| 1. |
- Jansen, Willemijn J, et al.
(författare)
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Prevalence Estimates of Amyloid Abnormality Across the Alzheimer Disease Clinical Spectrum.
- 2022
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Ingår i: JAMA neurology. - : American Medical Association (AMA). - 2168-6157 .- 2168-6149. ; 79:3, s. 228-243
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Tidskriftsartikel (refereegranskat)abstract
- One characteristic histopathological event in Alzheimer disease (AD) is cerebral amyloid aggregation, which can be detected by biomarkers in cerebrospinal fluid (CSF) and on positron emission tomography (PET) scans. Prevalence estimates of amyloid pathology are important for health care planning and clinical trial design.To estimate the prevalence of amyloid abnormality in persons with normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia and to examine the potential implications of cutoff methods, biomarker modality (CSF or PET), age, sex, APOE genotype, educational level, geographical region, and dementia severity for these estimates.This cross-sectional, individual-participant pooled study included participants from 85 Amyloid Biomarker Study cohorts. Data collection was performed from January 1, 2013, to December 31, 2020. Participants had normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia. Normal cognition and subjective cognitive decline were defined by normal scores on cognitive tests, with the presence of cognitive complaints defining subjective cognitive decline. Mild cognitive impairment and clinical AD dementia were diagnosed according to published criteria.Alzheimer disease biomarkers detected on PET or in CSF.Amyloid measurements were dichotomized as normal or abnormal using cohort-provided cutoffs for CSF or PET or by visual reading for PET. Adjusted data-driven cutoffs for abnormal amyloid were calculated using gaussian mixture modeling. Prevalence of amyloid abnormality was estimated according to age, sex, cognitive status, biomarker modality, APOE carrier status, educational level, geographical location, and dementia severity using generalized estimating equations.Among the 19097 participants (mean [SD] age, 69.1 [9.8] years; 10148 women [53.1%]) included, 10139 (53.1%) underwent an amyloid PET scan and 8958 (46.9%) had an amyloid CSF measurement. Using cohort-provided cutoffs, amyloid abnormality prevalences were similar to 2015 estimates for individuals without dementia and were similar across PET- and CSF-based estimates (24%; 95% CI, 21%-28%) in participants with normal cognition, 27% (95% CI, 21%-33%) in participants with subjective cognitive decline, and 51% (95% CI, 46%-56%) in participants with mild cognitive impairment, whereas for clinical AD dementia the estimates were higher for PET than CSF (87% vs 79%; mean difference, 8%; 95% CI, 0%-16%; P=.04). Gaussian mixture modeling-based cutoffs for amyloid measures on PET scans were similar to cohort-provided cutoffs and were not adjusted. Adjusted CSF cutoffs resulted in a 10% higher amyloid abnormality prevalence than PET-based estimates in persons with normal cognition (mean difference, 9%; 95% CI, 3%-15%; P=.004), subjective cognitive decline (9%; 95% CI, 3%-15%; P=.005), and mild cognitive impairment (10%; 95% CI, 3%-17%; P=.004), whereas the estimates were comparable in persons with clinical AD dementia (mean difference, 4%; 95% CI, -2% to 9%; P=.18).This study found that CSF-based estimates using adjusted data-driven cutoffs were up to 10% higher than PET-based estimates in people without dementia, whereas the results were similar among people with dementia. This finding suggests that preclinical and prodromal AD may be more prevalent than previously estimated, which has important implications for clinical trial recruitment strategies and health care planning policies.
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| 2. |
- Jansen, Willemijn J, et al.
(författare)
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Association of Cerebral Amyloid-β Aggregation With Cognitive Functioning in Persons Without Dementia.
