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- Pilla, Rachel M., et al.
(författare)
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Deeper waters are changing less consistently than surface waters in a global analysis of 102 lakes
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either surface water temperatures or thermal stability within lakes, and only 8.4% was explained by lake thermal region or local lake characteristics in a random forest analysis. These findings suggest that external drivers beyond our tested lake characteristics are important in explaining long-term trends in thermal structure, such as local to regional climate patterns or additional external anthropogenic influences.
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- Pilla, Rachel M., et al.
(författare)
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Global data set of long-term summertime vertical temperature profiles in 153 lakes
- 2021
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Ingår i: Scientific Data. - : Springer Nature. - 2052-4463. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of lake thermal structure in a time of rapid global and ecological change.
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- Siafarikas, N., et al.
(författare)
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Cerebrospinal fluid markers for synaptic function and Alzheimer type changes in late life depression
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- To explore markers for synaptic function and Alzheimer disease (AD) pathology in late life depression (LLD), predementia AD and normal controls (NC). A cross-sectional study to compare cerebrospinal fluid (CSF) levels of neurogranin (Ng), Beta-site amyloid-precursor-protein cleaving enzyme1 (BACE1), Ng/BACE1 ratio and Amyloid-beta 42/40 ratio, phosphorylated-tau and total-tau in LLD with (LLD AD) or without (LLD NoAD) AD pathology, predementia AD and normal controls (NC). We included 145 participants (NC = 41; predementia AD = 66 and LLD = 38). LLD comprised LLD AD (n = 16), LLD NoAD (n = 19), LLD with non-AD typical changes (n = 3, excluded). LLD AD (p(ADJ) < 0.05) and predementia AD (p(ADJ) < 0.0001) showed significantly higher Ng than NC. BACE1 and Ng/BACE1 ratio were altered similarly. Compared to LLD NoAD, LLD AD showed significantly higher Ng (p(ADJ) < 0.001), BACE1 (p(ADJ) < 0.05) and Ng/BACE1 ratio (p(ADJ) < 0.01). All groups had significantly lower A beta 42/40 ratio than NC (predementia AD and LLD AD, p < 0.0001; LLD NoAD, p < 0.05). Both LLD groups performed similarly on tests of memory and executive function, but significantly poorer than NC. Synaptic function in LLD depended on AD pathology. LLD showed an association to Amyloid dysmetabolism. The LLD groups performed poorer cognitively than NC. LLD AD may be conceptualized as "predementia AD with depression".
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- Eliassen, I. V., et al.
(författare)
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Predictive and diagnostic utility of brief neuropsychological assessment in detecting Alzheimer's pathology and progression to dementia
- 2020
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Ingår i: Neuropsychology. - : American Psychological Association (APA). - 1931-1559 .- 0894-4105. ; 34:8, s. 851-861
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To assess the role of brief neuropsychological assessments in prediction and identification of Alzheimer's disease (AD) pathology and progression to AD dementia. Method: Adults (N = 255; range = 40-81 years) with self-reported cognitive decline underwent baseline and 2-year follow-up clinical assessment, including a brief neuropsychological screening and lumbar puncture. Five different mild cognitive impairment (MCI) algorithms were applied on baseline cognitive test results: one conventional, three amnestic (lenient, stringent, multidomain), and one comprehensive criterion. We compared predictive and diagnostic accuracy of these MCI criteria by performing logistic regression analyses and calculating diagnostic accuracy measures for 2-year outcomes of (1) clinical diagnosis of AD dementia and (2) cerebrospinal fluid biomarkers in the Alzheimer's continuum. Results: The lenient amnestic MCI criterion showed the largest effect size for predicting progression to AD dementia (OR = 13.762, 99% CI = 1.969-96.194, p = .001) and AD biomarkers (OR = 4.855, 99% CI = 1.974-11.924, p < .001) after 2 years. This criterion was sensitive for progression to dementia (sensitivity = 92.0%, specificity = 54.8%, positive likelihood ratio [LR+] = 2.03, LR- = 0.15) and showed the highest overall diagnostic accuracy for AD biomarkers (sensitivity = 72.7%, specificity = 59.1%, LR+ = 1.78, negative likelihood ratio [LR-] = 0.46). The multidomain amnestic MCI criterion produced the highest specificity for dementia (sensitivity = 76.0%, specificity = 73.0%, LR+ = 2.82, LR- = 0.33) and AD biomarkers (sensitivity = 46.8% specificity = 70.9% LR+ = 1.61, LR- = 0.75). Conclusions: Defining MCI using a brief neuropsychological battery provided limited accuracy for progression to AD dementia and cerebrospinal fluid Aβ. The lenient amnestic MCI criterion identified the highest number of individuals who progressed to clinical AD or showed biomarker pathology, but this approach included a substantial number of false positives. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
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- Espenes, J., et al.
