Alzheimer Disease: Atwood CS

Casadesus G, Rolston RK, Webber KM, Atwood CS, Bowen RL, Perry G, Smith MA. · Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Adv Clin Chem. · Pubmed #18429496 No free full text.

Abstract: For decades, Alzheimer's disease (AD) has been linked to aging, gender, and menopause. Not surprisingly, this led most investigators to focus on the role of estrogen. While undoubtedly important, estrogen is unlikely the key determinant of disease pathogenesis. Rather, it appears that estrogen may work in conjunction with a novel determinant of disease pathogenesis, namely gonadotropins. The fact that gonadotropins, specifically luteinizing hormone, play a pivotal role in disease is apparent from significant etiological, epidemiological, and pathological evidences. Moreover, targeting gonadotropins appears to have beneficial actions as a therapeutic regimen.

Webber KM, Casadesus G, Atwood CS, Bowen RL, Perry G, Smith MA. · Department of Pathology, Case Western Reserve University, Cleveland, OH, USA. · Mol Cell Endocrinol. · Pubmed #17052835 No free full text.

Abstract: While there is ample experimental evidence supporting the role of estrogen in the pathogenesis of Alzheimer disease, recent inconclusive data regarding hormone replacement therapy (HRT), specifically, the unexpected results of the Women's Health Initiative (WHI) Memory Study has raised serious questions regarding the protective effects of estrogen. Because of this and other inconsistencies in the estrogen hypothesis, we propose that another hormone of the hypothalamic-pituitary-gonadal axis, luteinizing hormone, is a major factor in the pathogenesis of Alzheimer disease. Specifically, we suspect that the increase in gonadotropin concentrations, and not the decrease in steroid hormone (e.g., estrogen) production following menopause/andropause, is a primary causative factor for the development of Alzheimer disease. In this review, we examine how the gonadotropins may play a central and determining role in modulating the susceptibility to, and progression of, Alzheimer disease.

Casadesus G, Garrett MR, Webber KM, Hartzler AW, Atwood CS, Perry G, Bowen RL, Smith MA. · Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Drugs R D. · Pubmed #16752944 No free full text.

Abstract: Estrogen and other sex hormones have received a great deal of attention for their speculative role in Alzheimer's disease (AD), but at present a direct connection between estrogen and the pathogenesis of AD remains elusive and somewhat contradictory. For example, on one hand there is a large body of evidence suggesting that estrogen is neuroprotective and improves cognition, and that hormone replacement therapy (HRT) at the onset of menopause reduces the risk of developing AD decades later. However, on the other hand, studies such as the Women's Health Initiative demonstrate that HRT initiated in elderly women increases the risk of dementia. While estrogen continues to be investigated, the disparity of findings involving HRT has led many researchers to examine other hormones of the hypothalamic-pituitary-gonadal axis such as luteinising hormone (LH) and follicle-stimulating hormone. In this review, we propose that LH, rather than estrogen, is the paramount player in the pathogenesis of AD. Notably, both men and women experience a 3- to 4-fold increase in LH with aging, and LH receptors are found throughout the brain following a regional pattern remarkably similar to those neuron populations affected in AD. With respect to disease, serum LH level is increased in women with AD relative to non-diseased controls, and levels of LH in the brain are also elevated in AD. Mechanistically, we propose that elevated levels of LH may be a fundamental instigator responsible for the aberrant reactivation of the cell cycle that is seen in AD. Based on these aforementioned aspects, clinical trials underway with leuprolide acetate, a gonadotropin-releasing hormone agonist that ablates serum LH levels, hold great promise as a ready means of treatment in individuals afflicted with AD.

Webber KM, Casadesus G, Zhu X, Obrenovich ME, Atwood CS, Perry G, Bowen RL, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106. USA. · Curr Pharm Des. · Pubmed #16472159 No free full text.