- 2018
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Ingår i: JAMA psychiatry. - : American Medical Association (AMA). - 2168-6238 .- 2168-622X. ; 75:1, s. 84-95
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral amyloid-β aggregation is an early event in Alzheimer disease (AD). Understanding the association between amyloid aggregation and cognitive manifestation in persons without dementia is important for a better understanding of the course of AD and for the design of prevention trials.To investigate whether amyloid-β aggregation is associated with cognitive functioning in persons without dementia.This cross-sectional study included 2908 participants with normal cognition and 4133 with mild cognitive impairment (MCI) from 53 studies in the multicenter Amyloid Biomarker Study. Normal cognition was defined as having no cognitive concerns for which medical help was sought and scores within the normal range on cognitive tests. Mild cognitive impairment was diagnosed according to published criteria. Study inclusion began in 2013 and is ongoing. Data analysis was performed in January 2017.Global cognitive performance as assessed by the Mini-Mental State Examination (MMSE) and episodic memory performance as assessed by a verbal word learning test. Amyloid aggregation was measured with positron emission tomography or cerebrospinal fluid biomarkers and dichotomized as negative (normal) or positive (abnormal) according to study-specific cutoffs. Generalized estimating equations were used to examine the association between amyloid aggregation and low cognitive scores (MMSE score ≤27 or memory z score≤-1.28) and to assess whether this association was moderated by age, sex, educational level, or apolipoprotein E genotype.Among 2908 persons with normal cognition (mean [SD] age, 67.4 [12.8] years), amyloid positivity was associated with low memory scores after age 70 years (mean difference in amyloid positive vs negative, 4% [95% CI, 0%-7%] at 72 years and 21% [95% CI, 10%-33%] at 90 years) but was not associated with low MMSE scores (mean difference, 3% [95% CI, -1% to 6%], P=.16). Among 4133 patients with MCI (mean [SD] age, 70.2 [8.5] years), amyloid positivity was associated with low memory (mean difference, 16% [95% CI, 12%-20%], P<.001) and low MMSE (mean difference, 14% [95% CI, 12%-17%], P<.001) scores, and this association decreased with age. Low cognitive scores had limited utility for screening of amyloid positivity in persons with normal cognition and those with MCI. In persons with normal cognition, the age-related increase in low memory score paralleled the age-related increase in amyloid positivity with an intervening period of 10 to 15 years.Although low memory scores are an early marker of amyloid positivity, their value as a screening measure for early AD among persons without dementia is limited.
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| 3. |
- Jansen, Willemijn J, et al.
(författare)
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Prevalence of cerebral amyloid pathology in persons without dementia: a meta-analysis.
- 2015
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Ingår i: JAMA. - : American Medical Association (AMA). - 1538-3598 .- 0098-7484. ; 313:19, s. 1924-38
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral amyloid-β aggregation is an early pathological event in Alzheimer disease (AD), starting decades before dementia onset. Estimates of the prevalence of amyloid pathology in persons without dementia are needed to understand the development of AD and to design prevention studies.
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| 4. |
- Herukka, S. K., et al.
(författare)
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Amyloid-beta and Tau Dynamics in Human Brain Interstitial Fluid in Patients with Suspected Normal Pressure Hydrocephalus
- 2015
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 46:1, s. 261-269
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Tidskriftsartikel (refereegranskat)abstract
- Background: Amyloid-beta (A beta(1-42)), total tau (T-tau), and phosphorylated tau (P-tau(181)) in the cerebrospinal fluid (CSF) are the most promising biomarkers of Alzheimer's disease (AD). Still, little is known about the dynamics of these molecules in the living brain. In a transgenic mouse brain, soluble A beta decreases with increasing age and advanced A beta pathology as seen similarly in CSF. Objective: To assess the relationship between AD-related pathological changes in human brain tissue, ventricular and lumbar CSF, and brain interstitial fluid (ISF). Methods: Altogether 11 patients with suspected idiopathic normal pressure hydrocephalus underwent frontal cortical brain biopsy, 24-h intraventricular pressure monitoring, and a microdialysis procedure. AD-related biomarkers were analyzed from brain tissue, CSF, and ISF. Results: ISF T-tau levels decreased strongly within the first 12 h, then plateauing until the end of the experiment. A beta(1-42) and P-tau(181) remained stable during the experiment (n = 3). T-tau and P-tau were higher in the ISF than in ventricular or lumbar CSF, while A beta(1-42) levels were within similar range in both CSF and ISF samples. ISF P-tau correlated with the ventricular CSF T-tau (r = 0.70, p = 0.017) and P-tau(181) (r = 0.64, p = 0.034). Five patients with amyloid pathology in the brain biopsy tended to reveal lower ISF A beta(1-42) levels than those six without amyloid pathology. Conclusions: This is the first study to report ISF A beta and tau levels in the human brain without significant brain injury. The set-up used enables sampling from the brain ISF for at least 24 h without causing adverse effects due to the microdialysis procedure to follow the dynamics of the key molecules in AD pathogenesis in the living brain at various stages of the disease.
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| 5. |
- Leinonen, V., et al.
