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INTRODUCTION: We developed and validated a clinically applicable decision tree for the use of cerebrospinal fluid biomarkers in the diagnosis of Alzheimer's disease (AD). METHODS: Subjects with probable AD (n = 1004) and controls (n = 442) were included. A decision tree was modeled using Classification And Regression Tree analysis in a training cohort (AD n = 221; controls n = 221) and validated in an independent cohort (AD n = 783; controls n = 221). Diagnostic performance was compared to previously defined cutoffs (amyloid ß 1-42 < 813 pg/ml; tau>375 pg/ml). RESULTS: Two cerebrospinal fluid AD biomarker profiles were revealed: the "classical" AD biomarker profile (amyloid ß 1-42: 647-803 pg/ml; tau >374 pg/ml) and an "atypical" AD biomarker profile with strongly decreased amyloid ß 1-42 (<647 pg/ml) and normal tau concentrations (<374 pg/ml). Compared to previous cutoffs, the decision tree performed better on diagnostic accuracy (86% [84-88] vs 80% [78-83]). DISCUSSION: Two cerebrospinal fluid AD biomarker profiles were identified and incorporated in a readily applicable decision tree, which improved diagnostic accuracy.
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INTRODUCTION: To improve the detection of changes in Alzheimer's disease (AD), we designed the cognitive-functional composite (CFC). As a first validation step, we investigated its test-retest reliability and feasibility of use. METHODS: We performed a test-retest study with 2-3 weeks between assessments, including patients with mild cognitive impairment (MCI) or mild AD dementia and cognitively healthy participants. We calculated intraclass correlation coefficients (ICCs) type absolute agreement for all CFC measures and compared baseline and retest scores using paired-samples t-tests. We evaluated feasibility by interviewing participants. RESULTS: Forty-three patients (40% female, mean age = 69.9) and 30 controls (50% female, mean age = 65) were included. Subtest intraclass correlation coefficients ranged from .70 to .96. We found negligible improvements after retesting on only two subtests. Overall, patients perceived the administration of the CFC as feasible. DISCUSSION: The CFC is a stable and feasible measure in MCI and mild AD dementia, and thereby meets important quality metrics for clinically meaningful outcome measures.
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INTRODUCTION: This study explores clinicians' views on and experiences with when, how, and by whom decisions about diagnostic testing for Alzheimer's disease are made and how test results are discussed with patients. METHODS: Following a preparatory focus group with 13 neurologists and geriatricians, we disseminated an online questionnaire among 200 memory clinic clinicians. RESULTS: Respondents were 95 neurologists and geriatricians (response rate 47.5%). Clinicians (74%) indicated that decisions about testing are made before the first encounter, yet they favored a shared decision-making approach. Patient involvement seems limited to receiving information. Clinicians with less tolerance for uncertainty preferred a bigger say in decisions (P < .05). Clinicians indicated to always communicate the diagnosis (94%), results of different tests (88%-96%), and risk of developing dementia (66%). DISCUSSION: Clinicians favor patient involvement in deciding about diagnostic testing, but conversations about decisions and test results can be improved and supported.
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INTRODUCTION: This study aims to assess patients' and caregivers' views on and experiences with (1) decisions about diagnostic testing for Alzheimer's disease (AD) and (2) receiving test results. METHODS: We conducted separate focus groups with patients from three hospitals who underwent diagnostic testing for AD (N = 11) and their caregivers (N = 11). Audio recordings were transcribed verbatim and analyzed using MaxQDA. RESULTS: Patients and caregivers preferred and perceived active involvement in decision making, but the decision to initiate diagnostic testing seems to be made before the clinician-patient encounter. Patients and caregivers indicate that decisions are driven by a strong need to explain the patient's symptoms. They missed information on why different diagnostic tests were used, what the results of these tests were, and to what extent these results were (ab)normal. DISCUSSION: The decision-making process around diagnostic testing for AD and the information provision before and after diagnostic testing could be improved.
