How much Forgetting is Too Much?

Dr. Petersen says, "It's not always easy to differentiate forgetting a friend's name from pathological forgetting. One of the most difficult questions we get is, 'How much forgetfulness is too much?'"

Consider the forgetfulness that many people experience as they age. A man comes home, flips his keys on the counter, and then can't find them five minutes later. A woman misplaces her reading glasses or her checkbook. She can't come up with the name of a coworker in the elevator. Three floors later, of course, it comes to her.

This kind of incidental forgetfulness isn't too serious. Age-related memory changes are very common and most often not related to a disease process. As we get older, we have to pay more attention or focus more on certain activities. It gets more difficult, for example, to drive and talk on a cell phone at the same time, because neither activity is getting our full attention.

On the other hand, if a person finds that he still cannot remember an experience even when he is focusing on it, that may be a sign of concern. If he forgets things he used to remember fairly easily, it may be a red flag. "You have a doctor's appointment next Tuesday because you think you're having side effects with your blood pressure medicine," Dr. Petersen suggested. "Tuesday comes and goes. You don't show up. That can happen every now and then, but when it happens today and it happened three weeks ago and you're afraid it's going to happen two weeks from now—and your family is starting to notice—that's when you may need to speak to somebody about whether the forgetfulness is more than age-related memory loss."

The key question is whether behavior has become different from usual. For example, someone who has always calculated the tip on a restaurant check asks another person to do it. Someone uncharacteristically wants to get his tax returns done by an accountant after taking pride in doing them for years, or asks someone else to drive because he can't remember how to get to a very familiar destination.

Based on the results of a physical exam and tests of memory and cognitive skills, the doctor may decide that the memory problems are not a concern. On the other hand, the doctor may decide that the changes are a sign of amnestic MCI.

Previous: 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