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Comparison of histological delineations of medial temporal lobe cortices by four independent neuroanatomy laboratories. Hippocampus 2024; 34:241-260. [PMID: 38415962 PMCID: PMC11039382 DOI: 10.1002/hipo.23602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 01/25/2024] [Accepted: 02/04/2024] [Indexed: 02/29/2024]
Abstract
The medial temporal lobe (MTL) cortex, located adjacent to the hippocampus, is crucial for memory and prone to the accumulation of certain neuropathologies such as Alzheimer's disease neurofibrillary tau tangles. The MTL cortex is composed of several subregions which differ in their functional and cytoarchitectonic features. As neuroanatomical schools rely on different cytoarchitectonic definitions of these subregions, it is unclear to what extent their delineations of MTL cortex subregions overlap. Here, we provide an overview of cytoarchitectonic definitions of the entorhinal and parahippocampal cortices as well as Brodmann areas (BA) 35 and 36, as provided by four neuroanatomists from different laboratories, aiming to identify the rationale for overlapping and diverging delineations. Nissl-stained series were acquired from the temporal lobes of three human specimens (two right and one left hemisphere). Slices (50 μm thick) were prepared perpendicular to the long axis of the hippocampus spanning the entire longitudinal extent of the MTL cortex. Four neuroanatomists annotated MTL cortex subregions on digitized slices spaced 5 mm apart (pixel size 0.4 μm at 20× magnification). Parcellations, terminology, and border placement were compared among neuroanatomists. Cytoarchitectonic features of each subregion are described in detail. Qualitative analysis of the annotations showed higher agreement in the definitions of the entorhinal cortex and BA35, while the definitions of BA36 and the parahippocampal cortex exhibited less overlap among neuroanatomists. The degree of overlap of cytoarchitectonic definitions was partially reflected in the neuroanatomists' agreement on the respective delineations. Lower agreement in annotations was observed in transitional zones between structures where seminal cytoarchitectonic features are expressed less saliently. The results highlight that definitions and parcellations of the MTL cortex differ among neuroanatomical schools and thereby increase understanding of why these differences may arise. This work sets a crucial foundation to further advance anatomically-informed neuroimaging research on the human MTL cortex.
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Behaviorally meaningful functional networks mediate the effect of Alzheimer's pathology on cognition. Cereb Cortex 2024; 34:bhae134. [PMID: 38602736 PMCID: PMC11008686 DOI: 10.1093/cercor/bhae134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/25/2024] [Accepted: 03/12/2024] [Indexed: 04/12/2024] Open
Abstract
Tau pathology is associated with cognitive impairment in both aging and Alzheimer's disease, but the functional and structural bases of this relationship remain unclear. We hypothesized that the integrity of behaviorally meaningful functional networks would help explain the relationship between tau and cognitive performance. Using resting state fMRI, we identified unique networks related to episodic memory and executive function cognitive domains. The episodic memory network was particularly related to tau pathology measured with positron emission tomography in the entorhinal and temporal cortices. Further, episodic memory network strength mediated the relationship between tau pathology and cognitive performance above and beyond neurodegeneration. We replicated the association between these networks and tau pathology in a separate cohort of older adults, including both cognitively unimpaired and mildly impaired individuals. Together, these results suggest that behaviorally meaningful functional brain networks represent a functional mechanism linking tau pathology and cognition.
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Amyloid induced hyperexcitability in default mode network drives medial temporal hyperactivity and early tau accumulation. Neuron 2024; 112:676-686.e4. [PMID: 38096815 PMCID: PMC10922797 DOI: 10.1016/j.neuron.2023.11.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 09/01/2023] [Accepted: 11/14/2023] [Indexed: 02/24/2024]
Abstract
In early Alzheimer's disease (AD) β-amyloid (Aβ) deposits throughout association cortex and tau appears in the entorhinal cortex (EC). Why these initially appear in disparate locations is not understood. Using task-based fMRI and multimodal PET imaging, we assess the impact of local AD pathology on network-to-network interactions. We show that AD pathologies flip interactions between the default mode network (DMN) and the medial temporal lobe (MTL) from inhibitory to excitatory. The DMN is hyperexcited with increasing levels of Aβ, which drives hyperexcitability within the MTL and this directed hyperexcitation of the MTL by the DMN predicts the rate of tau accumulation within the EC. Our results support a model whereby Aβ induces disruptions to local excitatory-inhibitory balance in the DMN, driving hyperexcitability in the MTL, leading to tau accumulation. We propose that Aβ-induced disruptions to excitatory-inhibitory balance is a candidate causal route between Aβ and remote EC-tau accumulation.
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Comparison of histological delineations of medial temporal lobe cortices by four independent neuroanatomy laboratories. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.24.542054. [PMID: 37292729 PMCID: PMC10245880 DOI: 10.1101/2023.05.24.542054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The medial temporal lobe (MTL) cortex, located adjacent to the hippocampus, is crucial for memory and prone to the accumulation of certain neuropathologies such as Alzheimer's disease neurofibrillary tau tangles. The MTL cortex is composed of several subregions which differ in their functional and cytoarchitectonic features. As neuroanatomical schools rely on different cytoarchitectonic definitions of these subregions, it is unclear to what extent their delineations of MTL cortex subregions overlap. Here, we provide an overview of cytoarchitectonic definitions of the cortices that make up the parahippocampal gyrus (entorhinal and parahippocampal cortices) and the adjacent Brodmann areas (BA) 35 and 36, as provided by four neuroanatomists from different laboratories, aiming to identify the rationale for overlapping and diverging delineations. Nissl-stained series were acquired from the temporal lobes of three human specimens (two right and one left hemisphere). Slices (50 µm thick) were prepared perpendicular to the long axis of the hippocampus spanning the entire longitudinal extent of the MTL cortex. Four neuroanatomists annotated MTL cortex subregions on digitized (20X resolution) slices with 5 mm spacing. Parcellations, terminology, and border placement were compared among neuroanatomists. Cytoarchitectonic features of each subregion are described in detail. Qualitative analysis of the annotations showed higher agreement in the definitions of the entorhinal cortex and BA35, while definitions of BA36 and the parahippocampal cortex exhibited less overlap among neuroanatomists. The degree of overlap of cytoarchitectonic definitions was partially reflected in the neuroanatomists' agreement on the respective delineations. Lower agreement in annotations was observed in transitional zones between structures where seminal cytoarchitectonic features are expressed more gradually. The results highlight that definitions and parcellations of the MTL cortex differ among neuroanatomical schools and thereby increase understanding of why these differences may arise. This work sets a crucial foundation to further advance anatomically-informed human neuroimaging research on the MTL cortex.