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INTRODUCTION: The Alzheimer's biomarkers in daily practice (ABIDE) project is designed to translate knowledge on diagnostic tests (magnetic resonance imaging [MRI], cerebrospinal fluid [CSF], and amyloid positron emission tomography [PET]) to daily clinical practice with a focus on mild cognitive impairment (MCI). METHODS: ABIDE is a 3-year project with a multifaceted design and is structured into interconnected substudies using both quantitative and qualitative research methods. RESULTS: Based on retrospective data, we develop personalized risk estimates for MCI patients. Prospectively, we collect MRI and CSF data from 200 patients from local memory clinics and amyloid PET from 500 patients in a tertiary setting, to optimize application of these tests in daily practice. Furthermore, ABIDE will develop strategies for optimal patient-clinician conversations. DISCUSSION: Ultimately, this will result in a set of practical tools for clinicians to support the choice of diagnostic tests and facilitate the interpretation and communication of their results.
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OBJECTIVE: Hyperglycemia-associated microvascular disease may underlie changes in cerebral functioning and cognitive performance in patients with type 1 diabetes. Functional connectivity, an indicator of functional interactions and information exchange between brain regions, provides a measure of cerebral functioning. This study addresses functional connectivity and cognition in type 1 diabetic patients with and without proliferative retinopathy, relative to healthy control subjects, using magnetoencephalography. RESEARCH DESIGN AND METHODS: Fluctuations in magnetic field at scalp for Delta, theta, lower and upper alpha, beta, and lower and upper gamma frequency bands were measured using magnetoencephalography. Synchronization likelihood, a measure of functional connectivity, was computed. Using neuropsychological tests, cognitive functioning was assessed and its associations with functional connectivity were determined. RESULTS: Compared with control subjects, type 1 diabetic patients performed poorer on general cognitive ability, information processing speed, and motor speed, irrespective of their microvascular complication status. Functional connectivity, however, was lowest for type 1 diabetic patients with retinopathy, compared with type 1 diabetic patients without microvascular complications and control subjects, whereas type 1 diabetic patients without microvascular complications showed an increase relative to control subjects. Positive associations were found between functional connectivity and executive functioning, memory, information processing speed, motor speed, and attention. CONCLUSIONS: Compared with healthy control subjects, functional connectivity and cognition differed in type 1 diabetic patients irrespective of microvascular complication status, indicating that chronic hyperglycemia, among other factors, may negatively affect brain functioning even before microvascular damage becomes manifest. The association found between synchronization likelihood and cognition suggests functional connectivity plays a significant role in cognitive functioning.
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Encéfalo/fisiopatologia , Cognição/fisiologia , Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 1/psicologia , Angiopatias Diabéticas/fisiopatologia , Memória/fisiologia , Adulto , Análise de Variância , Encéfalo/fisiologia , Diabetes Mellitus Tipo 1/patologia , Angiopatias Diabéticas/patologia , Angiopatias Diabéticas/psicologia , Escolaridade , Feminino , Lobo Frontal/patologia , Lobo Frontal/fisiologia , Lobo Frontal/fisiopatologia , Lateralidade Funcional , Humanos , Inteligência , Magnetoencefalografia/métodos , Masculino , Pessoa de Meia-Idade , Lobo Occipital/patologia , Lobo Occipital/fisiologia , Lobo Occipital/fisiopatologia , Lobo Parietal/patologia , Lobo Parietal/fisiologia , Lobo Parietal/fisiopatologia , Valores de ReferênciaRESUMO
OBJECTIVE: The aim of this study was to demonstrate the involvement of the inflammatory proteins IL-6, ACT and CRP early in the pathology process of AD in patients with mild cognitive impairment (MCI) and AD. METHODS: IL-6, ACT, CRP, Abeta42, phospho-tau (p-tau) and total tau concentrations in serum and CSF of 145 patients with probable AD and 67 patients with MCI were measured by sandwich ELISA. MCI patients were characterized as high- respectively low-risk MCI according to their Abeta42/tau risk profile. RESULTS: CSF and serum CRP levels were significantly higher in MCI compared to AD patients after adjustment for age, ApoE epsilon4 genotype and cardiovascular diseases (p<0.01). This difference remained present in patients with a low-risk biomarker profile for AD after adjustment for abovementioned covariates. CSF IL-6 levels were also significantly higher in MCI patients with a low-risk CSF profile. CONCLUSIONS: These findings suggest that inflammatory processes might be involved in early stages of AD, even before Abeta and tau changes are present in CSF of MCI patients.
