Proteomic comparison between non-purified cerebrospinal fluid and cerebrospinal fluid-derived extracellular vesicles from patients with Alzheimer's, Parkinson's and Lewy body dementia.

Dementia is a leading cause of death worldwide, with increasing prevalence as global life expectancy increases. The most common neurodegenerative disorders are Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). With this study, we took an in-depth look at the proteome of the (non-purified) cerebrospinal fluid (CSF) and the CSF-derived extracellular vesicles (EVs) of AD, PD, PD-MCI (Parkinson's disease with mild cognitive impairment), PDD and DLB patients analysed by label-free mass spectrometry. This has led to the discovery of differentially expressed proteins that may be helpful for differential diagnosis. We observed a greater number of differentially expressed proteins in CSF-derived EV samples (N = 276) compared to non-purified CSF (N = 169), with minimal overlap between both datasets. This finding suggests that CSF-derived EV samples may be more suitable for the discovery phase of a biomarker study, due to the removal of more abundant proteins, resulting in a narrower dynamic range. As disease-specific markers, we selected a total of 39 biomarker candidates identified in non-purified CSF, and 37 biomarker candidates across the different diseases under investigation in the CSF-derived EV data. After further exploration and validation of these proteins, they can be used to further differentiate between the included dementias and may offer new avenues for research into more disease-specific pharmacological therapeutics.

Autopsy-diagnosed neurodegenerative dementia cases support the use of cerebrospinal fluid protein biomarkers in the diagnostic work-up.

Various proteins play a decisive role in the pathology of different neurodegenerative diseases. Nonetheless, most of these proteins can only be detected during a neuropathological assessment, although some non-specific biomarkers are routinely tested for in the cerebrospinal fluid (CSF) as a part of the differential diagnosis of dementia. In antemortem CSF samples from 117 patients with different types of neuropathologically confirmed neurodegenerative disease with dementia, we assessed total-tau (t-tau), phosphorylated-tau (181P) (p-tau), amyloid-beta (1-42) (Aß42), TAR DNA binding protein (TDP)-43, progranulin (PGRN), and neurofilament light (NfL) chain levels, and positivity of protein 14-3-3. We found t-tau levels and the t-tau/p-tau ratios were significantly higher in prion diseases compared to the other neurodegenerative diseases. Statistically significant differences in the t-tau/Aß42 ratio predominantly corresponded to t-tau levels in prion diseases and Aß42 levels in AD. TDP-43 levels were significantly lower in prion diseases. Additionally, the TDP-43/Aß42 ratio was better able to distinguish Alzheimer's disease from other neurodegenerative diseases compared to using Aß42 alone. In frontotemporal lobar degeneration, PRGN levels were significantly higher in comparison to other neurodegenerative diseases. There is an increasing need for biomarkers suitable for diagnostic workups for neurodegenerative diseases. It appears that adding TDP-43 and PGRN to the testing panel for neurodegenerative diseases could improve the resolution of differential diagnoses.

Cerebrospinal Fluid C18 Ceramide Associates with Markers of Alzheimer's Disease and Inflammation at the Pre- and Early Stages of Dementia.

BACKGROUND: Understanding how dysregulation in lipid metabolism relates to the severity of Alzheimer's disease (AD) pathology might be critical in developing effective treatments. OBJECTIVE: To identify lipid species in cerebrospinal fluid (CSF) associated with signature AD pathology and to explore their relationships with measures reflecting AD-related processes (neurodegeneration, inflammation, deficits in verbal episodic memory) among subjects at the pre- and early symptomatic stages of dementia. METHODS: A total of 60 subjects that had been referred to an Icelandic memory clinic cohort were classified as having CSF AD (n = 34) or non-AD (n = 26) pathology profiles. Untargeted CSF lipidomic analysis was performed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) for the detection of mass-to-charge ratio (m/z) features. CSF proteins reflecting neurodegeneration (neurofilament light [NFL]) and inflammation (chitinase-3-like protein 1 [YKL-40], S100 calcium-binding protein B [S100B], glial fibrillary acidic protein [GFAP]) were also measured. Rey Auditory Verbal Learning (RAVLT) and Story tests were used for the assessment of verbal episodic memory. RESULTS: Eight out of 1008 features were identified as best distinguishing between the CSF profile groups. Of those, only the annotation of the m/z feature assigned to lipid species C18 ceramide was confirmed with a high confidence. Multiple regression analyses, adjusted for age, gender, and education, demonstrated significant associations of CSF core AD markers (Aß42: st.ß= -0.36, p = 0.007; T-tau: st.ß= 0.41, p = 0.005) and inflammatory marker S100B (st.ß= 0.51, p = 0.001) with C18 ceramide levels. CONCLUSION: Higher levels of C18 ceramide associated with increased AD pathology and inflammation, suggesting its potential value as a therapeutic target.