Abstract: Several hypotheses have been proposed attempting to explain the pathogenesis of Alzheimer disease (AD) including theories involving amyloid deposition, tau phosphorylation, oxidative stress, metal ion dysregulation and inflammation. Strong evidence suggests that each one contributes to disease pathogenesis, though none of these mechanisms result in all the downstream changes that occur during the course of AD. For this reason, we and others have begun the search for a causative factor that predates known features found in AD, and that might be a fundamental initiator of the pathophysiological cascade. In this regard, we propose that the dysregulation of the cell cycle that occurs in neurons susceptible to degeneration in the hippocampus during AD is a potential causative factor that would initiate all known pathological events. Neuronal changes supporting alterations in cell cycle control in the etiology of AD include the ectopic expression of markers of the cell cycle, organelle kinesis and cytoskeletal alterations including tau phosphorylation. Given the early and presumably devastating consequences of cell cycle re-entry, we have made a concerted effort to elucidate the initiating factor that drives aberrant mitotic re-entry in AD. As a result of the gender bias present in AD, we suspect that postmenopausal and andropausal hormones may be involved and, with this in mind, in this review we specifically focus on the gonadotropins. Therapeutic interventions targeted at gonadotropins, if they are indeed the driving mitogenic force, could both prevent disease in those patients currently asymptomatic or halt, and even reverse, disease in those currently afflicted.

Gregory CW, Atwood CS, Smith MA, Bowen RL. · Voyager Pharmaceutical Corporation, Raleigh, NC 27615, USA. · Curr Pharm Des. · Pubmed #16472158 No free full text.

Abstract: A significant amount of research has been focused on the relationship between hormones and Alzheimer's disease. However, the majority of this work has been on estrogen and more recently testosterone. A serendipitous patient encounter led one of us (RLB) to question whether other hormones of the hypothalamic-pituitary-gonadal axis could be playing a role in the pathogenesis of Alzheimer's disease. The age-related decline in reproductive function results in a dramatic decrease in serum estrogen and testosterone concentrations and an equally dramatic compensatory increase in serum luteinizing hormone concentrations. Indeed, there is growing evidence that the gonadotropin, luteinizing hormone, which regulates serum estrogen and testosterone concentrations, could be an important causative factor in the development of Alzheimer's disease. This review provides information supporting the "gonadotropin hypothesis," puts forth a novel mechanism of how changes in serum luteinizing hormone concentrations could contribute to the pathogenesis of Alzheimer's disease, and discusses potential therapeutic anti-gonadotropin compounds.

Meethal SV, Smith MA, Bowen RL, Atwood CS. · Section of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison, Veterans Administration Hospital, Madison, 53705, USA. · Endocrine. · Pubmed #16034187 No free full text.

Abstract: Although not traditionally thought of as regulators of neuronal function, the hypothalamic-pituitary-gonadal (HPG) hormones luteinizing hormone (LH), gonadotropin-releasing hormone (GnRH), and activins possess neuronal receptors. These receptors are found throughout the limbic system on a number of different cell types, and, like reproductive tissues, the expression of these receptors is regulated by hormonal feedback loops. These hormones and their receptors regulate structure and a diverse range of functions in the brain. Therefore, it is not surprising that the dysregulation of the HPG axis with menopause and andropause (leading to elevated LH, GnRH, and activin signaling but decreased sex steroid signaling) might promote alterations in both the structure and function of neuronal cells. To date, most evidence has accumulated for a role of LH in promoting neurodegenerative changes. LH is known to cross the blood-brain barrier, receptors for LH are most concentrated in the hippocampus, that region of the brain most vulnerable to Alzheimer's disease (AD) and LH is significantly elevated in both the serum and the pyramidal neurons of AD subjects. LH promotes the amyloidogenic processing of the amyloid-beta precursor protein in vitro, and the antigonadotropin leuprolide acetate decreases amyloid generation in mice. Moreover, leuprolide acetate improves the cognitive performance and decreases amyloid-beta deposition in aged transgenic mice carrying the Swedish AbetaPP mutation. Therefore, the elevation of LH with the dysregulation of the HPG axis at menopause and andropause is a physiologically relevant signal that could promote neurodegeneration. Epidemiological support for a role of LH/GnRH in AD is evidenced by a reduction in neurodegenerative disease among prostate cancer patients a group known to GnRH agonists. Clinical trials are underway for the treatment of AD using GnRH analogs and should provide further insights into the gonadotropin connection in AD.