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Doença de Alzheimer , Transtornos Cognitivos , Idoso , Doença de Alzheimer/sangue , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/complicações , Peptídeos beta-Amiloides/metabolismo , Análise de Variância , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Proteína C-Reativa/metabolismo , Transtornos Cognitivos/sangue , Transtornos Cognitivos/líquido cefalorraquidiano , Transtornos Cognitivos/complicações , Ensaio de Imunoadsorção Enzimática , Feminino , Seguimentos , Humanos , Interleucina-6/metabolismo , Masculino , Pessoa de Meia-Idade , Fragmentos de Peptídeos/metabolismo , Estudos Retrospectivos , alfa 1-Antitripsina/metabolismo , Proteínas tau/metabolismoRESUMO
OBJECTIVE: To compare CSF levels of beta-amyloid 1-42 (Abeta(1-42)), total tau (tau) and tau phosphorylated at threonine 181 (ptau-181) between AD patients and controls according to age. METHODS: 248 AD patients (48% men) and 127 controls (51% men, 22 volunteers and 105 subjective complainers) underwent lumbar puncture. Both patients and controls were divided into a young (<65 years) and old (>or=65 years) group. RESULTS: All three biomarkers showed main effects of diagnosis (p<0.001). There was an interaction between diagnosis and age for all three biomarkers (p<0.05), as old controls had lower Abeta(1-42) and higher (p)tau than young controls (Abeta(1-42) 699+/-250 versus 866+/-191pg/ml, tau 408+/-245 versus 243+/-102pg/ml, ptau-181 60+/-28 versus 42+/-15pg/ml), but there was no difference according to age among AD patients (Abeta(1-42) 451+/-178 versus 425+/-146pg/ml, tau 741+/-460 versus 798+/-467pg/ml, ptau-181 91+/-42 versus 91+/-41pg/ml). CONCLUSION: We found that the older control group had lower Abeta(1-42) and higher (p)tau compared to the younger control group. This suggests that older individuals may have AD pathology, even in the absence of objective cognitive impairment.
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Envelhecimento/líquido cefalorraquidiano , Doença de Alzheimer/líquido cefalorraquidiano , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Proteínas tau/líquido cefalorraquidiano , Fatores Etários , Idade de Início , Idoso , Análise de Variância , Biomarcadores/líquido cefalorraquidiano , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Fosforilação , Escalas de Graduação Psiquiátrica , Punção Espinal , Proteínas tau/metabolismoRESUMO
BACKGROUND: Decreased amyloid beta (1-42) (Abeta42) and increased (phosphorylated) tau in cerebrospinal fluid (CSF) are considered to be a reflection of plaques, tangles, and neuronal degeneration in Alzheimer's disease (AD). Atrophy of the medial temporal lobe (MTA) on magnetic resonance imaging (MRI) reflects neuronal loss in this area. OBJECTIVE: To compare diagnostic accuracy of CSF biomarkers and MTA in AD versus controls. METHODS: Abeta42, tau and tau phosphorylated at threonine 181 (Ptau-181) were measured in CSF from 61 AD patients and 32 controls by sandwich enzyme-linked immunosorbent assay. A CSF biomarker profile for AD was constructed. MTA was rated visually on MRI. RESULTS: When AD patients and controls were evaluated separately, no correlations were present between the CSF markers and MTA score. Both MTA and CSF biomarker profile were independently associated with the diagnosis AD (MTA: OR (95% CI)=28 (3-239); CSF biomarker profile: OR (95% CI)=57 (13-262)). Among individuals younger than 65 years old and without MTA 60% suffered AD, and the finding of an abnormal CSF biomarker profile was limited to AD patients only. CONCLUSIONS: MTA and CSF biomarkers seem to be of incremental value for the diagnosis AD. CSF analysis is most sensitive in the absence of MTA, and especially among early-onset AD patients.