Blood TDP-43 Combined with Demographics Information Predicts Dementia Occurrence in Community Non-Dementia Elderly.

BACKGROUND: TAR DNA-binding protein-43 (TDP-43) and neurofilament light chain (NfL) are promising fluid biomarkers of disease progression for various dementia. OBJECTIVE: We would explore whether blood levels of NfL and TDP-43 could predict the long-term progression to dementia, and the relationship of TDP-43 levels between cerebrospinal fluid (CSF) and blood. METHODS: A total of 86 non-dementia elderly received 7-year follow-up, and were divided into 49 stable normal control (NC)/mild cognitive impairment (MCI) subjects, 19 subjects progressing from NC to MCI, and 18 subjects progressing from NC/MCI to dementia. Blood TDP-43 and NfL levels, and cognitive functions were measured in all subjects. Furthermore, another cohort of 23 dementia patients, including 13 AD and 10 non-AD patients received blood and CSF measurements of TDP-43. RESULTS: In cohort 1, compared to stable NC/MCI group, there were higher levels of blood TDP-43 at baseline in subjects progressing from NC/MCI to dementia. The combination of baseline blood TDP-43 levels with demographics including age, education, and diabetes had the detection for dementia occurrence. Baseline blood levels of NfL are negatively associated with cognitive function at 7-year follow-up. In cohort 2, we found there were no relationship between CSF and blood levels of TDP-43. Moreover, the levels of TDP-43 in CSF was positively associated with the age of patients, especially in AD group. CONCLUSION: Single blood TDP-43 could not estimate dementia occurrence; however, TDP-43 combined with demographics has the predictive effect for dementia occurrence and NfL level is associated with a decrease of cognitive function.

Accelerated long-term forgetting over three months in asymptomatic APOE ɛ4 carriers.

Accelerated long-term forgetting (ALF) refers to a rapid loss of information over days or weeks despite normal acquisition/encoding. Notwithstanding its potential relevance as a presymptomatic marker of cognitive dysfunction, no study has addressed the relationship between ALF and Alzheimer's disease (AD) biomarkers. We examined ALF in APOE ɛ4 carriers versus noncarriers, and its relationships with AD cerebrospinal fluid (CSF) biomarkers. We found ALF over three months in APOE ɛ4 carriers (F(1,19) = 5.60; P < 0.05; Cohen's d = 1.08), and this performance was associated with abnormal levels of the CSF Aß42 /ptau ratio (r = -.614; P < 0.01). Our findings indicate that ALF is detectable in at-risk individuals, and that there is a relationship between ALF and the pathophysiological processes underlying AD.

Cerebrospinal Fluid and Blood CX3CL1 as a Potential Biomarker in Early Diagnosis and Prognosis of Dementia.

