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Alzheimer's Disease

Alzheimer's Disease (AD), also known simply as Alzheimer's, is a neurodegenerative disease characterized by progressive cognitive deterioration together with declining activities of daily living and neuropsychiatric symptoms or behavioral changes. It is the most common type of dementia.

The most striking early symptom is loss of short-term memory (amnesia), which usually manifests as minor forgetfulness that becomes steadily more pronounced with illness progression, with relative preservation of older memories. As the disorder progresses, cognitive (intellectual) impairment extends to the domains of language (aphasia), skilled movements (apraxia), recognition (agnosia), and those functions (such as decision-making and planning) closely related to the frontal and temporal lobes of the brain as they become disconnected from the limbic system, reflecting extension of the underlying pathological process. This pathological process consists principally of neuronal loss or atrophy, principally in the temporoparietal cortex, but also in the frontal cortex, together with an inflammatory response to the deposition of amyloid plaques and neurofibrillary tangles.

The ultimate cause of the disease is unknown. Genetic factors are known to be important, and dominant mutations in three different genes have been identified that account for a much smaller number of cases of familial, early-onset AD. For the more common form of late onset AD (LOAD), ApoE is the only repeatibly confirmed susceptibility genes for AD. In 2007, evidence suggested a possible association between SORL1 alleles and AD.

Current Research

For current research articles click - here

History

In 1901, Dr. Alois Alzheimer, a German psychiatrist, interviewed a patient named Mrs. Auguste D., age 51. She was brought in by her husband, Karl Deter, who could not care for her declining mental health any longer. Dr. Alzheimer showed her several objects and later asked her what she had been shown. She could not recall. He would initially record her behavior as "amnesic writing disorder," but Mrs. Auguste D would be the first patient to be identified with Alzheimer's disease.

Alzheimer would later work in the laboratory of the preeminent Emil Kraepelin in Munich, Germany. Kraepelin was the author of a leading textbook in psychiatry and was a strong believer that neuropathology could be linked to clinical psychiatric function. Early in April 1906, Auguste D. died, and Alzheimer worked with two Italian physicians to examine her anatomy and neuropathology. On November 3, 1906, he presented Auguste D.'s case to the 37th Assembly of Southwest German Psychiatrists and described the neurofibrillary tangles and amyloid plaques that have come to be considered the hallmark of the disease. Kraepelin would later write about this case and others in his "Textbook for Students and Doctors" and index them under "Alzheimer's disease". By 1910, this denomination for the disease was well established among the specialist community. For most of the twentieth century, the diagnosis of Alzheimer's disease was reserved for individuals between the ages of 45-65 who developed symptoms of presenile dementia due to the histopathologic process discovered by Dr. Alzheimer (see below for description of brain tissue changes). During this time senile dementia itself (as a set of symptoms) was considered to be a more or less normal outcome of the aging process, and thought to be due to age-related brain arterial "hardening." In the 1970s and early-1980s, because the symptoms and brain pathology were identical for Alzheimer victims older and younger than age 65, the name "Alzheimer's disease" began to be used, within and outside the medical profession, equally for afflicted individuals of all ages, although in this period the term senile dementia of the Alzheimer type (SDAT) was often used to distinguish those over 65 who did not fit the classical age criterion. Eventually, the term Alzheimer's disease was adopted formally in the psychiatric and neurological nomenclature to describe individuals of all ages with the characteristic common symptom pattern, disease course, and neuropathology. The term Alzheimer disease (without the apostrophe and s) also continues to be used commonly in the literature.

Clinical Features

The usual first symptom noticed is short term memory loss which progresses from seemingly simple and often fluctuating forgetfulness (with which the disease should not be confused) to a more pervasive loss of short-term memory, then of familiar and well-known skills or objects or persons. Since family members are often the first to notice changes that might indicate the onset of the disease they should learn the early warning signs. Aphasia, disorientation and disinhibition often accompany the loss of memory. Alzheimer's disease may also include behavioral changes, such as outbursts of violence or excessive passivity in people who have no previous history of such behavior. In the later stages, deterioration of musculature and mobility, leading to bedfastness, inability to feed oneself, and incontinence, will be seen if death from some external cause (e.g. heart attack or pneumonia) does not intervene. Average duration of the disease is approximately 7–10 years, although cases are known where reaching the final stage occurs within 4–5 years, or in some reported cases up to 21 years.

