Cerebrospinal Fluid Aβ42 Levels Research Articles

Associations of self‐reported psychological stress with memory and cerebrospinal fluid biomarkers of Alzheimer’s disease in middle‐aged adults

AbstractBackgroundSelf‐reported psychological stress is associated with an increased risk of cognitive decline and dementia. However, it remains unclear whether stress is related to key biomarkers of Alzheimer’s disease (AD). This cross‐sectional study examined the relationship of psychological stress with memory and cerebrospinal fluid (CSF) biomarkers of AD in middle‐aged adults without dementia.MethodThe Healthy Brain Project (HBP) is a prospective web‐based study of adults aged between 40 and 70 years. A total of 2208 participants (76% female) completed the Depression, Anxiety, and Stress Scale (DASS) and Paired Associates Learning subtest of the CANTAB unsupervised on the HBP web platform. Additionally, a sub‐group of participants (n = 67; 41% APOE e4 carriers) attended an in‐person assessment where CSF samples were obtained to measure levels of amyloid‐beta (Aβ42), total tau (t‐tau), phosphorylated tau 181 (p‐tau), and neurofilament light chain (NFL). Separate linear regression analyses investigated associations of the DASS‐Stress score with memory performance and AD biomarkers. All analyses were adjusted for age, sex, education, and race.ResultIn the web‐based cohort, higher levels of self‐reported psychological stress were significantly associated with poorer memory (unstandardised β = ‐0.014, standard error [SE] = 0.004, p <.001). However, there were no significant associations between psychological stress and CSF levels of Aβ42, t‐tau, p‐tau, and NFL (all p > .05), with small effect sizes (Cohen’s f2 ≤ 0.05).ConclusionHigher levels of self‐reported psychological stress were associated with poorer memory in a large middle‐aged cohort but were not associated with AD biomarkers in a subset of participants with available CSF. One potential explanation is that non‐AD pathologies may underlie the relationship between stress and poorer memory; for example, poor coping strategies (e.g., smoking, overeating, and physical activity) might increase the risk of vascular cognitive impairment. However, it is also likely that the small sample size of the in‐clinic cohort was insufficient to detect any subtle relationships between stress and AD pathologies. Further research is needed to determine the associations between stress and the development of the clinical and biological manifestations of AD.

Predictive analysis between cytokine profile and Aβ42, p‐Tau, and p‐Tau/Aβ42 levels in the cerebrospinal fluid of older adults with and without cognitive impairment

AbstractBackgroundThe immune system activation observed in Alzheimer’s disease (AD) pathology contributes to its pathogenesis. It is proposed that ongoing interactions between β‐amyloid plaques, Tau protein, and neuroinflammatory mediators such as cytokines contribute to the maintenance of the inflammatory state in the brain. The aim was to evaluate whether cytokine profiles can predict variations in Aβ42, pTau, and pTau/Aβ42 cerebrospinal fluid (CSF) levels in older adults with and without objective cognitive impairment.MethodsEighty older adults were recruited, with a clinical diagnosis of AD dementia (36), with Mild Cognitive Impairment (MCI) (24), and without objective cognitive impairment (20). CSF levels of Aβ42, pTau, and 27 cytokines were assessed by the Luminex xMAP technique. Significant associations between Aβ42, p‐Tau, and p‐Tau/Aβ42 CSF levels and cytokines were explored in multiple linear regression analyses adjusted for age, education, and APOE ε4 carrier status.ResultsWe found that Granulocyte and Macrophage colony‐stimulating factors (GM‐CSF) (β = ‐.375; p = .010) and IL‐6 (β = ‐.370; p = .014) had a negative significant association with Aβ42, while IL‐8 (β = .452; p = .002) and IL‐4 (β = .488; p = .001) had positive significant association and higher magnitude of effect on Aβ42. For pTau, age (β = .240; p = .029), IL‐2 (β = .314; p = .012) and ε4 allele (β = 0.349; p = .002) had a positive significant association. The variable with the greatest magnitude of the effect was the presence of the ε4 allele. For the p‐Tau/Aβ42 ratio, G‐CSF (β = .423; p = .003) and GM‐CSF (β = .317; p = .019) had a significant positive association, while for IL‐8 (β = ‐.554; p = .001) and IL‐12 (β = ‐.334; p = .019) the association was significantly negative. IL‐8 had the greatest magnitude of effect on p‐Tau/Aβ42 ratio values.ConclusionThe higher levels of IL‐4 and the IL‐8 associated to a higher Aβ42 suggest their role at the beginning of the disease. On the other hand, the lower level of IL‐8 associated with a higher p‐Tau/Aβ42 suggests its inactivation as the disease progresses. Conversely, the higher levels of GM‐CSF associated with higher p‐Tau/Aβ42 suggests a more robust recruitment of the immune cell system at later stages.Reference: Aksnes, M., et al., (2021). Associations of cerebrospinal fluid amyloidogenic nanoplaques with cytokines in Alzheimer’s disease. Translational Neurodegeneration.

