Astrocytic centrin-2 expression in entorhinal cortex correlates with Alzheimer's disease severity.

Astrogliosis is a condition shared by acute and chronic neurological diseases and includes morphological, proteomic, and functional rearrangements of astroglia. In Alzheimer's disease (AD), reactive astrocytes frame amyloid deposits and exhibit structural changes associated with the overexpression of specific proteins, mostly belonging to intermediate filaments. At a functional level, amyloid beta triggers dysfunctional calcium signaling in astrocytes, which contributes to the maintenance of chronic neuroinflammation. Therefore, the identification of intracellular players that participate in astrocyte calcium signaling can help unveil the mechanisms underlying astrocyte reactivity and loss of function in AD. We have recently identified the calcium-binding protein centrin-2 (CETN2) as a novel astrocyte marker in the human brain and, in order to determine whether astrocytic CETN2 expression and distribution could be affected by neurodegenerative conditions, we examined its pattern in control and sporadic AD patients. By immunoblot, immunohistochemistry, and targeted-mass spectrometry, we report a positive correlation between entorhinal CETN2 immunoreactivity and neurocognitive impairment, along with the abundance of amyloid depositions and neurofibrillary tangles, thus highlighting a linear relationship between CETN2 expression and AD progression. CETN2-positive astrocytes were dispersed in the entorhinal cortex with a clustered pattern and colocalized with reactive glia markers STAT3, NFATc3, and YKL-40, indicating a human-specific role in AD-induced astrogliosis. Collectively, our data provide the first evidence that CETN2 is part of the astrocytic calcium toolkit undergoing rearrangements in AD and adds CETN2 to the list of proteins that could play a role in disease evolution.

A Map of Transcriptomic Signatures of Different Brain Areas in Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disorder that progressively involves brain regions with an often-predictable pattern. Damage to the brain appears to spread and worsen with time, but the molecular mechanisms underlying the region-specific distribution of AD pathology at different stages of the disease are still under-investigated. In this study, a whole-transcriptome analysis was carried out on brain samples from the hippocampus (HI), temporal and parietal cortices (TC and PC, respectively), cingulate cortex (CG), and substantia nigra (SN) of six subjects with a definite AD diagnosis and three healthy age-matched controls in duplicate. The transcriptomic results showed a greater number of differentially expressed genes (DEGs) in the TC (1571) and CG (1210) and a smaller number of DEGs in the HI (206), PC (109), and SN (60). Furthermore, the GSEA showed a difference between the group of brain areas affected early (HI and TC) and the group of areas that were subsequently involved (PC, CG, and SN). Notably, in the HI and TC, there was a significant downregulation of shared DEGs primarily involved in synaptic transmission, while in the PC, CG, and SN, there was a significant downregulation of genes primarily involved in protein folding and trafficking. The course of AD could follow a definite time- and severity-related pattern that arises from protein misfolding, as observed in the PC, CG, and SN, and leads to synaptic impairment, as observed in the HI and TC. Therefore, a map of the molecular and biological processes involved in AD pathogenesis may be traced. This could aid in the discovery of novel biological targets in order to develop effective and well-timed therapeutic approaches.

Expression pattern of perilipins in human brain during aging and in Alzheimer's disease.

AIMS: Perilipins are conserved proteins that decorate intracellular lipid droplets and are essential for lipid metabolism. To date, there is limited knowledge on their expression in human brain or their involvement in brain aging and neurodegeneration. The aim of this study was to characterise the expression levels of perilipins (Plin1-Plin5) in different cerebral areas from subjects of different age, with or without signs of neurodegeneration. METHODS: We performed real-time RT-PCR, western blotting, immunohistochemistry and confocal microscopy analyses in autoptic brain samples of frontal and temporal cortex, cerebellum and hippocampus from subjects ranging from 33 to 104 years of age, with or without histological signs of neurodegeneration. To test the possible relationship between Plins and inflammation, correlation analysis with IL-6 expression was also performed. RESULTS: Plin2, Plin3 and Plin5, but not Plin1 and Plin4, are expressed in the considered brain areas with different intensities. Plin2 appears to be expressed more in grey matter, particularly in neurons in all the areas analysed, whereas Plin3 and Plin5 appear to be expressed more in white matter. Plin3 seems to be expressed more in astrocytes. Only Plin2 expression is higher in old subjects and patients with early tauopathy or Alzheimer's disease and is associated with IL-6 expression. CONCLUSIONS: Perilipins are expressed in human brain but only Plin2 appears to be modulated with age and neurodegeneration and linked to an inflammatory state. We propose that the accumulation of lipid droplets decorated with Plin2 occurs during brain aging and that this accumulation may be an early marker and initial step of inflammation and neurodegeneration.

