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Alzheimer’s Disease: A Chronic Illness The Alzheimer’s Disease Plan: France (Menard)

Alzheimer’s Disease: A Chronic Illness The Alzheimer’s Disease Plan: France (Menard)

Teaser: 


Alzheimer’s Disease: A Chronic Illness
The Alzheimer’s Disease Plan: France

Speaker: Joël Ménard, MD, Professor of Public Health, Faculty of Medicine Paris-Descartes; Author, Alzheimer’s Disease Plan: France.

Dr. Ménard served as author of a report on the National Plan on Alzheimer’s and Related Diseases 2008-2012, commissioned by French President Nicolas Sarkozy. The report’s multiple objectives included advising on ethical concerns, research approaches, therapeutic methods, and care delivery. While efforts to further the patient-oriented national initiative continue, Dr. Ménard described the progress made in creating a national plan aimed at enabling researchers from differing domains (clinical care, research, government) to collaborate in long-term efforts to improve Alzheimer’s disease (AD) care at international, national, and local levels.

The initiative represented formal recognition that Alzheimer’s and related dementias meet criteria distinguishing key health priorities, according to Dr. Ménard. Specifically, dementia affects a large number of people; significant Disability-Adjusted Life Years are lost (DALYs); the incidence and prevalence of AD within an aging social demographic are growing; dementia produces significant emotional and practical difficulties for families and caregivers; and the condition requires complex medical and social care with correspondingly high costs.

The need for a national plan was also brought into focus as research better defined the growing burden of dementia in France. Dr. Ménard presented comparative data suggesting that the impact of AD compared to other illnesses such as cancer and cardiovascular disease is growing in significance, and in women specifically is now the most burdensome, producing the most DALYs lost.

The plan combines a concerted financial effort (200 million euros for research, 200 million euros for medical care, 1.2 billion euros for medico-social support) with a broader initiative to develop insights into the disease process and efforts to improve the quality of life of people with dementia and their caregivers. The committee reports to the Inspector General of Finance, and the Steering Committee and supervisory committees meet regularly. Finally, there is a working session with the President every 6 months.
The French national plan aims to facilitate the work of multidisciplinary centres. The goal is to attract new medical research teams and connect their work with existing teams, encourage young researchers to pursue dementia-related themes, and advance a national policy supporting PhD and postdoctoral researchers. There is also federal support for a scientific foundation aimed at attracting national and foreign researchers. The aim is to harmonize interprofessional efforts to coordinate the talents of those in different disciplines such as patient care, coordination and conducting of clinical trials, neuropsychology, neuroimaging, and biomarkers study.
The bulk of the research investments under the 2008-2012 Alzheimer plan is earmarked for basic research and biomarkers (70 million euros) and clinical research (45 million euros).

As a major component of the plan involves improving quality of life for patients and caregivers, part of the initiative includes developing better respite care services, funding facilities where families can be housed and patient day centres, and financing two training days for caregivers. Other initiatives include funding of memory clinics.

According to Dr. Ménard, the plan reflects a local vision that directly involves individuals, in addition to facilitating noninstitutional care programs.
Dr. Ménard concluded that the promise of such plans is that research and clinical advancements made in AD prevention and management will serve other chronic disease models and better patient care overall.

Discussion Session: Chronic Disease and Aging: Applying the Chronic Disease Model and Preventive Care among the Aged

Discussion Session: Chronic Disease and Aging: Applying the Chronic Disease Model and Preventive Care among the Aged

Teaser: 


Panel Discussion: Chronic Disease and Aging: Applying the Chronic Disease Model and Preventive Care among the Aged

Speakers: Dr. Wagner and Dr. Clarfield

Moderator: Renaldo Battista, MD, MPH, ScD, FRCPC, Professor, Department of Health Administration, Faculty of Medicine, Université de Montréal (DASUM).

Dr. Battista moderated a discussion focused on modifying the manner in which chronic care is delivered to the elderly, as well as the applicability of preventive care measures to a frail older patient segment. He observed that speakers Dr. Wagner and Dr. Clarfield offered differing but pragmatic approaches.
Audience members addressed continued concerns about the consequences of modifying surveillance of patients receiving chronic care. Dr. Clarfield had echoed Dr. Wagner’s and Dr. Kane’s call to replace the practice of regularly scheduled follow-ups with visits prompted by alterations in the patient’s condition or in response to flares of illness. This prompted requests for examples of how teams and systems following this model currently function.