Spatial navigation, physical activity, and Alzheimer disease biomarkers

AbstractBackgroundElevated levels of amyloid are associated with worse performance on cognitive mapping (CM), a spatial navigation task reliant on the hippocampus. Prior animal work found that exercise is associated with better learning in CM tasks. Hence, the first goal of the study was to examine whether physical activity moderates the relationship between amyloid deposition and CM. In addition, spatial navigation ability predicts Alzheimer disease (AD) clinical progression but there is a need to examine whether it also predicts subsequent levels of amyloid and tau. Hence, the second goal was to examine whether CM predicts later levels of PET‐Tau and longitudinal trajectories of PET‐Amyloid.MethodCognitively normal individuals (n = 65; age range 50‐84 years) were administered a CM task in a virtual environment and a self‐report measure of physical activity. For cross‐sectional analyses, amyloid deposition was estimated via cerebrospinal fluid levels of Aβ42. One assessment of PET‐Tau (n = 49) and repeated assessments of PET‐Amyloid (n = 59) were obtained following the CM session.ResultConcurrent amyloid deposition was associated with reduced learning (p = 0.002) and retention of the environment (p = 0.002) while greater physical activity was associated with better learning (p = 0.004). There was no moderation by physical activity (all p’s > 0.156). CM performance was not associated with longitudinal trajectories of PET‐Amyloid (all p’s > 0.330) or the subsequent levels of PET‐Tau (all p’s > 0.572).ConclusionThese results suggest that both current physical activity and levels of amyloid can be important predictors of spatial navigation skills. However, CM might be a limited predictor of AD biomarker accumulation. Future studies should use a larger sample size and greater number of assessments to examine these questions.

Alzheimer´s Disease initial cognitive profile in an Argentinian cohort of individuals with Down Syndrome

AbstractBackgroundDown Syndrome [DS] is the most frequent cause of genetic developmental and intellectual disability. The lifetime risk of Alzheimer’s Disease [AD] in people with DS is more than 90%, with an earlier age of onset than the general population. There is ongoing debate whether there are significant differences in dementia presentation in the specific context of DS, with some studies suggesting a predominantly frontal phenotype with behavioural symptoms and others suggesting a more frequent amnestic presentation.The aim of this study was to characterize the initial cognitive profile of AD in a cohort of Argentinian adults with DS.MethodAdults with DS and prodromal or established AD dementia who were part of the IASDA (Argentinian initiative for the study of DS and AD) cohort or spontaneusly attended our Memory Clinic were included. Initial cognitive profile was determined by a semi‐structured interview conducted by a cognitive neurologist with the subject, their family and caregivers.ResultSixteen adults with DS were included. Fifty‐six percent (n = 9) were males. Mean age was 51 yo (42‐59 yo). Sixty‐two percent (n = 10) had premorbid moderate intellectual disability [DI], 25% (n = 4) had severe DI and 13% (n = 2) had mild DI.Fifty‐six percent (n = 9) had a clinical diagnosis of prodromal AD, and the remaining individuals had clinically established AD dementia. Fifty percent (n = 8) had positive amiloid biomarkers (determined by cerebral PiB‐PET or cerebrospinal fluid levels of Aβ42, phosphorylated‐tau and total‐tau), while the remaining subjects did not undergo amiloid biomarker assessment. Due to cognitive impairment, premorbid language impairment and/or premorbid severe DI, only 25% (n = 4) of individuals completed neuropsychological testing (CAMDEX‐DS, Cued Recall Task).Initial cognitive profile was charactirized as amnestic (single‐domain amnestic or multiple‐domain amnestic) in 81% percent (n = 13) of the cohort. Only 13% (n = 2) of the subjects had initial non‐amnestic syndromes, and in one case (6%) the initial cognitive syndrome was uncertain.ConclusionAmnestic cognitive impariment was the most frequent presentation of AD in this small cohort of Latin American adults with DS.

Association between blood pressure and Alzheimer’s disease biomarkers in cognitively unimpaired adults

AbstractBackgroundHigh blood pressure is an established risk factor for dementia. However, the underlying mechanisms are not completely understood. We aimed to evaluate the association between blood pressure and Alzheimer’s disease (AD) biomarkers in cognitively unimpaired adults from the ALFA+ study.MethodWe analyzed data from 301 participants with available cross‐sectional blood pressure measures (acquired by trained staff with an oscillometric device after 5 minutes of rest) and cerebrospinal fluid (CSF) AD core biomarkers data (CSF p‐tau and t‐tau were measured with Elecsys® immunoassays and CSF Aβ42 and Aβ40 with the Roche NeuroToolKit, a panel of robust prototype assays, both from Roche Diagnostics International Ltd), and a subset of 278 participants with amyloid PET data, of whom 110 had a second follow‐up PET acquisition (3.4 years after in average). We used separate linear regression models to analyze the association of systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP = SBP‐DBP) with CSF and PET biomarkers at a cross‐sectional level, and their association with the annualized rate of change in amyloid PET [(follow‐up centiloids – baseline centiloids) / years between PET scan acquisition]. We adjusted all models by age, sex, APOE status, waist‐to‐hip ratio, dyslipidemia, diabetes, tobacco and alcohol consumption, physical activity, and antihypertensive treatment.ResultHigher baseline SBP (but not DBP or PP) was significantly associated with increased amyloid PET uptake over time (p = 0.043). In cross‐sectional analyses, DBP was negatively associated with Aβ42 (p = 0.013), Aβ40 (p = 0.026), and t‐tau (p = 0.045), and marginally associated with p‐tau (p = 0.069), but not with the Aβ42/40 ratio nor baseline amyloid PET uptake. Associations with Aβ42 and t‐tau were no longer significant after further adjustment by CSF Aβ40 levels. SBP and PP were not associated with CSF biomarkers or baseline amyloid PET uptake.ConclusionHigher SBP is associated with longitudinal brain amyloid accumulation, which reinforces the importance of blood pressure control in AD prevention. DBP is also associated at a cross‐sectional level with AD biomarker concentration in CSF, but the attenuation of this association after adjusting by Aβ40 suggests a non‐specific.

