Investigating alpha-synuclein co-pathology in Alzheimer's disease by means of cerebrospinal fluid alpha-synuclein seed amplification assay.

INTRODUCTION: Lewy body disease, a frequently observed co-pathology in Alzheimer's disease (AD), can be identified antemortem in cerebrospinal fluid (CSF) by α-synuclein seed amplification assay (αS-SAA). The prevalence and clinical impact of CSF αS-SAA positivity in AD are still unknown. METHODS: αS-SAA was performed on CSF samples from 240 AD patients (preclinical, prodromal, and dementia stages), 85 controls, 84 patients with Parkinson's disease (PD), and 21 patients with PD with dementia or dementia with Lewy bodies. In AD patients, associations between αS-SAA positivity and cognitive changes were also evaluated. RESULTS: In agreement with available neuropathological studies, αS-SAA positivity was observed in 30% of AD patients (vs 9% in controls), and was associated with cognitive decline, visuospatial impairment, and behavioral disturbances. DISCUSSION: αS-SAA positivity in AD patients reflects the prevalence observed in neuropathological series and is associated with a worse clinical outcome. These data confirm the validity of CSF αS-SAA positivity as biomarker of synucleinopathy.

Temporal lobe dysfunction in late-onset epilepsy of unknown origin.

OBJECTIVE: Epilepsy with onset in the adulthood is an increasing health problem, due to the progressive aging of the worldwide population. Whether the causes remain undetermined, the disease is defined as Late-Onset Epilepsy of Unknown origin (LOEU). The aim of this study was to evaluate the semiological, electroencephalographic, metabolic, and neuropsychological features of LOEU. METHODS: We selected patients with late-onset epilepsy (LOE) (≥55 years), whose causes of the disease have been excluded with a deep clinical-instrumental characterization, including brain MRI, EEG, 18F-labeled fluoro-2-deoxyglucose positron emission tomography (FDG-PET), and neuropsychological assessment. RESULTS: Twenty-three LOEU cases were retrospectively recruited. Half presented focal-onset seizures (FOS), the others focal to bilateral tonic-clonic seizures (FBTCS). All demonstrated a mild phenotype, with no recurrence of seizures on single antiseizure treatment at prolonged follow-up. Brain MRI scans were normal in 12 patients (52.3%) and showed nonspecific gliosis or mild atrophy in ten (43.5%); hippocampal sclerosis (HS) was observed in one. In 17/23 (73.9%), the EEG showed slow and/or epileptiform activity of the temporal areas. Brain FDG-PET revealed temporal lobe hypometabolism, mostly ipsilateral to EEG abnormal activity, or multifocal temporal and extra-temporal (cortical, subcortical and subtentorial) clusters of hypometabolism. The neuropsychological analysis demonstrated three different profiles: normal (43.5%), with focal deficits (39.1%) or mild multidomain impairment (17.4%). SIGNIFICANCE: Late-Onset Epilepsy of Unknown origin can present as FOS or FBTCS, both with good prognosis. The application of metabolic imaging and neurophysiology techniques in these patients points to the dysfunction of the temporal structures, whose role in the pathogenetic process of the disease remains to be clarified.

Age and the association between apolipoprotein E genotype and Alzheimer disease: A cerebrospinal fluid biomarker-based case-control study.

