Biomedical subjects

Kaj Blennow

Publications and source records attributed to Kaj Blennow.

At least 19 recordsLinked to original sources

PubMed2025

Synaptic protein CSF levels relate to memory scores in individuals without dementia.

BACKGROUND: We investigated how cerebrospinal fluid levels of synaptic proteins associate with memory function in normal cognition (CN) and mild cognitive impairment (MCI), and investigated the effect of amyloid positivity on these associations. METHODS: We included 242 CN (105(43%) abnormal amyloid), and 278 MCI individuals (183(66%) abnormal amyloid) from the European Medical Information Framework for Alzheimer's Disease Multimodal Biomarker Discovery (EMIF-AD MBD) and the Alzheimer's Disease Neuroimaging Initiative (ADNI). For 181 (EMIF-AD MBD) and 36 (ADNI) proteins with a synaptic annotation in SynGO, associations with word learning recall were analysed with linear models. RESULTS: Subsets of synaptic proteins showed lower levels with worse recall in preclinical AD (EMIF-AD MBD: 7, ADNI: 5 proteins, none overlapping), prodromal AD (EMIF-AD MBD only, 27 proteins) and non-AD MCI (EMIF-AD MBD: 1, ADNI: 7 proteins). The majority of these associations were specific to these clinical groups. CONCLUSIONS: Synaptic disturbance-related memory impairment occurred very early in AD, indicating it may be relevant to develop therapies targeting the synapse early in the disease.

Humans↗

PubMed2025

Proteomic analysis reveals distinct cerebrospinal fluid signatures across genetic frontotemporal dementia subtypes.

We used an untargeted mass spectrometric approach, tandem mass tag proteomics, for the identification of proteomic signatures in genetic frontotemporal dementia (FTD). A total of 238 cerebrospinal fluid (CSF) samples from the Genetic FTD Initiative were analyzed, including samples from 107 presymptomatic (44 C9orf72, 38 GRN, and 25 MAPT) and 55 symptomatic (27 C9orf72, 17 GRN, and 11 MAPT) mutation carriers as well as 76 mutation-negative controls ("noncarriers"). We found shared and distinct proteomic alterations in each genetic form of FTD. Among the proteins significantly altered in symptomatic mutation carriers compared with noncarriers, we found that a set of proteins including neuronal pentraxin 2 and fatty acid binding protein 3 changed across all three genetic forms of FTD and patients with Alzheimer's disease from previously published datasets. We observed differential changes in lysosomal proteins among symptomatic mutation carriers with marked abundance decreases in MAPT carriers but not other carriers. Further, we identified mutation-associated proteomic changes already evident in presymptomatic mutation carriers. Weighted gene coexpression network analysis combined with gene ontology annotation revealed clusters of proteins enriched in neurodegeneration and glial responses as well as synapse- or lysosome-related proteins indicating that these are the central biological processes affected in genetic FTD. These clusters correlated with measures of disease severity and were associated with cognitive decline. This study revealed distinct proteomic changes in the CSF of patients with genetic FTD, providing insights into the pathological processes involved in the disease. In addition, we identified proteins that warrant further exploration as diagnostic and prognostic biomarker candidates.

Humans↗

PubMed2022

Biological correlates of elevated soluble TREM2 in cerebrospinal fluid.

Cerebrospinal fluid (CSF) soluble triggering receptor expressed on myeloid cells-2 (sTREM2) is an emerging biomarker of neuroinflammation in Alzheimer's disease (AD). Yet, sTREM2 expression has not been systematically evaluated in relation to concomitant drivers of neuroinflammation. While associations between sTREM2 and tau in CSF are established, we sought to determine additional biological correlates of CSF sTREM2 during the prodromal stages of AD by evaluating CSF Aβ species (Aβx-40), a fluid biomarker of blood-brain barrier integrity (CSF/plasma albumin ratio), and CSF biomarkers of neurodegeneration measured in 155 participants from the Vanderbilt Memory and Aging Project. A novel association between high CSF levels of both sTREM2 and Aβx-40 was observed and replicated in an independent dataset. Aβx-40 levels, as well as the CSF/plasma albumin ratio, explained additional and unique variance in sTREM2 levels above and beyond that of CSF biomarkers of neurodegeneration. The component of sTREM2 levels correlated with Aβx-40 levels best predicted future cognitive performance. We highlight potential contributions of Aβ homeostasis and blood-brain barrier integrity to elevated CSF sTREM2, underscoring novel biomarker associations relevant to disease progression and clinical outcome measures.