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Examining the diagnostic value of the mnemonic discrimination task for classification of cognitive status and amyloid-beta burden. Neuropsychologia 2023; 191:108727. [PMID: 37939874 PMCID: PMC10764118 DOI: 10.1016/j.neuropsychologia.2023.108727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 10/20/2023] [Accepted: 11/03/2023] [Indexed: 11/10/2023]
Abstract
Alzheimer's disease (AD) is the most common type of dementia, characterized by early memory impairments and gradual worsening of daily functions. AD-related pathology, such as amyloid-beta (Aβ) plaques, begins to accumulate many years before the onset of clinical symptoms. Predicting risk for AD via related pathology is critical as the preclinical stage could serve as a therapeutic time window, allowing for early management of the disease and reducing health and economic costs. Current methods for detecting AD pathology, however, are often expensive and invasive, limiting wide and easy access to a clinical setting. A non-invasive, cost-efficient platform, such as computerized cognitive tests, could be potentially useful to identify at-risk individuals as early as possible. In this study, we examined the diagnostic value of an episodic memory task, the mnemonic discrimination task (MDT), for predicting risk of cognitive impairment or Aβ burden. We constructed a random forest classification algorithm, utilizing MDT performance metrics and various neuropsychological test scores as input features, and assessed model performance using area under the curve (AUC). Models based on MDT performance metrics achieved classification results with an AUC of 0.83 for cognitive status and an AUC of 0.64 for Aβ status. Our findings suggest that mnemonic discrimination function may be a useful predictor of progression to prodromal AD or increased risk of Aβ load, which could be a cost-efficient, noninvasive cognitive testing solution for potentially wide-scale assessment of AD pathological and cognitive risk.
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Medial temporal lobe functional network architecture supports sleep-related emotional memory processing in older adults. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.27.564260. [PMID: 37961192 PMCID: PMC10634911 DOI: 10.1101/2023.10.27.564260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Memory consolidation occurs via reactivation of a hippocampal index during non-rapid eye movement slow-wave sleep (NREM SWS) which binds attributes of an experience existing within cortical modules. For memories containing emotional content, hippocampal-amygdala dynamics facilitate consolidation over a sleep bout. This study tested if modularity and centrality-graph theoretical measures that index the level of segregation/integration in a system and the relative import of its nodes-map onto central tenets of memory consolidation theory and sleep-related processing. Findings indicate that greater network integration is tied to overnight emotional memory retention via NREM SWS expression. Greater hippocampal and amygdala influence over network organization supports emotional memory retention, and hippocampal or amygdala control over information flow are differentially associated with distinct stages of memory processing. These centrality measures are also tied to the local expression and coupling of key sleep oscillations tied to sleep-dependent memory consolidation. These findings suggest that measures of intrinsic network connectivity may predict the capacity of brain functional networks to acquire, consolidate, and retrieve emotional memories.
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NODDI-derived measures of microstructural integrity in medial temporal lobe white matter pathways are associated with Alzheimer's disease pathology and cognitive outcomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.11.561946. [PMID: 37905117 PMCID: PMC10614746 DOI: 10.1101/2023.10.11.561946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
INTRODUCTION Diffusion tensor imaging has been used to assess white matter (WM) changes in the early stages of Alzheimer's disease (AD). However, the tensor model is necessarily limited by its assumptions. Neurite Orientation Dispersion and Density Imaging (NODDI) can offer insights into microstructural features of WM change. We assessed whether NODDI more sensitively detects AD-related changes in medial temporal lobe WM than traditional tensor metrics. METHODS Standard diffusion and NODDI metrics were calculated for medial temporal WM tracts from 199 older adults drawn from ADNI3 who also received PET to measure pathology and neuropsychological testing. RESULTS NODDI measures in medial temporal tracts were more strongly correlated to cognitive performance and pathology than standard measures. The combination of NODDI and standard metrics exhibited the strongest prediction of cognitive performance in random forest analyses. CONCLUSIONS NODDI metrics offer additional insights into contributions of WM degeneration to cognitive outcomes in the aging brain.
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Effect of Alzheimer's Pathology on Task-Related Brain Network Reconfiguration in Aging. J Neurosci 2023; 43:6553-6563. [PMID: 37604690 PMCID: PMC10513069 DOI: 10.1523/jneurosci.0023-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 08/02/2023] [Accepted: 08/06/2023] [Indexed: 08/23/2023] Open
Abstract
Large-scale brain networks undergo widespread changes with older age and in neurodegenerative diseases such as Alzheimer's disease (AD). Research in young adults (YA) suggest that the underlying functional architecture of brain networks remains relatively consistent between rest and task states. However, it remains unclear whether the same is true in aging and to what extent any changes may be related to accumulation of AD pathology such as β-amyloid (Aβ) and tau. Here, we examined age-related differences in functional connectivity (FC) between rest and an object-scene mnemonic discrimination task using fMRI in young and older adults (OA; both females and males). We used an a priori episodic memory network (EMN) parcellation scheme associated with object and scene processing, that included anterior-temporal regions and posterior-medial regions. We also used positron emission topography to measure Aβ and tau in older adults. The correlation between rest and task FC (i.e., FC similarity) was reduced in older compared with younger adults. Older adults with lower FC similarity in EMN had higher levels of tau in the same EMN regions and performed worse during object, but not scene, trials during the fMRI task. These findings link AD pathology, particularly tau, to a less stable functional architecture in memory networks. They also suggest that smaller changes in FC organization between rest and task states may facilitate better performance in older age. Interpretations are limited by methodological factors related to different acquisition directions and durations between rest and task scans.SIGNIFICANCE STATEMENT The brain's large-scale network organization is relatively consistent between rest and task states in young adults (YA). We found that memory networks in older adults (OA) were less correlated between rest and (memory) task states compared with young adults. Older adults with less correlated brain networks also had higher levels of Alzheimer's disease (AD) pathology in the same regions, suggesting that a less stable network architecture may reflect the early evolution of AD. Older adults with less correlated brain networks also performed worse during the memory task suggesting that more similar network organization between rest and task states may facilitate better performance in older age.