BACKGROUND: A growing body of evidence highlights the crucial role of neuroinflammation and chemokine involvement in cognitive impairment pathophysiology. Fractalkine (CX3CL1) appears to be a relevant causative factor in the development of dementia, particularly at the early stages of the disease. However, limited data are available on the levels of CX3CL1 in the cerebrospinal fluid (CSF) and blood. Additionally, to date, its utility as a biomarker for MCI or AD has not been studied. OBJECTIVE: The aim of the present study was to evaluate the clinical utility of CX3CL1 in the early diagnosis of cognitive impairment. We also compared the diagnostic usefulness of CX3CL1 with other biomarkers associated with neuroinflammation. METHODS: A total of 60 patients with cognitive impairment, including 42 patients with AD and 18 subjects with MCI, as well as 20 cognitively healthy controls were enrolled in the study. CSF and blood concentrations of CX3CL1, CCL-2, and YKL-40 were measured by ELISA. RESULTS: Significantly higher CSF and blood concentrations of CX3CL1 were observed in MCI and AD patients compared to older individuals without cognitive impairment. The increase in the levels of CX3CL1 and YKL-40 in non-demented subjects was associated with MCI. The area under the ROC curve for CX3CL1 in MCI subjects was larger in comparison to classical AD markers. CONCLUSION: Presented results indicate a crucial role of CX3CL1 in the pathology of cognitive impairment and the potential usefulness of this protein in the early diagnosis of MCI and AD.

Affective Neuropsychiatric Symptoms as Early Signs of Dementia Risk in Older Adults.

BACKGROUND: Affective neuropsychiatric symptoms (aNPS: depression, anxiety, apathy, irritability) have been linked to increased dementia risk. However, less is known whether this association is independent of Alzheimer's disease (AD) pathophysiology. OBJECTIVE: To investigate the contribution of early aNPS to dementia risk in cognitively normal (CN) older adults and mild cognitive impairment (MCI) patients, with and without AD biomarker abnormality. METHODS: Participants included 763 community-dwelling, stroke-free older adults identified as CN and 617 with MCI at baseline, drawn from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Baseline assessments included a neuropsychological battery, the Neuropsychiatric Inventory (NPI), and apolipoprotein E ɛ4 (ApoE4) genotyping. A participant subset completed cerebrospinal fluid (CSF) AD biomarker assessment. Time to progression to dementia was measured based on months at follow-up when an individual was diagnosed with dementia, over the follow-up period of 48 months. RESULTS: Latent class analysis identified 3 subgroups of older adults in CN and MCI, indicated by the baseline profiles of neuropsychiatric symptoms (NPS). Subgroups with higher aNPS were at increased risk of progression to dementia in both CN (HR = 3.65, 95% CI [1.80, 7.40]) and MCI (HR = 1.52, 95% CI [1.16, 2.00]; HR = 1.86 [1.05, 3.30]) groups, adjusting for age, sex, global cognition, and ApoE4, compared with their counterparts with minimal NPS. There was no difference between higher aNPS and minimal NPS subgroups in their CSF AD biomarker profiles. CONCLUSION: Findings suggest that aNPS may represent a neurobiological vulnerability that uniquely contribute to the dementia risk, independent of AD biomarker profiles.

Small Vessel Disease and Associations with Cerebrospinal Fluid Amyloid, Tau, and Neurodegeneration (ATN) Biomarkers and Cognition in Young Onset Dementia.

BACKGROUND: Small vessel disease (SVD) and Alzheimer's disease (AD) frequently coexist; however, it remains unclear how they collectively affect cognition. OBJECTIVE: We investigated associations between SVD and AD biomarkers, namely amyloid, tau, and neurodegeneration (ATN) in young onset dementia (YOD) and explored how SVD and ATN interact to affect cognition. METHODS: 80 YOD individuals were recruited from a memory clinic. SVD burden (SVD+) was operationalized as a score >1 on the Staals scale and ATN was measured using cerebrospinal fluid (CSF). RESULTS: SVD+ was associated with lower CSF Aß1-42 (B = -0.20, 95% CI: -0.32 to -0.08) and greater neurodegeneration, indexed as hippocampal atrophy (B = -0.24, 95% CI: -0.40 to -0.04). SVD+ was not associated with tau. Cognitive impairment was associated with CSF Aß1-42 (B = -0.35, 95% CI: -0.55 to -0.18) but not SVD. Rather, SVD was indirectly associated with cognition via reduced CSF Aß1-42, specifically with global cognition (B = -0.03, 95% CI: -0.09 to -0.01) and memory (B = 0.08, 95% CI: -.01 to .21). SVD was indirectly associated with cognition via increased neurodegeneration in grey matter (Global cognition: B = -0.06, 95% CI: -0.17 to -0.03; Memory: B = 0.05, 95% CI: 0.01 to 0.18) and the hippocampus (Global cognition: B = -0.05, 95% CI: -0.11 to -0.01; Memory: B = 0.06, 95% CI: 0.01 to 0.17). CONCLUSION: In YOD, SVD burden was associated with AD pathology, namely CSF Aß1-42. SVD indirectly contributed to cognitive impairment via reducing CSF Aß1-42 and increasing neurodegeneration.