BACKGROUND: The ε4 allele of apolipoprotein E (APOE) gene and increasing age are two of the most important known risk factors for developing Alzheimer disease (AD). The diagnosis of AD based on clinical symptoms alone is known to have poor specificity; recently developed diagnostic criteria based on biomarkers that reflect underlying AD neuropathology allow better assessment of the strength of the associations of risk factors with AD. Accordingly, we examined the global and age-specific association between APOE genotype and AD by using the A/T/N classification, relying on the cerebrospinal fluid (CSF) levels of ß-amyloid peptide (A, ß-amyloid deposition), phosphorylated tau (T, pathologic tau), and total tau (N, neurodegeneration) to identify patients with AD. METHODS AND FINDINGS: This case-control study included 1,593 white AD cases (55.4% women; mean age 72.8 [range = 44-96] years) with abnormal values of CSF biomarkers from nine European memory clinics and the American Alzheimer's Disease Neuroimaging Initiative (ADNI) study. A total of 11,723 dementia-free controls (47.1% women; mean age 65.6 [range = 44-94] years) were drawn from two longitudinal cohort studies (Whitehall II and Three-City), in which incident cases of dementia over the follow-up were excluded from the control population. Odds ratio (OR) and population attributable fraction (PAF) for AD associated with APOE genotypes were determined, overall and by 5-year age categories. In total, 63.4% of patients with AD and 22.6% of population controls carried at least one APOE ε4 allele. Compared with non-ε4 carriers, heterozygous ε4 carriers had a 4.6 (95% confidence interval 4.1-5.2; p < 0.001) and ε4/ε4 homozygotes a 25.4 (20.4-31.2; p < 0.001) higher OR of AD in unadjusted analysis. This association was modified by age (p for interaction < 0.001). The PAF associated with carrying at least one ε4 allele was greatest in the 65-70 age group (69.7%) and weaker before 55 years (14.2%) and after 85 years (22.6%). The protective effect of APOE ε2 allele for AD was unaffected by age. Main study limitations are that analyses were based on white individuals and AD cases were drawn from memory centers, which may not be representative of the general population of patients with AD. CONCLUSIONS: In this study, we found that AD diagnosis based on biomarkers was associated with APOE ε4 carrier status, with a higher OR than previously reported from studies based on only clinical AD criteria. This association differs according to age, with the strongest effect at 65-70 years. These findings highlight the need for early interventions for dementia prevention to mitigate the effect of APOE ε4 at the population level.

Incremental value of amyloid-PET versus CSF in the diagnosis of Alzheimer's disease.

PURPOSE: To compare the incremental diagnostic value of amyloid-PET and CSF (Aß42, tau, and phospho-tau) in AD diagnosis in patients with mild cognitive impairment (MCI) or mild dementia, in order to improve the definition of diagnostic algorithm. METHODS: Two independent dementia experts provided etiological diagnosis and relative diagnostic confidence in 71 patients on 3 rounds, based on (1) clinical, neuropsychological, and structural MRI information alone; (2) adding one biomarker (CSF amyloid and tau levels or amyloid-PET with a balanced randomized design); and (3) adding the other biomarker. RESULTS: Among patients with a pre-biomarker diagnosis of AD, negative PET induced significantly more diagnostic changes than amyloid-negative CSF at both rounds 2 (CSF 67%, PET 100%, P = 0.028) and 3 (CSF 0%; PET 78%, P < 0.001); PET induced a diagnostic confidence increase significantly higher than CSF on both rounds 2 and 3. CONCLUSIONS: Amyloid-PET should be prioritized over CSF biomarkers in the diagnostic workup of patients investigated for suspected AD, as it provides greater changes in diagnosis and diagnostic confidence. TRIAL REGISTRATION: EudraCT no.: 2014-005389-31.

Long-Term Risk of Stroke After Transient Global Amnesia in Two Prospective Cohorts.

Background and Purpose- Transient global amnesia (TGA) is known as a benign syndrome, but recent data from neuroradiological studies support an ischemic cause in some cases, which might suggest an increased susceptibility to cerebrovascular events. We determined the long-term risk of stroke after a first TGA in 2 independent prospective cohorts. Methods- In 2 independent prospective cohorts of patients with TGA (OXVASC [Oxford Vascular Study], population-based; NU (Northern Umbria) cohort, TGA registry), cardiovascular risk factors and long-term outcomes, including stroke and major cardiovascular events, were identified on follow-up. Cardiovascular risk factors were treated according to primary prevention guidelines. In OXVASC, the age-/sex-adjusted risk of stroke during follow-up was compared with that expected from the rate in the underlying study population. Results- Among 525 patients with TGA (425 NU and 100 OXVASC), mean (SD) age was 65.1 (9.5) years and 42.5% male. Hypertension (58.1%), dyslipidemia (40.4%), and smoking (36.4%) were the most frequent cardiovascular risk factors. The risk of stroke was similar in the 2 cohorts, with a pooled annual risk of 0.6% (95% CI, 0.4-0.9) and a 5-year cumulative risk of 2.7% (1.1-4.3). Moreover, the stroke risk in OXVASC cases was no greater than that expected in the underlying study population (adjusted relative risk=0.73; 0.12-4.54; P=0.74). Conclusions- TGA does not carry an increased risk of stroke, at least when cardiovascular risk factors are treated according to primary prevention guidelines.

