| 1. |
- Damangir, Soheil, et al.
(författare)
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Multispectral MRI segmentation of age related white matter changes using a cascade of support vector machines
- 2012
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Ingår i: Journal of the Neurological Sciences. - : Elsevier BV. - 0022-510X .- 1878-5883. ; 322:1-2, s. 211-216
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Tidskriftsartikel (refereegranskat)abstract
- White matter changes (WMC) are the focus of intensive research and have been linked to cognitive impairment and depression in the elderly. Cumbersome manual outlining procedures make research on WMC labor intensive and prone to subjective bias. We present a fast, fully automated method for WMC segmentation using a cascade of reduced support vector machines (SVMs) with active learning. Data of 102 subjects was used in this study. Two MRI sequences (T1-weighted and FLAIR) and masks of manually outlined WMC from each subject were used for the image analysis. The segmentation framework comprises pre-processing, classification (training and core segmentation) and post-processing. After pre-processing, the model was trained on two subjects and tested on the remaining 100 subjects. The effectiveness and robustness of the classification was assessed using the receiver operating curve technique. The cascade of SVMs segmentation framework outputted accurate results with high sensitivity (90%) and specificity (99.5%) values, with the manually outlined WMC as reference. An algorithm for the segmentation of WMC is proposed. This is a completely competitive and fast automatic segmentation framework, capable of using different input sequences, without changes or restrictions of the image analysis algorithm.
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| 2. |
- Holleman, Jasper, et al.
(författare)
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Diurnal cortisol, neuroinflammation, and neuroimaging visual rating scales in memory clinic patients
- 2024
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Ingår i: Brain, behavior, and immunity. - : Elsevier. - 0889-1591 .- 1090-2139. ; 118, s. 499-509
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Neuroinflammation is a hallmark of the Alzheimer's disease (AD) pathogenic process. Cortisol dysregulation may increase AD risk and is related to brain atrophy. This cross-sectional study aims to examine interactions of cortisol patterns and neuroinflammation markers in their association with neuroimaging correlates.METHOD: 134 participants were recruited from the Karolinska University Hospital memory clinic (Stockholm, Sweden). Four visual rating scales were applied to magnetic resonance imaging or computed tomography scans: medial temporal lobe atrophy (MTA), global cortical atrophy (GCA), white matter lesions (WML), and posterior atrophy. Participants provided saliva samples for assessment of diurnal cortisol patterns, and underwent lumbar punctures for cerebrospinal fluid (CSF) sampling. Three cortisol measures were used: the cortisol awakening response, total daily output, and the ratio of awakening to bedtime levels. Nineteen CSF neuroinflammation markers were categorized into five composite scores: proinflammatory cytokines, other cytokines, angiogenesis markers, vascular injury markers, and glial activation markers. Ordinal logistic regressions were conducted to assess associations between cortisol patterns, neuroinflammation scores, and visual rating scales, and interactions between cortisol patterns and neuroinflammation scores in relation to visual rating scales.RESULT: Higher levels of angiogenesis markers were associated with more severe WML. Some evidence was found for interactions between dysregulated diurnal cortisol patterns and greater neuroinflammation-related biomarkers in relation to more severe GCA and WML. No associations were found between cortisol patterns and visual rating scales.CONCLUSION: This study suggests an interplay between diurnal cortisol patterns and neuroinflammation in relation to brain structure. While this cross-sectional study does not provide information on causality or temporality, these findings suggest that neuroinflammation may be involved in the relationship between HPA-axis functioning and AD.
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| 3. |
- Hooshmand, Babak, et al.
(författare)
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Vitamin D in Relation to Cognitive Impairment, Cerebrospinal Fluid Biomarkers, and Brain Volumes
- 2014
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Ingår i: The journals of gerontology. Series A, Biological sciences and medical sciences. - : Oxford University Press (OUP). - 1079-5006 .- 1758-535X. ; 69:9, s. 1132-1138
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Tidskriftsartikel (refereegranskat)abstract
- Background. Low vitamin D status is associated with poorer cognitive function in older adults, but little is known about the potential impact on cerebrospinal fluid (CSF) biomarkers and brain volumes. The objective of this study was to examine the relations between plasma 25-hydroxyvitamin D (25(OH)D) and cognitive impairment, CSF biomarkers of Alzheimer's disease (AD), and structural brain tissue volumes. Methods. A total of 75 patients (29 with subjective cognitive impairment, 28 with mild cognitive impairment, 18 with AD) referred to the Memory Clinic at Karolinska University Hospital, Huddinge, Sweden were recruited. Plasma 25(OH)D, CSF levels of amyloid beta (A beta(1-42)), total-tau, and phosphorylated tau, and brain tissue volumes have been measured. Results. After adjustment for several potential confounders, the odds ratios (95% confidence interval) for cognitive impairment were as follows: 0.969 (0.948-0.990) per increase of 1 nmol/L of 25(OH) D and 4.19 (1.30-13.52) for 24(OH) D values less than 50 nmol/L compared with values greater than or equal to 50 nmol/L. Adjusting for CSF A beta(1-42) attenuated the 25(OH) D-cognition link. In a multiple linear regression analysis, higher 25(OH)D levels were related to higher concentrations of CSF A beta(1-42) and greater brain volumes (eg, white matter, structures belonging to medial temporal lobe). The associations between 25(OH)D and tau variables were not significant. Conclusions. This study suggests that vitamin D may be associated with cognitive status, CSF A beta(1-42) levels, and brain tissue volumes.