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Functional network structure supports resilience to memory deficits in cognitively normal older adults with amyloid-β pathology. Sci Rep 2023; 13:13953. [PMID: 37626094 PMCID: PMC10457346 DOI: 10.1038/s41598-023-40092-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
Older adults may harbor large amounts of amyloid-β (Aβ) pathology, yet still perform at age-normal levels on memory assessments. We tested whether functional brain networks confer resilience or compensatory mechanisms to support memory in the face of Aβ pathology. Sixty-five cognitively normal older adults received high-resolution resting state fMRI to assess functional networks, 18F-florbetapir-PET to measure Aβ, and a memory assessment. We characterized functional networks with graph metrics of local efficiency (information transfer), modularity (specialization of functional modules), and small worldness (balance of integration and segregation). There was no difference in functional network measures between older adults with high Aβ (Aβ+) compared to those with no/low Aβ (Aβ-). However, in Aβ+ older adults, increased local efficiency, modularity, and small worldness were associated with better memory performance, while this relationship did not occur Aβ- older adults. Further, the association between increased local efficiency and better memory performance in Aβ+ older adults was localized to local efficiency of the default mode network and hippocampus, regions vulnerable to Aβ and involved in memory processing. Our results suggest functional networks with modular and efficient structures are associated with resilience to Aβ pathology, providing a functional target for intervention.
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Differential involvement of hippocampal subfields in the relationship between Alzheimer's pathology and memory interference in older adults. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2023; 15:e12419. [PMID: 37035460 PMCID: PMC10075195 DOI: 10.1002/dad2.12419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 02/15/2023] [Accepted: 02/28/2023] [Indexed: 04/11/2023]
Abstract
Introduction We tested whether Alzheimer's disease (AD) pathology predicts memory deficits in non-demented older adults through its effects on medial temporal lobe (MTL) subregional volume. Methods Thirty-two, non-demented older adults with cerebrospinal fluid (CSF) (amyloid-beta [Aβ]42/Aβ40, phosphorylated tau [p-tau]181, total tau [t-tau]), positron emission tomography (PET; 18F-florbetapir), high-resolution structural magnetic resonance imaging (MRI), and neuropsychological assessment were analyzed. We examined relationships between biomarkers and a highly granular measure of memory consolidation, retroactive interference (RI). Results Biomarkers of AD pathology were related to RI. Dentate gyrus (DG) and CA3 volume were uniquely associated with RI, whereas CA1 and BA35 volume were related to both RI and overall memory recall. AD pathology was associated with reduced BA35, CA1, and subiculum volume. DG volume and Aβ were independently associated with RI, whereas CA1 volume mediated the relationship between AD pathology and RI. Discussion Integrity of distinct hippocampal subfields demonstrate differential relationships with pathology and memory function, indicating specificity in vulnerability and contribution to different memory processes.
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Access to Workplace Supports is Positively Associated with Exclusive Breastfeeding among Formally Employed Mothers in Kenya. J Nutr 2023; 152:2888-2897. [PMID: 36040327 PMCID: PMC9839982 DOI: 10.1093/jn/nxac160] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/13/2022] [Accepted: 07/22/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Mothers in low-income settings who work in agricultural employment are challenged to meet breastfeeding (BF) recommendations. Recent legislation in Kenya mandates maternity leave and workplace supports, yet the relation of these benefits with BF practices is poorly understood. OBJECTIVES We evaluated the associations with workplace-provided BF supports and BF practices among formally employed mothers in Kenya. The availability of supports was hypothesized to be associated with a higher prevalence and greater odds of exclusive breastfeeding (EBF). METHODS We conducted repeated cross-sectional surveys among formally employed mothers at 1-4 d and 6, 14, and 36 wk (to estimate 24 wk) postpartum in Naivasha, Kenya. We used logistic regression adjusted for maternal age, education, physical burden of work, HIV status, and income to evaluate associations between workplace supports and EBF practices. RESULTS Among formally employed mothers (n = 564), those who used onsite workplace childcare were more likely to practice EBF than those who used community- or home-based childcare at both 6 wk (95.7% compared with 82.4%, P = 0.030) and 14 wk (60.6% compared with 22.2%, P < 0.001; adjusted OR: 5.11; 95% CI: 2.3, 11.7). Likewise, at 14 wk among mothers who currently used daycare centers, a higher proportion of mothers who visited daycare centers at or near workplaces practiced EBF (70.0%) than of those not visiting daycare centers (34.7%, P = 0.005). EBF prevalence was higher among mothers with access to workplace private lactation spaces than among mothers without such spaces (84.6% compared with 55.6%, P = 0.037), and among mothers who lived in workplace housing than those without onsite housing (adjusted OR: 2.06, 95% CI: 1.25, 3.41). CONCLUSIONS Formally employed mothers in Kenya who have access to and use workplace-provided BF supports were more likely to practice EBF than mothers who lacked these supports. As the Kenya Health Act is implemented, lactation rooms, onsite housing and daycare, and transportation to visit children can all support BF and EBF among employed mothers.
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Alzheimer’s pathology disrupts cortical processing of repeated stimuli in cognitively intact older adults. Alzheimers Dement 2022. [DOI: 10.1002/alz.069342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Functional network modularity and efficiency supports episodic memory in older adults with amyloid‐beta pathology. Alzheimers Dement 2022. [DOI: 10.1002/alz.062561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Locus coeruleus catecholamines link neuroticism and vulnerability to tau pathology in aging. Neuroimage 2022; 263:119658. [PMID: 36191755 PMCID: PMC10060440 DOI: 10.1016/j.neuroimage.2022.119658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 09/19/2022] [Accepted: 09/29/2022] [Indexed: 11/19/2022] Open
Abstract
Higher neuroticism is a risk factor for Alzheimer's disease (AD), and is implicated in disordered stress responses. The locus coeruleus (LC)-catecholamine system is activated during perceived threat and is a centerpiece of developing models of the pathophysiology of AD, as it is the first brain region to develop abnormal tau. We examined relationships among the "Big 5" personality traits, LC catecholamine synthesis capacity measured with [18F]Fluoro-m-tyrosine PET, and tau burden measured with [18F]Flortaucipir PET in cognitively normal older adults (n = 47). β-amyloid (Aβ) status was determined using [11C]Pittsburgh compound B PET (n = 14 Aβ positive). Lower LC catecholamine synthesis capacity was associated with higher neuroticism, more depressive symptoms as measured by the Geriatric Depression Scale, and higher amygdala tau-PET binding. Exploratory analyses with other personality traits revealed that low trait conscientiousness was also related to both lower LC catecholamine synthesis capacity, and more depressive symptoms. A significant indirect path linked both high neuroticism and low conscientiousness to greater amygdala tau burden via their mutual association with low LC catecholamine synthesis capacity. Together, these findings reveal LC catecholamine synthesis capacity to be a promising marker of affective health and pathology burden in aging, and identifies candidate neurobiological mechanisms for the effect of personality on increased vulnerability to dementia.