Sex‐specific CSF proteomic profiling of amyloid/tau positivity identifies distinctive sex‐specific alternation of multiple proteins involved in Alzheimer’s disease

AbstractBackgroundSporadic Alzheimer’s disease (AD) is a highly heterogeneous multifactorial disease in which females have a higher risk. Among 5.3 million senior Americans diagnosed with AD, over 60% are female. Despite the well‐established sex differences, sex‐specific molecular findings in AD are still limited. We therefore examined the role of sex in the proteomic alterations due to AD to elucidate potential protein markers of AD heterogeneity.MethodIn the discovery cohort, 599 preclinical AD and 435 controls underwent lumbar puncture. Over 7,000 proteins in cerebrospinal fluid (CSF) were measured using SomaLogic assay. Amyloid/tau positivity (AT classification) was determined using ELISA Aβ42 and pTau181 levels in CSF. Proteins with sex‐specific effects were identified through linear models focusing on the interaction term between AT classification and sex. Results were tested in the independent cohort (N = 732) using the identical approaches. We analyzed brain proteomics and transcriptomics data to validate the replicated sex‐specific proteins. We performed pathway enrichment, interaction network using ConsensusPathDB and drug‐target prediction.ResultWe identified 594 proteins with sex‐specific effects in discovery (P<0.05 and permutation FDR <0.05). Among them, 36 were validated in replication (P<0.05 and consistent direction). These proteins were found to be involved in neurologic disorders and highly enriched in axon regeneration (fold enrichment = 9.38 and FDR = 2.8×10−4). Among the 36 proteins identified, 13 were classified as female‐specific and 23 as male‐specific. These 36 proteins strongly predicted amyloid/tau positivity (AUC = 0.926) for all individuals as well as 13 female‐specific proteins for females (AUC = 0.929). The interaction network identified CCN2 as a hub and contained 10 additional proteins including JAG1 and DLL4 of Notch signaling pathway and CTSB, an amyloid precursor protein secretase, among others. The results of 36 proteins in brain proteomics and transcriptomics confirmed the sex‐specific effect of CCN2 and others on AD in different tissues. Drug target prediction suggests minocycline and etoposide as potential treatments for females as well amitriptyline and verteporfin for males.ConclusionWe robustly identified 36 proteins that showed significant sex‐specific alterations by preclinical AD. Several proteins involved in AD and neurodegeneration were highlighted. Our findings facilitate mechanistic understanding of sex differences for AD risk and progression.

Time of the day at sampling affects amyloid‐beta levels in CSF and plasma

AbstractBackgroundStudies suggest that cerebrospinal fluid (CSF) levels of Alzheimer’s disease (AD) biomarkers, amyloid‐β (Aβ) and tau, follow a circadian rhythm. However sustained sampling of CSF with indwelling intrathecal catheter used in most of these studies might have affected the observed fluctuations in the biomarker levels.MethodsWe included 38 individuals with either normal (N = 18) or abnormal (N = 20) CSF Aβ42/40 status. CSF and plasma were collected, at the same occasion, at two different visits separated by an average of 53 days with lumbar punctures and venepunctures performed either in the morning or evening. At the first visit, collection was performed in the morning for 17 participants and the order was reversed (evening collection first) for the remaining 21 participants. CSF and plasma samples were analyzed for Aβ42, Aβ40, GFAP, NfL, p‐tau181, p‐tau217 and p‐tau231. CSF samples were also tested for a battery of synaptic and lysosomal proteins.ResultsCSF Aβ42 (mean difference [MD] = 0.208ng/ml; p = 0.043), CSF Aβ40 (MD = 1.85ng/ml; p<0.001), plasma Aβ42 (MD = 1.65pg/ml; p = 0.002) and plasma Aβ40 (MD, 0.011ng/ml, p = 0.003) levels were increased in the evening samples compared with morning samples by 4.2%‐17.0% (Figures 1‐2). However, changes between morning and evening samples were not significant for either CSF or plasma Aβ42/40. Additional proteins in CSF, APP, STX1B, NPTXR and NPTX1, were also found increased in the evening samples (MDrange, 0.087–0.243; p<0.048) by 4.7%‐12.15% (Figure 3). No significant differences were found between morning and evening levels for any of the other biomarkers, including p‐tau’s, NfL and GFAP. There were no significant interactions between time of day at sample collection and either Aβ status or order in which samples were obtained.ConclusionOur findings provide further evidence for diurnal fluctuations in Aβ peptides, which is observed in both CSF and plasma. Additionally, CSF levels of some synaptic proteins followed circadian rhythm. Importantly, CSF and plasma Aβ42/40 ratios remained unaltered, suggesting that increased production or decreased clearance of Aβ peptides during daytime similarly affect the CSF and plasma levels of both Aβ42 and Aβ40. Thus, these ratios are more suitable for implementation as biomarkers of AD as they are not influenced by diurnal fluctuations.