Stages and symptoms

Mild — At the early stage of the disease, patients have a tendency to become less energetic or spontaneous, though changes in their behavior often go unnoticed even by the patients' immediate family. This stage of the disease has also been termed Mild Cognitive Impairment (MCI) although this term remains somewhat controversial.

Moderate — As the disease progresses to the middle stage, the patient might still be able to perform tasks independently, but may need assistance with more complicated activities.

Severe — As the disease progresses from the middle to late stage, the patient will undoubtedly not be able to perform even the simplest of tasks on their own and will need constant supervision. They may even lose the ability to walk or eat without assistance. They might forget to eat and starve.

Diagnosis

The diagnosis is made primarily on the basis of history, clinical observation, memory tests and intellectual functioning over a series of weeks or months, with various physical tests (blood tests and neuroimaging) being performed to rule out alternative diagnoses. No medical tests are available to diagnose Alzheimer's disease conclusively pre-mortem. Expert clinicians who specialize in memory disorders can now diagnose AD with an accuracy of 85–90%, but a definitive diagnosis of Alzheimer's disease must await microscopic examination of brain tissue, generally at autopsy. Functional neuroimaging studies such as PET and SPECT scans can provide a supporting role where dementia is clearly present, but the type of dementia is questioned. Recent studies suggest that SPECT neuroimaging approaches clinical exam in diagnostic accuracy and may outperform exam at differentiating types of dementia (Alzheimer's disease vs. vascular dementia). However, Alzheimer's disease remains a primarily clinical diagnosis based on the presence of characteristic neurological features and the absence of alternative diagnoses, with possible neuroimaging assistance. Interviews with family members and/or caregivers are extremely important in the initial assessment, as the sufferer him/herself may tend to minimize his symptomatology or may undergo evaluation at a time when his/her symptoms are less apparent, as quotidian fluctuations ("good days and bad days") are a fairly common feature. Such interviews also provide important information on the affected individual's functional abilities, which are a key indicator of the significance of the symptoms and the stage of dementia.

Initial suspicion of dementia may be strengthened by performing the mini mental state examination, after excluding clinical depression. Psychological testing generally focuses on memory, attention, abstract thinking, the ability to name objects, visuospatial abilities, and other cognitive functions. Results of psychological tests may not readily distinguish Alzheimer's disease from other types of dementia, but can be helpful in establishing the presence of and severity of dementia. They can also be useful in distinguishing true dementia from temporary (and more treatable) cognitive impairment due to depression or psychosis, which has sometimes been termed "pseudodementia". In addition, a 2004 study by Cervilla and colleagues showed that tests of cognitive ability provide useful predictive information up to a decade before the onset of dementia. However, when diagnosing individuals with a higher level of cognitive ability, in this study those with IQs of 120 or more, patients should not be diagnosed from the standard norm but from an adjusted high-I.Q norm that measured changes against the individual's higher ability level.

Pathology

Biochemical characteristics

Alzheimer's disease has been identified as a protein misfolding disease, or proteopathy, due to the accumulation of abnormally folded amyloid beta protein in the brains of AD patients. Amyloid beta, also written Aβ, is a short peptide that is a proteolytic byproduct of the transmembrane protein amyloid precursor protein (APP), whose function is unclear but thought to be involved in neuronal development. The presenilins are components of proteolytic complex involved in APP processing and degradation. Although amyloid beta monomers are soluble and harmless, they undergo a dramatic conformational change at sufficiently high concentration to form a beta sheet-rich tertiary structure that aggregates to form amyloid fibrils that deposit outside neurons in dense formations known as senile plaques or neuritic plaques, in less dense aggregates as diffuse plaques, and sometimes in the walls of small blood vessels in the brain in a process called amyloid angiopathy or congophilic angiopathy.

AD is also considered a tauopathy due to abnormal aggregation of the tau protein, a microtubule-associated protein expressed in neurons that normally acts to stabilize microtubules in the cell cytoskeleton. Like most microtubule-associated proteins, tau is normally regulated by phosphorylation; however, in AD patients, hyperphosphorylated tau accumulated as paired helical filaments that in turn aggregate into masses inside nerve cell bodies known as neurofibrillary tangles and as dystrophic neurites associated with amyloid plaques.