Comparison between plasma and cerebrospinal fluid biomarkers for the early diagnosis and association with survival in prion disease.

OBJECTIVE: To compare the diagnostic accuracy and the prognostic value of blood and cerebrospinal fluid (CSF) tests across prion disease subtypes. METHODS: We used a single-molecule immunoassay to measure tau and neurofilament light chain (NfL) protein levels in the plasma and assessed CSF total(t)-tau, NfL and protein 14-3-3 levels in patients with prion disease (n=336), non-prion rapidly progressive dementias (n=106) and non-neurodegenerative controls (n=37). We then evaluated each plasma and CSF marker for diagnosis and their association with survival, taking into account the disease subtype, which is a strong independent prognostic factor in prion disease. RESULTS: Plasma tau and NfL concentrations were higher in patients with prion disease than in non-neurodegenerative controls and non-prion rapidly progressive dementias. Plasma tau showed higher diagnostic value than plasma NfL, but a lower accuracy than the CSF proteins t-tau and 14-3-3. In the whole prion cohort, both plasma (tau and NfL) and CSF (t-tau, 14-3-3 and NfL) markers were significantly associated with survival and showed similar prognostic values. However, the intrasubtype analysis revealed that only CSF t-tau in sporadic Creutzfeldt-Jakob disease (sCJD) MM(V)1, plasma tau and CSF t-tau in sCJD VV2, and plasma NfL in slowly progressive prion diseases were significantly associated with survival after accounting for covariates. CONCLUSIONS: Plasma markers have lower diagnostic accuracy than CSF biomarkers. Plasma tau and NfL and CSF t-tau are significantly associated with survival in prion disease in a subtype-specific manner and can be used to improve clinical trial stratification and clinical care.

SWATH-MS analysis of cerebrospinal fluid to generate a robust battery of biomarkers for Alzheimer's disease.

Cerebrospinal fluid (CSF) Aß42 and tau protein levels are established diagnostic biomarkers of Alzheimer's disease (AD). However, their inadequacy to represent clinical efficacy in drug trials indicates the need for new biomarkers. Sequential window acquisition of all theoretical fragment ion spectra (SWATH)-based mass spectrometry (MS) is an advanced proteomic tool for large-scale, high-quality quantification. In this study, SWATH-MS showed that VGF, chromogranin-A, secretogranin-1, and opioid-binding protein/cell adhesion molecule were significantly decreased in 42 AD patients compared to 39 controls, whereas 14-3-3ζ was increased (FDR < 0.05). In addition, 16 other proteins showed substantial changes (FDR < 0.2). The expressions of the top 21 analytes were closely interconnected, but were poorly correlated with CSF Aß42, tTau, and pTau181 levels. Logistic regression analysis and data mining were used to establish the best algorithm for AD, which created novel biomarker panels with high diagnostic value (AUC = 0.889 and 0.924) and a strong correlation with clinical severity (all p < 0.001). Targeted proteomics was used to validate their usefulness in a different cohort (n = 36) that included patients with other brain disorders (all p < 0.05). This study provides a list of proteins (and combinations thereof) that could serve as new AD biomarkers.

Cerebrospinal Fluid/Plasma Albumin Ratio as a Biomarker for Blood-Brain Barrier Impairment Across Neurodegenerative Dementias.

