Vascular Dementia and Alzheimer's Disease

Both vascular disease and Alzheimer's disease cause problems with thinking and memory and the death of brain tissue, although by different processes. However, as many as half of all brain autopsies conducted on people with AD reveal lesions characteristic of Alzheimer's disease as well as vascular lesions.

Researchers in many labs are still trying to understand the connection between the two conditions. There is, however, evidence already that both can exist independently in the same person. "Two injuries are worse than one," Dr. DeCarli said. "You're not going to do as well if you have both of those disease processes."

Using sophisticated MRI technology that provides highly accurate pictures of the shape and volume of brain structures, Dr. DeCarli is comparing the impact of the two disorders on the brain. He is focusing on the hippocampal formation, where very early indications of AD show themselves. If imaging shows that the hippocampus has shrunk, that suggests AD. If the effects of vascular disease are visible in other regions of the brain but the hippocampus looks normal, the person's thinking problems are more likely a result of vascular dementia. If Dr. DeCarli sees both, he reasons that both disease processes are occurring simultaneously.

As a researcher who also takes care of patients, Dr. DeCarli has treated people whom he suspects have both vascular dementia and Alzheimer's disease. Treatments exist for the vascular diseases that, when untreated, can lead to dementia, and Dr. DeCarli emphasizes they should be used when vascular disease is also present in a person with AD.

If a person with Alzheimer's disease also has hypertension, the doctor should treat it, he says. If she has diabetes, the doctor should treat the diabetes along with the Alzheimer's. And, Dr. DeCarli says, treating both diseases is likely to yield a better outcome than treating one.

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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