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Effect of Alzheimer’s pathology on the functional architecture of memory networks during rest and task states in aging. Alzheimers Dement 2021. [DOI: 10.1002/alz.052380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Longitudinal tau accumulation in cognitively normal older adults is associated with baseline age, pathology, and activation. Alzheimers Dement 2021. [DOI: 10.1002/alz.050548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Fusiform Gyrus Phospho-Tau is Associated with Failure of Proper Name Retrieval in Aging. Ann Neurol 2021; 90:988-993. [PMID: 34590340 DOI: 10.1002/ana.26237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 09/01/2021] [Accepted: 09/26/2021] [Indexed: 11/06/2022]
Abstract
Difficulty retrieving proper names is common in older adults, coinciding with the accumulation of aggregated proteins in mid-life. We investigated the ability of healthy older adults to retrieve the names of famous faces in relation to positron emission tomography measurements of amyloid-β plaques and tau neurofibrillary tangles. More tau in the left fusiform and parahippocampal gyrus was related to reduced proper name retrieval performance and this effect was potentiated by amyloid-β. These findings provide an explanation for a common complaint of older adults and link proper name retrieval to neural systems involved in face perception, memory, and naming. ANN NEUROL 2021;90:988-993.
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Alzheimer's Pathology Is Associated with Dedifferentiation of Intrinsic Functional Memory Networks in Aging. Cereb Cortex 2021; 31:4781-4793. [PMID: 34037210 PMCID: PMC8408467 DOI: 10.1093/cercor/bhab122] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 11/14/2022] Open
Abstract
In presymptomatic Alzheimer's disease (AD), beta-amyloid plaques (Aβ) and tau tangles accumulate in distinct spatiotemporal patterns within the brain, tracking closely with episodic memory decline. Here, we tested whether age-related changes in the segregation of the brain's intrinsic functional episodic memory networks-anterior-temporal (AT) and posterior-medial (PM) networks-are associated with the accumulation of Aβ, tau, and memory decline using fMRI and PET. We found that AT and PM networks were less segregated in older than that in younger adults and this reduced specialization was associated with more tau and Aβ in the same regions. The effect of network dedifferentiation on memory depended on the amount of Aβ and tau, with low segregation and pathology associated with better performance at baseline and low segregation and high pathology related to worse performance over time. This pattern suggests a compensation phase followed by a degenerative phase in the early, preclinical phase of AD.
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Tau spreads through episodic memory networks in the aging brain. Alzheimers Dement 2020. [DOI: 10.1002/alz.037502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Medial temporal lobe hyperactivity during memory processing in older adults is associated with entorhinal tau deposition. Alzheimers Dement 2020. [DOI: 10.1002/alz.045507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Hippocampal‐retrosplenial connectivity is associated with tau pathology and memory in cognitively normal older adults. Alzheimers Dement 2020. [DOI: 10.1002/alz.046204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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22
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Effect of beta‐amyloid and tau pathology on neural network segregation and episodic memory in aging. Alzheimers Dement 2020. [DOI: 10.1002/alz.045474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Relationships Between Tau and Glucose Metabolism Reflect Alzheimer's Disease Pathology in Cognitively Normal Older Adults. Cereb Cortex 2020; 29:1997-2009. [PMID: 29912295 DOI: 10.1093/cercor/bhy078] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/22/2018] [Accepted: 03/20/2018] [Indexed: 12/26/2022] Open
Abstract
Tau is associated with hypometabolism in patients with Alzheimer's disease. In normal aging, the association between tau and glucose metabolism is not fully characterized. We used [18F] AV-1451, [18F] Fluorodeoxyglucose, and [11C] Pittsburgh Compound-B (PiB) PET to measure associations between tau and glucose metabolism in cognitively normal older adults (N = 49). Participants were divided into amyloid-negative (PiB-, n = 28) and amyloid-positive (PiB+, n = 21) groups to determine effects of amyloid-β. We assessed both local and across-brain regional tau-glucose metabolism associations separately in PiB-/PiB+ groups using correlation matrices and sparse canonical correlations. Relationships between tau and glucose metabolism differed by amyloid status, and were primarily spatially distinct. In PiB- subjects, tau was associated with broad regions of increased glucose metabolism. In PiB+ subjects, medial temporal lobe tau was associated with widespread hypometabolism, while tau outside of the medial temporal lobe was associated with decreased and increased glucose metabolism. We further found that regions with earlier tau spread were associated with stronger negative correlations with glucose metabolism. Our findings indicate that in normal aging, low levels of tau are associated with a phase of increased metabolism, while high levels of tau in the presence of amyloid-β are associated with hypometabolism at downstream sites.
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Cortical tau deposition follows patterns of entorhinal functional connectivity in aging. eLife 2019; 8:e49132. [PMID: 31475904 PMCID: PMC6764824 DOI: 10.7554/elife.49132] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/31/2019] [Indexed: 02/02/2023] Open
Abstract
Tau pathology first appears in the transentorhinal and anterolateral entorhinal cortex (alEC) in the aging brain. The transition to Alzheimer's disease (AD) is hypothesized to involve amyloid-β (Aβ) facilitated tau spread through neural connections. We contrasted functional connectivity (FC) of alEC and posteromedial EC (pmEC), subregions of EC that differ in functional specialization and cortical connectivity, with the hypothesis that alEC-connected cortex would show greater tau deposition than pmEC-connected cortex. We used resting state fMRI to measure FC, and PET to measure tau and Aβ in cognitively normal older adults. Tau preferentially deposited in alEC-connected cortex compared to pmEC-connected or non-connected cortex, and stronger connectivity was associated with increased tau deposition. FC-tau relationships were present regardless of Aβ, although strengthened with Aβ. These results provide an explanation for the anatomic specificity of neocortical tau deposition in the aging brain and reveal relationships between normal aging and the evolution of AD.