CSF Alzheimer’s Disease Biomarker Changes in Veterans with Mild Traumatic Brain Injury

AbstractBackgroundTraumatic brain injury (TBI) has been reported to increase risk of Alzheimer’s dementia (AD). It remains unknown whether mild TBI (mTBI) caused by blast in Veterans confers a similar increase of risk. This study investigated early AD changes defined by cerebrospinal fluid (CSF) AD biomarkers in Veterans with blast mTBI.MethodFifty‐one Veterans with mTBI, 34 non‐mTBI Veterans, and 51 non‐mTBI civilians were recruited from Seattle, Washington. Age‐matched Veteran and civilian non‐mTBI participants had no lifetime history of TBI. All blast‐mTBI Veterans had experienced at least one war zone blast or combined blast/impact exposure, with acute symptoms meeting VA/Department of Defense criteria for mTBI. All participants underwent standardized clinical and neuropsychological assessments and lumbar puncture for collection of CSF. CSF biomarkers were measured at the Clinical Neurochemistry Lab in Mölndal, Sweden, using Meso Scale Discovery (MSD) assays for Aβ40 and Aβ42, and Innotest ELISAs for phosphorylated Tau181 (pTau181) and total Tau (tTau).ResultDifferences in all 4 CSF AD biomarkers between participants with and without mTBI were highly age‐dependent and most pronounced in older ages (Figure 1). Both CSF Aβ40 and Aβ42 became lower as age increasing in the mTBI group starting around age 40‐45 years, while they increased with age in the non‐mTBI participants. In contrast, CSF tTau and pTau181 mean levels remained relatively constant with age in participants with mTBI, but increased after age 45 in the non‐mTBI participants. Consequently, for participants aged 50+ years, Veterans with mTBI had lower mean AD biomarkers than the non‐mTBI participants. Similarly, the differences in cognitive performance were age‐dependent, i.e., poorer performance in older Veterans with mTBI than in the non‐mTBI participants. Furthermore, the relationships between CSF Aβ42 and cognitive performance were also age‐dependent; specifically, in participants aged 45+ years, lower CSF Aβ42 level was associated with poorer performance on tests of verbal fluency and memory.ConclusionThe earliest AD biomarker, CSF Aβ42, started to decrease in middle‐aged Veterans with mTBI, more than a decade earlier than those without mTBI in our earlier study, suggesting mTBI may accelerate brain deposition of Aβ and increase risk for AD.

Associations between Alzheimer's disease biomarkers and postoperative delirium or cognitive dysfunction: A meta-analysis and trial sequential analysis of prospective clinical trials.

The relationship between Alzheimer's disease biomarkers and postoperative complications, such as postoperative delirium (POD) and postoperative cognitive dysfunction (POCD), remains a subject of ongoing debate. This meta-analysis aimed to determine whether there is an association between perioperative Alzheimer's disease biomarkers and postoperative complications. We conducted a meta-analysis of observational clinical studies that explored the correlation between Alzheimer's disease biomarkers and POD or POCD in patients who have undergone surgery, following PRISMA guidelines. The protocol was previously published (INPLASY: INPLASY202350001). A comprehensive search was conducted across PubMed, Embase, Web of Science, and Cochrane databases until March 2023. Surgical patients aged at least 18 years, studies focusing on POD or POCD, research involving Alzheimer's disease biomarkers, including Aβ or tau in blood or cerebrospinal fluid (CSF), and availability of the full text. Our meta-analysis included 15 studies: six focusing on POD and nine on POCD. The findings revealed a negative correlation between preoperative CSF β-amyloid 42 (Aβ42) levels and the onset of POD [mean difference -86.1, 95% confidence interval (CI), -114.15 to -58.05, I2 : 47%]; this association was strongly supported by trial sequential analysis (TSA). A similar negative correlation was discerned between preoperative CSF Aβ42 levels and the incidence of POCD (-165.01, 95% CI, -261.48 to -68.53, I2 : 95%). The TSA also provided robust evidence for this finding; however, the evidence remains insufficient to confirm a relationship between other Alzheimer's disease biomarkers [β-amyloid 40 (Aβ40), total tau (T-tau), phosphorylated tau (P-tau), and Aβ42/T-tau ratio] and POD or POCD. The study results indicate a negative correlation between preoperative CSF Aβ42 levels and the occurrence of both POD and POCD. Future investigations are warranted to identify the predictive cutoff value of preoperative CSF Aβ42 for POD and POCD.

