. However, few studies explore whether occupational complexity moderates the link between brain pathology and cognition.This study examines if occupational complexity affects cognition in later life and moderates the relationship between brain disease and cognitive performance.

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Introduction: Falls and fractures are common among older people. The Screening Tool of Older Persons Prescriptions in older adults with high fall risk (STOPPFall) provides a comprehensive list of fall-risk-increasing drugs (FRIDs). This study assesses the association between STOPPFall medications and future falls/fractures among a large cohort of community-dwelling people ≥65 years using The Irish Longitudinal Study on Ageing (TILDA) Waves 1-6, collected from 2009 to 2021.

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Background: The prevalence of Chronic Kidney Disease (CKD) is rising rapidly due to population ageing, with significant consequences for morbidity and mortality. The use of effective, predictive biomarkers would enable early introduction of targeted, proactive management of kidney disease.

Aim: The aim of this review is to summarise all available studies investigating the association of neurocardiovascular, inflammatory and epigenetic biomarkers with kidney function and their ability to predict CKD incidence or progression.

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This study investigates the relationship between white matter hyperintensities (WMHs) and longitudinal cognitive decline in older adults. Using data from The Irish Longitudinal Study on Ageing (TILDA), we examined WMH characteristics, including volume, location, and microstructural integrity, in a community-dwelling population of 497 individuals over a six-year period. WMHs were categorised into phenotypes based on their size, fractional anisotropy (FA), and mean diffusivity (MD), with subtypes for periventricular and deep white matter lesions.

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Article Synopsis
  • The study examines how aging affects cerebral blood flow (CBF) in older adults by investigating changes in brain structure and partial volume effects due to brain atrophy.
  • Findings show that while there is a general decline in global gray-matter CBF as people age, some specific brain regions may actually experience increases in CBF after correcting for partial volume effects.
  • The results highlight that although age-related reductions in CBF are evident, regional differences in blood flow are more accurately captured when accounting for partial volume effects in brain imaging.
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Purpose: To examine if changes in hemodynamic measures during an orthostatic challenge were associated with progression of age-related macular degeneration (AMD) over a 4-year period in The Irish Longitudinal Study on Ageing.

Methods: Participants with AMD who underwent an active stand (AS) test at wave 1 (2009/2010) and retinal photographs at both wave 1 and wave 3 (2014/2015) were included (N = 159: 121 with no AMD progression and 38 with progression). Beat-to-beat hemodynamic data were non-invasively collected using a Finometer MIDI device during the AS at wave 1, recording systolic blood pressure (sBP), diastolic blood pressure (dBP), mean arterial pressure (MAP), and heart rate.

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Recent research has indicated that the relationship between age-related cognitive decline and falling may be mediated by the individual's capacity to quickly cancel or inhibit a motor response. This longitudinal investigation demonstrates that higher white matter fibre density in the motor inhibition network paired with low physical activity was associated with falling in elderly participants. We measured the density of white matter fibre tracts connecting key nodes in the inhibitory control network in a large sample (n = 414) of older adults.

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Background: Impaired recovery of blood pressure (BP) in response to standing up is a prevalent condition in older individuals. We evaluated the relationship between the early recovery of hemodynamic responses to standing and brain health in adults over 50.

Methods: Participants from The Irish Longitudinal Study on Ageing (TILDA) (n=411; age 67.

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Background: In this observational study, we compared continuous physiological signals during an active standing test in adults aged 50 years and over, characterised as frail by three different criteria, using data from The Irish Longitudinal Study on Ageing (TILDA).

Methods: This study utilised data from TILDA, an ongoing landmark prospective cohort study of community-dwelling adults aged 50 years or older in Ireland. The initial sampling strategy in TILDA was based on random geodirectory sampling.

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Background: Sarcopenia, delayed blood pressure (BP) recovery following standing, and orthostatic hypotension (OH) pose significant clinical challenges associated with ageing. While prior studies have established a link between sarcopenia and impaired BP recovery and OH, the underlying haemodynamic mechanisms remain unclear.

Methods: We enrolled 107 participants aged 50 and above from a falls and syncope clinic, conducting an active stand test with continuous non-invasive haemodynamic measurements.

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Article Synopsis
  • The study explored the connection between the sizes of specific hippocampal subfields and cognitive decline over four years in healthy older adults, aiming to identify those at risk of cognitive impairment.
  • A total of 482 participants underwent brain imaging and cognitive tests, leading to classifications into three cognitive function groups: High-Stable, Mid-Stable, and Low-Declining.
  • The findings showed that certain hippocampal subfields, particularly the presubiculum and subiculum, had reduced volumes linked to global cognitive decline, confirming previous research on the predictive role of hippocampal atrophy in monitoring cognitive health.
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This study was carried out using a large cohort ( = 4265; 416 deceased) of older, community-dwelling adults from The Irish Longitudinal Study on Ageing (TILDA). The study compared the performance of a new 3-item health index (HI) with two existing measures, the 32-item frailty index (FI) and the frailty phenotype (FP), in predicting mortality risk. The HI was based on the objective measurement of resting-state systolic blood pressure sample entropy, sustained attention reaction time performance, and usual gait speed.