Dr. Wagner responded that the best use of such a system involves reliance on an electronic patient registry that carefully tracks conditions and the dates of major illness-related events. For example, doctors can access the database to monitor who, among his/her patients with diabetes, has not presented for a follow-up visit in longer than 3 months. It was reiterated that such a surveillance model is meant to serve a proactive model of care of planned interactions that involves partnership between patient and physician.
Physician-patient interactions would not conclude without some discussion of follow-up, which can be electronic rather than an in-person visit. The registry facilitates the gathering and accessing of critical information, such as the date of events. A good registry enables proactive care, Dr. Wagner stated. Improved systematic follow-up triggers visits at critical health junctures, and structures key health information according to its salience.

Other questioners voiced concern about events of psychological and social impact that affect health markers. Isolation and bereavement, for example, are correlates of health decrements. Dr. Clarfield agreed that these events impact health but can be hard to medicalize or approach objectively. Here he argued for the role of public health to intervene in this domain. Dr. Clarfield suggested that the numerous supportive communities developing for the aged in Israel could serve as a model. These communities function to prevent isolation and its consequences. He cautioned against the impulse to medicalize social problems.

This prompted consideration from listeners and the panelists on whether the model of chronic disease management could potentially lose sight of the individual person.

Dr. Wagner spoke of this loss as a consequence of the structure of research and data within the chronic disease/chronic care model. Individuals with chronic disease become identified and labeled as such, leading to theoretical and practical imprecision between addressing the person with diabetes versus management of diabetes per se. This may also be a consequence of the problem’s scale, he claimed: Dr. Wagner noted that 25% of people over the age of 65 have four or more chronic conditions. Improving management of multi-morbidity is essential. This necessitates an individualized approach, which may alleviate the forces that would contribute to generalizing patients broadly according to chronic health conditions. He noted that research is beginning to study the patient with specific interrelated health markers, such as heart disease plus depression.

The speakers were asked to elaborate further on the subject, given that acute hospitals are increasingly labouring to manage individuals with multiple diseases and nonspecific deterioration. How is the case for the chronic care model approach within the hospital to be made?

Dr. Wagner stated that children’s hospitals should be consulted as models, as they better integrate the role of the multispecialty practitioner and utilize a systematic approach. These hospitals are experiencing some success at caring for children with complex environmental and genetic problems, he claimed.

He further discussed creating closer links between public health and the chronic care model, based on his and colleagues’ experiences of working with the Centers for Disease Control and state health departments. There they have been implementing the chronic care model with quality improvement initiatives. Specifically, they have observed benefits associated with public health supporting the development of multilevel care systems. Public health can play a key role in facilitating development of community-based resources for providing care such as peer support and exercise programs. Public health can also facilitate the implementation of good information technology.

Finally, the issue of medical training was brought to the speakers’ attention. The panelists concurred that if medical education merely upholds and exemplifies the traditional healthcare delivery system, trainees will understandably opt out of primary care. Dr. Wagner and Dr. Clarfield concurred that if effective systems of care can be developed, trainees will choose it.

Chronic Disease and Aging: Prevention in the Elderly Person—Can We Get it Right?

Chronic Disease and Aging: Prevention in the Elderly Person—Can We Get it Right?

Teaser: 


Chronic Disease and Aging: Prevention in the Elderly Person—Can We Get it Right?

Speaker: A. Mark Clarfield, MD, FRCPC, Head of Geriatrics, Soroka Hospital, Sidonie Hecht Professor of Geriatrics, Faculty of Health Sciences, Ben-Gurion University, Israel.

Dr. Clarfield suggested the need for greater nuance to two key terms: prevention and elderly. Preventive measures recommended are not always appropriate for frail elderly adults, who are a heterogeneous population—some 80-year-old patients have years of vigour ahead, whereas others may require institutional care.

While preventive care is increasingly advocated, he noted that doctors are temperamentally ill-suited to doing substantial amounts of preventive care. They are well-trained to note the signs of health impairment that precede health decrements, and therapeutic efforts are more effective at these earlier stages.

At later stages of life, the benefits that accrue to screening are more modest. Screening, further, may fail to detect problems due to biases, e.g., lead-time biases. The oldest patients have lower physiologic reserves, more comorbidities, and more polypharmacy. Good data about the oldest-old are scarce. Additionally, preventive care can be time-consuming and may lead inexorably toward aggressive interventions that may not coincide with the wishes or best interests of the patient. Some of the screening recommendations are not appropriate for the eldest frail patients. Therefore, Dr. Clarfield ascribed greatest importance to confronting the symptoms that patients report.