Life during COVID-19 lockdown in Italy: the influence of cognitive state on psychosocial, behavioral and lifestyle profiles of older adults.

OBJECTIVE: Few studies have examined lockdown effects on the way of living and well-being of older adults stratified by cognitive state. Since cognitive deficits are common in this population, we investigated how cognition influenced their understanding of the pandemic, socio-behavioral responses and lifestyle adaptations during lockdown, and how these factors affected their mood or memory. METHOD: Telephone-based survey involving 204 older adults ≥65 y/o (median: 82) with previous assessments of cognitive state: 164 normal-old (NOLD), 24 mild-neurocognitive disorder (mild-NCD), 18 mild-moderate dementia. A structured questionnaire was developed to assess psychological and socio-behavioral variables. Logistic regression was used to ascertain their effects on mood and memory. RESULTS: With increasing cognitive deficits, understanding of the pandemic and the ability to follow lockdown policies, adapt to lifestyle changes, and maintain remote interactions decreased. Participants with dementia were more depressed; NOLDs remained physically and mentally active but were more bored and anxious. Sleeping and health problems independently increased the likelihood of depression (OR: 2.29; CI: 1.06-4.93; p = 0.034 and OR: 2.45; CI: 1.16-5.16; p = 0.018, respectively); Regular exercise was protective (OR: 0.30; CI: 0.12-0.72; p = 0.007). Worsening subjective memory complaints were associated with dementia (p = 0.006) and depression (p = 0.004); New-onset sleeping problems raised their odds (OR: 10.26; CI: 1.13-93.41; p = 0.039). Finally, >40% with health problems avoided healthcare mainly due to fear of contagion. DISCUSSION: NOLD and mild-NCD groups showed similar mood-behavioral profiles suggesting better tolerance of lockdown. Those with dementia were unable to adapt and suffered from depression and cognitive complaints. To counteract lockdown effects, physical and mental activities and digital literacy should be encouraged.

MINCR: A long non-coding RNA shared between cancer and neurodegeneration.

The multitasking nature of lncRNAs allows them to play a central role in both physiological and pathological conditions. Often the same lncRNA can participate in different diseases. Specifically, the MYC-induced Long non-Coding RNA MINCR is upregulated in various cancer types, while downregulated in Amyotrophic Lateral Sclerosis patients. Therefore, this work aims to investigate MINCR potential mechanisms of action and its implications in cancer and neurodegeneration in relation to its expression levels in SH-SY5Y cells through RNA-sequencing approach. Our results show that MINCR overexpression causes massive alterations in cancer-related genes, leading to disruption in many fundamental processes, such as cell cycle and growth factor signaling. On the contrary, MINCR downregulation influences a small number of genes involved in different neurodegenerative disorders, mostly concerning RNA metabolism and inflammation. Thus, understanding the cause and functional consequences of MINCR deregulation gives important insights on potential pathogenetic mechanisms both in cancer and in neurodegeneration.

Good outcome in adult-onset Rasmussen's encephalitis syndrome: is recovery possible?

A healthy 29-year-old man suffered from adult-onset epilepsy, characterized by polymorphic progressive seizures resistant to AEDs, leading to unilateral cortical deficits and atrophy of the left hemisphere. The disorder satisfied the clinical, EEG, and imaging criteria for a diagnosis of Rasmussen's encephalitis. During the acute phase of the disease, intrathecal synthesis of specific anti-CMV IgG was identified. This case was characterized by a very mild course and remission of seizures following a treatment with high-dose intravenous polyvalent immunoglobulins containing a high anti-CMV titre. The patient remained symptomless for more than 15 years from clinical onset and more than eight years after the discontinuation of immunological therapy. In agreement with a recent report, this case confirms that adult-onset Rasmussen's encephalitis syndrome may occur with a very mild clinical picture and persistent remission. In this case, the specific index for intrathecal production of anti-CMV antibodies suggested possible CMV involvement, indicating specific immuno-therapy as a treatment choice.