Cognitive performances in patients affected by late-onset epilepsy with unknown etiology: A 12-month follow-up study.

INTRODUCTION: Epilepsy has a growing frequency, particularly in the elderly. Several triggers may cause late-onset epilepsy; however, more than 20% of epilepsies, manifesting in the elderly, has an unknown etiology. Although cognition is frequently altered in patients affected by epilepsy, there is a paucity of studies specifically evaluating cognition in patients affected by late-onset epilepsy. The aim of the present study was to assess the cognitive profile of patients affected by late-onset epilepsy with an unknown etiology and followed for 12 months. METHODS: Patients affected by diagnosed late-onset epilepsy with unknown etiology were included in this observation. All patients were evaluated at the time of diagnosis (baseline) and at follow-up (12 months later). We distributed patients in subgroups based on seizure type (focal seizures [FS], secondarily generalized seizures [SGS], primarily generalized seizures [GS]) and antiepileptic drug (AED) regimen (mono- vs. polytherapy). Cognition was evaluated through standardized neuropsychological testing. RESULTS: Fifty-eight patients were included in this observation and distributed in three groups: 29 affected by FS, 14 affected by SGS, 15 affected by GS. Forty-five patients were in monotherapy, and 13 in polytherapy. The most frequent treatments were levetiracetam (n = 12), valproic acid (VPA) (n = 9), carbamazepine (n = 9), and oxcarbazepine (n = 7). We documented a significant decrease of Mini-Mental State Examination (MMSE) and memory scores at follow-up in the whole group. Verbal learning decreased exclusively in VPA users. CONCLUSION: Patients affected by late-onset epilepsy with unknown etiology showed a significant decline of cognition at follow-up, independently from number and efficacy of AEDs received. These results deserve verification in larger longitudinal cohorts.

Longitudinal reproducibility of automatically segmented hippocampal subfields: A multisite European 3T study on healthy elderly.

Recently, there has been an increased interest in the use of automatically segmented subfields of the human hippocampal formation derived from magnetic resonance imaging (MRI). However, little is known about the test-retest reproducibility of such measures, particularly in the context of multisite studies. Here, we report the reproducibility of automated Freesurfer hippocampal subfields segmentations in 65 healthy elderly enrolled in a consortium of 13 3T MRI sites (five subjects per site). Participants were scanned in two sessions (test and retest) at least one week apart. Each session included two anatomical 3D T1 MRI acquisitions harmonized in the consortium. We evaluated the test-retest reproducibility of subfields segmentation (i) to assess the effects of averaging two within-session T1 images and (ii) to compare subfields with whole hippocampus volume and spatial reliability. We found that within-session averaging of two T1 images significantly improved the reproducibility of all hippocampal subfields but not that of the whole hippocampus. Volumetric and spatial reproducibility across MRI sites were very good for the whole hippocampus, CA2-3, CA4-dentate gyrus (DG), subiculum (reproducibility error∼2% and DICE > 0.90), good for CA1 and presubiculum (reproducibility error ∼ 5% and DICE ∼ 0.90), and poorer for fimbria and hippocampal fissure (reproducibility error ∼ 15% and DICE < 0.80). Spearman's correlations confirmed that test-retest reproducibility improved with volume size. Despite considerable differences of MRI scanner configurations, we found consistent hippocampal subfields volumes estimation. CA2-3, CA4-DG, and sub-CA1 (subiculum, presubiculum, and CA1 pooled together) gave test-retest reproducibility similar to the whole hippocampus. Our findings suggest that the larger hippocampal subfields volume may be reliable longitudinal markers in multisite studies.