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Alzheimer's pathology targets distinct memory networks in the ageing brain. Brain 2019; 142:2492-2509. [PMID: 31199481 PMCID: PMC6658874 DOI: 10.1093/brain/awz154] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 03/13/2019] [Accepted: 04/10/2019] [Indexed: 12/27/2022] Open
Abstract
Alzheimer's disease researchers have been intrigued by the selective regional vulnerability of the brain to amyloid-β plaques and tau neurofibrillary tangles. Post-mortem studies indicate that in ageing and Alzheimer's disease tau tangles deposit early in the transentorhinal cortex, a region located in the anterior-temporal lobe that is critical for object memory. In contrast, amyloid-β pathology seems to target a posterior-medial network that subserves spatial memory. In the current study, we tested whether anterior-temporal and posterior-medial brain regions are selectively vulnerable to tau and amyloid-β deposition in the progression from ageing to Alzheimer's disease and whether this is reflected in domain-specific behavioural deficits and neural dysfunction. 11C-PiB PET and 18F-flortaucipir uptake was quantified in a sample of 131 cognitively normal adults (age: 20-93 years; 47 amyloid-β-positive) and 20 amyloid-β-positive patients with mild cognitive impairment or Alzheimer's disease dementia (65-95 years). Tau burden was relatively higher in anterior-temporal regions in normal ageing and this difference was further pronounced in the presence of amyloid-β and cognitive impairment, indicating exacerbation of ageing-related processes in Alzheimer's disease. In contrast, amyloid-β deposition dominated in posterior-medial regions. A subsample of 50 cognitively normal older (26 amyloid-β-positive) and 25 young adults performed an object and scene memory task while functional MRI data were acquired. Group comparisons showed that tau-positive (n = 18) compared to tau-negative (n = 32) older adults showed lower mnemonic discrimination of object relative to scene images [t(48) = -3.2, P = 0.002]. In a multiple regression model including regional measures of both pathologies, higher anterior-temporal flortaucipir (tau) was related to relatively worse object performance (P = 0.010, r = -0.376), whereas higher posterior-medial PiB (amyloid-β) was related to worse scene performance (P = 0.037, r = 0.309). The functional MRI data revealed that tau burden (but not amyloid-β) was associated with increased task activation in both systems and a loss of functional specificity, or dedifferentiation, in posterior-medial regions. The loss of functional specificity was related to worse memory. Our study shows a regional dissociation of Alzheimer's disease pathologies to distinct memory networks. While our data are cross-sectional, they indicate that with ageing, tau deposits mainly in the anterior-temporal system, which results in deficits in mnemonic object discrimination. As Alzheimer's disease develops, amyloid-β deposits preferentially in posterior-medial regions additionally compromising scene discrimination and anterior-temporal tau deposition worsens further. Finally, our findings propose that the progression of tau pathology is linked to aberrant activation and dedifferentiation of specialized memory networks that is detrimental to memory function.
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P2-353: SIGNAL COHERENCE IN THE HIPPOCAMPUS IS RELATED TO ITS FUNCTIONAL ISOLATION, PRECLINICAL ALZHEIMER'S DISEASE PATHOLOGY AND MEMORY IN AGING. Alzheimers Dement 2019. [DOI: 10.1016/j.jalz.2019.06.2760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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F4-02-02: TAU PET IMAGING IN AGING: CONTRIBUTIONS TO COGNITIVE DECLINE AND NEURAL DYSFUNCTION. Alzheimers Dement 2019. [DOI: 10.1016/j.jalz.2019.06.4719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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O4-12-03: CORTICAL TAU DEPOSITION FOLLOWS PATTERNS OF ENTORHINAL FUNCTIONAL CONNECTIVITY IN COGNITIVELY NORMAL OLDER ADULTS. Alzheimers Dement 2019. [DOI: 10.1016/j.jalz.2019.06.4808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Executive Function in Relation to White Matter in Preterm and Full Term Children. Front Pediatr 2019; 6:418. [PMID: 30697535 PMCID: PMC6341022 DOI: 10.3389/fped.2018.00418] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/18/2018] [Indexed: 11/13/2022] Open
Abstract
Background: Executive function (EF) refers to cognitive abilities used to guide goal-directed behavior. Diffusion Tensor Imaging (DTI) provides quantitative characterization of white matter tracts in the brain. Children with preterm birth often have EF impairments and white matter injury. Aim: To examine the degree of association between EF scores and white matter fractional anisotropy (FA) as measured by DTI in children born preterm and term Study design: Cross-sectional study Subjects: Participants, 9-16 years of age, born preterm (n = 25; mean gestational age 28.6 weeks; mean birth weight 1,191 grams), and full term (n = 20) Outcome measures: White matter FA analyzed with Tract-Based Spatial Statistics, a technique that generates a skeleton representing the core of white matter tracts throughout the brain. Behavioral scores from EF tasks examining working memory, spatial memory capacity, and multiple skills from the Stockings of Cambridge. Results: The groups performed comparably on all tasks. In both groups, unfavorable working memory strategy scores were associated with lower FA. Other measures of EF were not associated with whole skeleton FA in either group in either direction. Conclusions: Strategy score on a spatial working memory task was associated with FA in preterm and full term children, suggesting common underlying neurobiology in both groups. Associations were found in frontal-parietal connections and other major tracts. Lack of associations between other EF tasks and FA may be due to variation in how children accomplish these EF tasks. Future research is required to fully understand the neurobiology of EF in children born preterm.
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Dynamic frontotemporal systems process space and time in working memory. PLoS Biol 2018; 16:e2004274. [PMID: 29601574 PMCID: PMC5895055 DOI: 10.1371/journal.pbio.2004274] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 04/11/2018] [Accepted: 02/27/2018] [Indexed: 11/18/2022] Open
Abstract
How do we rapidly process incoming streams of information in working memory, a cognitive mechanism central to human behavior? Dominant views of working memory focus on the prefrontal cortex (PFC), but human hippocampal recordings provide a neurophysiological signature distinct from the PFC. Are these regions independent, or do they interact in the service of working memory? We addressed this core issue in behavior by recording directly from frontotemporal sites in humans performing a visuospatial working memory task that operationalizes the types of identity and spatiotemporal information we encounter every day. Theta band oscillations drove bidirectional interactions between the PFC and medial temporal lobe (MTL; including the hippocampus). MTL theta oscillations directed the PFC preferentially during the processing of spatiotemporal information, while PFC theta oscillations directed the MTL for all types of information being processed in working memory. These findings reveal an MTL theta mechanism for processing space and time and a domain-general PFC theta mechanism, providing evidence that rapid, dynamic MTL–PFC interactions underlie working memory for everyday experiences. How do we rapidly process incoming streams of information in working memory? Dominant views of working memory focus on the prefrontal cortex (PFC), but other data suggest a role for the medial temporal lobe (MTL). To delineate whether (and how) these brain regions interact during working memory, we recorded directly from PFC and MTL sites in humans performing a task that tests working memory for the types of “what,” “where,” and “when” information encountered every day. MTL oscillations in the theta band (3–7 Hz) directed PFC activity during the processing of spatiotemporal information, while PFC theta oscillations directed MTL activity for all types of information. This functional dissociation provides the first demonstration of bidirectional communication between the PFC and MTL during working memory. Our findings reveal that rapid, dynamic interactions between these two regions underlie working memory for everyday experiences, challenging dominant views on the central role of the PFC.