Alzheimer Disease↗

PubMed2018

Sex-specific genetic predictors of Alzheimer's disease biomarkers.

Cerebrospinal fluid (CSF) levels of amyloid-β 42 (Aβ42) and tau have been evaluated as endophenotypes in Alzheimer's disease (AD) genetic studies. Although there are sex differences in AD risk, sex differences have not been evaluated in genetic studies of AD endophenotypes. We performed sex-stratified and sex interaction genetic analyses of CSF biomarkers to identify sex-specific associations. Data came from a previous genome-wide association study (GWAS) of CSF Aβ42 and tau (1527 males, 1509 females). We evaluated sex interactions at previous loci, performed sex-stratified GWAS to identify sex-specific associations, and evaluated sex interactions at sex-specific GWAS loci. We then evaluated sex-specific associations between prefrontal cortex (PFC) gene expression at relevant loci and autopsy measures of plaques and tangles using data from the Religious Orders Study and Rush Memory and Aging Project. In Aβ42, we observed sex interactions at one previous and one novel locus: rs316341 within SERPINB1 (p = 0.04) and rs13115400 near LINC00290 (p = 0.002). These loci showed stronger associations among females (β = - 0.03, p = 4.25 × 10-8; β = 0.03, p = 3.97 × 10-8) than males (β = - 0.02, p = 0.009; β = 0.01, p = 0.20). Higher levels of expression of SERPINB1, SERPINB6, and SERPINB9 in PFC was associated with higher levels of amyloidosis among females (corrected p values < 0.02) but not males (p > 0.38). In total tau, we observed a sex interaction at a previous locus, rs1393060 proximal to GMNC (p = 0.004), driven by a stronger association among females (β = 0.05, p = 4.57 × 10-10) compared to males (β = 0.02, p = 0.03). There was also a sex-specific association between rs1393060 and tangle density at autopsy (pfemale = 0.047; pmale = 0.96), and higher levels of expression of two genes within this locus were associated with lower tangle density among females (OSTN p = 0.006; CLDN16 p = 0.002) but not males (p ≥ 0.32). Results suggest a female-specific role for SERPINB1 in amyloidosis and for OSTN and CLDN16 in tau pathology. Sex-specific genetic analyses may improve understanding of AD's genetic architecture.

Aged, 80 and over↗

PubMed2007

Cystatin C in cerebrospinal fluid and multiple sclerosis.

OBJECTIVE: A recent study using surface-enhanced laser desorption/ionization time-of-flight analysis of cerebrospinal fluid identified a 12.5 kDa truncated isoform of cystatin C (CysC) as a specific biomarker for multiple sclerosis (MS). METHODS: Surface-enhanced laser desorption/ionization time-of-flight analysis of cerebrospinal fluid samples from 43 MS patients and 46 healthy control subjects. RESULTS: Full-length CysC (13.4 kDa) concentration was similar in MS and control samples. The 12.5 kDa CysC protein was produced from full-length CysC by N-terminal cleavage during storage at -20 degrees C. INTERPRETATION: The 12.5 kDa CysC isoform is a storage-related artifact and is not useful as a diagnostic marker for MS.

Amino Acid Sequence↗

PubMed2006

Elevated cerebrospinal fluid F2-isoprostane levels indicating oxidative stress in healthy siblings of multiple sclerosis patients.

Lipid peroxidation has been implicated in the pathogenesis of multiple sclerosis (MS). Isoprostanes, isomers of prostaglandins, are produced by free radical-mediated peroxidation of fatty acids in vivo and can be quantified in biological fluids. This study examines the levels of cerebrospinal fluid (CSF) F2-isoprostanes (F2-iPs) in MS patients (n=46), their healthy siblings (n=46) and unrelated controls (n=50). The median CSF F2-iP concentration (range) was significantly higher in siblings of MS patients, as compared to healthy controls (40.0 [7.1-68.7] and 29.1 [6.4-60.3] pg/mL, respectively, p=0.031). MS patients demonstrated F2-iP levels intermediate between siblings and controls. F2-iP levels in MS patients and siblings correlated significantly (R=0.360, p=0.012). These results suggest that siblings of MS patients have an increased oxidative stress response to environmental and/or genetic factors that may be involved in MS pathogenesis.