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Purpose: Sarcopenia and delayed orthostatic blood pressure (BP) recovery are two disorders increasingly associated with adverse clinical outcomes in older adults. There may exist a pathophysiological link between the two via the skeletal muscle pump of the lower limbs. Previously in a large population-based study, we found an association between probable sarcopenia and orthostatic BP recovery.

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This study explores the relationship of life-course intergenerational social mobility with cognitive function and brain structure in older adults using Diagonal Reference Models. Data from the Irish Longitudinal Study on Ageing, a population-based cohort of adults aged 50 years and older (N = 4 620 participants; mean age: 66.1; standard deviation: 9.

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Background: Frailty in older adults has been associated with reduced brain health. However, structural brain signatures of frailty remain understudied. Our aims were: (1) Explore associations between a frailty index (FI) and brain structure on magnetic resonance imaging (MRI).

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Article Synopsis
  • * Researchers analyzed data from 347 participants, identifying two key networks: the "frailty network" (linked to visual network connectivity) and the "robustness network" (associated with the basal ganglia).
  • * The findings suggest a correlation between the Frailty Index (FI) and walking speed, but not with overall cognitive metrics, highlighting a complex relationship between physical frailty and brain connectivity patterns.
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In this study we investigated the association between information entropy in short length blood pressure signals and physical frailty status, in a group of patients aged 50+ recruited from the Falls and Syncope Unit at the Mercer's Institute for Successful Ageing in St James's Hospital, Dublin, Ireland. This work is an external clinical validation of findings previously derived in a population-based cohort from The Irish Longitudinal Study on Ageing (TILDA). The hypothesis under investigation was that dysregulation (as quantified by entropy) in continuous non-invasive blood pressure signals could provide a clinically useful marker of physical frailty status.

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Objectives: To investigate whether tooth loss was associated with regional grey matter volume (GMV) in a group of community dwelling older men and women from Ireland.

Methods: A group of 380 dementia-free men and women underwent a dental examination and had a Magnetic Resonance Imaging (MRI) scan as part of The Irish Longitudinal Study of Aging (TILDA). Cortical parcellation was conducted using Freesurfer utilities to produce volumetric measures of gyral based regions of interest.

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Cognitive reserve supports cognitive function in the presence of pathology or atrophy. Functional neuroimaging may enable direct and accurate measurement of cognitive reserve which could have considerable clinical potential. The present study aimed to develop and validate a measure of cognitive reserve using task-based fMRI data that could then be applied to independent resting-state data.

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Background: Sarcopenia and orthostatic hypotension are growing age-related health burdens associated with adverse outcomes, including falls. Despite a possible pathophysiological link, the association between the 2 disorders is not well elucidated. We sought to investigate this relationship in The Irish Longitudinal Study on Ageing (TILDA).

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Introduction: Lutein and zeaxanthin are diet-derived carotenoids that are proposed to help mitigate frailty risk and age-related declines in musculoskeletal health via their anti-oxidant and anti-inflammatory properties. Therefore, this study aimed to investigate the association between lutein and zeaxanthin status and indices of musculoskeletal health and incident frailty among community-dwelling adults aged ≥50 years in the Irish Longitudinal Study on Ageing (TILDA).

Methods: Cross-sectional analyses (n = 4513) of plasma lutein and zeaxanthin concentrations and grip strength, usual gait speed, timed up-and-go (TUG), probable sarcopenia (defined as grip strength <27 kg in men, <16 kg in women), and bone mass (assessed using calcaneal broadband ultrasound stiffness index) were performed at Wave 1 (2009-2011; baseline).

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Brachytherapy is an efficacious treatment option because of its benefits for patient recovery, dose localization and conformity, but these favorable outcomes can be ensured only if the transrectal ultrasound (TRUS) system is optimized for the specific application of ultrasound-guided prostate brachytherapy. The ability to delineate the prostate from surrounding tissue during TRUS-guided prostate brachytherapy is vital for treatment planning, and consequently, so is the contrast resolution. This study describes the development of task-specific contrast-detail phantoms with clinically relevant contrast and spherical target sizes for contrast-detail performance evaluation of TRUS systems used in the brachytherapy procedure.

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The Sustained Attention to Response Task (SART) is a computer-based go/no-go task to measure neurocognitive function in older adults. However, simplified average features of this complex dataset lead to loss of primary information and fail to express associations between test performance and clinically meaningful outcomes. Here, we combine a novel method to visualise individual trial (raw) information obtained from the SART test in a large population-based study of ageing in Ireland and an automatic clustering technique.

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