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[O1–06–03]: EFFECTS OF TAU DEPOSITION ON CEREBRAL GLUCOSE METABOLISM IN NORMAL OLDER ADULTS VARY BY AMYLOID LEVEL. Alzheimers Dement 2017. [DOI: 10.1016/j.jalz.2017.07.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Decreased and Increased Anisotropy along Major Cerebral White Matter Tracts in Preterm Children and Adolescents. PLoS One 2015; 10:e0142860. [PMID: 26560745 PMCID: PMC4641645 DOI: 10.1371/journal.pone.0142860] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 10/26/2015] [Indexed: 12/15/2022] Open
Abstract
Premature birth is highly prevalent and associated with neurodevelopmental delays and disorders. Adverse outcomes, particularly in children born before 32 weeks of gestation, have been attributed in large part to white matter injuries, often found in periventricular regions using conventional imaging. To date, tractography studies of white matter pathways in children and adolescents born preterm have evaluated only a limited number of tracts simultaneously. The current study compares diffusion properties along 18 major cerebral white matter pathways in children and adolescents born preterm (n = 27) and full term (n = 19), using diffusion magnetic resonance imaging and tractography. We found that compared to the full term group, the preterm group had significantly decreased FA in segments of the bilateral uncinate fasciculus and anterior segments of the right inferior fronto-occipital fasciculus. Additionally, the preterm group had significantly increased FA in segments of the right and left anterior thalamic radiations, posterior segments of the right inferior fronto-occipital fasciculus, and the right and left inferior longitudinal fasciculus. Increased FA in the preterm group was generally associated with decreased radial diffusivity. These findings indicate that prematurity-related white matter differences in later childhood and adolescence do not affect all tracts in the periventricular zone and can involve both decreased and increased FA. Differences in the patterns of radial diffusivity and axial diffusivity suggest that the tissue properties underlying group FA differences may vary within and across white matter tracts. Distinctive diffusion properties may relate to variations in the timing of injury in the neonatal period, extent of white matter dysmaturity and/or compensatory processes in childhood.
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Abstract
AIM Children born preterm (at ≤32wks) are at risk of developing deficits in reading ability. This meta-analysis aims to determine whether or not school-aged preterm children perform worse than those born at term in single-word reading (decoding) and reading comprehension. METHOD Electronic databases were searched for studies published between 2000 and 2013, which assessed decoding or reading comprehension performance in English-speaking preterm and term-born children aged between 6 years and 13 years, and born after 1990. Standardized mean differences in decoding and reading comprehension scores were calculated. RESULTS Nine studies were suitable for analysis of decoding, and five for analysis of reading comprehension. Random-effects meta-analyses showed that children born preterm had significantly lower scores (reported as Cohen's d values [d] with 95% confidence intervals [CIs]) than those born at term for decoding (d=-0.42, 95% CI -0.57 to -0.27, p<0.001) and reading comprehension (d=-0.57, 95% CI -0.68 to -0.46, p<0.001). Meta-regressions showed that lower gestational age was associated with larger differences in decoding (Q[1]=5.92, p=0.02) and reading comprehension (Q[1]=4.69, p=0.03) between preterm and term groups. Differences between groups increased with age for reading comprehension (Q[1]=5.10, p=0.02) and, although not significant, there was also a trend for increased group differences for decoding (Q[1]=3.44, p=0.06). INTERPRETATION Preterm children perform worse than peers born at term on decoding and reading comprehension. These findings suggest that preterm children should receive more ongoing monitoring for reading difficulties throughout their education.
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Sensory processing in preterm preschoolers and its association with executive function. Early Hum Dev 2015; 91:227-33. [PMID: 25706317 PMCID: PMC4392005 DOI: 10.1016/j.earlhumdev.2015.01.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 01/22/2015] [Accepted: 01/28/2015] [Indexed: 12/01/2022]
Abstract
BACKGROUND Symptoms of abnormal sensory processing have been related to preterm birth, but have not yet been studied specifically in preterm preschoolers. The degree of association between sensory processing and other domains is important for understanding the role of sensory processing symptoms in the development of preterm children. AIMS To test two related hypotheses: (1) preterm preschoolers have more sensory processing symptoms than full term preschoolers and (2) sensory processing is associated with both executive function and adaptive function in preterm preschoolers. STUDY DESIGN Cross-sectional study. SUBJECTS Preterm children (≤34weeks of gestation; n=54) and full term controls (≥37weeks of gestation; n=73) ages 3-5years. OUTCOME MEASURES Sensory processing was assessed with the Short Sensory Profile. Executive function was assessed with (1) parent ratings on the Behavior Rating Inventory of Executive Function - Preschool version and (2) a performance-based battery of tasks. Adaptive function was assessed with the Vineland Adaptive Behavior Scales-II. RESULTS Preterm preschoolers showed significantly more sensory symptoms than full term controls. A higher percentage of preterm than full term preschoolers had elevated numbers of sensory symptoms (37% vs. 12%). Sensory symptoms in preterm preschoolers were associated with scores on executive function measures, but were not significantly associated with adaptive function. CONCLUSIONS Preterm preschoolers exhibited more sensory symptoms than full term controls. Preterm preschoolers with elevated numbers of sensory symptoms also showed executive function impairment. Future research should further examine whether sensory processing and executive function should be considered independent or overlapping constructs.
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Abstract
Genetic recombination was demonstrated in the bacterial genus Nocardia. The compatibility mechanism governing recombination differs from that of Escherichia coli and the streptomycetes. Mutants of N. erythropolis or N. canicruria, of homologous origin, were incompatible, but mutants of heterologous origin were compatible. Such a compatibility system is suggestive of classic heterothallism which up to now has not been known among the bacteria.
