Medicine and Health Sciences Commons^™

Amylin As A Potential Link Between Type 2 Diabetes And Alzheimer Disease, Florin Despa, Larry B. Goldstein, Geert Jan Biessels

Pharmacology and Nutritional Sciences Faculty Publications

No abstract provided.

Distinct Patterns Of Default Mode And Executive Control Network Circuitry Contribute To Present And Future Executive Function In Older Adults, Christopher A. Brown, Frederick A. Schmitt, Charles D. Smith, Brian T. Gold

Neuroscience Faculty Publications

Executive function (EF) performance in older adults has been linked with functional and structural profiles within the executive control network (ECN) and default mode network (DMN), white matter hyperintensities (WMH) burden and levels of Alzheimer's disease (AD) pathology. Here, we simultaneously explored the unique contributions of these factors to baseline and longitudinal EF performance in older adults. Thirty-two cognitively normal (CN) older adults underwent neuropsychological testing at baseline and annually for three years. Neuroimaging and AD pathology measures were collected at baseline. Separate linear regression models were used to determine which of these variables predicted composite EF scores at baseline …

Motivators For Alzheimer's Disease Clinical Trial Participation, Shoshana H. Bardach, Sarah D. Holmes, Gregory A. Jicha

Graduate Center for Gerontology Faculty Publications

Background

Alzheimer’s disease (AD) research progress is impeded due to participant recruitment challenges. This study seeks to better understand, from the perspective of individuals engaged in clinical trials (CTs), research motivations.

Methods

Participants, or their caregivers, from AD treatment and prevention CTs were surveyed about research motivators.

Results

The 87 respondents had a mean age of 72.2, were predominantly Caucasian, 55.2% were male, and 56.3% had cognitive impairment. An overwhelming majority rated the potential to help themselves or a loved one and the potential to help others in the future as important motivators. Relatively few respondents were motivated by free …

Treated Hypothyroidism Is Associated With Cerebrovascular Disease But Not Alzheimer's Disease Pathology In Older Adults, Willa D. Brenowitz, Fang Han, Walter A. Kukull, Peter T. Nelson

Pathology and Laboratory Medicine Faculty Publications

Thyroid hormone (TH) disease is common among older adults and is associated with cognitive impairment. However, pathologic correlates are not well understood. We studied pathologic and clinical factors associated with hypothyroidism, the most common form of TH disease, in research subjects seen annually for clinical evaluations at U.S. Alzheimer’s Disease Centers. Thyroid disease and treatment status were assessed during clinician interviews. Among autopsied subjects, there were 555 participants with treated hypothyroidism and 2,146 with no known thyroid disease; hypothyroidism was associated with severe atherosclerosis (OR=1.35 95% CI: 1.02, 1.79) but not Alzheimer’s disease (AD) pathologies (amyloid plaques or neurofibrillary tangles). …

Genotype-Phenotype Study In Patients With Valosin-Containing Protein Mutations Associated With Multisystem Proteinopathy, Ebaa Al-Obeidi, Sejad Al-Tahan, Abhilasha Surampalli, Namita Goyal, Annabel K. Wang, Andreas Hermann, Molly Omizo, Charles D. Smith, Tahseen Mozaffar, Virginia Kimonis

Neurology Faculty Publications

Mutations in valosin‐containing protein (VCP), an ATPase involved in protein degradation and autophagy, cause VCP disease, a progressive autosomal dominant adult onset multisystem proteinopathy. The goal of this study is to examine if phenotypic differences in this disorder could be explained by the specific gene mutations. We therefore studied 231 individuals (118 males and 113 females) from 36 families carrying 15 different VCP mutations. We analyzed the correlation between the different mutations and prevalence, age of onset and severity of myopathy, Paget's disease of bone (PDB), and frontotemporal dementia (FTD), and other comorbidities. Myopathy, PDB and FTD was present in …

Cerebral Amyloid Angiopathy In Down Syndrome And Sporadic And Autosomal-Dominant Alzheimer's Disease, María Carmona-Iragui, Mircea Balasa, Bessy Benejam, Daniel Alcolea, Susana Fernández, Laura Videla, Isabel Sala, María Belén Sánchez-Saudinós, Estrella Morenas-Rodriguez, Roser Ribosa-Nogué, Ignacio Illán-Gala, Sofía Gonzalez-Ortiz, Jordi Clarimón, Frederick A. Schmitt, David K. Powell, Beatriz Bosch, Albert Lladó, Michael S. Rafii, Elizabeth Head, José Luis Molinuevo, Rafael Blesa, Sebastián Videla, Alberto Lleó, Raquel Sánchez-Valle, Juan Fortea

Sanders-Brown Center on Aging Faculty Publications

Introduction—We aimed to investigate if cerebral amyloid angiopathy (CAA) is more frequent in genetically determined than in sporadic early-onset forms of Alzheimer's disease (AD) (early-onset AD [EOAD]).

