Roberto Santangelo

Cross-validation of biomarkers for the early differential diagnosis and prognosis of dementia in a clinical setting

PurposeThe aim of this study was to evaluate the supportive role of molecular and structural biomarkers (CSF protein levels, FDG PET and MRI) in the early differential diagnosis of dementia in a large sample of patients with neurodegenerative dementia, and in determining the risk of disease progression in subjects with mild cognitive impairment (MCI).MethodsWe evaluated the supportive role of CSF Aβ42, t-Tau, p-Tau levels, conventional brain MRI and visual assessment of FDG PET SPM t-maps in the early diagnosis of dementia and the evaluation of MCI progression.ResultsDiagnosis based on molecular biomarkers showed the best fit with the final diagnosis at a long follow-up. FDG PET SPM t-maps had the highest diagnostic accuracy in Alzheimer’s disease and in the differential diagnosis of non-Alzheimer’s disease dementias. The p-tau/Aβ42 ratio was the only CSF biomarker providing a significant classification rate for Alzheimer’s disease. An Alzheimer’s disease-positive metabolic pattern as shown by FDG PET SPM in MCI was the best predictor of conversion to Alzheimer’s disease.ConclusionIn this clinical setting, FDG PET SPM t-maps and the p-tau/Aβ42 ratio improved clinical diagnostic accuracy, supporting the importance of these biomarkers in the emerging diagnostic criteria for Alzheimer’s disease dementia. FDG PET using SPM t-maps had the highest predictive value by identifying hypometabolic patterns in different neurodegenerative dementias and normal brain metabolism in MCI, confirming its additional crucial exclusionary role.

Optical coherence tomography and visual evoked potentials: which is more sensitive in multiple sclerosis?:

Objective: To assess the sensitivity of optic coherence tomography (OCT) and visual evoked potentials (VEPs) to visual pathway abnormalities in multiple sclerosis (MS). Methods: A total of 40 MS subjects, 28 with optic neuritis (ON) at least 3 months before (bilateral in 5), underwent assessment of visual acuity, Expanded Disability Status Scale (EDSS), OCT and VEPs, the latter quantified with a 0–4 conventional score. Results: OCT and VEPs were abnormal in 36% and 56% respectively in all eyes (p=0.11), 68% and 86% in eyes with previous ON (p=0.12), and in 19% versus 40% in eyes without ON history (p=0.007). Combining VEP and OCT increased sensitivity to 89% in ON and 44% in non-ON eyes. Considering all eyes, global retinal nerve fibre layer (RNFL) thickness and VEP score were significantly correlated between them (ρ=−0.63, p<0.001) and with EDSS (RNFL: ρ=0.40, p<0.001; VEP score: ρ=0.47, p<0.001). Disease duration correlated with VEP score (ρ=0.25, p=0.025) and RNFL thickness (ρ=−0.71, p<0.001). Conclusions: In eyes without ON, VEPs were more frequently abnormal than OCT, while the two techniques showed similar sensitivity in eyes previously affected by ON. The correlation of VEPs and OCT measures with disability prompts further exploration of the two techniques as potential markers of disease burden.

Pharmacogenomics in Alzheimer's disease: a genome-wide association study of response to cholinesterase inhibitors

We conducted a genome-wide association study in a cohort of 176 Italian Alzheimers disease (AD) patients with extreme phenotype of response to cholinesterase inhibitors. Patients were classified into responders in case of positive, stable, or ≤1 worsening of mini-mental state examination score and into nonresponders if >3 points worsening during a median follow-up of 0.85 years of treatment. Forty-eight single-nucleotide polymorphisms were selected for replication in 198 additional AD-treated patients. By using the dichotomous response trait and a quantitative trait approach (change of mini-mental state examination), a nominal replication and evidence of association when combining data were achieved for 2 single-nucleotide polymorphisms associated with response to treatment: rs6720975A (pcombined = 2.9 × 10(-5), beta regression coefficient: 1.61) and rs17798800A (pcombined = 6.8 × 10(-6), odds ratio = 0.38, 95% confidence interval = 0.25-0.58). Rs6720975 maps in the intronic region of PRKCE, a protein kinase involved in several cellular functions, whereas rs17798800 is intergenic and, according to expression quantitative trait locus (eQTL) analysis, it acts as a cis-regulator of NBEA, an A kinase-anchoring protein playing a substantial role in the maturation of the nervous system. Despite its limitations, this project paves the way for the application of personalized medicine in AD patients and for collaborative efforts in this field.

