Alzheimer's Disease: Unraveling the Mystery - 2 Introdu...

Alzheimer's Disease: Unraveling the Mystery - 2 Introduction

INTRODUCTION

"Never have I loved my husband of 41 years more than I do today....Though he may not know I'm his wife, he does know that my presence means his favorite foods and drinks are near at hand....I wonder why I can sit daily by his side as I play tapes, relate bits and pieces of news, hold his hand, tell him I love him. Yet I am content when I am with him, though I grieve for the loss of his smile, the sound of my name on his lips."

This excerpt from Lessons Learned: Shared Experiences in Coping, by participants of the Duke University Alzheimer Support Groups, gives a glimpse into what a person with Alzheimer’s disease (AD) and a family caregiver might experience as the disease progresses. The gradual slipping away of mind and memory is frightening and frustrating, both for the person with the disease and for family and friends, and can elicit strong feelings of love, grief, anger, and exhaustion.

AD is an irreversible, progressive brain disease that slowly destroys memory and thinking skills, eventually even the ability to carry out the simplest tasks. In most people with AD, symptoms first appear after age 60. AD is caused by a disease that affects the brain. In the absence of disease, the human brain often can function well into the 10th decade of life.

Not so long ago, we were not able to do much for people with AD. Today, that situation is changing. Thousands of scientists, voluntary organizations, and health care professionals are studying AD so that they can find ways to manage, treat, and one day prevent this terrible disease.


AD: A GROWING NATIONAL PROBLEM

For many older adults and their families, AD stands in the way of the “Golden Years.” It also presents a major problem for our health care system and society as a whole. AD is the most common cause of dementia among older people. Recent estimates of how many people in the United States currently have AD differ, with numbers ranging from 2.4 million to 4.5 million, depending on how AD is measured. But scientists agree that unless the disease can be effectively treated or prevented, the numbers will increase significantly if current population trends continue.

Our aging society makes AD an especially critical issue. A 2005 Census Bureau report on aging in the United States notes that the population age 65 and older is expected to double in size to about 72 million people within the next 25 years. Moreover, the 85 and older age group is now the fastest growing segment of the population. This is all the more important for a neurodegenerative disease like AD because the number of people with the disease doubles for every 5-year age interval beyond age 65.

AD not only affects the people with the disease, of course. The number of AD caregivers—and their needs—can be expected to rise rapidly as the population ages and as the number of people with AD grows. During their years of AD caregiving, spouses, relatives, and friends experience great emotional, physical, and financial challenges. As the disease runs its course and the abilities of people with AD steadily decline, family members face difficult, and often costly, decisions about the long-term care of their loved ones.

The growing number of people with AD and the costs associated with the disease also put a heavy economic burden on society. The national direct and indirect costs of caring for people with AD are estimated to be more than $100 billion a year. A 2004 study provided an equally sobering picture of the impact of AD. It is estimated that if current AD trends continue, total Federal Medicare spending to treat beneficiaries with the disease will increase from $62 billion in 2000 to $189 billion in 2015.

For these reasons, AD is an urgent research priority. We need to find ways to manage and treat AD because of its broad-reaching and devastating impact. We now know that the disease process begins many years, perhaps even decades, before symptoms emerge. Discovering ways to identify AD in the earliest stages and halt or slow its progress will benefit individuals, families, and the Nation as a whole.


ABOUT THIS BOOK

Thinking about AD leads to questions such as: What causes it? What can be done to cure it or prevent it? Will I get it? Scientists ask the same types of questions, and this book describes their search for answers. It is written for people with AD, their family members and friends, caregivers, and others interested in AD.

This book has four sections:

* Part 1 gives readers some basics about the healthy brain. Illustrations and text show what a healthy brain looks like and how it works.
* Part 2 focuses on what happens in the brain during AD.
* Part 3 talks about current research and the advances that are bringing us closer to ways of managing and eventually defeating AD.
* Part 4 focuses on issues important to AD caregivers and families, including current research that is finding ways to improve caregiver support.

The end of the book includes a list of publications and resources that people with AD, family members, and caregivers may find useful as they live day to day with the disease.