Multisite longitudinal reliability of tract-based spatial statistics in diffusion tensor imaging of healthy elderly subjects.

Large-scale longitudinal neuroimaging studies with diffusion imaging techniques are necessary to test and validate models of white matter neurophysiological processes that change in time, both in healthy and diseased brains. The predictive power of such longitudinal models will always be limited by the reproducibility of repeated measures acquired during different sessions. At present, there is limited quantitative knowledge about the across-session reproducibility of standard diffusion metrics in 3T multi-centric studies on subjects in stable conditions, in particular when using tract based spatial statistics and with elderly people. In this study we implemented a multi-site brain diffusion protocol in 10 clinical 3T MRI sites distributed across 4 countries in Europe (Italy, Germany, France and Greece) using vendor provided sequences from Siemens (Allegra, Trio Tim, Verio, Skyra, Biograph mMR), Philips (Achieva) and GE (HDxt) scanners. We acquired DTI data (2 × 2 × 2 mm(3), b = 700 s/mm(2), 5 b0 and 30 diffusion weighted volumes) of a group of healthy stable elderly subjects (5 subjects per site) in two separate sessions at least a week apart. For each subject and session four scalar diffusion metrics were considered: fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial (AD) diffusivity. The diffusion metrics from multiple subjects and sessions at each site were aligned to their common white matter skeleton using tract-based spatial statistics. The reproducibility at each MRI site was examined by looking at group averages of absolute changes relative to the mean (%) on various parameters: i) reproducibility of the signal-to-noise ratio (SNR) of the b0 images in centrum semiovale, ii) full brain test-retest differences of the diffusion metric maps on the white matter skeleton, iii) reproducibility of the diffusion metrics on atlas-based white matter ROIs on the white matter skeleton. Despite the differences of MRI scanner configurations across sites (vendors, models, RF coils and acquisition sequences) we found good and consistent test-retest reproducibility. White matter b0 SNR reproducibility was on average 7 ± 1% with no significant MRI site effects. Whole brain analysis resulted in no significant test-retest differences at any of the sites with any of the DTI metrics. The atlas-based ROI analysis showed that the mean reproducibility errors largely remained in the 2-4% range for FA and AD and 2-6% for MD and RD, averaged across ROIs. Our results show reproducibility values comparable to those reported in studies using a smaller number of MRI scanners, slightly different DTI protocols and mostly younger populations. We therefore show that the acquisition and analysis protocols used are appropriate for multi-site experimental scenarios.

Predictive value for cerebrospinal fluid Alzheimer's disease profile of different measures of verbal episodic memory in patients with MCI.

Neuropsychological evidence of memory impairment represents the main feature of the clinical onset of typical Alzheimer's disease (AD). Rey's Auditory Verbal Learning Test (RAVLT) and Logical Memory (LM) are two tests both assessing verbal episodic memory, widely used in clinical practice. Our aim was to investigate the added value of their combined use in predicting cerebrospinal fluid (CSF) AD biomarkers positivity in a retrospective consecutive series of patients with mild cognitive impairment (MCI). 169 MCI patients were included. For all of them neuropsychological assessment and CSF analysis were available. According to CSF A/T/(N) profile, 109 were defined as MCI due to AD (A+T+), and 60 were non-AD MCI (A-T-). Logistic regression model and receiver-operating characteristic (ROC) curves were analyzed to evaluate the discriminatory power of single and combined sub-measures between AD and non-AD patients. The combination of RAVLT-del with LM could acceptably discriminate the two groups (AUC: 0.69, CI 95% 0.617-0.761, sens: 0.75, spec. 0.58, p < 0.001), while the single tests did not show sufficient discriminative performance. Our study shows that the combination of RAVLT delayed recall with LM better predicts the biological AD diagnosis (A+T+), showing a good discriminative power between MCI-AD from non-AD MCI. Since RAVLT and LM assess different components of verbal episodic memory, they should be considered as complementary, rather than interchangeable, tests.