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| 4. |
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| 5. |
- Lebedev, Alexander V., et al.
(författare)
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Effects of daily L-dopa administration on learning and brain structure in older adults undergoing cognitive training : a randomised clinical trial
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Cognitive aging creates major individual and societal burden, motivating search for treatment and preventive care strategies. Behavioural interventions can improve cognitive performance in older age, but effects are small. Basic research has implicated dopaminergic signalling in plasticity. We investigated whether supplementation with the dopamine-precursor L-dopa improves effects of cognitive training on performance. Sixty-three participants for this randomised, parallel-group, double-blind, placebo-controlled trial were recruited via newspaper advertisements. Inclusion criteria were: age of 65–75 years, Mini-Mental State Examination score >25, absence of serious medical conditions. Eligible subjects were randomly allocated to either receive 100/25 mg L-dopa/benserazide (n = 32) or placebo (n = 31) prior to each of twenty cognitive training sessions administered during a four-week period. Participants and staff were blinded to group assignment. Primary outcomes were latent variables of spatial and verbal fluid intelligence. Compared to the placebo group, subjects receiving L-dopa improved less in spatial intelligence (−0.267 SDs; 95%CI [−0.498, −0.036]; p = 0.024). Change in verbal intelligence did not significantly differ between the groups (−0.081 SDs, 95%CI [−0.242, 0.080]; p = 0.323). Subjects receiving L-dopa also progressed slower through the training and the groups displayed differential volumetric changes in the midbrain. No statistically significant differences were found for the secondary cognitive outcomes. Adverse events occurred for 10 (31%) and 7 (23%) participants in the active and control groups, correspondingly. The results speak against early pharmacological interventions in older healthy adults to improve broader cognitive functions by targeting the dopaminergic system and provide no support for learning-enhancing properties of L-dopa supplements in the healthy elderly. The findings warrant closer investigation about the cognitive effects of early dopamine-replacement therapy in neurological disorders. This trial was preregistered at the European Clinical Trial Registry, EudraCT#2016-000891-54 (2016-10-05).
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| 6. |
- Liu, Yawu, et al.
(författare)
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Diffusion tensor imaging and tract-based spatial statistics in Alzheimer's disease and mild cognitive impairment
- 2011
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Ingår i: Neurobiology of Aging. - Fayetteville, N.Y. : Ankho International. - 0197-4580 .- 1558-1497. ; 32:9, s. 1558-1571
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to explore the changes in fractional anisotropy (FA) in subjects with mild cognitive impairment (MCI) and Alzheimer's disease (AD) by analyzing diffusion tensor imaging (DTI) data using the Tract-Based Spatial Statistics (TBSS). DTI data were collected from 17 AD patients, 27 MCI subjects and 19 healthy controls. Voxel-based analysis with TBSS was used to compare FA among the three groups. Additionally, guided by TBSS findings, a region of interest (ROI)-based analysis along the TBSS skeleton was performed on group-level and the accuracy of the method was assessed by the back-projection of ROIs to the native space FA. Neurofiber tracts with decreased FA included: the parahippocampal white matter, cingulum, uncinate fasciculus, inferior and superior longitudinal fasciculus, corpus callosum, fornix, tracts in brain stem, and cerebellar tracts. Quantitative ROI-analysis further demonstrated the significant decrease on FA values in AD patients relative to controls whereas FA values of MCI patients were found in between the controls and AD patients. We conclude that TBSS is a promising method in examining the degeneration of neurofiber tracts in MCI and AD patients.
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| 7. |
- Miralbell, Julia, et al.