Cerebrospinal Fluid Biomarkers Can Play a Pivotal Role in the Diagnostic Work Up of Primary Progressive Aphasia

BACKGROUND Three variants of primary progressive aphasia (PPA) have been currently characterized: non fluent/agrammatic (nfv-PPA), semantic (sv-PPA), and logopenic variant (lv-PPA). lv-PPA is most commonly associated with Alzheimers disease (AD), while nfv-PPA and sv-PPA are related to frontotemporal lobar degeneration. OBJECTIVE We aimed to determine whether cerebrospinal fluid (CSF) amyloid-β42 (Aβ42), total tau protein (t-tau), and phosphorylated tau (p-tau), frequently abnormal in AD, could constitute a useful tool in the PPA diagnostic work up, in order to identify subjects with an underlying AD pathology. METHODS We measured CSF biomarker levels in a group of twenty-eight patients, fourteen lv-PPA, nine nfv-PPA, and five sv-PPA. RESULTS Since there were no significant differences in any of the parameters investigated between nfv-PPA and sv-PPA, the two groups were considered as one (nfv/sv-PPA). At diagnosis, lv-PPA were older than nfv/sv-PPA patients (mean values: 70.7 versus 64.6 years, p = 0.02). CSF biomarker mean concentrations were significantly different in lv-PPA versus nfv/sv-PPA patients (p = 0.000): Aβ42 350.64 versus 661.64 ng/L; tau 631.21 versus 232.71 ng/L; p-tau 101 versus 38.21 ng/L. According to the recent AD diagnostic criteria, (Cummings et al., 2013) eleven lv-PPA and only one nfv/sv-PPA showed a liquoral pattern typical for AD. Finally lv-PPA had CSF biomarker levels very similar to a sample of 72 AD patients from our Department. CONCLUSIONS Our data showed that CSF biomarkers can easily and reliably detect those patients with language disorders due to an underlying AD pathology, thus offering the possibility of targeted therapeutic interventions. However, because of the small sample size, such analyses should be reproduced in larger populations of patients to confirm our data.

The Role of Single-Subject Brain Metabolic Patterns in the Early Differential Diagnosis of Primary Progressive Aphasias and in Prediction of Progression to Dementia

Background and Objective: Primary progressive aphasia (PPA) is a clinical syndrome due to different neurodegenerative conditions in which an accurate early diagnosis needs to be supported by a reliable diagnostic tool at the individual level. In this study, we investigated in PPA the FDG-PET brain metabolic patterns at the single-subject level, in order to assess the case-to-case variability and its relationship with clinical-neuropsychological findings. Material and Methods: 55 patients (i.e., 11 semantic variant/sv-PPA, 19 non fluent variant/nfv-PPA, 17 logopenic variant/lv-PPA, 3 slowly progressive anarthria/SPA, and 5 mixed PPA/m-PPA) were included. Clinical-neuropsychological information and FDG-PET data were acquired at baseline. A follow-up of 27.4±12.55 months evaluated the clinical progression. Brain metabolism was analyzed using an optimized and validated voxel-based SPM method at the single-subject level. Results: FDG-PET voxel-wise metabolic assessment revealed specific metabolic signatures characterizing each PPA variant at the individual level, reflecting the underlying neurodegeneration in language networks. Notably, additional dysfunctional patterns predicted clinical progression to specific dementia conditions. In the case of nfv-PPA, a metabolic pattern characterized by involvement of parietal, subcortical and brainstem structures predicted progression to a corticobasal degeneration syndrome or to progressive supranuclear palsy. lv-PPA and sv-PPA cases who progressed to Alzheimer’s disease and frontotemporal dementia at the follow-up presented with extended bilateral patterns at baseline. Discussion: Our results indicate that FDG-PET voxel-wise imaging is a valid biomarker for the early differential diagnosis of PPAs and for the prediction of progression to specific dementia condition. This study supports the use of FDG-PET imaging quantitative assessment in clinical settings for a better characterization of PPA individuals and prognostic definition of possible endo-phenotypes.

Combining Cerebrospinal Fluid Biomarkers and Neuropsychological Assessment: A Simple and Cost-Effective Algorithm to Predict the Progression from Mild Cognitive Impairment to Alzheimer’s Disease Dementia

BACKGROUND Correctly diagnosing Alzheimers disease (AD) in prodromal phases would allow the adoption of experimental therapeutic strategies that could selectively interrupt the pathogenetic process before neuronal damage becomes irreversible. Therefore, great efforts have been aimed at finding early reliable disease markers. OBJECTIVE The aim of this study was to identify a simple, cost effective, and reliable diagnostic algorithm to predict conversion from mild cognitive impairment (MCI) to AD. METHODS 96 consecutive MCI patients admitted to the Neurology department of San Raffaele Hospital in Milan between January 2009 and January 2015 were included. All patients underwent neuropsychological assessment and lumbar puncture with CSF analysis of amyloid-β 42 (Aβ42), total tau (t-tau), and phosphorylated tau (p-tau) levels. Each patient underwent clinical and neuropsychological follow-up, in order to identify a possible progression from MCI to AD. The mean follow up time was 36.73 months. RESULTS 37 out of 96 MCI converted to AD during follow up. CSF analysis and neuropsychological assessment reliably detected MCI patients who developed AD. In a subsample of 43 subjects, a Composite Cognitive Score (CCS) was calculated including episodic memory, executive function, and verbal fluency tests. Combining together CSF biomarkers and CCS increased the accuracy of the single predictors, correctly classifying 86% of patients with a specificity of 96% and a Positive Predictive Value of 93%. DISCUSSION Even if preliminary, our data seem to suggest that CSF analysis and neuropsychological assessment could detect MCI patients who will convert to AD with high confidence. Their relative low cost and availability could make them worldwide essential tools in future clinical trials.