Intrathecal B cell activation and memory impairment in multiple sclerosis.

BACKGROUND: Cognitive impairment (CI) is a common and disabling feature of people with multiple sclerosis (pwMS), but its underlying mechanisms are heterogenous and not fully understood. A role of infiltrating immune cells in the meninges and brain parenchyma has been hypothesized. This study aimed to explore the hypothesis that intrathecal B cells might influence cognitive performance in pwMS. METHODS: A retrospective study was performed on 39 newly diagnosed pwMS who underwent cerebrospinal fluid (CSF) analysis. Kappa (κ)-index was measured as a biomarker of intrathecal B cell activation. Cognitive performance was assessed using the Brief Repeatable Battery of Neuropsychological Tests (BRBN). Brain T2 lesions number (T2LN) and volume (T2LV) together with brain, cortical grey matter, thalamic and hippocampal volumes were calculated to account for MRI-visible damage. RESULTS: κ-index was higher in pwMS with verbal memory impairment (median 99.6, range 58.5-195.2 vs. median 37.2, range 2.3-396.9, p < 0.001), and it was negatively associated with BRBN tests exploring verbal memory and information processing speed. In multivariate models, higher κ-index was confirmed to be independently associated with worse scores of BRBN tests exploring verbal memory and with a higher probability of verbal memory impairment. CONCLUSION: Intrathecal B cells might drive memory impairment in pwMS independently of brain damage visible on MRI scans.

Repeatable Battery for the Assessment of Neuropsychological Status: Italian Normative Data for Older Adults.

OBJECTIVE: The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), widely used for detecting cognitive impairment in different neuropsychiatric conditions, is increasingly applied for measuring cognitive functioning in older individuals. Available normative data for RBANS Italian version suffer from under-representation of the older ages (>60 years) and are not corrected for education. Moreover, normative data are provided only for Indexes and Total scores. We thus administered RBANS Italian version in a larger sample of older adults, taking into account the effect of age, education and gender on all scores. METHOD: We used a regression-based model to assess the effect of age, education, and gender on RBANS Subtests, Indexes and Total scores in a consecutive series of healthy cognitively normal volunteers aged 60-79 years (N = 158). The obtained norms were compared with the Italian original normative data by means of Wilcoxon rank-sum test. RESULTS: Multiple linear regression analyses showed that age and educational level significantly influence performances on most RBANS scores. A free-to-use Excel to calculate subject's percentiles for any single score was developed. When compared with original normative values, our percentiles distribution of Indexes and Total scores did not reveal significant differences (p > .05). CONCLUSION: The obtained normative data show good concordance with previous norms. The instrument seems not significantly affected by educational level. The possibility to correct for any single score could make RBANS a more precise measure for capturing subtle cognitive deficits in prevention studies.

Clinical correlates of state and trait anxiety in multiple sclerosis.

BACKGROUND: Anxiety represents one of the most prevalent psychiatric symptoms in multiple sclerosis (MS), impacting the overall disease burden and quality of life. This psychopathological feature can be expressed as state (S-ANX) and trait (T-ANX) anxiety, but few studies specifically evaluated these two components in MS. The present study was aimed at investigating the prevalence and specific correlates of S-ANX and T-ANX in a cohort of people with MS (PwMS). METHODS: 88 in- and out-patients with MS were consecutively recruited. S-ANX and T-ANX were evaluated with the two subscales of the State and Trait Anxiety Inventory. Bivariate analyses were performed to compare PwMS who displayed clinically significant S-ANX and T-ANX and those who did not. Two logistic regression models were run in order to identify variables significantly associated with S-ANX and T-ANX. RESULTS: S-ANX and T-ANX presented a prevalence of 42% and 45.5%, respectively. S-ANX was more frequent in subjects hospitalized due to recent MS onset. PwMS and S-ANX more frequently had a recent relapse, as well as evidence of disease activity on brain magnetic resonance imaging. Subjects with T-ANX were more often females and displayed higher severity of fatigue. Depressive features at the Beck Depression Inventory were more severe in both S-ANX and T-ANX subjects. PwMS with S-ANX reported a higher prevalence of T-ANX and vice versa. At the logistic regressions, depression severity displayed a significant association with S-ANX and T-ANX. We also detected positive associations between S-ANX and inpatient status, as well as between T-ANX and female sex. CONCLUSION: Both S-ANX and T-ANX are highly prevalent features in PwMS. These two components of anxiety should be adequately identified and discriminated in the clinical practice. The higher severity of depression in PwMS with clinically significant anxiety should not be neglected.