Methods—Neuroimaging features of CAA, APOE, and cerebrospinal fluid-Aβ40 levels were studied in subjects with Down syndrome (DS, n = 117), autosomal-dominant AD (ADAD, n = 29), sporadic EOAD (n = 42), and healthy controls (n = 68).

Results—CAA was present in 31%, 38%, and 12% of cognitively impaired DS, symptomatic ADAD, and sporadic EOAD subjects and in 13% and 4% of cognitively unimpaired DS individuals and healthy controls, respectively. …

Hne-Modified Proteins In Down Syndrome: Involvement In Development Of Alzheimer Disease Neuropathology, Eugenio Barone, Elizabeth Head, D. Allan Butterfield, Marzia Perluigi

Sanders-Brown Center on Aging Faculty Publications

Down syndrome (DS), trisomy of chromosome 21, is the most common genetic form of intellectual disability. The neuropathology of DS involves multiple molecular mechanisms, similar to AD, including the deposition of beta-amyloid (Aβ) into senile plaques and tau hyperphosphorylating in neurofibrillary tangles. Interestingly, many genes encoded by chromosome 21, in addition to being primarily linked to amyloid-beta peptide (Aβ) pathology, are responsible for increased oxidative stress (OS) conditions that also result as a consequence of reduced antioxidant system efficiency. However, redox homeostasis is disturbed by overproduction of Aβ, which accumulates into plaques across the lifespan in DS as well as …

Clinically Silent Alzheimer's And Vascular Pathologies Influence Brain Networks Supporting Executive Function In Healthy Older Adults, Brian T. Gold, Christopher A. Brown, Jonathan G. Hakun, Leslie M. Shaw, John Q. Trojanowski, Charles D. Smith

Neuroscience Faculty Publications

Aging is associated with declines in executive function. We examined how executive functional brain systems are influenced by clinically silent Alzheimer’s disease (AD) pathology and cerebral white matter hyperintensities (WMHs). Twenty-nine younger adults and thirty-four cognitively normal older adults completed a working memory paradigm while functional magnetic resonance imaging (fMRI) was performed. Older adults further underwent lumbar cerebrospinal fluid (CSF) draw for assessment of AD pathology and FLAIR imaging for assessment of WMHs. Accurate working memory performance in both age groups was associated with high fronto-visual functional connectivity (fC). However, in older adults, higher expression of fronto-visual fC was linked …

Systems Biology Approach To Late-Onset Alzheimer's Disease Genome-Wide Association Study Identifies Novel Candidate Genes Validated Using Brain Expression Data And Caenorhabditis Elegans Experiments, Shubhabrata Mukherjee, Joshua C. Russell, Daniel T. Carr, Jeremy D. Burgess, Mariet Allen, Daniel J. Serie, Kevin L. Boehme, John S. K. Kauwe, Adam C. Naj, David W. Fardo, Dennis W. Dickson, Thomas J. Montine, Nilufer Ertekin-Taner, Matt R. Kaeberlein, Paul K. Crane

Biostatistics Faculty Publications

Introduction—We sought to determine whether a systems biology approach may identify novel late-onset Alzheimer's disease (LOAD) loci.

Methods—We performed gene-wide association analyses and integrated results with human protein-protein interaction data using network analyses. We performed functional validation on novel genes using a transgenic Caenorhabditis elegans Aβ proteotoxicity model and evaluated novel genes using brain expression data from people with LOAD and other neurodegenerative conditions.