Domain‐specific subtle cognitive decline associations with cerebrospinal fluid and plasma β‐amyloid and p‐tau Alzheimer’s disease biomarkers in cognitively unimpaired individuals

AbstractBackgroundPresence of Alzheimer’s disease (AD) core pathology, β‐amyloid (Aβ) and p‐tau, has been proven to impact cognitive function even in cognitively unimpaired (CU) individuals. Although the Aβ and p‐tau (AT) effect has been mainly associated with memory function, recent evidence (Tideman, P., 2022. Neurology) suggested that Aβ levels were associated independently of p‐tau with the cross‐sectional performance in executive functioning. The aim of the present study was to explore specific associations of cerebrospinal fluid (CSF) and plasma Aβ and p‐tau baseline levels with the longitudinal change in several cognitive domains in a sample of CU individuals at increased risk of AD.MethodWe analyzed the associations of baseline CSF Aβ42/40, and p‐tau181 as well as plasma Aβ42/40, and p‐tau231 levels, with domain‐specific cognitive changes 3 years after baseline in 337 CU participants from the ALFA+ study. We defined AT groups (A‐T‐, A+T‐, and A+T+) using CSF levels, and the A‐T‐ group’s baseline performance served as reference to compute z‐scores for Visual Processing, Semantic Fluency, Executive Functioning, Episodic Memory, and Attentional Processing. Delta scores were computed by subtracting baseline from follow‐up scores and then compared among AT groups by means of ANCOVAs. Multiple linear regressions were performed on the whole sample using CSF Aβ42/40, p‐tau181 and plasma Aβ42/40, p‐tau231 as predictors of change in cognitive function.ResultA+T+ individuals showed a significant decline in Executive Function (p = 0.005, Cohen’s d = 0.716), and Attentional Processing (p = 0.032, Cohen’s d = 0.563), but not in Episodic Memory (p = 0.334) when compared with A‐T‐ individuals. In the whole sample, CSF Aβ42/40 was associated independently of p‐tau181 with a decline in Semantic Fluency (β = 6.284, p = 0.013), Attentional Processing (β = 3.828, p = 0.020), and Episodic Memory (β = 3.513, p = 0.004). Plasma p‐tau231 levels were associated with a decline in Semantic Fluency (β = ‐0.413, p = 0.045). CSF p‐tau181 and plasma Aβ42/40 were not associated with cognitive changes.ConclusionExecutive Function and Attentional Processing were more sensitive than Episodic Memory in capturing the early subtle cognitive changes in CU individuals with underlying AD pathology. Attentional Processing was the only cognitive domain associated both with the status of AD biomarkers and with the effect of CSF Aβ levels independently of p‐tau.

A systematic review with meta-analysis to assess Alzheimer's disease biomarkers in adults with or without obstructive sleep apnoea

The aim was to design a meta-analysis evaluating the positron emission tomography (PET) uptake and cerebrospinal fluid (CSF), circulating levels of amyloid-β (Aβ), and tau proteins OSA group versus control group, as well as the association of these biomarkers with the severity of OSA. Four databases were searched until April 17, 2023, without any restrictions. The effect sizes were the standardized mean difference (SMD) along with a 95% confidence interval (CI). A total of 21 articles were entered into the meta-analysis. The pooled SMDs of the CSF levels in OSA adults compared to controls were: -0.82 (P=0.004) for Aβ42, -1.13 (P<0.001) for Aβ40, 0.17 (P=0.23) for p-tau, 0.04 (P=0.65) for t-tau, 0.08 (P=0.89) for Aβ42/Aβ40 ratio, and 0.81 (P=0.001) for t-tau/Aβ42 ratio. The pooled SMD for the PET uptake of Aβ burden in OSA adults compared to controls was 0.30 (P=0.03). The pooled SMDs of the circulating levels in OSA adults compared to controls were: 0.67 (P=0.002) for Aβ42, 0.11 (P=0.82) for Aβ40, 0.35 (P=0.06) for p-tau, and 1.41(P=0.005) for t-tau. The pooled SMDs for levels of Aβ42, Aβ40, total Aβ, p-tau, t-tau, and Aβ42/Aβ40 ratio in severe OSA adults compared to mild/moderate OSA adults were -0.15 (P=0.33), 0.25 (P=35), 0.04 (P=87), -2.53 (P=0.24), -0.24 (P=0.52), and -0.28 (P=0.30), respectively. The results indicated that CSF levels of Aβ42 and Aβ40 in OSA adults were significantly lower, but the CSF level of t-tau/Aβ42 ratio and PET Aβ burden uptake in OSA adults significantly were higher than in controls.

Cross-sectional associations of CSF tau levels with Rey's AVLT: A recency ratio study.

The preeminent in vivo cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) are amyloid β 1-42 (Aβ42), phosphorylated Tau (p-tau), and total Tau (t-tau). The goal of this study was to examine how well traditional (total and delayed recall) and process-based (recency ratio [Rr]) measures derived from Rey's Auditory Verbal Learning test (AVLT) were associated with these biomarkers. Data from 235 participants (Mage = 65.5, SD = 6.9), who ranged from cognitively unimpaired to mild cognitive impairment, and for whom CSF values were available, were extracted from the Wisconsin Registry for Alzheimer's Prevention. Bayesian regression analyses were carried out using CSF scores as outcomes, AVLT scores as predictors, and controlling for demographic data and diagnosis. We found moderate evidence that Rr was associated with both CSF p-tau (Bayesian factor [BFM] = 5.55) and t-tau (BFM = 7.28), above and beyond the control variables, while it did not correlate with CSF Aβ42 levels. In contrast, total and delayed recall scores were not linked with any of the AD biomarkers, in separate analyses. When comparing all memory predictors in a single regression, Rr remained the strongest predictor of CSF t-tau levels (BFM = 3.57). Our findings suggest that Rr may be a better cognitive measure than commonly used AVLT scores to assess CSF levels of p-tau and t-tau in nondemented individuals. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Different associations between amyloid-βeta 42, amyloid-βeta 40, and amyloid-βeta 42/40 with soluble phosphorylated-tau and disease burden in Alzheimer’s disease: a cerebrospinal fluid and fluorodeoxyglucose-positron emission tomography study