APOE 5'UTR Methylation Pattern Analysis in Blood and Brain Tissue from Alzheimer's Disease Affected Patients.

APOE ε4 allele is the major genetic risk factor for Alzheimer's Disease (AD). Furthermore, APOE methylation pattern has been described to be associated with the disease and to follow a bimodal pattern, with a hypermethylated CpG island and a hypomethylated promoter region. However, little is known about the methylation levels in the APOE 5'UTR region. Here, the methylation of two regions (R1 and R2) within APOE 5'UTR was investigated in both peripheral blood mononuclear cells (PBMCs) and hippocampus (HIC) samples to identify differentially methylated CpG sites and to associate clinical, genetic features and cerebrospinal fluid (CSF) biomarkers levels. DNA was extracted from PBMCs of 20 AD and 20 healthy controls (HC) and from 6 AD and 3 HC HIC samples. The methylation analysis was carried out by means of pyrosequencing. In AD PBMCs we found that R1 region displayed a higher methylation level, while the opposite trend was observed in R2. The presence of ε4 allele highlighted a marked increase in R1 methylation level and a decrease in R2. In AD PBMCs and HIC, age progression resulted to be associated with an increase in the methylation level of R1. Lastly, the methylation of a CpG site in R2 was found to be related to CSF biomarkers. Despite the lack of a statistical significance, the outcome from this exploratory analysis highlighted the presence of a difference in methylation in APOE 5'UTR in PBMCs of AD patients which seemed to be associated also with APOE genotype, age and CSF biomarkers level.

Functional analysis and transcriptome profile of meninges and skin fibroblasts from human-aged donors.

The central nervous system (CNS) is surrounded by three membranes called meninges. Specialised fibroblasts, originating from the mesoderm and neural crest, primarily populate the meninges and serve as a binding agent. Our goal was to compare fibroblasts from meninges and skin obtained from the same human-aged donors, exploring their molecular and cellular characteristics related to CNS functions. We isolated meningeal fibroblasts (MFs) from brain donors and skin fibroblasts (SFs) from the same subjects. A functional analysis was performed measuring cell appearance, metabolic activity, and cellular orientation. We examined fibronectin, serpin H1, ß-III-tubulin, and nestin through qPCR and immunofluorescence. A whole transcriptome analysis was also performed to characterise the gene expression of MFs and SFs. MFs appeared more rapidly in the post-tissue processing, while SFs showed an elevated cellular metabolism and a well-defined cellular orientation. The four markers were mostly similar between the MFs and SFs, except for nestin, more expressed in MFs. Transcriptome analysis reveals significant differences, particularly in cyclic adenosine monophosphate (cAMP) metabolism and response to forskolin, both of which are upregulated in MFs. This study highlights MFs' unique characteristics, including the timing of appearance, metabolic activity, and gene expression patterns, particularly in cAMP metabolism and response to forskolin. These findings contribute to a deeper understanding of non-neuronal cells' involvement in CNS activities and potentially open avenues for therapeutic exploration.

A Case of Reversible Dementia? Dementia vs Delirium in Lyme Disease.

Lyme disease is an uncommon cause of reversible dementia. A 75-year-old male patient, with a personal history of mild memory deficit, was admitted to Alzheimer's Disease Care Unit due to hallucinations, confusion and aggressive behavior unresponsive to antipsychotic therapy. A computed tomography (CT) scan of the brain was negative, while blood exams showed a rise in inflammatory parameters. A complete screening of infective diseases showed a positive serology for Borrelia burgdorferi, confirmed at Western blot. Even though the patient refused cerebrospinal fluid (CSF) exam, the brilliant clinical improvement after the appropriate antimicrobial therapy is strongly suggestive for a diagnosis of neuroborreliosis. This case report underlines the importance of a diagnostic approach to dementia, as to find out and treat the reversible causes.

Microglial Senescence and Activation in Healthy Aging and Alzheimer's Disease: Systematic Review and Neuropathological Scoring.