The Progranulin (GRN) Cys157LysfsX97 Mutation is Associated with Nonfluent Variant of Primary Progressive Aphasia Clinical Phenotype

The progranulin gene (GRN) g.10325_10331delCTGCTGT (relative to nt1 in NG_007886.1), alias Cys157LysfsX97, has been so far reported only once in a patient with frontotemporal dementia. Here, we describe a 63-year old patient carrying the same mutation, presenting with a 3-year history of language disorder, and diagnosed clinically with nonfluent variant of primary progressive aphasia according to current criteria. This patients description expands the spectrum of clinical presentations of frontotemporal lobar degeneration caused by the GRN Cys157LysfsX97 mutation.

FDG-PET and CSF biomarker accuracy in prediction of conversion to different dementias in a large multicentre MCI cohort

Background/aims In this multicentre study in clinical settings, we assessed the accuracy of optimized procedures for FDG-PET brain metabolism and CSF classifications in predicting or excluding the conversion to Alzheimers disease (AD) dementia and non-AD dementias. Methods We included 80 MCI subjects with neurological and neuropsychological assessments, FDG-PET scan and CSF measures at entry, all with clinical follow-up. FDG-PET data were analysed with a validated voxel-based SPM method. Resulting single-subject SPM maps were classified by five imaging experts according to the disease-specific patterns, as “typical-AD”, “atypical-AD” (i.e. posterior cortical atrophy, asymmetric logopenic AD variant, frontal-AD variant), “non-AD” (i.e. behavioural variant FTD, corticobasal degeneration, semantic variant FTD; dementia with Lewy bodies) or “negative” patterns. To perform the statistical analyses, the individual patterns were grouped either as “AD dementia vs. non-AD dementia (all diseases)” or as “FTD vs. non-FTD (all diseases)”. Aβ42, total and phosphorylated Tau CSF-levels were classified dichotomously, and using the Erlangen Score algorithm. Multivariate logistic models tested the prognostic accuracy of FDG-PET-SPM and CSF dichotomous classifications. Accuracy of Erlangen score and Erlangen Score aided by FDG-PET SPM classification was evaluated. Results The multivariate logistic model identified FDG-PET “AD” SPM classification (Expβ = 19.35, 95% C.I. 4.8–77.8, p < 0.001) and CSF Aβ42 (Expβ = 6.5, 95% C.I. 1.64–25.43, p < 0.05) as the best predictors of conversion from MCI to AD dementia. The “FTD” SPM pattern significantly predicted conversion to FTD dementias at follow-up (Expβ = 14, 95% C.I. 3.1–63, p < 0.001). Overall, FDG-PET-SPM classification was the most accurate biomarker, able to correctly differentiate either the MCI subjects who converted to AD or FTD dementias, and those who remained stable or reverted to normal cognition (Expβ = 17.9, 95% C.I. 4.55–70.46, p < 0.001). Conclusions Our results support the relevant role of FDG-PET-SPM classification in predicting progression to different dementia conditions in prodromal MCI phase, and in the exclusion of progression, outperforming CSF biomarkers.

CHRNA7 Gene and Response to Cholinesterase Inhibitors in an Italian Cohort of Alzheimer's Disease Patients.

Previous studies suggest that genetic variants in CHRNA7, which encodes for the major subunit of the acetylcholine receptor (α7-nAChR), are associated with the clinical response to cholinesterase inhibitors (ChEI) in Alzheimers disease (AD) patients. We sought to replicate the association of two SNPs in the CHRNA7 gene, rs6494223 and rs8024987, with response to ChEI treatment in an Italian cohort of 169 AD patients, further extending the study to gene-level analysis. None of the tested variants was associated with clinical response. However, rs6494223 showed a consistent effect direction (OR = 1.4; p = 0.17), which after meta-analysis with previous study yielded a significant result (OR = 1.57, p = 0.02, I2 = 0%).

Primary progressive multiple sclerosis presenting with severe predominant cognitive impairment and psychiatric symptoms: A challenging case

Severe cognitive dysfunction is a frequent feature of multiple sclerosis (MS), normally associated with later stages of the disease in adult population. Nevertheless, progressive cognitive and neuropsychiatric disturbances might rarely be the presenting and predominant symptom. In order to better characterize this peculiar phenotype of MS, we report on the case of a 38-year-old man who referred to our hospital with the suspect of hereditary leukodystrophy after 5 years of behavioral and mood abnormalities, global cognitive dysfunction, clumsiness, and very mild pyramidal and cerebellar signs. Brain and spinal magnetic resonance imaging (MRI) combined with cerebrospinal fluid (CSF) analysis prompted the diagnosis of MS.