As for the value of screening, he advised that data on mortality and life expectancy yield important information. The healthiest quartile have 10 years left to live and may see some benefit from screening, but those with poor health markers, often in long-term care, have often less than 3 years.
Dr. Clarfield further recommended considering the sensitivity and specificity of tests. In a context of finite resources, it is important to avoid the testing spiral. Further, it is essential to note risks as well as benefits to screening: for example, there is a risk of perforating the colon on colonoscopy. Patients should be involved interlocutors and physicians must remain cognizant of their values—patients may not want aggressive testing. This is particularly so when it comes to mammograms, where benefits can be modest.

He then recommended pursuing prevention measures within comorbidity. An example he outlined concerned falls prevention. He advocated identifying a vulnerable patient subgroup, e.g., those on Coumadin, at which to direct specific preventive measures.

Involving other health professionals to maximize resources, and improved health behaviours, may yield better benefits than screening. He identified the four primary areas of risk-factor modification: smoking cessation, moderate alcohol consumption, adequate intake of fruits and vegetables, and exercise.
At advanced stages of life he advised reconsidering or discontinuing pap smears, PSA testing, and coronary calcification measurements. In turn physicians should reconsider or commence moderating polypharmacy, assessing falls risk, and checking vision and hearing. Dr. Clarfield concluded that prevention can be effective if it is well-targeted. Clinicians should review available evidence and add their own clinical judgment. Preventive measures can benefit the elderly, but the risk-benefit ratio changes unpredictably with advancing age and frailty.

Chronic Disease and Aging: Applying the Chronic Disease Model to Older Persons

Chronic Disease and Aging: Applying the Chronic Disease Model to Older Persons

Teaser: 


Chronic Disease and Aging: Applying the Chronic Disease Model to Older Persons

Speaker: Edward Wagner, MD, MPH, FACP, Director, MacColl Institute for Healthcare Innovation, Group Health Cooperative, University of Washington.

Dr. Wagner observed that primary care is increasingly dominated by chronic illness and geriatric care, but the status quo model of the structure and provision of primary care is ill-suited to the changing population that it is serving.

Primary care serves a growing population of heterogeneous individuals with multiple chronic illnesses. The pressures thereby placed on primary care are giving rise to evocations of the “demise” or “collapse” of primary care. A large portion of patients are receiving inadequate evidence-based care that fails to control their chronic health conditions. Further, primary care visits are largely devoted to routine management of these conditions.

Physicians increasingly struggle to provide adequate, evidence-based care, but studies show that the time required to comply with evidence-based practice requirements would exceed the standard workday by several hours.
Dr. Wagner suggested approaches to improve healthcare outcomes under these circumstances. One, patients must receive adequate drug therapy; two, patients must self-manage their conditions and take greater responsibility for their health status; three, preventive interventions must be provided at timely intervals (with secondary prevention and early detection being key); four, there must be evidence-based monitoring and self-monitoring; and five, care must feature adequate follow-up tailored to the condition’s severity. Good surveillance is essential due to the fluctuating nature of chronic illness.
Dr. Wagner stated that, depending on the illness, roughly half of all patients or fewer are receiving evidence-based treatment for their conditions. For example, one-quarter of patients reporting depressive symptoms receive treatment or referral for treatment.

Discussing the “quality chasm,” he noted that the current care system is unequipped to handle the challenges described, and no increase in applied effort will improve a system failing at a structural level. Measures such as team changes, case management, patient reminders, and patient education have resulted in improved outcomes. Changes showing the greatest impact are those that educate patients to better manage their conditions. Other effective measures alter the organization and delivery of care. Further, use of nonphysician team members, planned encounters, modern self-management support, specialized care management for high-risk patients, and population management using electronic registries are effective.

Fundamentally, the most productive healthcare interactions result from the interaction between an informed, active patient, and a prepared practice team.
Such interactions take the form of the “planned visit,” using patient data, team and practice organization, and decisional support to assure productivity.
The most important IT enhancement is implementation of a patient registry that includes every patient who meets certain criteria for high risk (the presence of one or more chronic illnesses). This facilitates well-organized interactions. Registries can be a rapid source of information (patient details, medications), aid planning, and serve as a valuable tool for monitoring performance across the practice.

He emphasized that the vast majority of the population prefers a primary care physician; countries with better primary care have better health outcomes; and U.S. states with higher primary care/population ratios have reduced costs and better quality. He promoted primary care’s ability to marry gerontology with effective chronic disease management. Primary care must do this if it is to survive.

Discussion Session: Chronic Disease Care (Lapointe)

Discussion Session: Chronic Disease Care (Lapointe)

Teaser: 


Discussion Session: Chronic Disease Care

Speakers: Dr. Kane and Dr. Butler-Jones

Moderator: Liette Lapointe, PhD, Associate Professor; Director, Business and Management Research Center, Desautels Faculty of Management, McGill University.