Neuropathology

Both amyloid plaques and neurofibrillary tangles are clearly visible by microscopy in AD brains. At an anatomical level, AD is characterized by gross diffuse atrophy of the brain and loss of neurons, neuronal processes and synapses in the cerebral cortex and certain subcortical regions. This results in gross atrophy of the affected regions, including degeneration in the temporal lobe and parietal lobe, and parts of the frontal cortex and cingulate gyrus. Levels of the neurotransmitter acetylcholine are reduced. Levels of the neurotransmitters serotonin, norepinephrine, and somatostatin are also often reduced. Glutamate levels are usually elevated.

Disease mechanism

Three major competing hypotheses exist to explain the cause of the disease. The oldest, on which most currently available drug therapies are based, is known as the "cholinergic hypothesis" and suggests that AD is due to reduced biosynthesis of the neurotransmitter acetylcholine. The medications that treat acetylcholine deficiency have served to only treat symptoms of the disease and have neither halted nor reversed it. The cholinergic hypothesis has not maintained widespread support in the face of this evidence, although cholingeric effects have been proposed to initiate large-scale aggregation leading to generalized neuroinflammation.

Research after 2000 includes hypotheses centered on the effects of the misfolded and aggregated proteins, amyloid beta and tau. The two positions differ with one stating that the tau protein abnormalities initiate the disease cascade, while the other believes that beta amyloid deposits are the causative factor in the disease. The tau hypothesis is supported by the long-standing observation that deposition of amyloid plaques do not correlate well with neuron loss; however, a majority of researchers support the alternative hypothesis that amyloid is the primary causative agent.

The amyloid hypothesis is initially compelling because the gene for the amyloid beta precursor APP is located on chromosome 21, and patients with trisomy 21 - better known as Down syndrome - who thus have an extra gene copy almost universally exhibit AD-like disorders by 40 years of age. The traditional formulation of the amyloid hypothesis points to the cytotoxicity of mature aggregated amyloid fibrils, which are believed to be the toxic form of the protein responsible for disrupting the cell's calcium ion homeostasis and thus inducing apoptosis. A more recent and widely supported hypothesis suggests that the cytotoxic species is an intermediate misfolded form of amyloid beta, neither a soluble monomer nor a mature aggregated polymer but an oligomeric species. Relevantly, much early development work on lead compounds has focused on the inhibition of fibrillization, but the toxic-oligomer theory would imply that prevention of oligomeric assembly is the more important process or that a better target lies upstream, for example in the inhibition of APP processing to amyloid beta.

It should be noted further that ApoE4, the major genetic risk factor for AD, leads to excess amyloid build up in the brain before AD symptoms arise. Thus, beta-amyloid deposition precedes clinical AD. Another strong support for the amyloid hypothesis, which looks at the beta-amyloid as the common initiating factor for the Alzheimer's disease, is that transgenic mice solely expressing a mutant human APP gene develop first diffuse and then fibrillar beta-amyloid plaques, associated with neuronal and microglial damage.

Genetics

Rare cases of Alzheimer's are caused by dominant genes that run in families. These cases often have an early age of onset. Mutations in presenilin-1 or presenilin-2 genes have been documented in some families. Mutations of presenilin 1 (PS1) lead to the most aggressive form of familial Alzheimer's disease (FAD). Evidence from rodent studies suggests that the FAD mutation of PS1 results in impaired hippocampal-dependent learning which is correlated with reduced adult neurogenesis in the dentate gyrus. Mutations in the APP gene on chromosome 21 can also cause early onset disease. The presenilins have been identified as essential components of the proteolytic processing machinery that produces beta amyloid peptides through cleavage of APP.

Most cases identified are "sporadic" with no clear family history. Environmental factors sometimes claimed to increase risk of Alzheimer's include prior head injury, particularly repeated trauma, previous incidents of migraine headaches, exposure to defoliants, and low activity levels during adulthood. However, with the exception of previous concussion, none of these environmental risk factors are widely accepted.