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More on Clinical Renal GeneticsNewborn screening for Fabry disease in Taiwan reveals a high incidence of the later-onset mutation c.936+919G>A (IVS4+919G>A). Hum Mutat 30: 1397–1405, 2009Lanreotide reduces the volume of polycystic liver: A randomized, double-blind, placebo-controlled trial. Gastroenterology 137: 1661–1668, 2009Cerebrovascular disease related to COL4A1 mutations in HANAC syndrome. Neurology 73: 1873–1882, 2009Dominant renin gene mutations associated with early-onset hyperuricemia, anemia, and chronic renal failure. Am J Hum Genet 85: 204–213, 2009Mutations in the formin gene INF2 cause focal segmental glomerulosclerosis. Nat Genet 42: 72–76, 2009. Clin J Am Soc Nephrol 2010; 5:563-7. [DOI: 10.2215/cjn.01720210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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More on Clinical Renal Genetics. Clin J Am Soc Nephrol 2010. [DOI: 10.2215/01.cjn.0000927108.86094.d2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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TRANSDUCTION BY BACTERIOPHAGE P1: ABNORMAL PHAGE FUNCTION OF THE TRANSDUCING PARTICLES. Proc Natl Acad Sci U S A 2006; 44:590-4. [PMID: 16590247 PMCID: PMC528627 DOI: 10.1073/pnas.44.6.590] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
OBJECTIVE To identify the effect on door to needle (DTN) time of moving the site of thrombolysis delivery from the coronary care unit (CCU) to the emergency department (ED). To ascertain if moving the site of thrombolysis enables appropriate use of thrombolysis. DESIGN Prospective cohort study. SETTING CCU and ED of a 450 bed Scottish district general hospital without on-site primary angioplasty. PARTICIPANTS Primary site for thrombolysis of patients presenting to the hospital with ST elevation MI (STEMI) moved from CCU to ED on 1 April 2000. Study patients who had a confirmed STEMI and/or received thrombolytic therapy before this date were defined as the pre-change group; those who were diagnosed as STEMI and/or received thrombolytic therapy after this date were defined as the post-change group. STATISTICAL ANALYSIS Mann-Whitney test was used to compare medians and chi(2) test for categorical data. RESULTS 1349 patients were discharged from CCU with a diagnosis of STEMI or received thrombolysis in the ED or CCU between April 1998 and April 2002. There were 632 patients in the pre-change group and 654 patients in the post-change group. Sixty three patients were excluded. Median DTN time for the pre-change group (321 thrombolysed patients) was 64 minutes and median DTN time for the post-change group (324 thrombolysed patients) was 35 minutes, a median difference of 25 minutes (95% CI for difference 20 to 29 minutes, p<0.0001, Mann-Whitney U test). A total of 37 patients were thrombolysed but did not have a final diagnosis of STEMI. CONCLUSION A significant reduction in DTN times accompanied this change in practice in this hospital.
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Coronary artery spasm leading to life threatening arrhythmias. Heart 1998; 80:89-90. [PMID: 9764068 PMCID: PMC1728744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
A 39 year old woman sustained life threatening arrhythmias associated with coronary artery spasm. On both occasions she was attending hospital outpatient clinics and was successfully resuscitated. Electrocardiography performed during further episodes of pain suggested that spasm could occur in either the right or left coronary artery.
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Abstract
OBJECTIVE To establish the persistence of hibernating myocardium initially detected after myocardial infarction treated with thrombolysis. METHODS AND RESULTS Fourteen patients underwent gated positron emission tomography with 18-fluoro-deoxyglucose and N13-ammonia at a median of 8 days after first myocardial infarction. Repeat scans were performed at a median of 13 weeks post-infarction. A total of 148 (30.9%) myocardial segments showed reduced N13-ammonia uptake at the time of the first scan compared with 154.5 (32.2%) segments at the time of repeat imaging. The median change in the number of segments with reduced perfusion was -1.0. Initially 13 subjects had hibernating myocardium, seven patients had large areas and six had smaller regions. Six (46.2%) subjects had repeat scans showing unchanged areas of hibernating tissue and seven had second scans demonstrating changes in the size of the region of hibernating myocardium. One patient had no hibernating myocardium on either scan. CONCLUSIONS Positron emission tomography performed several months after myocardial infarction demonstrates significant changes in myocardial perfusion. However, a reduction in the number of segments with reduced perfusion does not always result in an improvement in myocardial metabolism and contraction. Whilst most regions of hibernating myocardium were still present several months after infarction, in only approximately half was the size of the mismatched region unchanged. Therefore it is not possible to predict the fate of hibernating myocardium which is present after infarction.
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Abstract
OBJECTIVE To assess the frequency with which paramedic skills were used in out of hospital cardiac arrest and the effect of tracheal intubation on outcome. DESIGN Retrospective analysis of ambulance service reports and hospital records. SETTING Scottish Ambulance Service and hospitals admitting acute patients throughout Scotland. RESULTS A total of 8651 out of hospital resuscitation attempts were recorded and tracheal intubation was attempted in 3427 (39.6%) arrests. One hundred and thirty six patients (3.7%) were intubated and 476 (9.1%) of the patients who were not intubated survived to hospital discharge (p < 0.001). Among the patients who were defibrillated the proportion intubated was highest in the patients who received the greatest number of shocks (p < 0.01). Among subjects receiving similar numbers of shocks survival rates were lower for intubated patients (p < 0.01). Patients with unwitnessed arrests were most frequently intubated and survival rates were lowest in this group. CONCLUSIONS Patients who are intubated seem to have lower survival rates. This may however reflect the difficulty of the resuscitation attempt rather than the effects of intubation. The use of basic life support skills rapidly after cardiac arrest is associated with the best survival rates.
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Abstract
OBJECTIVE To establish the incidence of hibernating myocardium after myocardial infarction treated with thrombolysis and to observe differences in the clinical outcome between patients with and without hibernating tissue. METHODS 41 patients underwent gated positron emission tomography with 18-fluorodeoxyglucose and 13N-ammonia at a median of eight days after first myocardial infarction. RESULTS All 41 subjects had a matched perfusion-metabolism deficit in the region of myocardium indicated as the site of infarction by an electrocardiograph; 32 patients (78%) had scans which also showed at least one area of reduced blood flow and contraction with a concomitant increase in glucose uptake, representing hibernating myocardium. Patients were followed up at a median of six months: all 41 were alive and none had sustained a further infarct or cardiac arrhythmia; 17 subjects with hibernating tissue (53.1%) and two without (25%) reported chest pain after myocardial infarction. CONCLUSIONS Hibernating myocardium is relatively common shortly after myocardial infarction treated with thrombolysis. It does not influence mortality or the incidence of postinfarction chest pain.