Adult↗

PubMed2006

Differential CSF biomarker levels in APOE-epsilon4-positive and -negative patients with memory impairment.

OBJECTIVES: To investigate the relationships between episodic memory, APOE genotype, CSF markers (total tau, T-tau; phospho-tau, P-tau; beta-amyloid, Abeta42) and longitudinal cognitive decline. METHODS: 124 memory clinic patients were retrospectively divided into 6 groups based on (i) episodic memory function (Rey Auditory Verbal Learning Test, RAVLT): severe, moderate or no impairment (SIM, MIM or NIM), and (ii) APOE genotype (epsilon4+ or epsilon4-). CSF marker levels and cognitive decline were compared across groups. RESULTS: Episodic memory function, according to RAVLT scores, was significantly correlated with CSF marker levels only among epsilon4+ subjects and not among epsilon4- subjects. When comparing the 6 subgroups, SIM epsilon4+ and MIM epsilon4+ groups showed significantly lower Abeta42 levels than the other groups. T-tau and P-tau levels were significantly increased in SIM epsilon4+ when compared to all the other groups, including the SIM epsilon4- group. However, both SIM epsilon4+ and SIM epsilon4- declined cognitively during the follow-up. CONCLUSION: It remains to be determined whether APOE genotype affects the expression of biomarkers in CSF, or whether the different biomarker patterns reflect different types of disease processes in patients with progressive cognitive dysfunction.

Amyloid beta-Protein Precursor↗

PubMed2006

Cerebrospinal fluid beta-amyloid 1-42 concentration may predict cognitive decline in older women.

BACKGROUND: Low levels of cerebrospinal fluid (CSF) beta-amyloid 1-42 (Abeta42) and high total tau (T-tau) are diagnostic for manifest Alzheimer's disease. It is not known, however, whether these biomarkers may be risk indicators for cognitive decline in otherwise healthy older people. METHODS: The longitudinal relationship between CSF markers, Abeta42 and T-tau, measured in 1992, and change in Mini-Mental State Examination (deltaMMSE) score between 1992 and 2002 were investigated in 55 women (aged 70-84 years, mean (SD) MMSE score = 28.3 (1.5)), who were participants in the Prospective Population Study of Women in Gothenburg, Sweden. These women did not have dementia when they experienced lumbar puncture in 1992-3. RESULTS: Over the 8-year follow-up period, deltaMMSE (range = +3 to -21 points) was correlated with Abeta42 (Spearman's r = 0.40, p = 0.002), such that lower levels of Abeta42 were related to greater decline. This was also observed after excluding 4 women who developed dementia between 1992 and 2002 (Spearman's r = 0.34, p = 0.019). A multivariate logistic regression model predicting a decline of > or = 5 points on the MMSE (observed in six women), or a risk of developing dementia over the 8-year follow-up period (observed in four women), including age, education, Abeta42 and T-tau as covariates, showed that Abeta42 was the sole predictor of significant cognitive decline or dementia (OR per 100 pg/ml Abeta42 = 2.24, 95% CI 1.19 to 4.22, p = 0.013). CONCLUSIONS: Low levels of CSF Abeta42 may predict cognitive decline among older women without dementia.

Aged↗

PubMed2006

An Alzheimer's disease-specific beta-amyloid fragment signature in cerebrospinal fluid.

Pathogenic events in Alzheimer's disease (AD) involve an imbalance between the production and clearance of the neurotoxic beta-amyloid peptide (Abeta), especially the 42 amino acid peptide Abeta1-42. While much is known about the production of Abeta1-42, many questions remain about how the peptide is degraded. To investigate the degradation pattern, we developed a method based on immunoprecipitation combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry that determines the Abeta degradation fragment pattern in cerebrospinal fluid (CSF). We found in total 18 C-terminally and 2 N-terminally truncated Abeta peptides and preliminary data indicated that there were differences in the detected Abeta relative abundance pattern between AD and healthy controls. Here, we provide direct evidence that an Abeta fragment signature consisting of Abeta1-16, Abeta1-33, Abeta1-39, and Abeta1-42 in CSF distinguishes sporadic AD patients from non-demented controls with an overall accuracy of 86%.