The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels" of internal and external perturbations and have long lifespans. We aim to emphasize microglial signatures in physiologic brain aging and Alzheimer's disease (AD). A systematic literature search of all published articles about microglial senescence in human healthy aging and AD was performed, searching for PubMed and Scopus online databases. Among 1947 articles screened, a total of 289 articles were assessed for full-text eligibility. Microglial transcriptomic, phenotypic, and neuropathological profiles were analyzed comprising healthy aging and AD. Our review highlights that studies on animal models only partially clarify what happens in humans. Human and mice microglia are hugely heterogeneous. Like a two-sided coin, microglia can be protective or harmful, depending on the context. Brain health depends upon a balance between the actions and reactions of microglia maintaining brain homeostasis in cooperation with other cell types (especially astrocytes and oligodendrocytes). During aging, accumulating oxidative stress and mitochondrial dysfunction weaken microglia leading to dystrophic/senescent, otherwise over-reactive, phenotype-enhancing neurodegenerative phenomena. Microglia are crucial for managing Aß, pTAU, and damaged synapses, being pivotal in AD pathogenesis.

Dementia and Risk Factors: Results from a Prospective, Population-Based Cohort Study.

The incidence rate of dementia varies between studies. The influence of some sociodemographic factors is reasonably established, but less is known about the role of comorbidities, which are common in the elderly. The objectives of this study was to estimate the incidence of dementia in a population of Italian elders and evaluate the role of walking speed, comorbidity and ApoE-ɛ4 as well as various sociodemographic factors on the new onset of dementia. The InveCe.Ab study is a population-based longitudinal study in people born between 1935 and 1939 and resident in Abbiategrasso, Milan, Italy. After excluding subjects with a diagnosis of dementia and those without a definite diagnosis, 1103 individuals with a median follow-up time of 4.1 years were included in the analyses. The cumulative four-year incidence of dementia was 5.3%. Demographic factors such as old age, male, less educated, ApoE-ɛ4 carrier status and slower gait were risk factors for dementia onset in a cognitively healthy sub-cohort. Comorbidity did not influence the onset of dementia; instead, slow walking speed appears to be a strong predictor of dementia onset.

Differential Neuropathology, Genetics, and Transcriptomics in Two Kindred Cases with Alzheimer's Disease and Lewy Body Dementia.

Alzheimer's disease (AD) and Lewy body dementia (LBD) are two different forms of dementia, but their pathology may involve the same cortical areas with overlapping cognitive manifestations. Nonetheless, the clinical phenotype is different due to the topography of the lesions driven by the different underlying molecular processes that arise apart from genetics, causing diverse neurodegeneration. Here, we define the commonalities and differences in the pathological processes of dementia in two kindred cases, a mother and a son, who developed classical AD and an aggressive form of AD/LBD, respectively, through a neuropathological, genetic (next-generation sequencing), and transcriptomic (RNA-seq) comparison of four different brain areas. A genetic analysis did not reveal any pathogenic variants in the principal AD/LBD-causative genes. RNA sequencing highlighted high transcriptional dysregulation within the substantia nigra in the AD/LBD case, while the AD case showed lower transcriptional dysregulation, with the parietal lobe being the most involved brain area. The hippocampus (the most degenerated area) and basal ganglia (lacking specific lesions) expressed the lowest level of dysregulation. Our data suggest that there is a link between transcriptional dysregulation and the amount of tissue damage accumulated across time, assessed through neuropathology. Moreover, we highlight that the molecular bases of AD and LBD follow very different pathways, which underlie their neuropathological signatures. Indeed, the transcriptome profiling through RNA sequencing may be an important tool in flanking the neuropathological analysis for a deeper understanding of AD and LBD pathogenesis.

Centrin 2: A Novel Marker of Mature and Neoplastic Human Astrocytes.

As microtubule-organizing centers (MTOCs), centrosomes play a pivotal role in cell division, neurodevelopment and neuronal maturation. Among centrosomal proteins, centrin-2 (CETN2) also contributes to DNA repair mechanisms which are fundamental to prevent genomic instability during neural stem cell pool expansion. Nevertheless, the expression profile of CETN2 in human neural stem cells and their progeny is currently unknown. To address this question, we interrogated a platform of human neuroepithelial stem (NES) cells derived from post mortem developing brain or established from pluripotent cells and demonstrated that while CETN2 retains its centrosomal location in proliferating NES cells, its expression pattern changes upon differentiation. In particular, we found that CETN2 is selectively expressed in mature astrocytes with a broad cytoplasmic distribution. We then extended our findings on human autoptic nervous tissue samples. We investigated CETN2 distribution in diverse anatomical areas along the rostro-caudal neuraxis and pointed out a peculiar topography of CETN2-labeled astrocytes in humans which was not appreciable in murine tissues, where CETN2 was mostly confined to ependymal cells. As a prototypical condition with glial overproliferation, we also explored CETN2 expression in glioblastoma multiforme (GBM), reporting a focal concentration of CETN2 in neoplastic astrocytes. This study expands CETN2 localization beyond centrosomes and reveals a unique expression pattern that makes it eligible as a novel astrocytic molecular marker, thus opening new roads to glial biology and human neural conditions.