CSF neurochemical profile and cognitive changes in Parkinson's disease with mild cognitive impairment.

Pathophysiological substrate(s) and progression of Parkinson's disease (PD) with mild cognitive impairment (PD-MCI) are still matter of debate. Baseline cerebrospinal fluid (CSF) neurochemical profile and cognitive changes after 2 years were investigated in a retrospective series of PD-MCI (n = 48), cognitively normal PD (PD-CN, n = 40), prodromal Alzheimer's disease (MCI-AD, n = 25) and cognitively healthy individuals with other neurological diseases (OND, n = 44). CSF biomarkers reflecting amyloidosis (Aß42/40 ratio, sAPPα, sAPPß), tauopathy (p-tau), neurodegeneration (t-tau, NfL, p-NfH), synaptic damage (α-syn, neurogranin) and glial activation (sTREM2, YKL-40) were measured. The great majority (88%) of PD-MCI patients was A-/T-/N-. Among all biomarkers considered, only NfL/p-NfH ratio was significantly higher in PD-MCI vs. PD-CN (p = 0.02). After 2 years, one-third of PD-MCI patients worsened; such worsening was associated with higher baseline levels of NfL, p-tau, and sTREM2. PD-MCI is a heterogeneous entity requiring further investigations on larger, longitudinal cohorts with neuropathological verification.

Clinical and Instrumental Characterization of Patients With Late-Onset Epilepsy.

Epilepsy is classically considered a childhood disease. However, it represents the third most frequent neurological condition in the elderly, following stroke, and dementia. With the progressive aging of the general population, the number of patients with Late-Onset Epilepsy (LOE) is constantly growing, with important economic and social consequences, in particular for the more developed countries where the percentage of elderly people is higher. The most common causes of LOE are structural, mainly secondary to cerebrovascular or infectious diseases, brain tumors, trauma, and metabolic or toxic conditions. Moreover, there is a growing body of evidence linking LOE with neurodegenerative diseases, particularly Alzheimer's disease (AD). However, despite a thorough characterization, the causes of LOE remain unknown in a considerable portion of patients, thus termed as Late-Onset Epilepsy of Unknown origin (LOEU). In order to identify the possible causes of the disease, with an important impact in terms of treatment and prognosis, LOE patients should always undergo an exhaustive phenotypic characterization. In this work, we provide a detailed review of the main clinical and instrumental techniques for the adequate characterization of LOE patients in the clinical practice. This work aims to provide an easy and effective tool that supports routine activity of the clinicians facing LOE.

Cognitive impairment in multiple sclerosis: lessons from cerebrospinal fluid biomarkers.

Cognitive impairment is a common clinical manifestation of multiple sclerosis, but its pathophysiology is not completely understood. White and grey matter injury together with synaptic dysfunction do play a role. The measurement of biomarkers in the cerebrospinal fluid and the study of their association with cognitive impairment may provide interesting in vivo evidence of the biological mechanisms underlying multiple sclerosis-related cognitive impairment. So far, only a few studies on this topic have been published, giving interesting results that deserve further investigation. Cerebrospinal fluid biomarkers of different pathophysiological mechanisms seem to reflect different neuropsychological patterns of cognitive deficits in multiple sclerosis. The aim of this review is to discuss the studies that have correlated cerebrospinal fluid markers of immune, glial and neuronal pathology with cognitive impairment in multiple sclerosis. Although preliminary, these findings suggest that cerebrospinal fluid biomarkers show some correlation with cognitive performance in multiple sclerosis, thus providing interesting insights into the mechanisms underlying the involvement of specific cognitive domains.