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Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Imageamento por Ressonância Magnética/métodos , Fragmentos de Peptídeos/líquido cefalorraquidiano , Lobo Temporal/metabolismo , Lobo Temporal/patologia , Proteínas tau/líquido cefalorraquidiano , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/patologia , Biomarcadores/líquido cefalorraquidiano , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: Frontotemporal dementia (FTD) is pathologically heterogeneous, sometimes revealing intraneuronal inclusions of neurofilaments. We therefore measured CSF neurofilament profiles in patients with FTD, patients with early onset Alzheimer's disease (EAD) and healthy control subjects to explore the discriminative potential of CSF neurofilaments compared with the existing CSF biomarkers amyloid-beta(1-42), tau and tau phosphorylated at threonine-181. METHODS: CSF levels of light chain, heavy chain and hyperphosphorylated heavy chain neurofilaments (NfL, t-NfH and P-NfH) were compared between 17 subjects with FTD, 20 with EAD and 25 cognitively healthy controls. RESULTS: A subgroup of FTD patients had remarkably high CSF levels of both NfL and NfH. The degree of NfH phosphorylation was increased in FTD compared to both other groups. The levels of CSF NfL were significantly higher in EAD compared to controls. CONCLUSION: Differences in CSF biomarker profiles might reflect differential involvement of neurofilaments and tau in FTD and EAD. The subgroup of FTD patients with high CSF neurofilament levels may have a different neuropathological substrate and future studies addressing this specific issue are needed.
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Doença de Alzheimer/líquido cefalorraquidiano , Demência/líquido cefalorraquidiano , Proteínas de Neurofilamentos/líquido cefalorraquidiano , Proteínas tau/líquido cefalorraquidiano , Idoso , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Peptídeos beta-Amiloides/metabolismo , Biomarcadores/líquido cefalorraquidiano , Biomarcadores/metabolismo , Demência/patologia , Feminino , Humanos , Masculino , Análise por Pareamento , Pessoa de Meia-Idade , Proteínas de Neurofilamentos/metabolismo , Fragmentos de Peptídeos/líquido cefalorraquidiano , Fragmentos de Peptídeos/metabolismo , Fosforilação , Valores de Referência , Proteínas tau/metabolismoAssuntos
Peptídeos beta-Amiloides/líquido cefalorraquidiano , Transtornos Cognitivos/líquido cefalorraquidiano , Doenças do Sistema Nervoso/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Transtornos Cognitivos/diagnóstico , Ensaio de Imunoadsorção Enzimática , Humanos , Estudos Longitudinais , Doenças do Sistema Nervoso/diagnóstico , Manejo de Espécimes , Fatores de TempoRESUMO
Homocysteine accumulation, frequently observed in plasma of AD patients, may be a sign of a reduced activity of the brain methionine-homocysteine transmethylation cycle. S-Adenosylmethionine (SAM) is the main methyl donor in several transmethylation reactions. The demethylated product of SAM, S-adenosylhomocysteine (SAH), is hydrolyzed to yield homocysteine, which can be remethylated to methionine by transfer of a methyl group of 5-methyltetrahydrofolate (5-MTHF). A reduced activity of the transmethylation cycle in the brain may result in hypomethylation of the promoter of the presenilin 1 (PS1) gene, which will lead to overexpression of presenilin 1 and, consequently, to increased Abeta(1-42) (Abeta42) formation. Brain transmethylation was studied in 30 patients with 'probable' AD and 28 age-matched non-demented controls by measuring the cerebrospinal fluid (CSF) levels of SAM, SAH and 5-MTHF. 5-MTHF was determined by HPLC with electrochemical detection, while SAM and SAH were assayed by stable isotope dilution tandem mass spectrometry. We found no statistical differences between AD patients and controls for 5-MTHF, SAM and SAH levels, and the SAM/SAH-ratio in CSF. These findings argue against a possible change in methylation of the promoter and expression of PS1.