(författare)
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Demographically adjusted trail making test norms in a Scandinavian sample from 41 to 84 years
- 2020
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Ingår i: Clinical Neuropsychologist. - : Informa UK Limited. - 1385-4046 .- 1744-4144. ; 34:suppl. 1, s. 110-126
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Tidskriftsartikel (refereegranskat)abstract
- Objective The trail making test (TMT) is one of the most widely used neuropsychological tests. TMT-A provides measures of visual scanning/visuomotor speed and TMT-B involves additional demands on executive functions. Derived scores TMT B-A and TMT B/A enhance measures of executive functioning. However, simple B-A subtraction may lead to false estimates of executive dysfunction in clinical samples. Norms for TMT have been published in several countries but are currently lacking for Scandinavia. Methods A total of 292 healthy controls between age 41 and 84 years were included from the Norwegian "Dementia Disease Initiation" (DDI) study (n = 170) and the Gothenburg Mild Cognitive Impairment (MCI) study (n = 122). We used a regression-based procedure to develop demographically adjusted norms for basic (TMT-A and TMT-B) and derived measures (TMT B-A and B/A). We also propose a regression-based alternative to the TMT B-A measure named "TMT-beta". The proposed norms were compared to norms from Heaton et al. and Tombaugh. Results Due to differences in the estimated normative effects of demographics on performance, the proposed norms for TMT were better suited in the Scandinavian sample compared with published non-Scandinavian norms. The proposed TMT-beta measure was highly correlated to TMT B-A (r = 0.969,p < 0.001). Conclusion We here propose demographically adjusted norms for the TMT for ages 41 through 84 years based on a Scandinavian sample. We also present the regression-based derived measure TMT-beta which may resolve issues with the conventional TMT B-A measure.
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| 11. |
- Espenes, J., et al.
(författare)
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Regression-based normative data for the Rey Auditory Verbal Learning Test in Norwegian and Swedish adults aged 49-79 and comparison with published norms
- 2023
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Ingår i: Clinical Neuropsychologist. - : Informa UK Limited. - 1385-4046 .- 1744-4144. ; 37:6, s. 1276-1301
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The Rey Auditory Verbal Learning Test (RAVLT) is a widely used measure of episodic verbal memory. To our knowledge, culturally adapted and demographically adjusted norms for the RAVLT are currently not available for Norwegian and Swedish adults, and imported North American norms are often used. We here develop regression-based norms for Norwegian and Swedish adults and compare our norms to North American norms in an independent sample of cognitively healthy adults. Method: Participants were 244 healthy adults from Norway and Sweden between the aged 49 and 79 years, with between 6 and 24 years of education. Using a multiple multivariate regression-based norming procedure, we estimated effects of age, sex, and years of education on basic and derived RAVLT test scores. The newly developed norms were assessed in an independent comparison group of cognitively healthy adults (n = 145) and compared to recently published North American regression-based norms. Results: Lower age, female sex and more years of education predicted higher performance on the RAVLT. The new norms adequately adjusted for age, education, and sex in the independent comparison group. The American norms corrected for demographics on all RAVLT trials except trials 4, 7, list B, and trials 1-5 total. Test-retest (M = 2.55 years) reliability varied from poor to good. Conclusion: We propose regression-based norms for the RAVLT adjusting for pertinent demographics. The norms may be used for assessment of Norwegian and Swedish adults between the aged of 49 and 79 years, with between 6 and 24 years of education.