Inheritance of the ε4 allele of the ApoE gene is regarded as a risk factor for development of disease, but large-scale genetic association studies raise the possibility that even this does not indicate susceptibility so much as how early one is likely to develop Alzheimer's. There is speculation among genetic experts that there are other risk and protective factor genes that may influence the development of late onset Alzheimer's disease (LOAD). Researchers are investigating the possibility that the regulatory regions of various Alzheimer's associated genes could be important in sporadic Alzheimer's, especially inflammatory activation of these genes. These hypotheses include the amyloid-β precursor protein (APP), the beta secretase enzymes insulin-degrading enzyme endothelin-converting enzymes and inflammatory 5-lipoxygenase gene.

Genetic linkage

Alzheimer's disease is definitely linked to the 1st, 14th, and 21st chromosomes, but other linkages are controversial and not, as yet, confirmed. While some genes predisposing to AD have been identified , such as ApoE4 on chromosome 19, sporadic AD also involves other risk and protective genes still awaiting confirmation.

Epidemiology and Prevention

Alzheimer's disease is the most frequent type of dementia in the elderly and affects almost half of all patients with dementia. Correspondingly, advancing age is the primary risk factor for Alzheimer's. Among people aged 65, 2-3% show signs of the disease, while 25–50% of people aged 85 have symptoms of Alzheimer's and an even greater number have some of the pathological hallmarks of the disease without the characteristic symptoms. Every five years after the age of 65, the probability of having the disease doubles. The share of Alzheimer's patients over the age of 85 is the fastest growing segment of the Alzheimer's disease population in the US, although current estimates suggest the 75-84 population has about the same number of patients as the over 85 population.

The evidence relating certain behaviors, dietary intakes, environmental exposures, and diseases to the likelihood of developing Alzhemier's varies in quality and its acceptance by the medical community. It is important to understand that interventions that reduce the risk of developing disease in the first place may not alter disease progression after symptoms become apparent. Due to their observational design, studies examining disease risk factors are often at risk from confounding variables. Several recent large, randomized controlled trials—in particular the Women's Health Initiative—have called into question preventive measures based on cross-sectional studies. Some proposed preventive measures are even based on studies conducted solely in animals.

Risk Reducers

Intellectual stimulation (e.g., playing chess or doing crosswords)
Regular physical exercise
Regular social interaction
A Mediterranean diet with fruits and vegetables and low in saturated fat, supplemented in particular with:
- B vitamins;
- Omega-3 fatty acids, especially Docosahexaenoic acid;
- Fruit and vegetable juice;
- High doses of the antioxidant Vitamin E (in combination with vitamin C) seem to reduce Alzheimer's risk in cross sectional studies but not in a randomized trial and so are not currently a recommended preventive measure because of observed increases in overall mortality
Cholesterol-lowering drugs (statins) reduce Alzheimer's risk in observational studies but so far not in randomized controlled trials
Female Hormone replacement therapy is no longer thought to prevent dementia based on data from the Women's Health Initiative
Long-term usage of non-steroidal anti-inflammatory drugs (NSAIDs), used to reduce joint inflammation and pain, are associated with a reduced likelihood of developing AD, according to some observational studies. The risks appear to outweigh the drugs' benefit as a method of primary prevention.
One recent research study has found that cannabinoids, the psychoactive compounds in marijuana, "succeed in preventing the neurodegenerative process occurring in the disease."However, this finding has not been replicated.

Risk factors

Advancing age
ApoE epsilon 4 genotype (in some populations)
Head injury
Poor cardiovascular health (including smoking, diabetes, hypertension, high cholesterol)

Treatment

There is currently no cure for Alzheimer's disease. Currently available medications offer relatively small symptomatic benefit for some patients but do not slow disease progression. The American Association for Geriatric Psychiatry published a consensus statement on Alzheimer's treatment in 2006.

Acetylcholinesterase Inhibitors

Acetylcholinesterase (AChE) inhibition was thought to be important because there is a reduction in activity of the cholinergic neurons. AChE-inhibitors reduce the rate at which acetylcholine (ACh) is broken down and hence increase the concentration of ACh in the brain (combatting the loss of ACh caused by the death of the cholinergin neurons). Acetylcholinesterase-inhibitors seemed to modestly moderate symptoms but do not alter the course of the underlying dementing process.