Aged↗

PubMed2006

Normalisation of cerebrospinal fluid biomarkers parallels improvement of neurological symptoms following HAART in HIV dementia--case report.

BACKGROUND: Since the introduction of HAART the incidence of HIV dementia has declined and HAART seems to improve neurocognitive function in patients with HIV dementia. Currently, HIV dementia develops mainly in patients without effective treatment, though it has also been described in patients on HAART and milder HIV-associated neuropsychological impairment is still frequent among HIV-1 infected patients regardless of HAART. Elevated cerebrospinal fluid (CSF) levels of markers of neural injury and immune activation have been found in HIV dementia, but neither of those, nor CSF HIV-1 RNA levels have been proven useful as diagnostic or prognostic pseudomarkers in HIV dementia. CASE PRESENTATION: We report a case of HIV dementia (MSK stage 3) in a 57 year old antiretroviral naïve man who was introduced on zidovudine, lamivudine and ritonavir boosted indinavir, and followed with consecutive lumbar punctures before and after two and 15 months after initiation of HAART. Improvement of neurocognitive function was paralleled by normalisation of CSF neural markers (NFL, Tau and GFAP) levels and a decline in CSF and serum neopterin and CSF and plasma HIV-1 RNA levels. CONCLUSION: The value of these CSF markers as prognostic pseudomarkers of the effect of HAART on neurocognitive impairment in HIV dementia ought to be evaluated in longitudinal studies.

AIDS Dementia Complex↗

PubMed2006

Alzheimer's disease.

Alzheimer's disease is the most common cause of dementia. Research advances have enabled detailed understanding of the molecular pathogenesis of the hallmarks of the disease--ie, plaques, composed of amyloid beta (Abeta), and tangles, composed of hyperphosphorylated tau. However, as our knowledge increases so does our appreciation for the pathogenic complexity of the disorder. Familial Alzheimer's disease is a very rare autosomal dominant disease with early onset, caused by mutations in the amyloid precursor protein and presenilin genes, both linked to Abeta metabolism. By contrast with familial disease, sporadic Alzheimer's disease is very common with more than 15 million people affected worldwide. The cause of the sporadic form of the disease is unknown, probably because the disease is heterogeneous, caused by ageing in concert with a complex interaction of both genetic and environmental risk factors. This seminar reviews the key aspects of the disease, including epidemiology, genetics, pathogenesis, diagnosis, and treatment, as well as recent developments and controversies.

Aged↗

PubMed2006

The taqI DRD2 A1 allele is associated with alcohol-dependence although its effect size is small.

BACKGROUND: Numerous studies of the relationship between the TaqIA DRD2 A1 allele and alcohol-dependence have been performed and many of these have shown an association whereas others have not (Noble, 2003). This has consequently generated some controversy as to whether such an association actually exists (Noble, 2003). In the two recent meta-analyses by Noble (2003) and Young et al. (2004) some very important methodological issues have been discussed, which need to be addressed in forthcoming studies. Thus, the sample size is of great importance. In case-control studies it has been estimated that to detect the role of genes with small effect size of approximately 2, which is in the range of the DRD2 A1 allele-alcoholism relationship, case-control sets of 300-400 subjects are necessary (Noble, 2003). METHODS: In the present study, we have consequently recruited a large number of subjects, 375 alcohol-dependent individuals, who were treated as inpatients for alcohol withdrawal symptoms and out of these 357 could be evaluated. As controls, 578 individuals screened and 254 individuals unscreened for alcohol consumption were used. Thus, the total number of subjects was 1217. RESULTS: In the present study, in which the TaqI A1/A2 DRD2 polymorphism was in Hardy-Weinberg equilibrium in the patient group and the two control groups, we found that the TaqI DRD2 A1/A2 genotype frequency differed significantly between the alcohol-dependent group and both the total and screened control groups. Furthermore, the TaqI DRD2 A1 allele frequency was significantly overrepresented in the alcohol-dependent subjects as compared with both the total and screened control groups. The odds ratio for alcohol-dependency being associated with the A1 allele was 1.34. CONCLUSIONS: Consequently, the findings in this study lend further support to the notion of an association between the DRD2 A1 allele and alcohol-dependence, although the effect size of the DRD2 A1 allele is small.