COVID-19 Pathology in the Lung, Kidney, Heart and Brain: The Different Roles of T-Cells, Macrophages, and Microthrombosis.

Here, we aim to describe COVID-19 pathology across different tissues to clarify the disease's pathophysiology. Lungs, kidneys, hearts, and brains from nine COVID-19 autopsies were compared by using antibodies against SARS-CoV-2, macrophages-microglia, T-lymphocytes, B-lymphocytes, and activated platelets. Alzheimer's Disease pathology was also assessed. PCR techniques were used to verify the presence of viral RNA. COVID-19 cases had a short clinical course (0-32 days) and their mean age was 77.4 y/o. Hypoxic changes and inflammatory infiltrates were present across all tissues. The lymphocytic component in the lungs and kidneys was predominant over that of other tissues (p < 0.001), with a significantly greater presence of T-lymphocytes in the lungs (p = 0.020), which showed the greatest presence of viral antigens. The heart showed scant SARS-CoV-2 traces in the endothelium-endocardium, foci of activated macrophages, and rare lymphocytes. The brain showed scarce SARS-CoV-2 traces, prominent microglial activation, and rare lymphocytes. The pons exhibited the highest microglial activation (p = 0.017). Microthrombosis was significantly higher in COVID-19 lungs (p = 0.023) compared with controls. The most characteristic pathological features of COVID-19 were an abundance of T-lymphocytes and microthrombosis in the lung and relevant microglial hyperactivation in the brainstem. This study suggests that the long-term sequelae of COVID-19 derive from persistent inflammation, rather than persistent viral replication.

The expression pattern of GDF15 in human brain changes during aging and in Alzheimer's disease.

Introduction: Growth Differentiation Factor 15 (GDF15) is a mitochondrial-stress-responsive molecule whose expression strongly increases with aging and age-related diseases. However, its role in neurodegenerative diseases, including Alzheimer's disease (AD), is still debated. Methods: We have characterized the expression of GDF15 in brain samples from AD patients and non-demented subjects (controls) of different ages. Results: Although no difference in CSF levels of GDF15 was found between AD patients and controls, GDF15 was expressed in different brain areas and seems to be predominantly localized in neurons. The ratio between its mature and precursor form was higher in the frontal cortex of AD patients compared to age-matched controls (p < 0.05). Moreover, this ratio was even higher for centenarians (p < 0.01), indicating that aging also affects GDF15 expression and maturation. A lower expression of OXPHOS complexes I, III, and V in AD patients compared to controls was also noticed, and a positive correlation between GDF15 and IL-6 mRNA levels was observed. Finally, when GDF15 was silenced in vitro in dermal fibroblasts, a decrease in OXPHOS complexes transcript levels and an increase in IL-6 levels were observed. Discussion: Although GDF15 seems not to be a reliable CSF marker for AD, it is highly expressed in aging and AD brains, likely as a part of stress response aimed at counteracting mitochondrial dysfunction and neuroinflammation.

Alzheimer and Purinergic Signaling: Just a Matter of Inflammation?

Alzheimer's disease (AD) is a widespread neurodegenerative pathology responsible for about 70% of all cases of dementia. Adenosine is an endogenous nucleoside that affects neurodegeneration by activating four membrane G protein-coupled receptor subtypes, namely P1 receptors. One of them, the A2A subtype, is particularly expressed in the brain at the striatal and hippocampal levels and appears as the most promising target to counteract neurological damage and adenosine-dependent neuroinflammation. Extracellular nucleotides (ATP, ADP, UTP, UDP, etc.) are also released from the cell or are synthesized extracellularly. They activate P2X and P2Y membrane receptors, eliciting a variety of physiological but also pathological responses. Among the latter, the chronic inflammation underlying AD is mainly caused by the P2X7 receptor subtype. In this review we offer an overview of the scientific evidence linking P1 and P2 mediated purinergic signaling to AD development. We will also discuss potential strategies to exploit this knowledge for drug development.

A2A Adenosine Receptor as a Potential Biomarker and a Possible Therapeutic Target in Alzheimer's Disease.