Webber KM, Casadesus G, Marlatt MW, Perry G, Hamlin CR, Atwood CS, Bowen RL, Smith MA. · Institute of Pathology, Case Western Reserve University, 2085 Adelbert Rd., Cleveland, OH 44106, USA. · Ann N Y Acad Sci. · Pubmed #16024763 No free full text.

Abstract: Epidemiological data showing a predisposition of women to develop Alzheimer disease (AD) led many researchers to investigate the role of sex steroids, namely estrogen, in disease pathogenesis. Although there is circumstantial support for the role of estrogen, the unexpected results of the Women's Health Initiative (WHI) Memory Study, which reported an increase in the risk for probable dementia and impaired cognitive performance in postmenopausal women treated with a combination of estrogen and progestin, have raised serious questions regarding the protective effects of estrogen. Although explanations for these surprising results vary greatly, the WHI Memory Study cannot be correctly interpreted without a complete investigation of the effects of the other hormones of the hypothalamic-pituitary-gonadal (HPG) axis on the aging brain. Certain hormones of the HPG axis, namely, the gonadotropins (luteinizing hormone and follicle-stimulating hormone), are not only involved in regulating reproductive function via a complex feedback loop but are also known to cross the blood-brain barrier. We propose that the increase in gonadotropin concentrations, and not the decrease in steroid hormone (e.g., estrogen) production following menopause/andropause, is a potentially primary causative factor for the development of AD. In this review, we examine how the gonadotropins may play a central and determining role in modulating the susceptibility to, and progression of, AD. On this basis, we suggest that the results of the WHI Memory Study are not only predictable but also avoidable by therapeutically targeting the gonadotropins instead of the sex steroids.

Webber KM, Casadesus G, Perry G, Atwood CS, Bowen R, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Alzheimer Dis Assoc Disord. · Pubmed #15942328 No free full text.

Abstract: Epidemiological data reporting the predisposition of women to Alzheimer disease has provided researchers with an important clue as to the identity of the driving pathogenic force and lead many to question the potential role of sex steroids, namely estrogen, in disease pathogenesis. However, while estrogen has become the primary focus of research in the field, inconclusive data regarding estrogen replacement therapy has lead some researchers to begin investigating the effects of the other hormones of the hypothalamic-pituitary-gonadal (HPG) axis on the aging brain. Certain hormones of the HPG axis, namely the gonadotropins (luteinizing hormone and follicle-stimulating hormone), are not only involved in regulating reproductive function via a complex feedback loop but are also known to cross the blood-brain barrier. Recently, we proposed that an increase in gonadotropin concentrations, not the decrease in steroid hormone (eg, estrogen) production following menopause/andropause, is a potentially primary causative factor for the development of Alzheimer disease. In this review, we examine how the gonadotropins may play a central and determining role in modulating the susceptibility to, and progression of, Alzheimer disease. Based on this, we suggest that therapeutic interventions targeted at gonadotropins may both prevent disease in those patients currently asymptomatic or may halt, and even reverse, disease in those currently afflicted.

Atwood CS, Meethal SV, Liu T, Wilson AC, Gallego M, Smith MA, Bowen RL. · Section of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison, 53705, USA. · J Neuropathol Exp Neurol. · Pubmed #15751223 No free full text.

Abstract: Senescence is characterized neurologically by a decline in cognitive function, which we propose is the result of degenerative processes initiated by the dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis with menopause and andropause. Compelling epidemiologic evidence to support this assertion includes the increased prevalence of Alzheimer disease (AD) in women, the correlation of serum HPG hormones with disease and the decreased incidence, and delay in the onset of AD following hormone replacement therapy. Dysregulation of the axis at this time leads to alterations in the concentrations of all serum HPG hormones (decreased neuronal sex steroid signaling, but increased neuronal gonadotropin releasing hormone, luteinizing hormone, and activin signaling). Hormones of the HPG axis, receptors for which are present in the adult brain, are important regulators of cell proliferation and differentiation during growth and development. Based on this, we propose that dysregulated HPG hormone signaling with menopause/andropause leads to the abortive reentry of differentiated neurons into the cell cycle via a process we term "dyosis." Interestingly, the major biochemical and neuropathologic changes reported for the AD brain also are intimately associated with neuron division: altered AbetaPP metabolism, Abeta deposition, tau phosphorylation, mitochondrial alterations, chromosomal replication, synapse loss, and death of differentiated neurons. Recent evidence supports the premise that AD-related biochemical changes are likely the combined result of increased mitotic signaling by gonadotropins and GnRH, decreased differentiative and neuroprotective signaling via sex steroids, and increased differentiative signaling via activins. This results in a hormonal milieu that is permissive of cell cycle reentry but does not allow completion of metaphase. Partial resetting of the axis following administration of normal endogenous sex steroids delays the onset and decreases the incidence of AD. Ideally, supplementation with HPG hormones should mimic closely the serum concentrations of all HPG hormones in reproductive men and cycling women to prevent dyotic signaling and attempted neuron division.