BackgroundDespite the high sensitivity of cerebrospinal fluid (CSF) amyloid beta (Aβ)42 to detect amyloid pathology, the Aβ42/Aβ40 ratio (amyR) better estimates amyloid load, with higher specificity for Alzheimer’s disease (AD). However, whether Aβ42 and amyR have different meanings and whether Aβ40 represents more than an Aβ42-corrective factor remain to be clarified. Our study aimed to compare the ability of Aβ42 and amyR to detect AD pathology in terms of p-tau/Aβ42 ratio and brain glucose metabolic patterns using fluorodeoxyglucose-positron emission tomography (FDG-PET).MethodsCSF biomarkers were analyzed with EUROIMMUN ELISA. We included 163 patients showing pathological CSF Aβ42 and normal p-tau (A + T − = 98) or pathological p-tau levels (A + T + = 65) and 36 control subjects (A − T −). A + T − patients were further stratified into those with normal (CSFAβ42 + /amyR − = 46) and pathological amyR (CSFAβ42 + /amyR + = 52). We used two distinct cut-offs to determine pathological values of p-tau/Aβ42: (1) ≥ 0.086 and (2) ≥ 0.122. FDG-PET patterns were evaluated in a subsample of patients (n = 46) and compared to 24 controls.ResultsCSF Aβ40 levels were the lowest in A − T − and in CSFAβ42 + /amyR − , higher in CSFAβ42 + /amyR + and highest in A + T + (F = 50.75; p < 0.001), resembling CSF levels of p-tau (F = 192; p < 0.001). We found a positive association between Aβ40 and p-tau in A − T − (β = 0.58; p < 0.001), CSFAβ42 + /amyR − (β = 0.47; p < 0.001), and CSFAβ42 + /amyR + patients (β = 0.48; p < 0.001) but not in A + T + . Investigating biomarker changes as a function of amyR, we observed a weak variation in CSF p-tau (+ 2 z-scores) and Aβ40 (+ 0.8 z-scores) in the normal amyR range, becoming steeper over the pathological threshold of amyR (p-tau: + 5 z-scores, Aβ40: + 4.5 z-score). CSFAβ42 + /amyR + patients showed a significantly higher probability of having pathological p-tau/Aβ42 than CSFAβ42 + /amyR − (cut-off ≥ 0.086: OR 23.3; cut-off ≥ 0.122: OR 8.8), which however still showed pathological values of p-tau/Aβ42 in some cases (cut-off ≥ 0.086: 35.7%; cut-off ≥ 0.122: 17.3%) unlike A − T − . Accordingly, we found reduced FDG metabolism in the temporoparietal regions of CSFAβ42 + /amyR − compared to controls, and further reduction in frontal areas in CSFAβ42 + /amyR + , like in A + T + .ConclusionsPathological p-tau/Aβ42 and FDG hypometabolism typical of AD can be found in patients with decreased CSF Aβ42 levels alone. AmyR positivity, associated with higher Aβ40 levels, is accompanied by higher CSF p-tau and widespread FDG hypometabolism.

Associations between Neuropsychiatric Symptoms and Alzheimer's Disease Biomarkers in People with Mild Cognitive Impairment.

Neuropsychiatric symptoms (NPS) are associated with faster decline in mild cognitive impairment (MCI). This study aimed to investigate the association between NPS severity and Alzheimer's disease (AD) biomarkers, i.e., amyloid-β (Aβ), phosphorylated tau protein (p-tau) and hippocampal volume ratio (HR), to characterise in more detail MCI patients with a poor prognosis. A total of 506 individuals with MCI and 99 cognitively unimpaired older adults were selected from the ADNI dataset. The patients were divided into three different groups based on their NPI-Q total scores: no NPS (n = 198), mild NPS (n = 160) and severe NPS (n = 148). Regression models were used to assess the association between the severity of NPS and each biomarker level and positivity status. Cerebrospinal fluid Aβ levels were positively associated with older age and lower MMSE scores, while higher p-tau levels were associated with female sex and lower MMSE scores. Only patients with severe NPS had a lower HR (β = -0.18, p = 0.050), i.e., more pronounced medio-temporal atrophy, than those without NPS. Only HR was associated with the presence of NPS, partially in line with previous evidence showing that severe NPS may be explained primarily by greater grey matter loss. Future longitudinal studies will be needed to ascertain the relevance of this finding.

Sleep Dysregulation Is Associated with 18F-FDG PET and Cerebrospinal Fluid Biomarkers in Alzheimer's Disease.