(författare)
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Grey matter and cognitive patterns in cognitive impaired subjects using CSF biomarker cut-offs
- 2012
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 29:4, s. 741-749
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate brain tissue volumes, grey matter (GM) distribution, and cognitive performance for cognitively impaired subjects using cerebrospinal fluid (CSF) biomarker cut-offs as grouping criteria. 41 subjects attending the Memory Clinic, Karolinska University Hospital, Huddinge, Sweden, were divided into groups based on normal or abnormal CSF levels of Aβ1-42, t-tau, and p-tau181. SIENAX algorithms were employed for brain tissue volumes estimation and voxel-based morphometry (VBM) for mapping the differences in GM patterns. VBM revealed significant lower GM volumes in temporo-parietal, occipital, and prefrontal cortices for those subjects belonging to abnormal CSF t-tau and p-tau181 groups. No differences were found between groups according to CSF Aβ1-42 cut-offs. Patients with abnormal CSF p-tau181 showed lower cognitive performance compared to those with normal levels. Patients with abnormal levels of CSF tau (but not Aβ1-42) showed an Alzheimer's disease-like pattern for both GM distribution and cognitive profile, compared to those with normal levels. These results support the hypothesis that CSF t-tau or p-tau181 levels may be of direct value for the evaluation of disease severity.
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| 8. |
- Spulber, Gabriela, et al.
(författare)
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Evolution of global and local grey matter atrophy on serial MRI scans during the progression from MCI to AD
- 2012
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Ingår i: Current Alzheimer Research. - : Bentham Science Publishers Ltd.. - 1567-2050 .- 1875-5828. ; 9:4, s. 516-524
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Tidskriftsartikel (refereegranskat)abstract
- Mild cognitive impairment (MCI) often represents a prodromal form of dementia, conferring a significantly higher risk of converting to probable Alzheimer's disease (AD). The aim of this study is to characterise the differences of grey matter (GM) distribution and dynamics between progressive and stable MCI subjects during a 2 year period preceding the conversion to AD. We included 48 stable MCI and 12 progressive MCI cases based on the availability of 3 serial scans acquired with approximately 1 year scan interval. For the progressive MCI group, the third scan was acquired at the time of the clinical diagnosis of AD, while the first two scans were acquired approximately 2 and 1 years earlier. For the stable MCI group, the three scans were acquired at approximately 1 year intervals during a period free from significant cognitive decline. We used longitudinal voxel-based morphometry (VBM) for mapping the progression of GM loss over time. For the progressive MCI group, the cross-sectional analysis revealed areas of lower GM volumes in the parahippocampal gyrus, precuneus and posterior cingulate 12 months before the AD diagnosis. For the longitudinal VBM analysis the progressive MCI group revealed increased GM loss in cortical regions belonging to the temporal neocortex, parahippocampal cortex, and cingulate gyrus. The frontal lobe, insula and the cerebellum were also affected. This accelerated atrophy may offer new insights into the understanding of neurodegenerative pathology and the clinical relevance of these changes remains to be verified by subsequent studies.
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| 9. |
- Spulber, Gabriela, et al.
(författare)
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Whole brain atrophy rate predicts progression from MCI to Alzheimer's disease
- 2010
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 31:9, s. 1601-1605
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Tidskriftsartikel (refereegranskat)abstract
- For both clinical and research reasons, it is essential to identify which mild cognitive impairment (MCI) subjects subsequently progress to Alzheimer's disease (AD). The prediction may be facilitated by accelerated whole brain atrophy exhibited by AD subjects. Iterative principal component analysis (IPCA) was used to characterize whole brain atrophy rates using sequential MRI scans for 102 MCI subjects from the Kuopio University Hospital. We modelled the likelihood of progression to probable AD, and found that each additional percent of annualized whole brain atrophy rate was associated with a higher odds ratio (OR) of progression (OR=1.30, p=0.01, 95% CI=1.05-1.60). Our study demonstrates an association between whole brain atrophy rate and subsequent rate of clinical progression from MCI to AD. These findings suggest that IPCA could be an effective brain-imaging marker of progression to AD and useful tool for the evaluation of disease-modifying treatments.
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| 10. |
- Vuorinen, Miika, et al.
(författare)
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Changes in vascular factors 28 years from midlife and late-life cortical thickness
- 2013
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 34:1, s. 100-109
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Tidskriftsartikel (refereegranskat)abstract
- We assessed midlife blood pressure (BP), body mass index, total cholesterol, and their changes over time in relation to cortical thickness on magnetic resonance imaging 28 years later in 63 elderly at risk of dementia. Participants in the population-based Cardiovascular Risk Factors, Aging, and Dementia study were first examined at midlife. A first follow-up was conducted after 21 years, and a second follow-up after an additional 7 years. Magnetic resonance images from the second follow-up were analyzed using algorithms developed at McGill University, Montreal, Canada. Midlife hypertension was related to thinner cortex in several brain areas, including insular, frontal, and temporal cortices. In elderly with thinner insular cortex, there was a continuous decline in systolic BP and an increase in pulse pressure after midlife, while in elderly with thicker insular cortex the decline in systolic BP started at older ages, paralleled by a decline in pulse pressure. No associations were found between body mass index, cholesterol, or apolipoprotein E ε4 allele and cortical thickness in this group of elderly at risk individuals.
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