Casadesus G, Atwood CS, Zhu X, Hartzler AW, Webber KM, Perry G, Bowen RL, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Cell Mol Life Sci. · Pubmed #15723165 No free full text.

Abstract: Differences in the prevalence and age of onset of Alzheimer disease (AD) in men and women, and observations that hormone replacement therapy (HRT) may prevent the development of AD, caused many to hypothesize that estrogen deficiency contributes to AD. However, recent trials using estrogen failed to show any benefit in preventing or alleviating the disease. To address this and other inconsistencies in the estrogen hypothesis, we suspect that another hormone of the hypothalamic-pituitary-gonadal axis, luteinizing hormone (LH), as a major factor in AD pathogenesis. Individuals with AD have elevated levels of LH when compared with controls, and both LH and its receptor are present in increased quantities in brain regions susceptible to degeneration in AD. LH is also known to be mitogenic, and could therefore initiate the cell cycle abnormalities known to be present in AD-affected neurons. In cell culture, LH increases amyloidogenic processing of amyloid-beta protein precursor, and in animal models of AD, pharmacologic suppression of LH and FSH reduces plaque formation. Given the evidence supporting a pathogenic role for LH in AD, a trial of leuprolide acetate, which suppresses LH release, has been initiated in patients.

Atwood CS. · Section of Geriatrics and Gerontology, Department of Medicine, University of Wisconsin-Madison, Veterans Administration Hospital, Madison, Wisconsin 53705, USA. · Cell Mol Life Sci. · Pubmed #15723161 No free full text.

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Casadesus G, Zhu X, Atwood CS, Webber KM, Perry G, Bowen RL, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA. · Curr Drug Targets CNS Neurol Disord. · Pubmed #15379604 No free full text.

Abstract: Based on epidemiological and observational studies, estrogen and hormone-replacement therapy were until recently viewed as major factors in the prevention of Alzheimer's disease (AD). However, a recent randomized clinical trial revealed that hormone replacement therapy using estrogen plus progestin may actually exacerbate the incidence of dementia when administered to elderly women. These contradictory reports have cast grave doubt on the role of estrogen in disease pathogenesis and led us to consider an alternate hypothesis that would be consistent with both observations. Specifically, we suspect that hormones of the hypothalamic pituitary gonadal axis such as gonadotropins, that are regulated by estrogen (or in males by testosterone), are involved in the pathogenesis of Alzheimer's disease. One such gonadotropin, luteinizing hormone (LH), is significantly elevated in both the sera and brain tissue of patients with AD and leads to an increased production of amyloid-beta. Importantly, a key role in disease pathogenesis is further supported by the fact that the distribution of neuronal receptors for LH parallels those populations of neurons that degenerate during the course of the disease. That gonadotropins, not estrogen nor testosterone, mediate disease pathogenesis has led to a paradigm shift, not only for the treatment of AD but a wide variety of other age-related diseases. Therefore, the effects of agents that abolish LH, such as leuprolide acetate, which are currently being evaluated in Phase II clinical trials for the treatment of AD, are eagerly anticipated.

Verdile G, Fuller S, Atwood CS, Laws SM, Gandy SE, Martins RN. · Sir James McCusker Alzheimer's Disease Research Unit, School of Psychiatry and Clinical Neurosciences, University of Western Australia, Hollywood Private Hospital, Monash Avenue, Nedlands, WA 6009, Australia. · Pharmacol Res. · Pubmed #15304237 No free full text.