Adult↗

PubMed2006

Clusterin in cerebrospinal fluid: analysis of carbohydrates and quantification of native and glycosylated forms.

Clusterin is suggested to be involved in the pathogenesis of Alzheimer's disease. Clusterin expression is increased in brain tissue in affected regions of Alzheimer patients, and intense clusterin staining is found in both senile plaques and in neuronal and glia cells. In contrast, the cerebrospinal fluid level of clusterin in Alzheimer patients has, thus far, been found unchanged. Clusterin is a glycosylated protein, and an alteration of its glycosylation in Alzheimer's disease might influence accurate quantification in cerebrospinal fluid through interference of antibody binding to the protein. Using enzymatic deglycosylation of clusterin isolated from cerebrospinal fluid, we found that the carbohydrates attached to clusterin were of the N-linked type and sialic acids. Based on this finding, cerebrospinal fluid samples from Alzheimer patients (n=99) and controls (n=39) were analysed. The samples were treated with peptide: N-glycanase F, cleaving off N-linked carbohydrates, and clusterin was quantified before and after deglycosylation using a new sandwich enzyme-linked immunosorbent assay. Clusterin was significantly increased in Alzheimer patients, in both native (7.17+/-2.43 AU versus 5.73+/-2.09 AU; p=0.002), and deglycosylated samples (12.19+/-5.00 AU versus 9.68+/-4.38 AU; p=0.004). Deglycosylation led to increased measured levels of clusterin by 70% (p<0.001) in Alzheimer patients and 67% (p<0.001) in controls. These findings indicate that glycosylation of proteins may interfere with their quantification. The results show that clusterin is significantly increased in cerebrospinal fluid from Alzheimer patients as a group, supporting that clusterin might be involved in the pathogenesis of Alzheimer's disease. However, the individual clusterin levels overlap between the two groups, and thus cerebrospinal fluid clusterin measurement is not suitable as a biochemical marker in the diagnosis of Alzheimer's disease.

Aged↗

PubMed2006

Neurochemical aftermath of amateur boxing.

BACKGROUND: Little solid information is available on the possible risks for neuronal injury in amateur boxing. OBJECTIVE: To determine whether amateur boxing and severity of hits are associated with elevated levels of biochemical markers for neuronal injury in cerebrospinal fluid. DESIGN: Longitudinal study. SETTING: Referral center specializing in evaluation of neurodegenerative disorders. PARTICIPANTS: Fourteen amateur boxers (11 men and 3 women) and 10 healthy male nonathletic control subjects. INTERVENTIONS: The boxers underwent lumbar puncture 7 to 10 days and 3 months after a bout. The control subjects underwent LP once. MAIN OUTCOME MEASURES: Neurofilament light protein, total tau, glial fibrillary acidic protein, phosphorylated tau, and beta-amyloid protein 1-40 (Abeta([1-40])) and 1-42 (Abeta([1-42])) concentrations in cerebrospinal fluid were measured. RESULTS: Increased levels after a bout compared with after 3 months of rest from boxing were found for 2 markers for neuronal and axonal injury, neurofilament light protein (mean +/- SD, 845 +/- 1140 ng/L vs 208 +/- 108 ng/L; P = .008) and total tau (mean +/- SD, 449 +/- 176 ng/L vs 306 +/- 78 ng/L; P = .006), and for the astroglial injury marker glial fibrillary acidic protein (mean +/- SD, 541 +/- 199 ng/L vs 405 +/- 138 ng/L; P = .003). The increase was significantly higher among boxers who had received many hits (>15) or high-impact hits to the head compared with boxers who reported few hits. In the boxers, concentrations of neurofilament light protein and glial fibrillary acidic protein, but not total tau, were significantly elevated after a bout compared with the nonathletic control subjects. With the exception of neurofilament light protein, there were no significant differences between boxers after 3 months of rest from boxing and the nonathletic control subjects. CONCLUSIONS: Amateur boxing is associated with acute neuronal and astroglial injury. If verified in longitudinal studies with extensive follow-up regarding the clinical outcome, analyses of cerebrospinal fluid may provide a scientific basis for medical counseling of athletes after boxing or head injury.