Examples include:

tacrine - no longer clinically used

donepezil - (marketed as Aricept)

galantamine - (marketed as Razadyne in the U.S.A. Marketed as Reminyl or Nivalin in the rest of the world)

rivastigmine - (marketed as Exelon)

There is significant doubt as to the effectiveness of cholinesterase inhibitors. A number of recent articles have criticized the design of studies reporting benefit from these drugs, concluding that they have doubtful clinical utility, are costly, and confer many side effects. The pharmaceutical companies, but also some independent clinicians, dispute the conclusions of these articles. A transdermal patch is under development that may ease administration of rivastigmine.

Ginkgo Biloba

One of the natural extracts that has been examined in Alzheimer's is Ginkgo (Ginkgo biloba), also known as the Maidenhair Tree. The extract of the Ginkgo leaves contains flavonoid glycosides and terpenoids, and both seeds and leaves have been used pharmaceutically in China and the West. Examining over 50 studies conducted on Ginkgo for the treatment of "cognitive impairment and dementia," a Cochrane Review concludes that "there is promising evidence of improvement in cognition and function associated with Ginkgo." According to this review the two randomized controlled studies that focused on Alzheimer's patients both showed significant improvement in these areas. The review calls for a large study which can "provide robust estimates of the size and mechanism of any treatment effects."The AAGP review did not recommend Ginkgo neither did it warn against its use. A large, randomized clinical study in the US called the GEM study is underway (fully enrolled) and examining the effect of Ginkgo to prevent dementia.

NMDA Antagonists

Recent evidence of the involvement of glutamatergic neuronal excitotoxicity causes Alzheimer's disease led to the development and introduction of memantine. Memantine is a novel NMDA receptor antagonist, and has been shown to be moderately clinically efficacious. Memantine is marketed as Akatinol, Axura, Ebixa and Namenda.

Psychosocial Interventions

Cognitive and behavioral interventions and rehabilitation strategies may be used as an adjunct to pharmacologic treatment, especially in the early to moderately advanced stages of disease. Treatment modalities include counseling, psychotherapy (if cognitive functioning is adequate), reminiscent therapy, reality orientation therapy, and behavioral reinforcements as well as cognitive rehabilitation training.

Treatments in Clinical Development

A large number of potential treatments for Alzheimer's disease are currently under investigation, including four compounds being studied in phase 3 clinical trials. Xaliproden had been shown to reduce neurodegeneration in animal studies. Tramiprosate (3APS or Alzhemed) is a GAG-mimetic molecule that is believed to act by binding to soluble amyloid beta to prevent the accumulation of the toxic plaques. R-flurbiprofen (MPC-7869) is a gamma secretase modulator sometimes called a selective amyloid beta 42 lowering agent. It is believed to reduce the production of the toxic amyloid beta in favor of shorter forms of the peptide. Leuprolide is has also been studied for Alzheimer’s. It is hypothesized to work by reducing leutenizing hormone levels which may be causing damage in the brain as one ages.

Vaccines or immunotherapy for Alzheimer's, unlike typical vaccines, would be used to treat diagnosed patients rather than for disease prevention. Ongoing efforts are based on the idea that, by training the immune system to recognize and attack beta-amyloid, the immune system might reverse deposition of amyloid and thus stop the disease. Initial results using this approach in animals were promising, and clinical trials of the drug candidate AN-1792 showed results in 20% of patients. However, in 2002 it was reported that 6% of multi-dosed participants (18 of 300) developed symptoms resembling meningoencephalitis, and the trials were stopped. Participants in the halted trials continued to be followed, and 20% "developed high levels of antibodies to beta-amyloid" and some showed slower progression of the disease, maintaining memory-test levels while placebo-patients worsened. Microcerebral haemorrhages with passive immunisation and meningoencephalitis with active immunisation still remains to be potent threats to this strategy. Work is continuing on less toxic Aβ vaccines, such as a DNA-based therapy that recently showed promise in mice. Researchers from University of South Florida announced a patch version of the drug was shown to be safe and effective when tested on mice.
Proposed alternative treatments for Alzheimer's include a range of herbal compounds and dietary supplements. In the AAGP review from 2006, Vitamin E in doses below 400 IU was mentioned as having conflicting evidence in efficacy to prevent AD. Higher doses were discouraged as these may be linked with higher mortality related to cardiac events.

