Defining Early Changes

For years Alzheimer's disease could not be diagnosed until the person died and an autopsy revealed an abundance of plaques and tangles in the brain. However, scientists and clinicians around the world have been developing effective techniques to diagnose AD even in its early stages. The diagnostic approaches consider a range of factors, including the results of physical exams, changes in performance on periodic neuropsychological tests (tests that measure memory, language and math skills, and other cognitive abilities), subtle changes in behavior over time, and sometimes brain scans.

Today, neurologists can be fairly confident of a diagnosis of clinically probable Alzheimer's disease. Studies have shown that specialized memory centers or doctors experienced in neurodegenerative diseases can diagnose AD with up to 90 percent accuracy, an impressive feat considering the complexity of the disease and the fact that, in the early stages, it can be difficult to distinguish from other types of age-related cognitive decline.

Diagnostic techniques are so important because the earlier that physicians diagnose AD, the better they may be able to treat the symptoms and track the disease process. Early diagnosis can also help spur people with memory problems to make the most of their abilities and interests while they still can. It also helps their families adjust to changing roles and realities and plan for the future.

Neurologist Dr. Ron Petersen has been a pioneer in classifying and diagnosing different forms of early-stage memory loss. He is the director of the Mayo Clinic's Alzheimer's Disease Research Center in Rochester, Minnesota and Jacksonville, Florida. The Mayo Clinic center is one of a network of twenty-nine Alzheimer's Disease Research Centers around the country funded by the National Institute on Aging and specializing in research on Alzheimer's disease.

Back in 1994, Dr. Ron Petersen and colleagues at the Mayo Clinic diagnosed the beginnings of Alzheimer's disease in former president Ronald Reagan. President and Mrs. Reagan were open with each other—and the public—about the fact that the former president's forgetfulness was an early stage of AD. "This diagnosis was important to them. They felt that for the community and for the world at large, their recognition might show that if the president of the United States can develop Alzheimer's disease, anybody can. By encouraging people not to ignore possible signs of change, they made an important contribution to society," says Dr. Petersen.

Previous: The Stages of Alzheimer's Disease

Next: Mild Cognitive Impairment

Excerpted from THE ALZHEIMER'S PROJECT: MOMENTUM IN SCIENCE, published by Public Affairs, www.publicaffairsbooks.com.

Alzheimer's Disease (AD)

A progressive degenerative disease of the brain that causes impairment of memory and other cognitive abilities.

Amyloid Precursor Protein (APP)

The larger protein from which beta-amyloid is formed.

ApoE Gene

A gene that codes for a protein that carries cholesterol to and within cells; different forms of the ApoE gene are associated with differing risks for late-onset Alzheimer's disease. This gene may be referred to as a risk factor gene or a "susceptibility gene" because one form of the gene, called APOE4, is associated with the risk of developing late onset AD.

Beta-Amyloid

Derived from the amyloid precursor protein and found in plaques, the insoluble deposits outside neurons. May also be called A-beta.

Beta-Amyloid Plaque

A largely insoluble deposit found in the space between nerve cells in the brain. The plaques in Alzheimer's disease are made of beta-amyloid and other molecules, surrounded by non-nerve cells (glia) and damaged axons and dendrites from nearby neurons.

Cognitive Reserve

The brain's ability to operate effectively even when some damage to cells or brain cell communications has occurred.

Dementia

A broad term referring to a decline in cognitive function that interferes with daily life and activities. Alzheimer's disease is one form of dementia.

Functional MRI (fMRI)

An adaptation of an MRI (see magnetic resonance imaging) technique that measures brain activity during a mental task, such as one involving memory, language, or attention.

Hippocampal Formation

A structure in the brain that plays a major role in learning and memory and is involved in converting short-term to long-term memory. Also called the hippocampus.

Inflammation

The process by which the body responds to cellular injury by attempting to eliminate foreign matter and damaged tissue.

Insulin Resistance

A condition in which the pancreas makes enough insulin, but the cells do not respond properly to it; characterizes and precedes type 2 diabetes.

Magnetic Resonance Imaging (MRI)

A diagnostic and research technique that uses magnetic fields to generate a computer image of internal structures in the body.

Mild Cognitive Impairment (MCI)

A condition in which a person has cognitive problems greater than those expected for his or her age. Amnestic MCI includes memory problems, but not the personality or other cognitive problems that characterize AD.

Neurodegenerative Disease

A disease characterized by a progressive decline in the structure and function of brain tissue. These diseases include AD, Parkinson's disease, frontotemporal lobar degeneration, and dementia with Lewy bodies. They are usually more common in older people.

Oligomers

Clusters of a small number of beta-amyloid peptides.

Oxidative Damage

Damage that can occur to cells when they are exposed to too many free radicals.

Pittsburgh Compound B (PiB)

The radioactive tracer compound used during a PET (see Positron Emission Tomography) scan of the brain to show beta-amyloid deposits.

Pittsburgh Compound B (PiB)

The radioactive tracer compound used during a PET (see Positron Emission Tomography) scan of the brain to show beta-amyloid deposits.

Synapse

The tiny gap between nerve cells across which neurotransmitters and nerve signals pass.

Tau

A protein that helps to maintain the structure of microtubules in normal nerve cells. Abnormal tau is a principal component of the paired helical filaments in neurofibrillary tangles.

Tangles

A protein that helps to maintain the structure of microtubules in normal nerve cells. Abnormal tau is a principal component of the paired helical filaments in neurofibrillary tangles.

Memory

Normal Aging

Genetic Risk Factor

Dominant and Recessive Genes

Genes and Proteins

Protein-Misfolding Disease

Cholesterol

Biomarkers

Disease-Modifying Drug

Transgenic Mice

An animal that has had a gene (such as the human APP gene) inserted into its chromosomes for the purpose of research. Mice carrying a mutated human APP gene often develop plaques in their brains as they age.

Pathology

Microglia

Insulin & Insulin Resistance

Susceptibility Gene

A variant in a cell's DNA that does not cause a disease by itself but may increase the chance that a person will develop a disease.

Susceptibility Genes

A variant in a cell's DNA that does not cause a disease by itself but may increase the chance that a person will develop a disease.

Genome-Wide Association Study

Vascular Disease

Genetics

Genetics

Normal Aging