BACKGROUND: Previous studies have shown an association between disruption of the blood-brain-barrier (BBB) and dementias of different etiologies. The protein concentration of cerebrospinal fluid (CSF) can be used as an indirect measurement for the permeability of the BBB using the CSF/plasma albumin quotient (Q-Alb) or total CSF protein. OBJECTIVE: In the current study, we wanted to investigate Q-Alb and CSF protein concentration in dementias of different etiologies and the possible confounding factors. METHODS: A total of 510 patients and healthy controls were included in the current study. The patients were diagnosed with Alzheimer's disease (AD), dementia with Lewy bodies (DLB), vascular dementia (VaD), or frontotemporal dementia (FTD). RESULTS: We found that Q-Alb was significantly different between the groups (p = 0.002, F = 3.874). Patients with DLB and VaD showed the largest Q-Alb. Although not significant for CSF total protein, we found the same overall pattern for DLB and VaD. When examining confounding factors, we found a positive association with age and a lower Fazekas score in DLB as compared to VaD. CONCLUSION: These results suggest that Q-Alb can contribute to our understanding of the pathophysiological mechanisms in DLB, and Q-Alb may serve as a supplementary diagnostic marker. Furthermore, we found a positive association with age, which may be due to differences in vascular co-morbidities. In addition, in patients with DLB, the increased Q-Alb is not due to vascular lesions. Studies are needed to validate the possible diagnostic value of Q-Alb in a larger cohort.

Beta amyloid levels in cerebrospinal fluid of HIV-infected people vary by exposure to antiretroviral therapy.

BACKGROUND: HIV-associated neurocognitive disorders (HAND) persist despite the widespread implementation of combined antiretroviral therapy (ART). As people with HIV (PWH) age on ART regimens, the risk of age-related comorbidities, such as Alzheimer's disease may increase. However, questions remain as to whether HIV or ART will alter such risks. Beta amyloid (Aß) and phosphorylated-tau (p-tau) proteins are associated with Alzheimer's disease and their levels are altered in the CSF of Alzheimer's disease cases. METHODS: To better understand how these Alzheimer's disease-related markers are affected by HIV infection and ART, postmortem CSF collected from 70 well characterized HIV+ decedents was analyzed for Aß1-42, Aß1-40, and p-tau levels. RESULTS: Aß1-42 and Aß1-40 CSF levels were higher in cases that were exposed to ART. Aß1-42 and Aß1-40 CSF levels were also higher in cases on protease inhibitors compared with those with no exposure to protease inhibitors. Aß1-42 and Aß1-40 levels in CSF were lowest in HIV+ cases with HIV-associated dementia (HAD) and levels were highest in those diagnosed with asymptomatic neurocognitive impairment (ANI) and minor neurocognitive disorder (MND). Aß1-42 and Aß1-40 were inversely related with p-tau levels in all cases, as previously reported. CONCLUSION: These data suggest that ART exposure is associated with increased levels of Aß1-42 and Aß1-40 in the CSF. Also, HAD, but not ANI/MND diagnosis is associated with decreased levels of Aß1-42 and Aß1-40 in CSF, potentially suggesting impaired clearance. These data suggest that HIV infection and ART may impact pathogenic mechanisms involving Aß1-42 and Aß1-40, but not p-tau.

Soluble TREM2 is elevated in Parkinson's disease subgroups with increased CSF tau.

Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's disease and affects 1% of the population above 60 years old. Although Parkinson's disease commonly manifests with motor symptoms, a majority of patients with Parkinson's disease subsequently develop cognitive impairment, which often progresses to dementia, a major cause of morbidity and disability. Parkinson's disease is characterized by α-synuclein accumulation that frequently associates with amyloid-ß and tau fibrils, the hallmarks of Alzheimer's disease neuropathological changes; this co-occurrence suggests that onset of cognitive decline in Parkinson's disease may be associated with appearance of pathological amyloid-ß and/or tau. Recent studies have highlighted the appearance of the soluble form of the triggering receptor expressed on myeloid cells 2 (sTREM2) receptor in CSF during development of Alzheimer's disease. Given the known association of microglial activation with advancing Parkinson's disease, we investigated whether CSF and/or plasma sTREM2 differed between CSF biomarker-defined Parkinson's disease participant subgroups. In this cross-sectional study, we examined 165 participants consisting of 17 cognitively normal elderly subjects, 45 patients with Parkinson's disease with no cognitive impairment, 86 with mild cognitive impairment, and 17 with dementia. Stratification of subjects by CSF amyloid-ß and tau levels revealed that CSF sTREM2 concentrations were elevated in Parkinson's disease subgroups with a positive tau CSF biomarker signature, but not in Parkinson's disease subgroups with a positive CSF amyloid-ß biomarker signature. These findings indicate that CSF sTREM2 could serve as a surrogate immune biomarker of neuronal injury in Parkinson's disease.

Spatial navigation ability predicts progression of dementia symptomatology.

INTRODUCTION: Spatial navigation deficits are observed in Alzheimer's disease cross-sectionally, but prediction of longitudinal clinical decline has been less examined. METHODS: Cognitive mapping (CM) was assessed in 95 participants and route learning (RL) was assessed in 65 participants at baseline. Clinical progression over an average of 4 to 5 years was assessed using the clinical dementia rating (CDR) scale. Relative predictive ability was compared to episodic memory, hippocampus, and cerebrospinal fluid biomarkers (phosphorylated tau/amyloid ß 42 (ptau181 /Aß42 ) ratio). RESULTS: CM and RL were predictors of clinical progression (P's < 0.032). All measures, except RL-Learning remained predictors with episodic memory in models (P's < 0.048). Only RL-Retrieval remained a predictor when ptau181 /Aß42 was included (P < 0.001). CM interacted with hippocampus and ptau181 /Aß42 in prediction (P's < 0.013). CM, RL, and episodic memory evidenced strong diagnostic accuracy (area under the curve (AUC) = 0.894, 0.794, and 0.735, respectively); CM tended to perform better than episodic memory (P = 0.056). DISCUSSION: Baseline spatial navigation performance may be appropriate for assessing risk of clinical progression.

Cerebrospinal Fluid Levels of Interleukin-8 in Delirium, Dementia, and Cognitively Healthy Patients.

BACKGROUND: Delirium is a common and serious complication in geriatric patients. The pathophysiology of delirium is not known. OBJECTIVE: The objective of the current study was to test the hypothesis that cerebrospinal fluid (CSF) levels of inflammatory markers at the time of spinal anesthesia for hip surgery are associated with delirium. METHODS: In total 133 hip fracture patients and 125 cognitively healthy controls undergoing elective surgery, together with 73 Alzheimer's disease (AD) dementia patients, were recruited at Oslo University Hospital and Diakonhjemmet Hospital, Oslo, Norway. Delirium was evaluated daily in hip fracture patients by the Confusion Assessment Method (CAM). Depression was evaluated by Cornell Scale for Depression in Dementia (CSDD). Tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1ß), and interleukin-8 (IL-8) levels were measured in CSF using a Mesoscale Discovery (MSD) immunoassay. RESULTS: Hip fracture patients had significantly higher IL-8 levels (p < 0.001) compared to cognitively healthy controls or patients with stable AD dementia. Furthermore, preoperative IL-8 levels were significantly higher (p = 0.013) in hip fracture patients who developed delirium (incident delirium) after surgery as compared to patients with no delirium. However, subgroup analyses showed that IL-8 levels were only significantly higher in delirium patients without dementia (p = 0.006). In contrast, depression subgroup analysis showed that IL-8 concentration was significantly higher (p = 0.002) in delirium patients with depression. Both TNF-α and IL-1ß were undetected in most patients. CONCLUSIONS: Our study suggests that IL-8 levels are associated with delirium onset and that underlying depression or dementia influences IL-8 levels.

Dementia and CSF-biomarkers for Alzheimer's disease predict mortality after acute hip fracture.