Abstract: The beta amyloid (A beta) protein is a key molecule in the pathogenesis of Alzheimer's disease (AD). The tendency of the A beta peptide to aggregate, its reported neurotoxicity, and genetic linkage studies, have led to a hypothesis of AD pathogenesis that many AD researchers term the amyloid cascade hypothesis. In this hypothesis, an increased production of A beta results in neurodegeneration and ultimately dementia through a cascade of events. In the past 15 years, debate amongst AD researchers has arisen as to whether A beta is a cause or an effect of the pathogenic process. Recent in vitro and in vivo research has consolidated the theory that A beta is the primary cause, initiating secondary events, culminating in the neuropathological hallmarks associated with AD. This research has led to the development of therapeutic agents, currently in human clinical trials, which target A beta.

Zhu X, Webber KM, Casadesus G, Raina AK, Lee HG, Marlatt M, Hartzler A, Atwood CS, Perry G, Smith MA. · Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, Ohio 44106, USA. · Curr Drug Targets. · Pubmed #15270202 No free full text.

Abstract: In this review, we discuss the role of cell cycle dysfunction in the pathogenesis of Alzheimer disease and propose that such mitotic catastrophe, as one of the earliest events in neuronal degeneration, may, in fact, be sufficient to initiate the neurodegenerative cascade. The question as to what molecule initiates cell cycle dysfunction is now beginning to become understood and, in this regard, the gender-predication, age-related penetrance and regional susceptibility of specific neuronal populations led us to consider luteinizing hormone as a key mediator of the abnormal mitotic process. As such, agents targeted toward luteinizing hormone or downstream sequelae may be of great therapeutic value in the treatment of Alzheimer disease.

Webber KM, Bowen R, Casadesus G, Perry G, Atwood CS, Smith MA. · Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, Ohio 44106, USA. · Acta Neurobiol Exp (Wars). · Pubmed #15190686 links to  free full text

Abstract: The search for a definitive gender bias in Alzheimer's disease has resulted in a multitude of epidemiological findings that point to a higher prevalence and incidence of Alzheimer's disease in women. Due to this reported predisposition of women to Alzheimer's disease, the sex steroid estrogen has become the primary focus of research in this field, however, inconclusive data regarding estrogen replacement therapy has lead some researchers to further investigate the role of the other hormones of the hypothalamic-pituitary-gonadal (HPG) axis that have been, for the most, part overlooked. The hormones of the HPG axis, such as the gonadotropin, (luteinizing hormone and follicle-stimulating hormone), are involved in regulating reproductive function via a complex feedback loop. We propose that it is in fact the increase in gonadotropin concentrations and not the decrease in steroid hormone (e.g., estrogen) production following menopause/andropause that results in an increased risk of Alzheimer's disease. Furthermore, when the role of gonadotropins is taken into account, the data obtained from recent epidemiological studies and randomized trials suggesting the ineffectiveness estrogen may indeed be misinterpreted. In this review, we examine how hormones of the hypothalamic-pituitary-gonadal axis, in particular the gonadotropins, play a central and determining role in modulating the susceptibility to and progression of Alzheimer's disease. Based on this, we suggest that therapeutic interventions targeted at gonadotropins could both prevent disease in those patients currently asymptomatic or halt, and even reverse, disease in those currently afflicted.

Veurink G, Fuller SJ, Atwood CS, Martins RN. · The Sir James McCusker Alzheimer's Disease Research Unit, Hollywood Private Hospital, Perth, Australia. · Ann Hum Biol. · Pubmed #14675907 No free full text.

Abstract: This paper reviews a wide range of recent studies that have linked AD-associated biochemical and physiological changes with oxidative stress and damage. Some of these changes include disruptions in metal ion homeostasis, mitochondrial damage, reduced glucose metabolism, decreased intracellular pH and inflammation. Although the changes mentioned above are associated with oxidative stress, in most cases, a cause and effect relationship is not clearcut, as many changes are interlinked. Increases in the levels of Abeta peptides, the main protein components of the cerebral amyloid deposits of AD, have been demonstrated to occur in inherited early-onset forms of AD, and as a result of certain environmental and genetic risk factors. Abeta peptides have been shown to exhibit superoxide dismutase activity, producing hydrogen peroxide which may be responsible for the neurotoxicity exhibited by this peptide in vitro. This review also discusses the biochemical aspects of oxidative stress, antioxidant defence mechanisms, and possible antioxidant therapeutic measures which may be effective in counteracting increased levels of oxidative stress. In conclusion, this review provides support for the theory that damage caused by free radicals and oxidative stress is a primary cause of the neurodegeneration seen in AD with Abeta postulated as an initiator of this process.