Alzheimer's disease (AD) is one of the most common neurodegenerative pathologies. Its incidence is in dramatic growth in Western societies and there is a need of both biomarkers to support the clinical diagnosis and drugs for the treatment of AD. The diagnostic criteria of AD are based on clinical data. However, it is necessary to develop biomarkers considering the neuropathology of AD. The A2A receptor, a G-protein coupled member of the P1 family of adenosine receptors, has different functions crucial for neurodegeneration. Its activation in the hippocampal region regulates synaptic plasticity and in particular glutamate release, NMDA receptor activation and calcium influx. Additionally, it exerts effects in neuroinflammation, regulating the secretion of pro-inflammatory cytokines. In AD patients, its expression is increased in the hippocampus/entorhinal cortex more than in the frontal cortex, a phenomenon not observed in age-matched control brains, indicating an association with AD pathology. It is upregulated in peripheral blood cells of patients affected by AD, thus reflecting its increase at central neuronal level. This review offers an overview on the main AD biomarkers and the potential role of A2A adenosine receptor as a new marker and therapeutic target.

Homocysteine, Folic Acid, Cyanocobalamin, and Frailty in Older People: Findings From the "Invece. Ab" Study.

Frailty is an important age-related syndrome associated with several adverse health outcomes. Its biological basis is undefined. Raised plasma homocysteine (HOcy) is an established risk factor for cardiovascular disease, dementia, cognitive impairment, and mortality, but little is known about the possible role of plasma HOcy, cyanocobalamin (B12), and folate (FO levels in the development of frailty. Our first aim was to explore the possible association between frailty and plasma concentrations of HOcy, FO, and B12 in a cohort of community-dwelling older people. The second was to assess the influence of these metabolic factors on six-year incidence of frailty in the 875 individuals eligible for inclusion in this study (those with a full follow-up dataset). This research is based on data from three waves - 2012 (herein taken as baseline), 2014, and 2018 - of a longitudinal study (InveCe.Ab) in which non-frail men and women born between 1935 and 1939 underwent multidimensional assessments. Frailty was estimated using a deficit accumulation-based frailty index (FI). HOcy concentration was significantly positively correlated with FI at all timepoints, while B12 and FO levels were not. Plasma concentration of HOcy emerged as a predictor of six-year cumulative incidence of frailty, independent of age, sex, and education, while B12 and FO levels showed no relationship with frailty incidence. Individuals with plasma HOcy in the top quintile showed five months less frailty-free survival (HR 1.487; 95% CI: 1.063-2.078), regardless of age, sex, and education. These results demonstrate that higher HOcy is a risk factor for frailty onset in older adults.

Upregulation of Cortical A2A Adenosine Receptors Is Reflected in Platelets of Patients with Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative pathology covering about 70%of all cases of dementia. Adenosine, a ubiquitous nucleoside, plays a key role in neurodegeneration, through interaction with four receptor subtypes. The A2A receptor is upregulated in peripheral blood cells of patients affected by Parkinson's and Huntington's diseases, reflecting the same alteration found in brain tissues. However, whether these changes are also present in AD pathology has not been determined. OBJECTIVE: In this study we verified any significant difference between AD cases and controls in both brain and platelets and we evaluated whether peripheral A2A receptors may reflect the status of neuronal A2A receptors. METHODS: We evaluated the expression of A2A receptors in frontal white matter, frontal gray matter, and hippocampus/entorhinal cortex, in postmortem AD patients and control subjects, through [3H]ZM 241385 binding experiments. The same analysis was performed in peripheral platelets from AD patients versus controls. RESULTS: The expression of A2A receptors in frontal white matter, frontal gray matter, and hippocampus/entorhinal cortex, revealed a density (Bmax) of 174±29, 219±33, and 358±84 fmol/mg of proteins, respectively, in postmortem AD patients in comparison to 104±16, 103±19, and 121±20 fmol/mg of proteins in controls (p < 0.01). The same trend was observed in peripheral platelets from AD patients versus controls (Bmax of 214±17 versus 95±4 fmol/mg of proteins, respectively, p < 0.01). CONCLUSION: AD subjects show significantly higher A2A receptor density than controls. Values on platelets seem to correlate with those in the brain supporting a role for A2A receptor as a possible marker of AD pathology and drug target for novel therapies able to modify the progression of dementia.