(författare)
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S- F-18 THK-5117-PET and C-11 PIB-PET Imaging in Idiopathic Normal Pressure Hydrocephalus in Relation to Confirmed Amyloid-beta Plaques and Tau in Brain Biopsies
- 2018
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 64:1, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- Background: Detection of pathological tau aggregates could facilitate clinical diagnosis of Alzheimer's disease (AD) and monitor drug effects in clinical trials. S-[F-18] THK-5117 could be a potential tracer to detect pathological tau deposits in brain. However, no previous study have correlated S-[F-18] THK-5117 uptake in PET with brain biopsy verified tau pathology in vivo. Objective: Here we aim to evaluate the association between cerebrospinal fluid (CSF) AD biomarkers, S-[F-18] THK-5117, and [C-11] PIB PET against tau and amyloid lesions in brain biopsy. Methods: Fourteen patients with idiopathic normal pressure hydrocephalus (iNPH) with previous shunt surgery including right frontal cortical brain biopsy and CSF A beta(1-42), total tau, and P-tau(181) measures, underwent brain MRI, [C-11] PIB PET, and S-[F-18] THK-5117 PET imaging. Results: Seven patients had amyloid-beta(A beta, 4G8) plaques, two both A beta and phosphorylated tau (P tau, AT8) and one only P tau in biopsy. As expected, increased brain biopsy A beta was well associated with higher [C-11] PIB uptake in PET. However, S-[F-18] THK-5117 uptake did not show any statistically significant correlation with either brain biopsy P tau or CSF P-tau(181) or total tau. Conclusions: S-[F-18] THK-5117 lacked clear association with neuropathologically verified tau pathology in brain biopsy probably, at least partially, due to off-target binding. Further studies with larger samples of patients with different tau tracers are urgently needed. The detection of simultaneous A beta and tau pathology in iNPH is important since that may indicate poorer and especially shorter response for CSF shunt surgery compared with no pathology.
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| 6. |
- Oliveira, F., et al.
(författare)
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Data driven diagnostic classification in Alzheimer's disease based on different reference regions for normalization of PiB-PET images and correlation with CSF concentrations of A beta species
- 2018
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Ingår i: Neuroimage-Clinical. - : Elsevier BV. - 2213-1582. ; 20, s. 603-610
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Tidskriftsartikel (refereegranskat)abstract
- Positron emission tomography (PET) neuroimaging with the Pittsburgh Compound_B (PiB) is widely used to assess amyloid plaque burden. Standard quantification approaches normalize PiB-PET by mean cerebellar gray matter uptake. Previous studies suggested similar pons and white-matter uptake in Alzheimer's disease (AD) and healthy controls (HC), but lack exhaustive comparison of normalization across the three regions, with data-driven diagnostic classification. We aimed to compare the impact of distinct reference regions in normalization, measured by data-driven statistical analysis, and correlation with cerebrospinal fluid (CSF) amyloid beta (A beta) species concentrations. 243 individuals with clinical diagnosis of AD, HC, mild cognitive impairment (MCI) and other dementias, from the Biomarkers for Alzheimer's/Parkinson's Disease (BIOMARKAPD) initiative were included. PiB-PET images and CSF concentrations of A beta(38), A beta(40) and A beta(42) were submitted to classification using support vector machines. Voxel-wise group differences and correlations between normalized PiB-PET images and CSF A beta concentrations were calculated. Normalization by cerebellar gray matter and pons yielded identical classification accuracy of AD (accuracy-96%, sensitivity-96%, specificity-95%), and significantly higher than A beta concentrations (best accuracy 91%). Normalization by the white-matter showed decreased extent of statistically significant multivoxel patterns and was the only method not outperforming CSF biomarkers, suggesting statistical inferiority. A beta(38) and A beta(40) correlated negatively with PiB-PET images normalized by the white-matter, corroborating previous observations of correlations with non-AD-specific subcortical changes in white-matter. In general, when using the pons as reference region, higher voxel-wise group differences and stronger correlation with A beta(42), the A beta(42)/A beta(40) or A beta(42)/A beta(38) ratios were found compared to normalization based on cerebellar gray matter.
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| 7. |
- Seppala, T. T., et al.