Atwood CS, Obrenovich ME, Liu T, Chan H, Perry G, Smith MA, Martins RN. · Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, OH 44106, USA. · Brain Res Brain Res Rev. · Pubmed #14499458 No free full text.

Abstract: Although much maligned, the amyloid-beta (Abeta) protein has been shown to possess a number of trophic properties that emanate from the protein's ability to bind Cu, Fe and Zn. Abeta belongs to a group of proteins that capture redox metal ions (even under mildly acidotic conditions), thereby preventing them from participating in redox cycling with other ligands. The coordination of Cu appears to be crucial for Abeta's own antioxidant activity that has been demonstrated both in vitro as well as in the brain, cerebrospinal fluid and plasma. The chelation of Cu by Abeta would therefore be predicted to dampen oxidative stress in the mildly acidotic and oxidative environment that accompanies acute brain trauma and Alzheimer's disease (AD). Given that oxidative stress promotes Abeta generation, the formation of diffuse amyloid plaques is likely to be a compensatory response to remove reactive oxygen species. This review weighs up the evidence supporting both the trophic and toxic properties of Abeta, and while evidence for direct Abeta neurotoxicity in vivo is scarce, we postulate that the product of Abeta's antioxidant activity, hydrogen peroxide (H(2)O(2)), is likely to mediate toxicity as the levels of this oxidant rise with the accumulation of Abeta in the AD brain. We propose that metal ion chelators, antioxidants, antiinflammatories and amyloid-lowering drugs that target the reduction of H(2)O(2) and/or Abeta generation may be efficacious in decreasing neurotoxicity. However, given the antioxidant activity of Abeta, we suggest that the excessive removal of Abeta may prevent adequate chelation of metal ions and removal of O(2)(-z.ccirf;), leading to enhanced, rather than reduced, neuronal oxidative stress.

Perry G, Taddeo MA, Petersen RB, Castellani RJ, Harris PL, Siedlak SL, Cash AD, Liu Q, Nunomura A, Atwood CS, Smith MA. · Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, Ohio 44106, USA. · Biometals. · Pubmed #12572666 No free full text.

Abstract: Central to oxidative damage in Alzheimer disease is the production of metal-catalyzed hydroxyl radicals that damage every category of macromolecule. Studies on redox-competent copper and iron indicate that redox activity in Alzheimer disease resides exclusively within the cytosol of vulnerable neurons and that chelation with deferoxamine or DTPA removes this activity. We have also found that while proteins that accumulate in Alzheimer disease such as tau, amyloid beta, and apolipoprotein E possess metal-binding sites, metal-associated cellular redox activity is more dependent on metal-nucleic acid binding. Consistent with this finding is the large amount of cytoplasmic RNA in pyramidal neurons. Still, the source of metal-catalyzed redox activity is controversial. Heme oxygenase-1, an enzyme that catalyzes the conversion of heme to iron and biliverdin, is increased in Alzheimer disease suggesting increased heme turnover as a source of redox-active iron. Additionally, the role of mitochondria as a potential source of redox-active metals and oxygen radical production is assuming more prominence. In recent studies, we have found that while mitochondrial DNA and cytochrome C oxidase activity are increased in Alzheimer disease, the number of mitochondria is decreased, indicating accelerated mitochondria turnover. This finding, as well as preliminary studies demonstrating a reduction in microtubule density in neurons in Alzheimer disease suggests mitochondrial dysfunction as a potentially inseparable component of the initiation and progression of Alzheimer disease.

Perry G, Nunomura A, Cash AD, Taddeo MA, Hirai K, Aliev G, Avila J, Wataya T, Shimohama S, Atwood CS, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA. · J Neural Transm Suppl. · Pubmed #12456052 No free full text.