Sleep impairment has been commonly reported in Alzheimer's disease (AD) patients. The association between sleep dysregulation and AD biomarkers has been separately explored in mild cognitive impairment (MCI) and AD patients. The present study investigated cerebrospinal-fluid (CSF) and 18F-fluoro-deoxy-glucose positron emission tomography (18F-FDG-PET) biomarkers in MCI and AD patients in order to explore their association with sleep parameters measured with polysomnography (PSG). MCI and AD patients underwent PSG, 18F-FDG-PET, and CSF analysis for detecting and correlating these biomarkers with sleep architecture. Thirty-five patients were included in the study (9 MCI and 26 AD patients). 18F-FDG uptake in left Brodmann area 31 (owing to the posterior cingulate cortex) correlated negatively with REM sleep latency (p = 0.013) and positively with REM sleep (p = 0.033). 18F-FDG uptake in the hippocampus was negatively associated with sleep onset latency (p = 0.041). Higher CSF orexin levels were associated with higher sleep onset latency (p=0.042), Non-REM stage 1 of sleep (p=0.031), wake after sleep onset (p=0.028), and lower sleep efficiency (p=0.045). CSF levels of Aβ42 correlated negatively with the wake bouts index (p = 0.002). CSF total-tau and phosphorylated tau levels correlated positively with total sleep time (p=0.045) and time in bed (p=0.031), respectively. Sleep impairment, namely sleep fragmentation, REM sleep dysregulation, and difficulty in initiating sleep correlates with AD biomarkers, suggesting an effect of sleep on the pathological processes in different AD stages. Targeting sleep for counteracting the AD pathological processes represents a timely need for clinicians and researchers.

Cerebrospinal-fluid biomarkers for predicting phenoconversion in patients with isolated rapid-eye movement sleep behavior disorder.

Patients with isolated rapid-eye-movement sleep behavior disorder (iRBD) have an increased risk of developing neurodegenerative diseases. This study assessed cerebrospinal-fluid (CSF) biomarkers of neurodegeneration and blood-brain barrier (BBB) alteration in patients with iRBD compared to controls and ascertain whether these biomarkers may predict phenoconversion to alpha-synucleinopathies (Parkinson's Disease (PD), Dementia with Lewy bodies (DLB), Multiple System Atrophy (MSA)). Patients and controls underwent between 2012 and 2016 a neurological assessment, a lumbar puncture for CSF biomarker analysis (β-amyloid42 - Aβ42; total-tau, and phosphorylated tau), and BBB alteration (CSF/serum albumin ratio). All patients with iRBD were followed until 2021 and then classified into patients who converted to alpha-synucleinopathies (iRBD converters, cRBD) or not (iRBD non-converters, ncRBD). Thirty-four patients with iRBD (mean age 67.12 ± 8.14) and 33 controls (mean age 64.97 ± 8.91) were included. At follow-up (7.63 ± 3.40 years), eight patients were ncRBD and 33 patients were cRBD: eleven converted to PD, 10 to DLB, and two to MSA. Patients with iRBD showed lower CSF Aβ42 levels and higher CSF/serum albumin ratio than controls. Cox regression analysis showed that the phenoconversion rate increases with higher motor impairment (hazard ratio [HR] = 1.23, p = 0.032). CSF Aβ42 levels predicted phenoconversion to DLB (HR = 0.67, p = 0.038) and BBB alteration predicted phenoconversion to PD (HR = 1.20, p = 0.038). This study showed that low CSF Aβ42 levels and high BBB alteration may predict the phenoconversion to DLB and PD in patients with iRBD, respectively. These findings highlight the possibility to discriminate phenoconversion in iRBD patients through CSF biomarkers; however, further studies are needed.

Evidence of Clinical Efficacy and Pharmacological Mechanisms of Resveratrol in the Treatment of Alzheimer's Disease.

To evaluate the efficacy and pharmacological mechanisms of resveratrol in Alzheimer's disease (AD) patients. We conducted a thorough exploration of existing randomized controlled trials concerning the treatment of Alzheimer's disease patients using resveratrol, utilizing accessible open databases. Quantitative variables were represented as a standardized mean difference (SMD), accompanied by a 95% confidence interval (CI). Additionally, we examined the potential targets and plausible pathways associated with the impact of resveratrol on Alzheimer's disease using network pharmacology techniques. Our meta-analysis comprised five trials involving 271 AD patients, of whom 139 received resveratrol treatment and 132 received placebo treatment. Compared with placebo therapy, resveratrol treatment resulted in a significant improvement in Alzheimer's Disease Cooperative Study- Activities of Daily Living (ADAS-ADL) scores (SMD=0.51; 95% CI, 0.24 to 0.78) and cerebrospinal fluid (CSF) Aβ40 (SMD=0.84; 95% CI, 0.21 to 1.47) and plasma Aβ40 levels (SMD=0.43; 95% CI, 0.07 to 0.79). However, the improvement in the resveratrol-treated group compared with the placebo treatment group on the Mini-Mental State Examination (MMSE) score, CSF Aβ42 and plasma Aβ42 levels, and brain volume was not significant. There were no noteworthy statistical variances in the occurrence of adverse effects noted between the two groups. The outcomes of network pharmacology divulged that the principal enriched interaction pathway between resveratrol and Alzheimer's disease is primarily concentrated within the PI3K signaling pathways. Resveratrol's potential key targets for the treatment of AD include MAKP1, HRAS, EGFR, and MAPK2K1. While having a high safety profile, resveratrol has efficacy in AD patients to a certain extent, and more data are required to validate the efficacy of resveratrol for the treatment of AD in the future. Suppression of the PI3K signaling pathways could hold significant importance in the treatment of AD patients using resveratrol.