Laboratory studies with cells and animals continually fuel the pipeline of potential treatments. Some currently approved drugs such as statins and thiazolidinediones have also been under investigation for the treatment and prevention of Alzheimer’s. Recent clinical trials for Phase 2 and Phase 3 in this category have taken 12 to 18 months under study drug, plus additional months for patient enrollment and analysis. Compounds that are just entering into human trials or are in pre-clinical trials would be at least 4 years from being available to the public and would be available only if they can demonstrate safety and efficacy in human trials.

Occupational and Lifestyle Therapies

Modifications to the living environment and lifestyle of the Alzheimer's patient can improve functional performance and ease caretaker burden. Assessment by an occupational therapist is often indicated. Adherence to simplified routines and labeling of household items to cue the patient can aid with activities of daily living, while placing safety locks on cabinets, doors, and gates and securing hazardous chemicals and guns can prevent accidents and wandering. Changes in routine or environment can trigger or exacerbate agitation, whereas well-lit rooms, adequate rest, and avoidance of excess stimulation all help prevent such episodes. Appropriate social and visual stimulation, however, can improve function by increasing awareness and orientation. For instance, boldly colored tableware aids those with severe AD, helping people overcome a diminished sensitivity to visual contrast to increase food and beverage intake.

Social Issues

Alzheimer's is a major public health challenge since the median age of the industrialized world's population is increasing gradually. Indeed, much of the concern about the solvency of governmental social safety nets is founded on estimates of the costs of caring for baby boomers, assuming that they develop Alzheimer's in the same proportions as earlier generations. For this reason, money spent informing the public of available effective prevention methods may yield disproportionate benefits.

The role of family caregivers has also become more prominent, as care in the familiar surroundings of home may delay onset of some symptoms and delay or eliminate the need for more professional and costly levels of care. However, home-based care may entail tremendous economic, emotional, and even psychological costs as well (see elderly care). Family caregivers often give up time from work and forego pay to spend 47 hours per week on average with an affected loved one who frequently cannot be left alone. From a survey of patients with long term care insurance, direct and indirect costs of caring for an Alzheimer's patient average $77,500 per year.

Statistics on Alzheimer's Disease

In the United States of America, AD was the 7th leading cause of death in 2004, with 65,829 number of deaths (and rising).
At over $100 billion per year, AD is the third most costly disease in the U.S., after heart disease and cancer.
There are an estimated 24 million people with dementia worldwide. More than 5 million Americans are estimated to have Alzheimer’s disease.
By 2040, it is projected that this figure will have increased to 81 million.
It is projected that 14.3 million Americans will have the disease by mid-century: a 350 percent increase from 2000.
The federal government estimates spending approximately $647 million for Alzheimer’s disease research in fiscal year 2005.
The average lifetime cost of care for an individual with Alzheimer’s is $174,000.

Notable Cases

Notable cases of Alzheimer's disease have included Ronald Reagan, Harold Wilson, Iris Murdoch, Eddie Robinson, Charlton Heston, Ferenc Puskas, Rita Hayworth and Australia's Hazel Hawke.

(adapted from Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Alzheimer)

Findings From Current Research

Brain Structural Alterations Before Mild Cognitive Impairment

Authors: Smith CD, Chebrolu H, Wekstein DR, Schmitt FA, Jicha GA, Cooper G, Markesbery WR

MRISC, Room 62, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536. csmith@mri.uky.edu

OBJECTIVE: To determine whether alterations of brain structure in normal aged individuals precede the development of mild cognitive impairment (MCI) or Alzheimer disease (AD). BACKGROUND: Persons with MCI and AD demonstrate cortical volume losses vs. asymptomatic aged individuals, particularly in the hippocampus, amygdale, and entorhinal cortex. It is unknown whether these losses or other volumetric changes are present, and to what degree, in cognitively normal individuals before the clinical diagnosis of MCI. METHODS: Structural MRI was performed on a cross-section of 136 longitudinally examined normal aged subjects. All subjects were cognitively normal at the time of their scan, but 23 later developed MCI, and 9 of these 23 went on to an AD diagnosis. Extracted volumes from voxel-based morphometric analysis were combined with clinical data to compare the 23 subjects who eventually developed MCI to 113 subjects who remained cognitively normal over an average follow-up of 5.4 years. RESULTS: Initially normal subjects who eventually developed MCI demonstrated decreased gray matter volumes in the anteromedial temporal lobes bilaterally and left angular gyrus while still cognitively normal. CONCLUSION: Structural brain changes in anatomic areas involved in higher cognitive processes precede clinical signs and symptoms in longitudinally followed normal subjects destined to develop mild cognitive impairment.