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Doença de Alzheimer/líquido cefalorraquidiano , Encéfalo/metabolismo , S-Adenosil-Homocisteína/líquido cefalorraquidiano , S-Adenosilmetionina/líquido cefalorraquidiano , Tetra-Hidrofolatos/líquido cefalorraquidiano , Idoso , Doença de Alzheimer/metabolismo , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Masculino , Espectrometria de Massas , Proteínas de Membrana/metabolismo , Metilação , Pessoa de Meia-Idade , Presenilina-1 , Regiões Promotoras Genéticas , S-Adenosil-Homocisteína/metabolismo , S-Adenosilmetionina/metabolismo , Tetra-Hidrofolatos/metabolismoAssuntos
Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/diagnóstico , Demência/diagnóstico , Feminino , Humanos , Imunoensaio/métodos , Masculino , Pessoa de Meia-Idade , Curva ROC , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: Reported concentrations of amyloid beta (1-42) (A beta 42) and tau in cerebrospinal fluid (CSF) differ among reports. We investigated the effects of storage temperature, repeated freeze/thaw cycles, and centrifugation on the concentrations of A beta 42 and tau in CSF. METHODS: Stability of samples stored at -80 degrees C was determined by use of an accelerated stability testing protocol according to the Arrhenius equation. A beta 42 and tau concentrations were measured in CSF samples stored at 4, 18, 37, and -80 degrees C. Relative CSF concentrations (%) of the biomarkers after one freeze/thaw cycle were compared with those after two, three, four, five, and six freeze/thaw cycles. In addition, relative A beta 42 and tau concentrations in samples not centrifuged were compared with samples centrifuged after 1, 4, 48, and 72 h. RESULTS: A beta 42 and tau concentrations were stable in CSF when stored for a long period at -80 degrees C. CSF A beta 42 decreased by 20% during the first 2 days at 4, 18, and 37 degrees C compared with -80 degrees C. CSF tau decreased after storage for 12 days at 37 degrees C. After three freeze/thaw cycles, CSF A beta 42 decreased 20%. CSF tau was stable during six freeze/thaw cycles. Centrifugation did not influence the biomarker concentrations. CONCLUSIONS: Repeated freeze/thaw cycles and storage at 4, 18, and 37 degrees C influence the quantitative result of the A beta 42 test. Preferably, samples should be stored at -80 degrees C immediately after collection.
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Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Manejo de Espécimes , Proteínas tau/líquido cefalorraquidiano , Idoso , Doença de Alzheimer/diagnóstico , Peptídeos beta-Amiloides/normas , Biomarcadores/líquido cefalorraquidiano , Centrifugação , Feminino , Congelamento , Calefação , Humanos , Masculino , Pessoa de Meia-Idade , Fragmentos de Peptídeos/normas , Serviços Postais , Fatores de TempoRESUMO
BACKGROUND: Frontotemporal dementia (FTD) is a pathologically heterogeneous group of presenile neurodegenerative disorders, with or without the deposition of hyperphosphorylated tau protein in affected brain regions. Mutations in the tau gene have been found in the familial form of FTD, linked to chromosome 17q21-22, showing a spectrum of tauopathy. OBJECTIVE: To evaluate levels of total tau, phosphorylated tau 181 (Ptau-181), and amyloid-beta1-42 in the cerebrospinal fluid (CSF) of patients with FTD, with special emphasis on FTD due to tau mutations. DESIGN: Case-control study. SETTING: Outpatient neurology clinics at 2 university medical centers, in Rotterdam and Amsterdam (the Netherlands). PATIENTS: Twenty-six patients with FTD (9 with tau mutations 7 P301L and 2 G272V), 18 patients with Alzheimer disease (AD), and 13 nondemented controls. METHODS: Total tau, Ptau-181, and amyloid-beta1-42 levels in CSF, obtained by lumbar puncture, were determined by sandwich enzyme-linked immunosorbent assay. Patients were diagnosed after clinical examination, neuropsychologic evaluation, and neuroimaging. Differences between patient groups were statistically evaluated using nonparametric tests. RESULTS: Although CSF levels of total tau were mildly increased in FTD patients compared with nondemented controls (P =.05), median CSF total tau levels were low in the subgroup with tau mutations compared with AD patients. Furthermore, CSF levels of Ptau-181 and amyloid-beta1-42 were not different in FTD patients, including the patients with tau mutations, compared with nondemented controls. CONCLUSIONS: The tauopathy in P301L and G272V does not appear to be associated with an evident increase in CSF levels of Ptau-181 in FTD patients with these tau mutations, in contrast with findings in patients with AD.