Dr. Lapointe, an academician whose research interests include resistance to information technology and the implementation of information systems in the healthcare industry, moderated the discussion between Dr. Kane and Dr. Butler-Jones.

Both presenters had considered chronic disease’s role in healthcare resource utilization, and the burden of chronic disease on patients themselves and the society at large. Dr. Lapointe noted that three uniting concerns bridged the speakers’ presentations. They both discussed the extent to which aging is properly seen as a challenge; both addressed which health and policy achievements qualified as indices of success (e.g., cure versus care, how to best assess outcomes, and the best provision of resources); and, finally, both considered how health professionals in clinical care and those that work with governments can ensure improvements in managing aging and chronic disease on a systemic level, highlighting the role of information technology in the process.

Dr. Kane was queried on the value of making changes at the level of medical training to better meet the challenges of frailty, disability, and dependency among aging adults. Dr. Kane offered doubt that medical schools represented the best site of intervention due to several factors. Training methods and content tend to be conservative and challenging to alter. Further, given the delay between instituting philosophical and practical change and when effects manifest, change may be excessively belated and the information possibly anachronistic. Finally, trainees may enter the clinical context with the correct knowledge, but the environments in which they work may be inhospitable to change.

Dr. Butler-Jones concurred, adding that there is no single site at which to make the changes necessary to better deal with the increasing chronic disease burden. He added that interventions should not ignore the medical schools, however, given increasing interdisciplinarity among healthcare professionals, as well as the mobility and dynamism between academic, clinical, and policy contexts. These represent multiple target points for new research findings.

Another issue raised was that of the Baby Boomer generation and the effect their entry into the ranks of seniors will have. Does the size of the demographic mean that they are bound to reshape health policy? Dr. Butler-Jones affirmed the notion, noting that the generation has altered society at every stage of life. Dr. Kane in turn challenged the suggestion, noting that the greatest changes they stand to institute come in the form of their advocacy for their parents’ generation. Once they themselves become infirm, their capacity to serve as radical advocates for themselves or for wider change within the healthcare system will be compromised.

Dr. Kane was given the opportunity to elaborate several of his ideas on optimizing healthcare delivery in an environment of burgeoning chronic disease prevalence. He had advocated eliminating regularly scheduled follow-up consultations in favour of primary care utilization based on change in health status. Rather than seeing this as a reduction in follow-up visits, Dr. Kane described the practice as one that facilitates systemic tracking of chronic illness.

Dr. Butler-Jones agreed that this revised approach to follow-up care could enhance monitoring. Other forms of patient tracking outside of regularly scheduled follow-up appointments could improve patient health behaviours, he stated, citing study data finding that weekly/bi-weekly calls from a nurse reduced subsequent emergency room visits, and improved treatment adherence.

Dr. Kane was challenged on his suggestion that team-based care leads to inefficiencies and fails to alter outcomes. Dr. Kane advised that team approaches can experience success when team participants have well-defined roles and adhere to them, and function with trust of their partners. Research and clinical experience has shown that collaborative care can instead be duplicative and an inefficient use of time.

As up to one-third of current health professionals are nearing retirement age, panelists were asked to consider the severity of shortages in primary care availability and how patients’ access to primary care practitioners might be assured.

Dr. Kane responded that if the importance of primary care is not affirmed institutionally, governmentally, and societally, the crisis in care availability will worsen. Remuneration must be improved, and costs must be recouped in the context of an economic model that accounts for reduced hospitalization and crisis visits. The sustainability of the healthcare system depends on the society’s ability to meet the challenge of chronic disease, and investments must occur in primary care rather than large hospitals.

Dr. Butler-Jones hoped that more effort would occur on the level of training to encourage practitioners to enter the field, rather than continuing to foster a sense of elitism and upholding the specialist as the model practitioner.

Chronic Disease and Aging: A Public Health Perspective (Butler)

Chronic Disease and Aging: A Public Health Perspective (Butler)

Teaser: 


Chronic Disease and Aging: A Public Health Perspective

Speaker: David Butler-Jones, MD, MHSc, LLD(h), FRCPC, FACPM, CCFP, Chief Public Health Officer of Canada.

While the challenges posed by chronic disease to Canada’s aging adults justly occupied the attention of the conference’s participants, Chief Public Health Officer of Canada Dr. Butler-Jones urged participants to refocus attention on the value of aging. While rising rates of chronic disease are a formidable problem, he observed that aging adults remain key contributors to society and that aging with chronic disease is preferable to dying young. He noted that aging is not the problem; how we live makes a difference—it is not just a matter of length of life.