Results—We identified 13 novel candidate LOAD genes outside chromosome 19. Of those, RNA interference knockdowns of the C. elegans orthologs of UBC, NDUFS3, EGR1, and ATP5H were associated with Aβ …

Impact Of Home Visit Capacity On Genetic Association Studies Of Late-Onset Alzheimer's Disease, David W. Fardo, Laura E. Gibbons, Shubhabrata Mukherjee, M. Maria Glymour, Wayne Mccormick, Susan M. Mccurry, James D. Bowen, Eric B. Larson, Paul K. Crane

Biostatistics Faculty Publications

INTRODUCTION—Findings for genetic correlates of late-onset Alzheimer's disease (LOAD) in studies that rely solely on clinic visits may differ from those with capacity to follow participants unable to attend clinic visits.

METHODS—We evaluated previously identified LOAD-risk single nucleotide variants in the prospective Adult Changes in Thought study, comparing hazard ratios (HRs) estimated using the full data set of both in-home and clinic visits (n = 1697) to HRs estimated using only data that were obtained from clinic visits (n = 1308). Models were adjusted for age, sex, principal components to account for ancestry, and additional health indicators.

RESULTS …

Alzheimer's Disease Genetics And Abca7 Splicing, Jared B. Vasquez, James F. Simpson, Ryan Harpole, Steven Estus

Physiology Faculty Publications

Both common and rare polymorphisms within ABCA7 have been associated with Alzheimer’s disease (AD). In particular, the rare AD associated polymorphism rs200538373 was associated with altered ABCA7 exon 41 splicing and an AD risk odds ratio of ∼1.9. To probe the role of this polymorphism in ABCA7 splicing, we used minigene studies and qPCR of human brain RNA. We report aberrant ABCA7 exon 41 splicing in the brain of a carrier of the rs200538373 minor C allele. Moreover, minigene studies show that rs200538373 acts as a robust functional variant in vitro. Lastly, although the ABCA7 isoform with an extended …

Nfatc2 Modulates Microglial Activation In The Aβpp/Ps1 Mouse Model Of Alzheimer's Disease, Gunjan D. Manocha, Atreyi Ghatak, Kendra L. Puig, Susan D. Kraner, Christopher M. Norris, Colin K. Combs

Pharmacology and Nutritional Sciences Faculty Publications

Alzheimer’s disease (AD) brains are characterized by fibrillar amyloid-β (Aβ) peptide containing plaques and associated reactive microglia. The proinflammatory phenotype of the microglia suggests that they may negatively affect disease course and contribute to behavioral decline. This hypothesis predicts that attenuating microglial activation may provide benefit against disease. Prior work from our laboratory and others has characterized a role for the transcription factor, nuclear factor of activated T cells (NFAT), in regulating microglial phenotype in response to different stimuli, including Aβ peptide. We observed that the NFATc2 isoform was the most highly expressed in murine microglia cultures, and inhibition or …

Transcriptional Signatures Of Brain Aging And Alzheimer's Disease: What Are Our Rodent Models Telling Us?, Kendra E. Hargis, Eric M. Blalock

Pharmacology and Nutritional Sciences Faculty Publications

Aging is the biggest risk factor for idiopathic Alzheimer’s disease (AD). Recently, the National Institutes of Health released AD research recommendations that include: appreciating normal brain aging, expanding data-driven research, using open-access resources, and evaluating experimental reproducibility. Transcriptome data sets for aging and AD in humans and animal models are available in NIH-curated, publically accessible databases. However, little work has been done to test for concordance among those molecular signatures. Here, we test the hypothesis that brain transcriptional profiles from animal models recapitulate those observed in the human condition. Raw transcriptional profile data from twenty-nine studies were analyzed to produce …

Calcium's Role As Nuanced Modulator Of Cellular Physiology In The Brain, Hilaree N. Frazier, Shaniya Maimaiti, Katie L. Anderson, Lawrence D. Brewer, John C. Gant, Nada M. Porter, Olivier Thibault

Pharmacology and Nutritional Sciences Faculty Publications

Neuroscientists studying normal brain aging, spinal cord injury, Alzheimer’s disease (AD) and other neurodegenerative diseases have focused considerable effort on carefully characterizing intracellular perturbations in calcium dynamics or levels. At the cellular level, calcium is known for controlling life and death and orchestrating most events in between. For many years, intracellular calcium has been recognized as an essential ion associated with nearly all cellular functions from cell growth to degeneration. Often the emphasis is on the negative impact of calcium dysregulation and the typical worse-case-scenario leading inevitably to cell death. However, even high amplitude calcium transients, when executed acutely can …