A book like this is possible only because of the major progress that scientists throughout the world have made. Not long ago, we knew very little about AD other than some facts about its major characteristics. Today, we are beginning to understand more about what AD is and who gets it, how and why it develops, and what course it follows. We are learning about the complex interface between AD and normal age-related changes in the brain. We also are getting much better at diagnosing it early and accurately. Most important, we now have some promising leads on possible treatments. Studies also are beginning to focus on preventive strategies by examining lifestyle factors that might influence a person’s risk of developing AD.

Since the 1970s, research supported by NIA and other organizations has deepened our understanding of this devastating disease. It also has expanded our knowledge of brain function in healthy older people and identified ways we might lessen normal age-related declines in mental function. Most importantly, this accumulated research has increased our appreciation for just how complex AD is. It is now clear that many scientific and clinical disciplines need to work together to untangle the genetic, biological, and environmental factors that, over many years, set a person on a course that ultimately results in AD.

Visit the National Institute on Aging (NIA) Alzheimer’s Disease Education and Referral (ADEAR) Center website at www.nia.nih.gov/Alzheimers/ADvideo to view an animation that helps this part of the book come alive.


THEN AND NOW: THE FAST PACE OF DEVELOPMENTS IN AD RESEARCH

As shown in this timeline, we have learned a lot since Dr. Alzheimer presented the case of his patient, Auguste D. The pace of research continues to accelerate as new findings open more and more doors to discovery.

1906

* Dr. Alois Alzheimer, a German neurologist and psychiatrist, describes the case of a 51-year-old woman, Auguste D., who had been admitted to a hospital 5 years earlier with a cluster of unusual symptoms, including problems with comprehension and memory, an inability to speak, disorientation, behavioral problems, and hallucinations. After her death, Dr. Alzheimer examined her brain tissue and described two of the hallmarks of AD—numerous globs of sticky proteins in the spaces between neurons (beta-amyloid plaques) and a tangled bundle of fibrils within neurons (neurofibrillary tangles).

1910s – 1940s

* Belief persists that “senile dementia” is a normal part of aging.

1950s

* Scientists study the biological structure of plaques and tangles.

1960s

* Scientists discover a link between dementia and the number of plaques present in the brain. AD is recognized as a distinct disease, not a normal part of aging.

1970s

* Scientists find that levels of acetylcholine, a neurotransmitter important in memory formation, falls sharply in people with AD. This discovery is one of the first to link AD with biochemical changes in the brain.
* “Alzheimer’s disease” becomes a common term as recognition of AD as a major public health problem grows.
* NIA is established.

1980s

* Diagnostic criteria for AD are established.
* Genetic links to early-onset AD begin to surface.
* Congress mandates NIA as lead Federal agency for AD research.
* Scientists start to unravel the biological pathways that lead to the development of beta amyloid plaques in the brain.
* Abnormal tau protein in tangles is identified.

1990s

* The U.S. Food and Drug Administration (FDA) approves tacrine (Cognex®), the first drug used to treat AD. This drug has since been replaced by other medications.
* Genetic mutations linked to early-onset and late-onset AD are discovered.
* The first transgenic mouse model of AD is created.
* Additional diagnostic criteria are developed for AD.
* Characteristics of mild cognitive impairment are described and defined.
* NIA launches the Alzheimer’s Disease Education and Referral Center, AD Cooperative Study, and other initiatives to conduct and support AD treatment and prevention clinical trials.

2000s

* The FDA approves other AD drugs, including rivastigmine (Exelon®), galantamine (Razadyne®), donepezil (Aricept®), and memantine (Namenda®) to treat symptoms of AD.
* Early work on an AD vaccine begins.
* Many new AD clinical trials, initiatives, and studies are launched, looking at a broad array of translational, treatment, and prevention issues.
* New transgenic mouse models, including one that develops both plaques and tangles, are developed.
* Pittsburgh Compound B (PiB) is developed, allowing researchers to “see” beta-amyloid plaques in the brains of living people.
* The growing sophistication of neuroimaging techniques, genetics, memory and cognitive tests, structured interviews, and other technologies improve our ability to identify people at high risk of AD.