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- Grambaite, R, et al.
(författare)
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Correlates of Subjective and Mild Cognitive Impairment: Depressive Symptoms and CSF Biomarkers
- 2013
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Ingår i: Dementia and geriatric cognitive disorders extra. - : S. Karger AG. - 1664-5464. ; 3:1, s. 291-300
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Tidskriftsartikel (refereegranskat)abstract
- <b><i>Aims:</i></b> To improve early diagnosis of dementia disease, this study investigates correlates of cognitive complaints and cognitive test performance in patients with subjective (SCI) and mild (MCI) cognitive impairment. <b><i>Methods:</i></b> Seventy patients from a memory clinic, aged 45-79, with a score of 2 (n = 23) or 3 (n = 47) on the Global Deterioration Scale, were included. CSF biomarkers [Aβ<sub>42</sub>, total tau (T-tau) and phosphorylated tau (P-tau)], depressive symptoms, cognitive performance, and complaints were examined. <b><i>Results:</i></b> Correlation analysis showed that cognitive complaints increased with decreasing cognitive performance in SCI and decreased with decreasing performance in MCI. Linear regression models revealed that cognitive complaints were associated with depressive symptoms in both groups of patients, while cognitive performance was associated with CSF Aβ<sub>42</sub> and P-tau in SCI and with T-tau and P-tau in MCI. <b><i>Conclusion:</i></b> These results suggest that depressive symptoms are associated with cognitive complaints, while degenerative changes are associated with objective cognitive decline in high-risk predementia states.
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| 20. |
- Stav, AL, et al.
(författare)
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Hippocampal subfield atrophy in relation to cerebrospinal fluid biomarkers and cognition in early Parkinson's disease: a cross-sectional study
- 2016
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Ingår i: NPJ Parkinson's disease. - : Springer Science and Business Media LLC. - 2373-8057. ; 2, s. 15030-
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Tidskriftsartikel (refereegranskat)abstract
- Cognition is often affected early in Parkinson’s disease (PD). Lewy body and amyloid β (Aβ) pathology and cortical atrophy may be involved. The aim of this study was to examine whether medial temporal lobe structural changes may be linked to cerebrospinal fluid (CSF) biomarker levels and cognition in early PD. PD patients had smaller volumes of total hippocampus, presubiculum, subiculum, CA2–3, CA4-DG, and hippocampal tail compared with normal controls (NCs). In the PD group, lower CSF Aβ38 and 42 were significant predictors for thinner perirhinal cortex. Lower Aβ42 and smaller presubiculum and subiculum predicted poorer verbal learning and delayed verbal recall. Smaller total hippocampus, presubiculum and subiculum predicted poorer visuospatial copying. Lower Aβ38 and 40 and thinner perirhinal cortex predicted poorer delayed visual reproduction. In conclusion, smaller volumes of hippocampal subfields and subhippocampal cortex thickness linked to lower CSF Aβ levels may contribute to cognitive impairment in early PD. Thirty-three early PD patients (13 without, 5 with subjective, and 15 with mild cognitive impairment) and NC had 3 T magnetic resonance imaging (MRI) scans. The MRI scans were post processed for volumes of hippocampal subfields and entorhinal and perirhinal cortical thickness. Lumbar puncture for CSF biomarkers Aβ38, 40, 42, total tau, phosphorylated tau (Innogenetics), and total α-synuclein (Meso Scale Diagnostics) were performed. Multiple regression analyses were used for between-group comparisons of the MRI measurements in the NC and PD groups and for assessment of CSF biomarkers and neuropsychological tests in relation to morphometry in the PD group.