Public health comprises a set of programs and services but is also a way of “understanding the causes of the causes.” According to Dr. Butler-Jones, public health efforts facilitate better understanding of the interrelationship of physical health and the social environment. Public health is uniquely positioned to advise other sectors, provides leadership in promoting healthy aging, and is capable of engaging valued partners across society to build healthy, enabling environments.

Public health acknowledges the importance of supporting health throughout the life course, and that health outcomes are an end stage of a lifelong trajectory. For example, poverty in infancy is associated with a doubled stroke risk in later life. He also noted that public health research has produced insights on the interaction of forces that serve as determinants of health, such as the relationship between social markers, chronic conditions, and health vulnerabilities. Dr. Butler-Jones discussed his 2008 Chief Public Health Officer’s Report on the State of Public Health in Canada, stressing that understanding the determinants of health is essential as they provide the context and direction for prevention and interventions. He also noted that mortality in the recent SARS and listeria infection outbreaks in Canada were associated with underlying chronic conditions. An aging population elevates vulnerability.

Other important factors in aging and chronic disease vulnerability include poor self-rated health and lack of social connectivity. Those without close social networks (family, friends, colleagues, etc.) have twice the risk of dying of those not socially isolated.

Regarding the prevalence of chronic disease among aging adults, Dr. Butler-Jones noted that approximately 85% of those aged 65-79 and more than 90% of those 80 years and over reported at least one chronic disease in 2005.
Dr. Butler-Jones emphasized that the approach to chronic illness should not pose preventive care against clinical care but focus on their coordination and improvement. He discussed disease-specific interventions, and noted that healthy living should not be seen in opposition but as an opportunity for interaction and cross over, for example, in terms of interventions and risk factors. The broader perspective appreciates contextual factors that improve health and build healthy environments, such as promoting those community features and infrastructures that support healthy aging (e.g., more liveable, safer communities that enhance social support and connectedness, illustrated by the example of the Age Friendly Communities Model).

Key examples of where aging and chronic disease intersect and where there are public health opportunities for healthy aging include the domains of fall prevention (involving design and infrastructure at the community level, plus awareness, education, assessment, exercise, hazard reduction, etc.), mental health, better caregiver support (one in 12 Canadian seniors provides care to another senior with a long-term health problem), emergency preparedness, elder abuse, and promoting age-friendly communities. Finally, he noted that seniors are not merely a vulnerable population but represent a key resource in the community, and are essential partners in public health efforts promoting effective healthcare improvements and safety planning.

Chronic Disease and Aging: Two Separate or Related Problems?

Chronic Disease and Aging: Two Separate or Related Problems?

Teaser: 


Chronic Disease and Aging: Two Separate or Related Problems?

Speaker: Robert Kane, MD, Professor and Minnesota Chair in Long-Term Care and Aging, University of Minnesota, School of Public Health.

Geriatrics represents the intersection of gerontology and chronic disease care. The elderly predominate in chronic disease. Gerontology includes various syndromes and involves managing multiple simultaneous problems across multiple domains (physical, social, economic). Both imply the need to find better ways of delivering care (effectiveness) and to control costs (efficiency). Success in chronic care must be measured in terms of actual versus expected clinical trajectories. Strategies to improve chronic care involve reorganizing care delivery systems.

To promote proactive primary care with improved decision support, more effective disease management and better care coordination (e.g., medical home) are needed. Patient empowerment is central. A critical question is whether there is a business case for better primary care. Can more active care actually achieve subsequent costs savings through reduced resource use? Getting physicians actively involved in primary care will involve removing barriers such fee-for-service payment, which is the anathema of chronic disease care. Dr. Kane supported the creation of incentives (financial, recognition, practice satisfaction) for doing the right thing. Dr. Kane stressed the need for measures that would increase efficiency. For example, we should eliminate scheduled return appointments and instead base revisits on clinical trajectories.

Sexuality in the Aging Couple, Part II: The Aging Male

Sexuality in the Aging Couple, Part II: The Aging Male

Teaser: 

Irwin W. Kuzmarov, MD, FRCSC, Assistant Professor, Department of Surgery (Urology), McGill University; Director of Professional and Hospital Services, Santa Cabrini Hospital, Montreal, QC; Past President, Canadian Society for the Study of the Aging Male.
Jerald Bain, BScPhm, MD, MSc, FRCPC, CertEndo, BA, Professor Emeritus, Department of Medicine, Division of Endocrinology and Metabolism, Mount Sinai Hospital; University of Toronto, Toronto, ON; Past President, Canadian Society for the Study of the Aging Male.