Lower Cerebrospinal Fluid Amyloid-β42 Predicts Sooner Time to Antipsychotic Use in Alzheimer's Disease.

Cerebrospinal fluid (CSF) biomarkers of amyloid-β42 (Aβ42) and phosphorylated-tau help clinicians accurately diagnose Alzheimer's disease (AD). Whether biomarkers help prognosticate behavioral and psychological symptoms of dementia (BPSD) is unclear. Determine whether CSF biomarker levels aid prognostication of BPSD in AD. This retrospective cohort study included patients over 65 with a diagnosis of AD based on CSF biomarkers. We measured time from CSF testing to the first antipsychotic use in the following months. We then analyzed time to antipsychotic (AP) use with respect to Aβ42, total tau, phosphorylated tau, and amyloid-to-tau index using a survival analysis approach. Of 86 AD patients (average 72±5 years, 46.5% male), 11 patients (12.7%) received APs following CSF testing. Patients with Aβ42 below the median had sooner time-to-AP use. This was significant on a log-rank test (p = 0.04). There was no difference in time-to-AP use if the group was stratified by levels of total tau, phosphorylated tau, or amyloid-to-tau index. These results suggest a relationship between lower CSF Aβ42 levels and sooner AP use. This supports prior reports suggesting a correlation between BPSD and Aβ deposition on PET. These results highlight the need for further prospective studies on Aβ levels and BPSD.

The dynamic functional role of triggering receptor expressed on myeloid cells 2 (TREM2) assessed with cerebrospinal fluid and positron emission tomography measures

AbstractBackgroundTriggering receptor expressed on myeloid cells 2 (TREM2) regulates several microglial activities and is essential for microglia to switch to an activated state. The role of TREM2 in the pathogenesis of Alzheimer’s disease (AD) is unclear, however. Following its role in microglial activity, the ectodomain of TREM2 is cleaved into the soluble proteolytic end product of TREM2 (sTREM2), which is released from the transmembrane domain into the cerebrospinal fluid (CSF) and, therefore, CSF sTREM2 is considered a biomarker of TREM2 activity.MethodTo examine the role of TREM2, we explored the relationships between CSF sTREM2, amyloid‐beta (Aβ42), phosphorylated tau‐181 (p‐tau‐181), and total‐tau (t‐tau) in a cohort of 495 participants (100 patients with AD, 257 patients with MCI, and 138 controls) whose data were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Associations between CSF sTREM2 and 18F‐fluorodeoxyglucose (18F‐FDG) positron emission tomography (PET), 18F‐florbetapir (18F‐AV45) PET, and grey matter volume (GMV) were also investigated.ResultCSF sTREM2 levels were stable across AD, MCI and cognitively normal subgroups. In the whole cohort, CSF sTREM2 positively correlated with age (r = 0.214,p&lt;0.001), CSF Aβ42 (r = 0.118,p = 0.009), CSF t‐tau (r = 0.423,p&lt;0.001), and CSF p‐tau‐181 (r = 0.396,p&lt;0.001), and negatively correlated with MMSE score (r = ‐0.105,p = 0.019). CSF sTREM2, t‐tau and p‐tau‐181 could significantly predict CSF Aβ42 levels, while CSF sTREM2 and Aβ42 could significantly predict CSF p‐tau‐181 and t‐tau levels. Higher CSF sTREM2 was associated with greater amyloid load, decreased glucose metabolism, and reduced GMV in MCI, but not in AD, in certain brain regions.ConclusionCSF sTREM2 levels were comparable across clinical groups, and with CSF sTREM2 correlating with markers of AD and neuronal damage, we predict that changes in neuropathological processes occurring in relation to changes in CSF sTREM2 levels are a result of alterations in TREM2 function, rather than quantity. Taken together with the relationships between CSF sTREM2 and imaging findings, these results suggest that sTREM2 appears early on in the AD trajectory, probably in response to early microglial activation in MCI in response to evolving pathological processes.

CSF Aβ42 and tau biomarkers in cognitively unimpaired Aβ- middle-aged and older APOE ε4 carriers

This study aimed to determine the relationship between the apolipoprotein E (APOE) ε4 allele and cerebrospinal fluid (CSF) and neuroimaging biomarkers of Alzheimer’s disease, and cognition in cognitively unimpaired (CU) middle-aged adults (n = 82; Mage = 58.2), and in Aβ- CU older adults (n = 71; Mage = 71.8). Aβ- CU middle-aged ε4 carriers showed lower CSF Aβ42 levels, higher levels of CSF total tau (t-tau) and neurofilament light (NfL), and poorer cognitive performance compared to noncarriers (Cohen’s d: 0.30–0.56). In Aβ- CU older adults, ε4 carriers also had lower CSF Aβ42 levels and higher levels of CSF t-tau and p-tau181, compared to noncarriers (Cohen’s d: 0.65–0.74). In both Aβ- middle-aged and older adults, hippocampal and total brain volume were equivalent between ε4 carriers and noncarriers. In Aβ- CU middle-aged adults, APOE ε4 is associated with decreased levels of Aβ, increased tau and NfL, and poorer cognition. Similar relationships were observed in Aβ- CU older adults. These results have implications for understanding clinicopathological relationships between APOE ε4 and the emergence of cognitive and biomarker abnormalities in Aβ- adults.