BACKGROUND: Mortality is high after an acute hip fracture (AHF) surgery. Are cognitive impairment and/or altered levels of Alzheimer's Disease (AD)-biomarkers in cerebrospinal fluid (CSF) predictors of mortality in AHF-patients, as retrospective studies indicate? METHODS: Prospective single-center study including 373 AHF-patients, operated in spinal anesthesia. Cognitive status was evaluated by clinical dementia rating (CDR); CSF was analyzed for AD-biomarker concentrations (total tau (T-tau), phosphorylated tau (P-tau), amyloid beta ratio (Aß42/Aß40). CDR and biomarker levels were related to mortality up to one-year post-surgery, using univariate logistic regression analysis. RESULTS: Survival analyses showed that mortality was associated to the degree of dementia. In the entire patient cohort 30-, 90-, and 365-day mortality rates were 7.2%, 15.5%, and 25.5%, respectively, but only 2.7%, 5.5%, and 12.6%, for cognitively intact vs 16.3%, 31.7%, and 42.3% for demented patients (OR = 2.2-2.8 [CI = 1.6-4.9]; P = .0001). High CSF T-tau (OR = 1.19 [CI = 1.05-1.33]; P = .004) and low Aß42/Aß40-ratio (OR = 0.85 [CI = 0.74-0.97]; P = .017) were associated with increased 90-day mortality. Analysis of 4 subgroups (Cognitive impairment ± and Biomarkers ±) showed significant associations of dementia and CSF biomarker concentrations to mortality after an AHF. Even cognitively intact patients presenting with abnormal AD-biomarkers showed an increased 90-day mortality which, however, was statistically insignificant. CONCLUSIONS: Cognitive impairment and altered CSF biomarker concentrations indicative of AD pathology can predict increased mortality in patients with an AHF, and so probably even before clinical dementia diagnosis by early biomarker analysis; a notion that may have substantial clinical implications by improving perioperative treatment and postoperative rehabilitation.

Characteristic Biomarker and Cognitive Profile in Incipient Mixed Dementia.

BACKGROUND: Research has shown that mixed dementia is more common than previously believed but little is known of its early stages. OBJECTIVE: To examine if incipient mixed dementia can be differentiated from incipient Alzheimer's disease (AD) and subcortical ischemic vascular dementia (SVD) using neuropsychological tests, cerebrospinal fluid (CSF) markers, and magnetic resonance imaging markers. METHODS: We included 493 patients and controls from the Gothenburg MCI study and used the dementia groups for marker selection (CSF total-tau (T-tau), phospho-tau (P-tau), and amyloid-ß42 (Aß42), 11 neuropsychological tests, and 92 regional brain volumes) and to obtain cut-off values which were then applied to the MCI groups. RESULTS: Incipient mixed dementia was best differentiated from incipient AD by the Word fluency F-A-S test and the Trail making test A. CSF T-tau, P-tau, and Aß42 differentiated incipient mixed dementia from incipient SVD. CONCLUSION: Incipient mixed dementia is characterized by an AD-like biomarker profile and an SVD-like cognitive profile. Incipient mixed dementia can be separated from incipient AD and incipient SVD using CSF markers and cognitive testing.

PET and CSF amyloid-ß status are differently predicted by patient features: information from discordant cases.