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- Creed, Irena F., et al.
(författare)
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Global change-driven effects on dissolved organic matter composition : Implications for food webs of northern lakes
- 2018
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 24:8, s. 3692-3714
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Forskningsöversikt (refereegranskat)abstract
- Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.
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- Grontvedt, GR, et al.
(författare)
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Association of Klotho Protein Levels and KL-VS Heterozygosity With Alzheimer Disease and Amyloid and Tau Burden
- 2022
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Ingår i: JAMA network open. - : American Medical Association (AMA). - 2574-3805. ; 5:11, s. e2243232-
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Tidskriftsartikel (refereegranskat)abstract
- Identification of proteins and genetic factors that reduce Alzheimer disease (AD) pathology is of importance when searching for novel AD treatments. Heterozygosity of the KL-VS haplotype has been associated with reduced amyloid and tau burden. Whether this association is mediated by the Klotho protein remains unclear.ObjectivesTo assess concentrations of Klotho in cerebrospinal fluid (CSF) and plasma among cognitively healthy controls and patients with AD and to correlate these findings with KL-VS heterozygosity status and amyloid and tau burden.Design, Setting, and ParticipantsThis case-control study combined 2 independent case-control AD cohorts consisting of 243 referred patients with AD and volunteer controls recruited from January 1, 2009, to December 31, 2018. Klotho levels were measured in CSF and plasma and correlated with KL-VS heterozygosity status and levels of CSF amyloid-β 42 (Aβ42), total tau, and phosphorylated tau. Statistical analysis was performed from January 1, 2021, to March 1, 2022.Main Outcomes and MeasuresAssociations of Klotho levels in CSF and plasma with levels of CSF biomarkers were analyzed using linear regression. Association analyses were stratified separately by clinical groups, APOE4 status, and KL-VS heterozygosity. Pearson correlation was used to assess the correlation between CSF and plasma Klotho levels.ResultsA total of 243 participants were included: 117 controls (45 men [38.5%]; median age, 65 years [range, 41-84 years]), 102 patients with mild cognitive impairment due to AD (AD-MCI; 59 men [57.8%]; median age, 66 years [range, 46-80 years]), and 24 patients with dementia due to AD (AD-dementia; 12 men [50.0%]; median age, 64.5 years [range, 54-75 years]). Median CSF Klotho levels were higher in controls (1236.4 pg/mL [range, 20.4-1726.3 pg/mL]; β = 0.103; 95% CI, 0.023-0.183; P = .01) and patients with AD-MCI (1188.1 pg/mL [range, 756.3-1810.3 pg/mL]; β = 0.095; 95% CI, 0.018-0.172; P = .02) compared with patients with AD-dementia (1073.3 pg/mL [range, 698.2-1661.4 pg/mL]). Higher levels of CSF Klotho were associated with lower CSF Aβ42 burden (β = 0.519; 95% CI, 0.201-0.836; P &lt; .001) and tau burden (CSF total tau levels: β = −0.884; 95% CI, 0.223 to −0.395; P &lt; .001; CSF phosphorylated tau levels: β = −0.672; 95% CI, −1.022 to −0.321; P &lt; .001) independent of clinical, KL-VS heterozygosity, or APOE4 status. There was a weak correlation between Klotho CSF and plasma levels among the entire cohort (Pearson correlation r = 0.377; P &lt; .001).Conclusions and RelevanceThe findings of this case-control study suggest that Klotho protein levels were associated with clinical stages of AD, cognitive decline, and amyloid and tau burden and that these outcomes were more clearly mediated by the protein directly rather than the KL-VS heterozygosity variant. When selecting individuals at risk for clinical trials, the Klotho protein level and not only the genetic profile should be considered.
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