Interleukin-17 affects synaptic plasticity and cognition in an experimental model of multiple sclerosis.

Cognitive impairment (CI) is a disabling concomitant of multiple sclerosis (MS) with a complex and controversial pathogenesis. The cytokine interleukin-17A (IL-17A) is involved in the immune pathogenesis of MS, but its possible effects on synaptic function and cognition are still largely unexplored. In this study, we show that the IL-17A receptor (IL-17RA) is highly expressed by hippocampal neurons in the CA1 area and that exposure to IL-17A dose-dependently disrupts hippocampal long-term potentiation (LTP) through the activation of its receptor and p38 mitogen-activated protein kinase (MAPK). During experimental autoimmune encephalomyelitis (EAE), IL-17A overexpression is paralleled by hippocampal LTP dysfunction. An in vivo behavioral analysis shows that visuo-spatial learning abilities are preserved when EAE is induced in mice lacking IL-17A. Overall, this study suggests a key role for the IL-17 axis in the neuro-immune cross-talk occurring in the hippocampal CA1 area and its potential involvement in synaptic dysfunction and MS-related CI.

White Matter Hyperintensities Are No Major Confounder for Alzheimer's Disease Cerebrospinal Fluid Biomarkers.

BACKGROUND: The cerebrospinal fluid (CSF) biomarkers amyloid-ß 1-42 (Aß42), total and phosphorylated tau (t-tau, p-tau) are increasingly used to assist in the clinical diagnosis of Alzheimer's disease (AD). However, CSF biomarker levels can be affected by confounding factors. OBJECTIVE: To investigate the association of white matter hyperintensities (WMHs) present in the brain with AD CSF biomarker levels. METHODS: We included CSF biomarker and magnetic resonance imaging (MRI) data of 172 subjects (52 controls, 72 mild cognitive impairment (MCI), and 48 AD patients) from 9 European Memory Clinics. A computer aided detection system for standardized automated segmentation of WMHs was used on MRI scans to determine WMH volumes. Association of WMH volume with AD CSF biomarkers was determined using linear regression analysis. RESULTS: A small, negative association of CSF Aß42, but not p-tau and t-tau, levels with WMH volume was observed in the AD (r2 = 0.084, p = 0.046), but not the MCI and control groups, which was slightly increased when including the distance of WMHs to the ventricles in the analysis (r2 = 0.105, p = 0.025). Three global patterns of WMH distribution, either with 1) a low, 2) a peak close to the ventricles, or 3) a high, broadly-distributed WMH volume could be observed in brains of subjects in each diagnostic group. CONCLUSION: Despite an association of WMH volume with CSF Aß42 levels in AD patients, the occurrence of WMHs is not accompanied by excess release of cellular proteins in the CSF, suggesting that WMHs are no major confounder for AD CSF biomarker assessment.

Late-Onset Epilepsy With Unknown Etiology: A Pilot Study on Neuropsychological Profile, Cerebrospinal Fluid Biomarkers, and Quantitative EEG Characteristics.