BACKGROUND: Amyloid-ß PET and CSF Aß42 yield discordant results in 10-20% of memory clinic patients, possibly providing unique information. Although the predictive power of demographic, clinical, genetic, and imaging features for amyloid positivity has previously been investigated, it is unknown whether these features differentially predict amyloid-ß status based on PET or CSF or whether this differs by disease stage. METHODS: We included 768 patients (subjective cognitive decline (SCD, n = 194), mild cognitive impairment (MCI, n = 127), dementia (AD and non-AD, n = 447) with amyloid-ß PET and CSF Aß42 measurement within 1 year. Ninety-seven (13%) patients had discordant PET/CSF amyloid-ß status. We performed parallel random forest models predicting separately PET and CSF status using 17 patient features (demographics, APOE4 positivity, CSF (p)tau, cognitive performance, and MRI visual ratings) in the total patient group and stratified by syndrome diagnosis. Thereafter, we selected features with the highest variable importance measure (VIM) as input for logistic regression models, where amyloid status on either PET or CSF was predicted by (i) the selected patient feature and (ii) the patient feature adjusted for the status of the other amyloid modality. RESULTS: APOE4, CSF tau, and p-tau had the highest VIM for PET and CSF in all groups. In the amyloid-adjusted logistic regression models, p-tau was a significant predictor for PET-amyloid in SCD (OR = 1.02 [1.01-1.04], pFDR = 0.03), MCI (OR = 1.05 [1.02-1.07], pFDR < 0.01), and dementia (OR = 1.04 [1.03-1.05], pFDR < 0.001), but not for CSF-amyloid. APOE4 (OR = 3.07 [1.33-7.07], punc < 0.01) was associated with CSF-amyloid in SCD, while it was only predictive for PET-amyloid in MCI (OR = 9.44 [2.93, 30.39], pFDR < 0.01). Worse MMSE scores (OR = 1.21 [1.03-1.41], punc = 0.02) were associated to CSF-amyloid status in SCD, whereas worse memory (OR = 1.17 [1.05-1.31], pFDR = 0.02) only predicted PET positivity in dementia. CONCLUSION: Amyloid status based on either PET or CSF was predicted by different patient features, and this varied by disease stage, suggesting that PET-CSF discordance yields unique information. The stronger associations of both APOE4 carriership and worse memory z-scores with CSF-amyloid in SCD suggest that CSF-amyloid is more sensitive early in the disease course. The higher predictive value of CSF p-tau for a positive PET scan suggests that PET is more specific to AD pathology.

Progression to dementia in memory clinic patients with mild cognitive impairment and normal ß-amyloid.

BACKGROUND: Determination of ß-amyloid (Aß) positivity and likelihood of underlying Alzheimer's disease (AD) relies on dichotomous biomarker cut-off values. Individuals with mild cognitive impairment (MCI) and Aß within the normal range may still have a substantial risk of developing dementia, primarily of Alzheimer type. Their prognosis, as well as predictors of clinical progression, are not fully understood. The aim of this study was to explore the associations of cerebrospinal fluid (CSF) biomarkers (Aß42, total tau, phosphorylated tau) and other characteristics, including modifiable vascular factors, with the risk of progression to dementia among patients with MCI and normal CSF Aß42. METHODS: Three hundred eighteen memory clinic patients with CSF and clinical data, and at least 1-year follow-up, were included. Patients had normal CSF Aß42 levels based on clinical cut-offs. Cox proportional hazard models with age as time scale and adjusted for sex, education, and cognition (Mini-Mental State Examination) were used to investigate predictors of progression to dementia and Alzheimer-type dementia. Potential predictors included CSF biomarkers, cognitive performance (verbal learning and memory), apolipoprotein E (APOE) ε4 genotype, medial temporal lobe atrophy, family history of dementia, depressive symptoms, and vascular factors, including the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) risk score. Predictive performance of patient characteristics was further explored with Harrell C statistic. RESULTS: Lower normal Aß42 and higher total tau and phosphorylated tau were associated with higher dementia risk, and the association was not driven by Aß42 values close to cut-off. Additional predictors included poorer cognition, APOE ε4 genotype, higher systolic blood pressure, and lower body mass index, but not the CAIDE dementia risk score. Aß42 individually and in combination with other CSF biomarkers improved the risk prediction compared to age and cognition alone. Medial temporal lobe atrophy or vascular factors did not increase the predictive performance. CONCLUSIONS: Possibility of underlying AD pathology and increased dementia risk should not be ruled out among MCI patients with CSF Aß42 within the normal range. While cut-offs may be useful in clinical practice to identify high-risk individuals, personalized risk prediction tools incorporating continuous biomarkers may be preferable among individuals with intermediate risk. The role of modifiable vascular factors could be explored in this context.