Neuropathological And Genetic Correlates Of Survival And Dementia Onset In Synucleinopathies: A Retrospective Analysis, David J. Irwin, Murray Grossman, Daniel Weintraub, Howard I. Hurtig, John E. Duda, Sharon X. Xie, Edward B. Lee, Vivianna M. Van Deerlin, Oscar L. Lopez, Julia K. Kofler, Peter T. Nelson, Gregory A. Jicha, Randy Woltjer, Joseph F. Quinn, Jeffery Kaye, James B. Leverenz, Debby Tsuang, Katelan Longfellow, Dora Yearout, Walter Kukull, C. Dirk Keene, Thomas J. Montine, Cyrus P. Zabetian, John Q. Trojanowski

Sanders-Brown Center on Aging Faculty Publications

Background

Great heterogeneity exists in survival and the interval between onset of motor symptoms and dementia symptoms across synucleinopathies. We aimed to identify genetic and pathological markers that have the strongest association with these features of clinical heterogeneity in synucleinopathies.

Methods

In this retrospective study, we examined symptom onset, and genetic and neuropathological data from a cohort of patients with Lewy body disorders with autopsy-confirmed α synucleinopathy (as of Oct 1, 2015) who were previously included in other studies from five academic institutions in five cities in the USA. We used histopathology techniques and markers to assess the burden of …

Aβ Vaccination In Combination With Behavioral Enrichment In Aged Beagles: Effects On Cognition, Aβ, And Microhemorrhages, Paulina R. Davis, Ginevra Giannini, Karin Rudolph, Nathaniel Calloway, Christopher M. Royer, Tina L. Beckett, M. Paul Murphy, Frederick Bresch, Dieter Pagani, Thomas Platt, Xiaohong Wang, Amy Skinner Donovan, Tiffany L. Sudduth, Wenjie Lou, Erin L. Abner, Richard J. Kryscio, Donna M. Wilcock, Edward G. Barrett, Elizabeth Head

Sanders-Brown Center on Aging Faculty Publications

Beta-amyloid (Aβ) immunotherapy is a promising intervention to slow Alzheimer’s disease (AD). Aging dogs naturally accumulate Aβ and show cognitive decline. An active vaccine against fibrillar Aβ 1–42 (VAC) in aged beagles resulted in maintenance but not improvement of cognition along with reduced brain Aβ. Behavioral enrichment (ENR) led to cognitive benefits but no reduction in Aβ. We hypothesized cognitive outcomes could be improved by combining VAC with ENR in aged dogs. Aged dogs (11–12 years) were placed into 4 groups: (1) control/control (C/C); (2) control/VAC (C/V); (3) ENR/control (E/C); (4) ENR and VAC (E/V) and treated for 20 months. …

Widespread Tau Seeding Activity At Early Braak Stages, Jennifer L. Furman, Jaime Vaquer-Alicea, Charles L. White, Nigel J. Cairns, Peter T. Nelson, Marc I. Diamond

Pathology and Laboratory Medicine Faculty Publications

Transcellular propagation of tau aggregates may underlie the progression of pathology in Alzheimer's disease (AD) and other tauopathies. Braak staging (B1, B2, B3) is based on phospho-tau accumulation within connected brain regions: entorhinal cortex (B1); hippocampus/limbic system (B2); and frontal and parietal lobes (B3). We previously developed a specific and sensitive assay that uses flow cytometry to quantify tissue seeding activity based on fluorescence resonance energy transfer (FRET) in cells that stably express tau reporter proteins. In a tauopathy mouse model, we have detected seeding activity far in advance of histopathological changes. It remains unknown whether individuals with AD also …

Network-Driven Plasma Proteomics Expose Molecular Changes In The Alzheimer's Brain, Philipp A. Jaeger, Kurt M. Lucin, Markus Britschgi, Badri Vardarajan, Ruo-Pan Huang, Elizabeth D. Kirby, Rachelle Abbey, Bradley F. Boeve, Adam L. Boxer, Lindsay A. Farrer, Nicole Finch, Neill R. Graff-Radford, Elizabeth Head, Matan Hofree, Ruochun Huang, Hudson Johns, Anna Karydas, David S. Knopman, Andrey Loboda, Eliezer Masliah, Ramya Narasimhan, Ronald C. Petersen, Alexei Podtelezhnikov, Suraj Pradhan, Rosa Rademakers, Chung-Huan Sun, Steven G. Younkin, Bruce L. Miller, Trey Ideker, Tony Wyss-Coray