Journal: Neurology. 2007 Apr 17;68(16):1268-73.
Adapted from PubMed; click here to access full journal article.

Outcome Measures in Clinical Trials on Medicinal Products for the Treatment of Dementia: A European Regulatory Perspective

Authors: Broich K

Federal Institute for Drugs and Medical Devices, Bonn, Germany.

Based on efficacy and safety data, several drugs have been approved for symptomatic improvement of dementia of the Alzheimer type and one for the symptomatic improvement of dementia associated with Parkinson's disease. However, established treatment effects must be considered as modest. Randomized clinical trials in other subtypes of dementia (e.g. vascular dementia) have not been able to demonstrate clinically relevant symptomatic improvement, nor has it yet been possible to establish disease-modifying effects in any dementia syndrome or its subtypes. Recent progress in basic science and molecular biology of the dementias has now fostered new interest for more efficacious symptomatic treatments as well as for disease-modifying approaches in the degenerative dementias. For regulatory purposes this requires better standardization and refinement of diagnostic criteria, which allow the study of homogeneous disease populations in specialized academic centers as well as in the general community setting. Depending on the disease stages (early versus late, mild to moderate to severe impairment) and disease entities, distinct assessment tools for cognitive, functional and global endpoints should be used or newly developed. The typical design to show symptomatic improvement is a randomized, double-blind, placebo-controlled, parallel group study comparing change in two primary endpoints, one of them reflecting the cognitive domain and the second preferably reflecting the functional domain of impairment. The changes must be robust and clinically meaningful in favor of active treatment versus placebo. If a treatment claim for prevention of the emergence, slowing or stabilizing deterioration is strived for, it has to be shown that the treatment has an impact on the underlying neurobiology and pathophysiology of the process of dementia. Establishing such an effect in a highly variable progressing syndrome is complex and difficult; however, a variety of trial designs has been provided, including baseline designs, survival designs, randomized start or randomized withdrawal designs, with or without incorporation of biomarkers as surrogate endpoints (e.g. magnetic resonance tomography, emission tomography, cerebrospinal fluid markers). To be accepted as a surrogate endpoint such a biomarker ideally should respond to treatment, predict clinical response and be compellingly related to the pathophysiological process of the dementia. However, careful and sufficient validation of proposed biomarkers as a potential surrogate endpoint is a prerequisite for acceptance by regulatory bodies. This review outlines the regulatory requirements for approval of a new medicinal product for symptomatic improvement or disease-modifying effects in patients with dementia, with special emphasis on the importance of validation of the assessment tools and potential surrogate endpoints based on recent experience and discussion regarding anti-dementia drugs in the European framework.

Journal: Int Psychogeriatr. 2007 Apr 16;:1-16
Adapted from PubMed; click here to access full journal article.

The Epidemiology of Adiposity and Dementia

Authors: Whitmer RA

Kaiser Permanente Division of Research, Etiology and Prevention; 2000 Broadway; Oakland, CA 94612, USA. Rachel.Whitmer@kp.org.

Adipose tissue is the largest endocrine gland in the body, yet only recently has its role in neurodegenerative disease been considered. Prospective population level evidence has emerged to show that both obesity and overweight, is associated with an increased risk of all cause dementia, Alzheimer's disease (AD), and underlying neurodegenerative changes. Weight loss in late life however is associated with dementia, and those categorized as underweight are also at a greater risk of dementia. Given the current epidemic of obesity, and the expected age-related increase in dementia incidence, even a small association between these two diseases has far reaching public health implications. However, due to the effects of both AD-associated weight loss and age-related changes in body composition, there are methodological challenges in appropriately evaluating obesity as a risk factor for developing dementia. There is a need to take a 'life course approach' and to consider the role of risk factors prior to the onset of old age. Our work has shown that both obesity and overweight, as measured by body mass index and skinfold thickness, in middle-age are strongly associated with an increased risk of all cause dementia, Alzheimer disease & Vascular dementia, independent of the development of diabetes and cardiovascular-related morbidities. There is also value in assessing regional body shape distributions of adiposity, particular the role of abdominal obesity. Mechanistic pathways such as adipocyte secreted proteins and hormones, and inflammatory cytokines could explain the association between obesity and increased risk of dementia.