Introduction: Despite the fact that epilepsy has been associated with cognitive decline, neuropsychological, neurobiological, and neurophysiological features in patients with late-onset epilepsy of unknown etiology (LOEU) are still unknown. This cross-sectional study aims to investigate the neuropsychological profile, cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD), and resting-state quantitative electroencephalographic (qEEG) cortical rhythms in LOEU patients with mild cognitive impairment (LOEU-MCI) and with normal cognition (LOEU-CN), compared to non-epileptic MCI (NE-MCI) and cognitively normal (CN) controls. Methods: Consecutive patients in two clinical Units diagnosed with LOEU-CN (19), LOEU-MCI (27), and NE-MCI (21) were enrolled, and compared to age and sex-matched cognitively normal subjects CN (11). Patients underwent standardized comprehensive neuropsychological evaluation and CSF core AD biomarkers assessment (i.e., CSF Aß42, phospho-tau and total tau, classified through A/T/(N) system). Recordings of resting-state eyes-closed electroencephalographic (EEG) rhythms were collected and cortical source estimation of delta (<4 Hz) to gamma (>30 Hz) bands with exact Low Resolution Electromagnetic Tomography (eLORETA) was performed. Results: Most LOEU patients had an MCI status at seizure onset (59%). Patients with LOEU-MCI performed significantly worse on measures of global cognition, visuo-spatial abilities, and executive functions compared to NE-MCI patients (p < 0.05). Regarding MCI subtypes, multiple-domain MCI was 3-fold more frequent in LOEU-MCI than in NE-MCI patients (OR 3.14, 95%CI 0.93-10.58, p = 0.06). CSF Aß42 levels were lower in the LOEU-MCI compared with the LOEU-CN group. Finally, parietal and occipital sources of alpha (8-12 Hz) rhythms were less active in the LOEU-MCI than in the NE-MCI and CN groups, while the opposite was true for frontal and temporal cortical delta sources. Discussion: MCI status was relatively frequent in LOEU patients, involved multiple cognitive domains, and might have been driven by amyloidosis according to CSF biomarkers. LOEU-MCI status was associated with abnormalities in cortical sources of EEG rhythms related to quiet vigilance. Future longitudinal studies should cross-validate our findings and test the predictive value of CSF and EEG variables.

Biomarker-Based Signature of Alzheimer's Disease in Pre-MCI Individuals.

Alzheimer's disease (AD) pathology begins decades before the onset of clinical symptoms. It is recognized as a clinicobiological entity, being detectable in vivo independently of the clinical stage by means of pathophysiological biomarkers. Accordingly, neuropathological studies that were carried out on healthy elderly subjects, with or without subjective experience of cognitive decline, reported evidence of AD pathology in a high proportion of cases. At present, mild cognitive impairment (MCI) represents the only clinically diagnosed pre-dementia stage. Several attempts have been carried out to detect AD as early as possible, when subtle cognitive alterations, still not fulfilling MCI criteria, appear. Importantly, pre-MCI individuals showing the positivity of pathophysiological AD biomarkers show a risk of progression similar to MCI patients. In view of successful treatment with disease modifying agents, in a clinical setting, a timely diagnosis is mandatory. In clinical routine, biomarkers assessment should be taken into consideration whenever a subject with subtle cognitive deficits (pre-MCI), who is aware of his/her decline, requests to know the cause of such disturbances. In this review, we report the available neuropsychological and biomarkers data that characterize the pre-MCI patients, thus proposing pre-MCI as the first clinical manifestation of AD.

The added value of Aß42/Aß40 in the CSF signature for routine diagnostics of Alzheimer's disease.

The cerebrospinal fluid (CSF) signature of Alzheimer's disease (AD) includes abnormal levels of amyloid-ß 1-42 (Aß42), total tau (t-Tau) and phosphorylated tau (p-Tau). Several studies have reported that the CSF Aß42/Aß40 ratio could outperform CSF Aß42 as a more accurate marker of brain amyloidosis, since it normalizes the CSF Aß42 levels according to the total production of Aß in the brain. In the present study, we wanted to assess the diagnostic utility of adding the Aß42/Aß40 ratio within the core AD CSF biomarkers for the classification of patients, according to NIA-AA criteria and Erlangen score. We consecutively recruited 168 patients (62 with AD and 106 with other neurological diseases) who referred to our Memory Clinic for diagnostic work- up from 2003 to 2016. The use of CSF Aß42/Aß40 ratio increased the percentage of correctly diagnosed AD patients from 72.0% to 82.8%. The high gain in sensitivity (from 75.8% to 85.5%) was obtained in face of loss of specificity (from 95.3% to 82.5%). Our study showed that the use of CSF Aß42/Aß40 could significantly improve the routine diagnostic work up of AD.