(författare)
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CSF biomarkers for Alzheimer disease correlate with cortical brain biopsy findings
- 2012
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Ingår i: Neurology. - 0028-3878 .- 1526-632X. ; 78:20, s. 1568-1575
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To assess the relationship between Alzheimer disease (AD)-related pathologic changes in frontal cortical brain biopsy and AD biomarkers in ventricular vs lumbar CSF, and to evaluate the relationships of AD biomarkers in CSF and cortical biopsy with the final clinical diagnosis of AD. Methods: In 182 patients with presumed normal pressure hydrocephalus (152 with known APOE carrier status), A beta plaques and tau in the cortical brain biopsies were correlated with the ventricular and lumbar CSF A beta 42, total tau, and p-tau levels measured by ELISA. In a median follow-up of 2.0 years, 51 patients developed AD dementia. Results: The patients with A beta 42 plaques in the cortical biopsy had lower (p = 0.009) CSF A beta 42 levels than those with no A beta plaques. The patients with tau in the cortical biopsy had lower (p = 0.014) A beta 42 but higher (p = 0.015) p-tau 181 in CSF as compared to those with no tau in the cortical biopsy. The patients with amyloid + tau + biopsies had the lowest A beta 42 and highest tau and p-tau 181 levels in CSF. The A beta 42 levels were lower and the tau and p-tau 181 higher in the ventricular vs corresponding lumbar CSF samples. In multivariate analysis, the presence of cortical A beta was independently predicted by the APOE epsilon 4 carrier status and age but not by CSF A beta 42 or tau levels. Conclusions: Amyloid plaques and hyperphosphorylated tau in cortical brain biopsies are reflected by low CSF A beta 42 and high CSF tau and p-tau levels, respectively. Neurology (R) 2012;78:1568-1575
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| 8. |
- Snellman, Anniina, et al.
(författare)
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APOE epsilon 4 gene dose effect on imaging and blood biomarkers of neuroinflammation and beta-amyloid in cognitively unimpaired elderly
- 2023
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Ingår i: Alzheimers Research & Therapy. - 1758-9193. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundNeuroinflammation, characterized by increased reactivity of microglia and astrocytes in the brain, is known to be present at various stages of the Alzheimer's disease (AD) continuum. However, its presence and relationship with amyloid pathology in cognitively normal at-risk individuals is less clear. Here, we used positron emission tomography (PET) and blood biomarker measurements to examine differences in neuroinflammation and beta-amyloid (A beta) and their association in cognitively unimpaired homozygotes, heterozygotes, or non-carriers of the APOE epsilon 4 allele, the strongest genetic risk for sporadic AD.MethodsSixty 60-75-year-old APOE epsilon 4 homozygotes (n = 19), heterozygotes (n = 21), and non-carriers (n = 20) were recruited in collaboration with the local Auria biobank. The participants underwent C-11-PK11195 PET (targeting 18-kDa translocator protein, TSPO), C-11-PiB PET (targeting A beta), brain MRI, and neuropsychological testing including a preclinical cognitive composite (APCC). C-11-PK11195 distribution volume ratios and C-11-PiB standardized uptake value ratios (SUVRs) were calculated for regions typical for early A beta accumulation in AD. Blood samples were drawn for measuring plasma glial fibrillary acidic protein (GFAP) and plasma A beta(1-42/1.40).ResultsIn our cognitively unimpaired sample, cortical C-11-PiB-binding increased according to APOE epsilon 4 gene dose (median composite SUVR 1.47 (range 1.38-1.66) in non-carriers, 1.55 (1.43-2.02) in heterozygotes, and 2.13 (1.61-2.83) in homozygotes, P = 0.002). In contrast, cortical composite C-11-PK11195-binding did not differ between the APOE epsilon 4 gene doses (P = 0.27) or between A beta-positive and A beta-negative individuals (P = 0.81) and associated with higher A beta burden only in APOE epsilon 4 homozygotes (Rho = 0.47, P = 0.043). Plasma GFAP concentration correlated with cortical C-11-PiB (Rho = 0.35, P = 0.040), but not C-11-PK11195-binding (Rho = 0.13, P = 0.47) in A beta-positive individuals. In the total cognitively unimpaired population, both higher composite C-11-PK11195-binding and plasma GFAP were associated with lower hippocampal volume, whereas elevated C-11-PiB-binding was associated with lower APCC scores.ConclusionsOnly A beta burden measured by PET, but not markers of neuroinflammation, differed among cognitively unimpaired elderly with different APOE epsilon 4 gene dose. However, APOE epsilon 4 gene dose seemed to modulate the association between neuroinflammation and A beta.