Journal: Curr Alzheimer Res. 2007 Apr;4(2):117-22.
Adapted from PubMed; click here to access full journal article.

Relation of Diabetes to Mild Cognitive Impairment

Authors: Luchsinger JA, Reitz C, Patel B, Tang MX, Manly JJ, Mayeux R.

Department of Medicine, Taub Institute for Research of Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY 10032, USA. jal94@columbia.edu

BACKGROUND: Type 2 diabetes mellitus is an important risk factor for Alzheimer disease and is more prevalent in elderly minority persons compared with non-Hispanic white persons. OBJECTIVE: To determine whether diabetes is related to a higher risk of mild cognitive impairment (MCI), a transitional stage between normal cognition and Alzheimer disease, in a multiethnic cohort with a high prevalence of diabetes. DESIGN: Longitudinal cohort study. SETTING: Northern Manhattan in New York, NY. PARTICIPANTS: We studied persons without prevalent MCI or dementia at baseline and with at least 1 follow-up interval. Of 1772 participants with a complete neuropsychological evaluation, 339 (19.1%) were excluded because of prevalent dementia, 304 were excluded because of prevalent MCI (17.2%), and 211 were excluded because of loss to follow-up (11.9%), resulting in a final sample of 918 participants for longitudinal analyses. MAIN OUTCOME MEASURES: We related diabetes defined by self-report to incident all-cause MCI, amnestic MCI, and nonamnestic MCI. We conducted multivariate analyses with proportional hazards regression adjusting for age, sex, years of education, ethnic group, apolipoprotein E (APOE) epsilon4 allele, hypertension, low-density lipoprotein level, current smoking, heart disease, and stroke. RESULTS: A total of 334 persons had incident MCI, 160 (47.9%) had amnestic MCI, and 174 (52.1%) had nonamnestic MCI. Diabetes was related to a significantly higher risk of all-cause MCI and amnestic MCI after adjustment for all covariates. Diabetes was also related to a higher risk of nonamnestic MCI, but this association was appreciably attenuated after adjustment for socioeconomic variables and vascular risk factors. The risk of MCI attributable to diabetes was 8.8% for the whole sample and was higher for African American persons (8.4%) and Hispanic persons (11.0%) compared with non-Hispanic white persons (4.6%), reflecting the higher prevalence of diabetes in minority populations in the United States. CONCLUSION: Diabetes is related to a higher risk of amnestic MCI in a population with a high prevalence of this disorder.

Journal: Arch Neurol. 2007 Apr;64(4):570-5.
Adapted from PubMed; click here to access full journal article.

The Influence of Galantamine on Reaction Time, Attention Processes, and Performance Variability in Elderly Alzheimer Patients

Authors: Gorus E, Lambert M, De Raedt R, Mets T

Gerontology, Faculty of Medicine & Pharmacy, Vrije Universiteit Brussel, Belgium

OBJECTIVE: To examine the effect of galantamine in elderly patients with mild to moderate Alzheimer disease (AD) on reaction time (RT), selective (SA) and alternating attention (AA), errors, and on interindividual and intraindividual variability. METHODS: Forty-one outpatients with AD were included in an open-label prospective trial and evaluated at baseline and after 8 and 22 weeks of treatment using a RT test that allows differentiation between the decision and movement time components of the total RT. The various tasks of the RT test allowed calculation of SA and AA. Standard AD evaluation tests were performed at baseline and after 22 weeks. RESULTS: After 8 and 22 weeks of treatment, an improvement of decision time and RT at all complexity levels was noted. For movement time, improvements were less pronounced and not present at both follow-up moments or at all complexity levels. Selective attention, but not AA, improved significantly after 22 weeks. A decrease in the number of errors was noted. At several complexity levels, both at 8 and 22 weeks, the interindividual and intraindividual variability decreased. Changes in Mini Mental State Evaluation score were correlated with those in SA. CONCLUSIONS: Our study provides arguments that galantamine treatment improves various parameters of the RT, attention, and interindividual and intraindividual variability in elderly AD patients. Because the study is not a controlled trial, further investigation is needed.

Journal: J Clin Psychopharmacol. 2007 Apr;27(2):182-7.
Adapted from PubMed; click here to access full journal article.

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