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Abstract
The risk of administering thrombolysis to patients with suspected myocardial infarction who subsequently do not sustain an infarct, but develop complications associated with thrombolysis is of concern to all physicians. The objective of this study was to ascertain the effect of altering the criteria for the administration of thrombolysis on the number of patients who received thrombolysis in the absence of infarction. During 1990 and 1992 details of all admissions with chest pain were recorded. During 1991 the policy for the administration of thrombolysis was altered so that only patients with ST elevation were eligible. A total of 1473 patients were admitted with chest pain in 1990 and 1967 in 1992. Of the patients admitted in 1990, 663 (45%) had confirmed infarction of whom 378 (57.0%) received thrombolysis. In 1992, 855 (43%) were admitted with infarction and of these 450 (52.6%) had thrombolytic therapy. 118 patients had no evidence of myocardial infarction, but received thrombolysis. 91 (77.1%) were admitted in 1990 and 27 (22.9%) in 1992 (P < 0.01). Of these only 24 (20%) subjects had ST elevation or bundle branch block on the admission electrocardiograph and 41 (35%) had normal tracings. Four (3%) subjects had serious complications of whom one (0.8%) died. The implementation of ECG criteria resulted in a significant reduction in the number of patients without infarction who received thrombolysis, but did not significantly alter the rate of thrombolysis in those with definite myocardial infarction.
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Aortic distensibility and stiffness index measured by magnetic resonance imaging in patients with Marfan's syndrome. Heart 1995; 73:265-9. [PMID: 7727188 PMCID: PMC483810 DOI: 10.1136/hrt.73.3.265] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVES To use magnetic resonance imaging to measure the elastic properties of the aorta of adults with Marfan's syndrome and to compare these results with those obtained by echocardiography. PATIENTS AND METHODS 12 patients with Marfan's syndrome and 12 controls matched for age. Transverse luminal areas of the ascending and descending aorta were measured using electrocardiographic gated magnetic resonance imaging. Echocardiography was used to measure the diameter of the ascending aorta and aortic arch in patients with Marfan's syndrome. Blood pressure was measured during both scans. RESULTS In diastole, transverse luminal areas of the ascending and descending aorta were significantly greater in patients with Marfan's syndrome when measured by magnetic resonance imaging and corrected for body surface area; P < 0.02 and P < 0.05 respectively. Patients with Marfan's syndrome had a higher stiffness index (112.77 v 5.78, P < 0.05) and a lower distensibility (0.0066 v 0.0105, P < 0.05) than controls. Results produced by MRI and echocardiography were not significantly different. CONCLUSIONS Magnetic resonance imaging gives good quality reproducible images of the ascending and descending aorta. In patients with Marfan's syndrome, aortic distensibility and stiffness index measured by magnetic resonance imaging were abnormal (but did not always relate directly to the size of the aorta.
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Delay between the onset of symptoms of acute myocardial infarction and seeking medical assistance is influenced by left ventricular function at presentation. Heart 1995; 73:125-8. [PMID: 7696020 PMCID: PMC483777 DOI: 10.1136/hrt.73.2.125] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVE To determine whether the interval between the onset of symptoms of acute myocardial infarction and the patient's call for medical assistance (patient delay) is related to left ventricular function at the time of presentation. DESIGN Prospective observational study. SETTING Coronary care unit of Aberdeen Royal Infirmary. PATIENTS 93 consecutive patients with acute myocardial infarction. MAIN OUTCOME MEASURES Left ventricular stroke distance, expressed as a percentage of the age predicted normal value, measured first on admission, and then daily for 10 days or until discharge. Patients were questioned at admission to determine the time of onset of symptoms and the time of their call for medical assistance. RESULTS Median (range) patient delay was 30 (1-360) min. Mean (SD) stroke distance on admission was 70(18)%, rising to 77(19)% on the second recording, and to 84(18)% on the day of discharge. Linear regression of log(e)(patient delay) against first, second, and last measurements of stroke distance gave correlation coefficients of 0.28 (P < 0.01), 0.18 (not significant), and 0.11 (not significant), respectively. CONCLUSIONS Patient delay within the first 4 h after the onset of symptoms of acute myocardial infarction is positively related to left ventricular function on admission. A possible explanation is that deteriorating left ventricular function influences the patient's decision to call for help. This tendency for patients with more severe infarction to call for help sooner is an added reason for giving thrombolytic treatment at the first opportunity: those who call early have most to gain from prompt management.
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Abstract
OBJECTIVE To determine whether women with myocardial infarction are treated differently from men of the same age and to assess the effect of changes in the coronary care unit admission policy. DESIGN Clinical audit. SETTING The coronary care unit and general medical wards of a teaching hospital. In 1990 the age limit for admission to coronary care was 65 years. This age limit was removed in 1991. PATIENTS 539 female and 977 male patients admitted with myocardial infarction between 1990 and 1992. MAIN OUTCOMES Admission to the coronary care unit, administration of thrombolysis, and in-hospital mortality. RESULTS 409 men and 254 women were admitted with myocardial infarction in 1990 and 568 men and 285 women in 1992. Removal of the age limit for admission to the coronary care unit resulted in an increase in the numbers of both sexes admitted with myocardial infarction. In both years, however, proportionately more men with infarction were admitted to coronary care: 226 men (55%) and 96 women (38%) (P < 0.01) (95% CI 7 to 28) in 1990 and 459 men (81%) and 200 women (70%) (P < 0.01) (%CI 2 to 19) in 1992. Some 246 men (60%) and 133 women (52%) with infarction (P < 0.01) received thrombolytic treatment in 1990 compared with 319 men (56%) and 130 women (46%) (P < 0.01) in 1992. The mean age of women sustaining a myocardial infarction was significantly greater in both years studied. In 1992 a total of 78 men (7%) and 34 women (4%) (P < 0.05) admitted with chest pain underwent cardiac catheterisation before discharge from hospital. CONCLUSIONS Differences in admission rates to the coronary care unit and the rate of thrombolysis between the sexes can be explained by the older age of women sustaining infarction. The application of age limits for admission to coronary care or administration of thrombolysis places elderly patients at a disadvantage. As women sustain myocardial infarctions at an older age they are placed at a greater disadvantage.
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Warfarin therapy in the elderly. Br J Hosp Med (Lond) 1994; 51:392-3. [PMID: 8081574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The use of anticoagulation in the elderly is increasing. Although several studies show that elderly patients are at greater risk of anticoagulant-associated haemorrhage, most studies suggest that there is no increased risk if the international normalized ratio is well controlled.
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