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| 9. |
- Snellman, Anniina, et al.
(författare)
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ASIC-E4: Interplay of Beta-Amyloid, Synaptic Density and Neuroinflammation in Cognitively Normal Volunteers With Three Levels of Genetic Risk for Late-Onset Alzheimer's Disease - Study Protocol and Baseline Characteristics
- 2022
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background:& nbsp;Detailed characterization of early pathophysiological changes in preclinical Alzheimer's disease (AD) is necessary to enable development of correctly targeted and timed disease-modifying treatments. ASIC-E4 study ( "Beta-Amyloid, Synaptic loss, Inflammation and Cognition in healthy APOE epsilon 4 carriers ") combines state-of-the-art neuroimaging and fluid-based biomarker measurements to study the early interplay of three key pathological features of AD, i.e., beta-amyloid (A beta) deposition, neuroinflammation and synaptic dysfunction and loss in cognitively normal volunteers with three different levels of genetic (APOE-related) risk for late-onset AD.& nbsp;Objective:& nbsp;Here, our objective is to describe the study design, used protocols and baseline demographics of the ASIC-E4 study.& nbsp;Methods/Design:& nbsp;ASIC-E4 is a prospective observational multimodal imaging study performed in Turku PET Centre in collaboration with University of Gothenburg. Cognitively normal 60-75-year-old-individuals with known APOE epsilon 4/epsilon 4 genotype were recruited via local Auria Biobank (Turku, Finland). Recruitment of the project has been completed in July 2020 and 63 individuals were enrolled to three study groups (Group 1: APOE epsilon 4/epsilon 4, N = 19; Group 2: APOE epsilon 4/epsilon 3, N = 22; Group 3: APOE epsilon 3/epsilon 3, N = 22). At baseline, all participants will undergo positron emission tomography imaging with tracers targeted against A beta deposition (C-11-PIB), activated glia (C-11-PK11195) and synaptic vesicle glycoprotein 2A (C-11-UCB-J), two brain magnetic resonance imaging scans, and extensive cognitive testing. In addition, blood samples are collected for various laboratory measurements and blood biomarker analysis and cerebrospinal fluid samples are collected from a subset of participants based on additional voluntary informed consent. To evaluate the predictive value of the early neuroimaging findings, neuropsychological evaluation and blood biomarker measurements will be repeated after a 4-year follow-up period.& nbsp;Discussion:& nbsp;Results of the ASIC-E4 project will bridge the gap related to limited knowledge of the synaptic and inflammatory changes and their association with each other and A beta in "at-risk " individuals. Thorough in vivo characterization of the biomarker profiles in this population will produce valuable information for diagnostic purposes and future drug development, where the field has already started to look beyond A beta.
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| 10. |
- Snellman, Anniina, et al.
(författare)
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Head-to-head comparison of plasma p-tau181, p-tau231 and glial fibrillary acidic protein in clinically unimpaired elderly with three levels of APOE4-related risk for Alzheimer's disease
- 2023
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Ingår i: Neurobiology of Disease. - 0969-9961. ; 183
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Tidskriftsartikel (refereegranskat)abstract
- Plasma phosphorylated tau (p-tau) and glial fibrillary acidic protein (GFAP) both reflect early changes in Alzheimer's disease (AD) pathology. Here, we compared the biomarker levels and their association with regional S-amyloid (AS) pathology and cognitive performance head-to-head in clinically unimpaired elderly (n = 88) at three levels of APOE4-related genetic risk for sporadic AD (APOE4/4 n = 19, APOE3/4 n = 32 or non-carriers n = 37). Concentrations of plasma p-tau181, p-tau231 and GFAP were measured using Single molecule array (Simoa), regional AS deposition with 11C-PiB positron emission tomography (PET), and cognitive performance with a preclinical composite. Significant differences in plasma p-tau181 and p-tau231, but not plasma GFAP concentrations were present between the APOE4 gene doses, explained solely by brain AS load. All plasma biomarkers correlated positively with AS PET in the total study population. This correlation was driven by APOE3/3 carriers for plasma p-tau markers and APOE4/4 carriers for plasma GFAP. Voxel-wise associations with amyloid-PET revealed different spatial patterns for plasma p-tau markers and plasma GFAP. Only higher plasma GFAP correlated with lower cognitive scores. Our observations suggest that plasma p-tau and plasma GFAP are both early AD markers reflecting different AS-related processes.
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