Sexual desire and activity continue well into later life, and advanced age alone is not a deterrent to a happy and healthy sex life; however, clinicians should be aware that the normal sexual response of men and women may change with aging. When sexual dysfunction occurs, studies show that men and women tend to view sexual dysfunction differently. Part I addressed sexual function and dysfunction with age in females. Part II of this two-part article series addresses sexuality and sexual dysfunction in aging men. For the emotional well-being of their patients, it is crucial that family doctors be aware of sexuality in the aging couple, and be able to evaluate and manage problems that may arise.
Key words: aging, sexual activity, sexual dysfunction, men, testosterone therapy.

Sexuality in the Aging Couple, Part I: The Aging Woman

Sexuality in the Aging Couple, Part I: The Aging Woman

Teaser: 

Irwin W. Kuzmarov, MD, FRCSC, Assistant Professor, Department of Surgery (Urology), McGill University; Director of Professional and Hospital Services, Santa Cabrini Hospital, Montreal, QC; Past President, Canadian Society for the Study of the Aging Male.
Jerald Bain, BScPhm, MD, MSc, FRCPC, CertEndo, BA, Professor Emeritus, Department of Medicine, Department of Endocrinology and Metabolism, Mount Sinai Hospital; University of Toronto, Toronto, ON; Past President, Canadian Society for the Study of the Aging Male.

Sexuality and sexual activity do not end when a person reaches a certain age. Sexual desire and activity continue well into later life, and age is not a deterrent to a happy and healthy sex life. However, clinicians should be aware that the normal sexual response of men and women may change with aging. When sexual dysfunction occurs, studies show that men and women tend to view sexual dysfunction differently. Part I of this article addresses sexuality and sexual dysfunction in aging women; Part II ( will address the male side of the picture. It is crucial that family doctors be aware of sexuality in the aging couple, and be able to evaluate and manage problems that may arise.
Key Words: aging, sexual activity, sexual dysfunction, women, testosterone therapy.

Sarcopénie et vieillissement musculaire

Sarcopénie et vieillissement musculaire

Teaser: 

Sarcopénie et vieillissement musculaire

Conférencier : Patrick Dehail, M.D., Ph. D., service de Médecine Physique et Réadaptation & EA 4136, CHU de Bordeaux, Université de Bordeaux 2; Bordeaux, France.

Le Dr Patrick Dehail s'est intéressé aux mécanismes, à l’impact fonctionnel et aux approches thérapeutiques de la sarcopénie et du vieillissement musculaire.

Définition de la sarcopénie
La sarcopénie est une perte progressive de la masse musculaire associée au vieillissement. Sa prévalence est élevée, entre 10 et 24 % de la population âgée de 65 à 70 ans et jusqu'à plus de 30 % après 80 ans.

La sarcopénie se définit par un index de masse musculaire (IMM) (masse musculaire appendiculaire [kg]/taille2 [m2]) inférieur à au moins deux écarts-type par rapport à celui d’une population de référence plus jeune1. Il serait très utile de disposer d’un seuil qui tienne compte de la performance musculaire et qui décrive la perte de masse musculaire associées aux conséquences fonctionnelles.

Chez la personne âgée, le déclin de la masse musculaire est associé à une augmentation de la masse grasse. Il est important de considérer les deux phénomènes, puisque les conséquences de la sarcopénie seront différentes en fonction de la masse grasse.

Modifications du tissu musculaire liées au vieillissement et mécanismes associés
La sarcopénie est associée à des modifications du tissu musculaire, notamment une réduction du nombre de fibres de type II et une atrophie de ces fibres, les fibres de type I étant relativement épargnées (Figure 1). Au niveau moléculaire, le vieillissement est associé à une diminution de l’expression des isoformes des chaînes lourdes de myosine (MHC) de type IIa et IIx, sans grande modification de l’expression de la MHC de type I. On observe également une augmentation du nombre de fibres hybrides, qui vont co-exprimer différents types d’isoformes de MHC.

Les mécanismes impliqués dans le vieillissement musculaire sont notamment des modifications des unités motrices, l'inactivité, la dérégulation de la synthèse protéique musculaire et l’apoptose.

Le vieillissement est associé à une réduction de 25 à 50 % du nombre de motoneurones-a (MN-a). Les MN de petite taille, mieux préservés que les MN de grande taille, vont continuer à innerver les fibres de type I. La perte des MN-a de grande taille est compensée pendant longtemps par un phénomène de bourgeonnement, où les MN de petite taille vont prendre en charge les fibres musculaires orphelines de type II, qui prendront des caractéristiques de type I. Ce phénomène de bourgeonnement a des limites, cependant, et ces nouvelles unités motrices géantes finiront par être perdues. À partir d’un certain seuil, cette perte aura des conséquences fonctionnelles.