Abstract: Over the past decade, oxidative stress has been established as the earliest cytological feature of Alzheimer disease and an attractive therapeutic target. The major challenges now are establishing the source of the reactive oxygen and what oxidative stress tells us about the etiology of Alzheimer disease. These are complex issues since a variety of enzymatic and non-enzymatic processes are involved in reactive oxygen formation and damage to macromolecules. In this review, we consider disease mechanisms that show the greatest promise for future research.

Perry G, Nunomura A, Hirai K, Zhu X, Pérez M, Avila J, Castellani RJ, Atwood CS, Aliev G, Sayre LM, Takeda A, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA. · Free Radic Biol Med. · Pubmed #12446204 No free full text.

Abstract: In less than a decade, beginning with the demonstration by Floyd, Stadtman, Markesbery et al. of increased reactive carbonyls in the brains of patients with Alzheimer's disease (AD), oxidative damage has been established as a feature of the disease. Here, we review the types of oxidative damage seen in AD, sites involved, possible origin, relationship to lesions, and compensatory changes, and we also consider other neurodegenerative diseases where oxidative stress has been implicated. Although much data remain to be collected, the broad spectrum of changes found in AD are only seen, albeit to a lesser extent, in normal aging with other neurodegenerative diseases showing distinct spectrums of change.

Bishop GM, Robinson SR, Liu Q, Perry G, Atwood CS, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Dev Neurosci. · Pubmed #12401957 No free full text.

Abstract: Brains from patients with Alzheimer disease (AD) show a disruption in the metabolism of iron, such that there is an accumulation of iron in senile plaques, and an altered distribution of iron transport and storage proteins. One of the earliest events in AD is the generation of oxidative stress, which may be related to the generation of free radicals by the excess iron that is observed in the disease. Iron has also been shown to mediate the in vitro toxicity of amyloid-beta peptide, and the presence of iron in most in vitro systems could underlie the toxicity that is normally attributed to amyloid-beta in these studies. In contrast, several recent studies have suggested that amyloid-beta may decrease oxidative stress and decrease the toxicity of iron. Continued examination of the complex interactions that occur between iron and amyloid-beta may assist in the elucidation of the mechanisms that underlie the neurodegeneration that leads to dementia in AD.

Atwood CS, Bishop GM, Perry G, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106 USA. · J Neurosci Res. · Pubmed #12391596 No free full text.

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Atwood CS, Robinson SR, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA. · J Alzheimers Dis. · Pubmed #12226539 No free full text.

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Rottkamp CA, Atwood CS, Joseph JA, Nunomura A, Perry G, Smith MA. · Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, OH 44106, USA. · Peptides. · Pubmed #12128090 No free full text.

Abstract: Investigators studying the primary culprit responsible for Alzheimer disease have, for the past two decades, primarily focused on amyloid-beta (Abeta). Here, we put Abeta on trial and review evidence amassed by the prosecution that implicate Abeta and also consider arguments and evidence gathered by the defense team who are convinced of the innocence of their client. As in all trials, the arguments provided by the prosecution and defense revolve around the same evidence, with opposing interpretations. Below, we present a brief synopsis of the trial for you, the jury, to decide the verdict. Amyloid-beta: guilty or not-guilty?

Perry G, Sayre LM, Atwood CS, Castellani RJ, Cash AD, Rottkamp CA, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · CNS Drugs. · Pubmed #11994023 No free full text.

Abstract: Abnormalities in the metabolism of the transition metals iron and copper have been demonstrated to play a crucial role in the pathogenesis of various neurodegenerative diseases. Metal homeostasis as it pertains to alterations in brain function in neurodegenerative diseases is reviewed in this article in depth. While there is documented evidence for alterations in the homeostasis, redox-activity and localisation of transition metals, it is also important to realise that alterations in specific copper- and iron-containing metalloenzymes appear to play a crucial role in the neurodegenerative process. These changes provide the opportunity to identify pathways where modification of the disease process can occur, potentially offering opportunities for clinical intervention. As understanding of disease aetiology evolves, so do the tools with which diseases are treated. In this article, we examine not only the possible mechanism of disease but also how pharmaceuticals may intervene, from direct and indirect antioxidant therapy to strategies involving gene therapy.