Pharmacology and Nutritional Sciences Faculty Publications

Background: Biological pathways that significantly contribute to sporadic Alzheimer’s disease are largely unknown and cannot be observed directly. Cognitive symptoms appear only decades after the molecular disease onset, further complicating analyses. As a consequence, molecular research is often restricted to late-stage post-mortem studies of brain tissue. However, the disease process is expected to trigger numerous cellular signaling pathways and modulate the local and systemic environment, and resulting changes in secreted signaling molecules carry information about otherwise inaccessible pathological processes.

Results: To access this information we probed relative levels of close to 600 secreted signaling proteins from patients’ blood samples using …

The Role Of Capillaries In The Lesser Ailments Of Old Age And In Alzheimer's Disease And Vascular Dementia: The Potential Of Pro-Therapeutic Angiogenesis, Charles T. Ambrose

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Apart from chronic diseases (arthritis, diabetes, etc.), old age is generally characterized by three lesser ailments: muscle weakness, minor memory lapses, and cold intolerance. This trio of complaints may have a common, underlying cause, namely, the age-associated reduced microcirculation in muscles, brain, skin, and elsewhere in the body. The Angiogenesis Hypothesis proposes that old age is in part a deficiency disease due to the decline in angiogenic (AG) factors, resulting in a reduced capillary density (CD) throughout the body. Over fifty published papers document waning levels of AG factors and/or decreased CD in various organ systems of aged animals and …

Self-Reported Head Injury And Risk Of Late-Life Impairment And Ad Pathology In An Ad Center Cohort, Erin L. Abner, Peter T. Nelson, Frederick A. Schmitt, Steven R. Browning, David W. Fardo, Lijie Wan, Gregory A. Jicha, Gregory E. Cooper, Charles D. Smith, Allison M. Caban-Holt, Linda J. Van Eldik, Richard J. Kryscio

Sanders-Brown Center on Aging Faculty Publications

Aims: To evaluate the relationship between self-reported head injury and cognitive impairment, dementia, mortality, and Alzheimer's disease (AD)-type pathological changes. Methods: Clinical and neuropathological data from participants enrolled in a longitudinal study of aging and cognition (n = 649) were analyzed to assess the chronic effects of self-reported head injury. Results: The effect of self-reported head injury on the clinical state depended on the age at assessment: for a 1-year increase in age, the OR for the transition to clinical mild cognitive impairment (MCI) at the next visit for participants with a history of head injury was 1.21 and 1.34 …

Early Stage Drug Treatment That Normalizes Proinflammatory Cytokine Production Attenuates Synaptic Dysfunction In A Mouse Model That Exhibits Age-Dependent Progression Of Alzheimer's Disease-Related Pathology, Adam D. Bachstetter, Christopher M. Norris, Pradoldej Sompol, Donna M. Wilcock, Danielle Goulding, Janna H. Neltner, Daret St. Clair, D. Martin Watterson, Linda J. Van Eldik

Sanders-Brown Center on Aging Faculty Publications

Overproduction of proinflammatory cytokines in the CNS has been implicated as a key contributor to pathophysiology progression in Alzheimer's disease (AD), and extensive studies with animal models have shown that selective suppression of excessive glial proinflammatory cytokines can improve neurologic outcomes. The prior art, therefore, raises the logical postulation that intervention with drugs targeting dysregulated glial proinflammatory cytokine production might be effective disease-modifying therapeutics if used in the appropriate biological time window. To test the hypothesis that early stage intervention with such drugs might be therapeutically beneficial, we examined the impact of intervention with MW01-2-151SRM (MW-151), an experimental therapeutic that …

Rna Oxidation Adducts 8-Ohg And 8-Oha Change With Aβ42 Levels In Late-Stage Alzheimer's Disease, Adam M. Weidner, Melissa A. Bradley, Tina L. Beckett, Dana M. Niedowicz, Amy L.S. Dowling, Sergey V. Matveev, Harry Levine, Mark A. Lovell, M. Paul Murphy