Adolescent↗

PubMed2006

The cathepsin D rs17571 polymorphism: effects on CSF tau concentrations in Alzheimer disease.

The lysosomal protease cathepsin D (CtsD, EC 3.4.23.5; gene, CTSD) has been associated with Alzheimer disease (AD) due to its cerebral expression being increased early in the course of AD; additionally, a CTSD exon 2 polymorphism (rs17571; NT_009237.17:g.569834T>C) may confer risk to AD. Functionally, it may be implicated in amyloid precursor protein (APP) processing and tau protein degradation. The objective of this study was to determine whether the CTSD exon 2 polymorphism affects cerebrospinal fluid (CSF), concentrations of beta-amyloid (Abeta42) and tau in two independent samples from Germany (n=73) and Sweden (n=66). Patients carrying the CTSD rs17571-T allele had significantly decreased CSF levels of tau (Munich, p=0.003; Swedish, p=0.029; combined sample, p<0.001), whereas no significant effect was observed on Abeta42 concentrations. Likewise, no significant impact was observed on Mini Mental State Examination (MMSE) scores. The data of both independent samples suggest that the CTSD rs17571 polymorphism does not affect APP processing but shows significant effects on tau processing. The result may corroborate the implication of the lysosomal system in the pathogenesis of AD and is of particular importance if CSF tau is used as a diagnostic biomarker.

Alzheimer Disease↗

PubMed2006

Dissociation between CSF total tau and tau protein phosphorylated at threonine 231 in Creutzfeldt-Jakob disease.

To study the potential diagnostic value of abnormally phosphorylated tau protein in Creutzfeldt-Jakob disease (CJD) compared to Alzheimer's disease (AD), we determined levels of tau phosphorylated at threonine 231 (p-tau231) and of total tau (t-tau) in cerebrospinal fluid (CSF) of CJD patients, AD patients, and healthy controls (HC). CJD patients showed excessively high t-tau levels but relatively low p-tau(231) concentrations compared to the AD group. t-tau alone yielded the best diagnostic accuracy to differentiate between CJD and AD patients, when compared to p-tau231 and the p-tau231/t-tau ratio (97, 78, and 95% correctly allocated cases, respectively). Our findings indicate a dissociation in the direction of change in CSF levels of t-tau and p-tau231 in CJD when compared to AD.

Age Distribution↗

PubMed2006

Association between CSF biomarkers and incipient Alzheimer's disease in patients with mild cognitive impairment: a follow-up study.

BACKGROUND: Disease-modifying treatment strategies for Alzheimer's disease have led to an urgent need for biomarkers to identify the disease at a very early stage. Here, we assess the association between CSF biomarkers and incipient Alzheimer's in patients with mild cognitive impairment (MCI). METHODS: From a series of 180 consecutive patients with MCI, we assessed 137 who underwent successful lumbar puncture at baseline. Patients at risk of developing dementia were followed clinically for 4-6 years. Additionally, 39 healthy individuals, cognitively stable over 3 years, served as controls. We analysed CSF concentrations of beta amyloid(1-42) (Abeta42), total tau (T-tau), and phosphorylated tau (P-tau181) using Luminex xMAP technology. FINDINGS: During follow-up, 57 (42%) patients with MCI developed Alzheimer's disease, 21 (15%) developed other forms of dementia, and 56 (41%) remained cognitively stable for 5.2 years (range 4.0-6.8). A combination of CSF T-tau and Abeta42 at baseline yielded a sensitivity of 95% and a specificity of 83% for detection of incipient AD in patients with MCI. The relative risk of progression to Alzheimer's disease was substantially increased in patients with MCI who had pathological concentrations of T-tau and Abeta42 at baseline (hazard ratio 17.7, p<0.0001). The association between pathological CSF and progression to Alzheimer's disease was much stronger than, and independent of, established risk factors including age, sex, education, APOE genotype, and plasma homocysteine. The combination of T-tau and Abeta42/P-tau181 ratio yielded closely similar results (sensitivity 95%, specificity 87%, hazard ratio 19.8). INTERPRETATION: Concentrations of T-tau, P-tau181, and Abeta42 in CSF are strongly associated with future development of Alzheimer's disease in patients with MCI.

Aged↗

PubMed2006

Plasma Abeta in Alzheimer's disease--up or down?

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Alzheimer Disease↗