On considère l’inactivité comme un facteur étiologique du phénomène sarcopénique. Cependant, on ne sait pas dans quelles proportions l’inactivité est la conséquence des modifications neuromusculaires (phénomène adaptatif) ou contribue à ces changements.

Le Dr Dehail a expliqué que la dérégulation de la synthèse des protéines musculaires est un élément central du phénomène sarcopénique. La séquestration splanchnique détourne les acides aminés vers le foie ou l'intestin. D’autre part, l'insulino-résistance, dont la prévalence augmente avec l'âge, joue un rôle défavorable en augmentant la protéolyse des protéines musculaires. La diminution du taux des hormones anaboliques (testostérone, axe GH-IGF1, DHEA) contribue également à ce trouble. Enfin, l'augmentation du taux des cytokines pro-inflammatoires (notamment l'Il6 et le TNF-a) chez la personne âgée stimule le processus protéolytique. La diminution du taux de MGF (facteur qui stimule le pool des cellules satellites), l’augmentation du taux de myostatine (inhibiteur de la croissance musculaire) et l’apoptose contribuent aussi à la sarcopénie.
Le vieillissement est également associé à des troubles de la microcirculation qui affectent le tissu musculaire.

Les personnes âgées présentent fréquemment une malnutrition, une anorexie et une diminution du taux de vitamine D et du nombre de récepteurs VDR à la vitamine D. La prévalence de la carence en vitamine D dépasse les 90 % chez les personnes âgées hospitalisées. La vitamine D agit sur les capacités fonctionnelles du tissu musculaire et sur la synthèse protéique, et il existe une corrélation entre le taux de 25-hydroxy vitamine D (25-OHD) et la perte de force musculaire. Visser et ses collègues ont montré que les personnes qui ont un taux de 25-OHD < 25 nmol/l étaient plus susceptibles de perdre leur force de préhension à trois ans. Une diminution du taux circulant de 25-OHD a également été corrélée à une diminution du temps de marche ou du temps de réalisation d’une épreuve de lever de chaise2.

Impact fonctionnel du vieillissement musculaire
Les modifications du tissu musculaire vont retentir sur la performance et la force musculaire. Cette perte de force musculaire commence tôt, mais va rester insignifiante jusqu'à 50-60 ans. C’est surtout la force musculaire isocinétique, concentrique et des membres inférieurs qui est initiatement touchée. De plus, la perte de force musculaire est asymétrique au niveau des groupes musculaires antagonistes.

Le seuil de tolérance en matière de perte fonctionnelle varie en fonction des individus et de la tâche fonctionnelle, mais des auteurs ont proposé des seuils cliniques au-dessous desquels la majorité des sujets connaîtront des problèmes. Par exemple, Janssen et ses collègues ont trouvé qu’un IMM inférieur à 5,75 chez les femmes et 8,5 chez les hommes était corrélé à un niveau plus élevé d’incapacité fonctionnelle3. Ploutz-Snyder et ses collègues estiment qu’un rapport « force isométrique des quadriceps/poids corporel » < 3 Nm/kg est associé à une dégradation des capacités fonctionnelles, notamment celles en rapport avec la locomotion (marche, montée de marches d’escalier, transfert assis-debout)4. Lauretani et ses collègues ont proposé une méthode encore plus simple, montrant qu’une force de préhension inférieure à 30 kg pour les hommes ou 20 kg pour les femmes permet d’identifier les personnes âgées ayant une vitesse de marche ou des capacités locomotrices moindres5.

Sur le plan fonctionnel, il est important de considérer la perte de puissance musculaire, car elle est impliquée dans beaucoup d'activités basiques importantes pour la personne âgée, comme le transfert assis-debout, la montée de marches d'escalier ou la marche. La puissance musculaire est extrêmement utile en situation de déséquilibre (chute), car elle permet un réajustement postural. Elle permet également aux personnes âgées de conserver leur indépendance.

Avec l'âge, la qualité musculaire (mesure de force par unité de masse musculaire) se dégrade également. Une détérioration de la conduction de la voie corticospinale et une augmentation des co-contractions entre muscle agoniste et antagoniste parasitent le mouvement volontaire. On observe également des modifications des propriétés rhéologiques du muscle squelettique, avec une prolongation du temps nécessaire pour obtenir une contraction musculaire et une augmentation du temps de demi-relaxation. Une diminution de la raideur tendineuse va entraver la transmission de la force musculaire au segment articulaire.