Sanders-Brown Center on Aging Faculty Publications

While research supports amyloid-β (Aβ) as the etiologic agent of Alzheimer's disease (AD), the mechanism of action remains unclear. Evidence indicates that adducts of RNA caused by oxidation also represent an early phenomenon in AD. It is currently unknown what type of influence these two observations have on each other, if any. We quantified five RNA adducts by gas chromatography/mass spectroscopy across five brain regions from AD cases and age-matched controls. We then used a reductive directed analysis to compare the RNA adducts to common indices of AD neuropathology and various pools of Aβ. Using data from four disease-affected brain …

Human Cerebral Neuropathology Of Type 2 Diabetes Mellitus, Peter T. Nelson, Charles D. Smith, Erin L. Abner, Frederick A. Schmitt, Stephen W. Scheff, Gregory J. Davis, Jeffrey N. Keller, Gregory A. Jicha, Daron Davis, Wang-Xia Wang, Adria Hartman, Douglas G. Katz, William R. Markesbery

Pathology and Laboratory Medicine Faculty Publications

The cerebral neuropathology of Type 2 diabetes (CNDM2) has not been positively defined. This review includes a description of CNDM2 research from before the ‘Pubmed Era’. Recent neuroimaging studies have focused on cerebrovascular and white matter pathology. These and prior studies about cerebrovascular histopathology in diabetes are reviewed. Evidence is also described for and against the link between CNDM2 and Alzheimer's disease pathogenesis. To study this matter directly, we evaluated data from University of Kentucky Alzheimer's Disease Center (UK ADC) patients recruited while non-demented and followed longitudinally. Of patients who had come to autopsy (N = 234), 139 met …

The Expression Of Microrna Mir-107 Decreases Early In Alzheimer's Disease And May Accelerate Disease Progression Through Regulation Of Β-Site Amyloid Precursor Protein-Cleaving Enzyme 1, Wang-Xia Wang, Bernard W. Rajeev, Arnold J. Stromberg, Na Ren, Guiliang Tang, Qingwei Huang, Isidore Rigoutsos, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are small regulatory RNAs that participate in posttranscriptional gene regulation in a sequence-specific manner. However, little is understood about the role(s) of miRNAs in Alzheimer's disease (AD). We used miRNA expression microarrays on RNA extracted from human brain tissue from the University of Kentucky Alzheimer's Disease Center Brain Bank with near-optimal clinicopathological correlation. Cases were separated into four groups: elderly nondemented with negligible AD-type pathology, nondemented with incipient AD pathology, mild cognitive impairment (MCI) with moderate AD pathology, and AD. Among the AD-related miRNA expression changes, miR-107 was exceptional because miR-107 levels decreased significantly even in patients with …

Expansion Of The Calcium Hypothesis Of Brain Aging And Alzheimer's Disease: Minding The Store, Olivier Thibault, John C. Gant, Philip W. Landfield

Pharmacology and Nutritional Sciences Faculty Publications

Evidence accumulated over more than two decades has implicated Ca2+ dysregulation in brain aging and Alzheimer's disease (AD), giving rise to the Ca2+ hypothesis of brain aging and dementia. Electrophysiological, imaging, and behavioral studies in hippocampal or cortical neurons of rodents and rabbits have revealed aging-related increases in the slow afterhyperpolarization, Ca2+ spikes and currents, Ca2+transients, and L-type voltage-gated Ca2+ channel (L-VGCC) activity. Several of these changes have been associated with age-related deficits in learning or memory. Consequently, one version of the Ca2+ hypothesis has been that increased L-VGCC activity drives many of the other Ca2+-related biomarkers of hippocampal aging. …

The Toxicology Of Aluminum In The Brain: A Review, Robert A. Yokel

Pharmaceutical Sciences Faculty Publications

Aluminum is environmentally ubiquitous, providing human exposure. Usual human exposure is primarily dietary. The potential for significant Al absorption from the nasal cavity and direct distribution into the brain should be further investigated. Decreased renal function increases human risk of Al-induced accumulation and toxicity. Brain Al entry from blood may involve transferrin-receptor mediated endocytosis and a more rapid process transporting small molecular weight Al species. There appears to be Al efflux from the brain, probably as Al citrate. There is prolonged retention of a fraction of Al that enters the brain, suggesting the potential for accumulation with repeated exposure. Al …