Enfin, le Dr Dehail a parlé de la notion importante de force soutenue (capacité à maintenir un niveau de contraction maximal lors d’un effort soutenu). Le Dr Dehail et ses collègues ont comparé le coefficient d'endurance isocinétique (rapport de force entre les trois dernières contractions musculaires concentriques par rapport aux trois premières) et l'évolution de la perte de force musculaire chez des personnes jeunes et âgées6. Les personnes les plus âgées et les plus fragiles (moyenne d'âge : 85 ans) ne montraient pas de perte de force, et leur coefficient d'endurance restait proche de 1. Chez des sujets un peu moins âgés (moyenne d’âge : 75 ans), le coefficient d'endurance passait à 0,92, par rapport à 0,85 chez des sujets jeunes (étudiants). En fait, lors d'un effort soutenu, les personnes plus jeunes vont d’abord utiliser les fibres de type II, puis les fibres de type I. Les personnes âgées fragiles et hospita-lisées vont mettre en jeu directement les fibres de type I, ce qui explique que leur coefficient d'endurance reste proche de 1.

Approches thérapeutiques
Renforcement musculaire

Le renforcement musculaire reste essentiel pour lutter contre la sarcopénie : c’est la méthode qui s’est montrée le plus efficace. Tous les types de renforcement musculaire sont appropriés, mais il faut adapter le mode d'exercice au patient. Les protocoles varient, mais en moyenne il faut compter au moins trois séances par semaine, pendant 12 semaines (temps nécessaire pour obtenir le gain de force maximale).

Durant les trois premières semaines, les performances s’améliorent sans adaptation au niveau nerveux ou musculaire. De la 3e à la 6e semaine, le gain de force est le plus important, principalement en raison du mécanisme d'adaptation des unités motrices (meilleur recrutement, augmentation de la fréquence de décharge, meilleure synchronisation) et à une diminution des phénomènes de co-activation musculaire. De la 6e à la 12e semaine, ce sont les mécanismes d'adaptation musculaire qui prédominent (légère augmentation de masse musculaire et hypertrophie modérée des fibres). Au-delà de 12 semaines de renforcement musculaire, la personne âgée ne va plus gagner en force musculaire, mais va maintenir la puissance musculaire tant qu’elle continue les exercices au même rythme.

Le Dr Dehail a cité une étude de Yarasheski et ses collègues, qui ont montré que, au terme de deux semaines de renforcement musculaire, la synthèse de protéines musculaires était équivalente chez les sujets jeunes (23-32 ans) et les sujets âgés (78-84 ans)7.

Dans une revue systématique, Latham et ses collègues ont montré que les sujets âgés qui suivent un programme de renforcement musculaire améliorent considérablement leur force musculaire (augmentation de 20 à 200 % de la 1 RM [répétition maximale] selon les études)8.

Le renforcement musculaire améliore la force et la puissance musculaires, améliore légèrement la vitesse de marche et le temps de transfert assis-debout, et réduit le risque de chute. Néanmoins, on n’en connaît pas bien les conséquences sur les AVQ ou sur la qualité de vie. L’association d’une supplémentation nutritionnelle est importante pour optimiser les résultats chez les personnes âgées malnutries.

Médicaments
Selon le Dr Dehail, la testostérone et l'hormone de croissance (GH) n’améliorent les performances musculaires que pour les sujets hypogonadiques ou ayant une déficience en GH. La DHEA ne montre aucun bienfait en terme de performance musculaire. La vitamine D diminue le risque de chute, mais cet effet bénéfique ne semble pas être directement associé à une amélioration de la force ou de la puissance musculaire.

Les inhibiteurs de l’ECA pourraient s’avérer bénéfiques. Une étude d'observation a montré des résultats positifs sur la puissance et la masse musculaires. Des essais comparatifs sont nécessaires pour confirmer ces résultats.

D'autres molécules sont à l'étude, comme les SARM (des modulateurs des récepteurs aux androgènes sélectifs), les inhibiteurs de la myostatine ou certains acides aminés (leucine).

Conclusion
La sarcopénie est corrélée à une augmentation de l’incapacité fonctionnelle dans les AVQ, à une augmentation du risque de chute, à un syndrome de fragilité et à un état de dépendance. Elle est également associée à un taux plus élevé de mortalité, notamment chez les personnes âgées hospitalisées, en raison d’une augmentation des infections nosocomiales.

Enfin, la sarcopénie est associée à une augmentation très nette du coût des soins de santé (surcoût d’environ 900 $ par an et par patient âgé sarcopénique aux É.-U.).

Bibliographie

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  3. Janssen I, Baumgartner RN, Ross R, Rosenberg IH, Roubenoff R. Skeletal muscle cutpoints associated with elevated physical disability risk in older men and women. Am J Epidemiol 2004;159:413-21.
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