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Alzheimer's Disease Health Center

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Glossary of Alzheimer's Disease Terms


Choline: A natural substance required by the body that is obtained from various foods, such as eggs; an essential component of acetylcholine.

Choline acetyltransferase (CAT): An enzyme that controls the production of acetylcholine. CAT appears to be depleted in the brains of individuals with Alzheimer's disease.

Cholinergic system: The system of nerve cells that uses acetylcholine to communicate between cells and is damaged in the brains of individuals with Alzheimer's disease.

Cholinesterase: An enzyme that breaks down acetylcholine into active parts that can be recycled.

Chromosome: An H-shaped structure inside the cell nucleus made up of tightly coiled strands of genes. Each chromosome is numbered (in humans, 1-46). Genes on chromosomes 1, 14, 19, and 21 are associated with Alzheimer's disease.

Clinical psychologist: See psychologist.

Clinical social worker: An individual who has specialized training in identifying and accessing community resources, such as adult daycare, home care, or nursing home services, as well as skills in individual and group counseling.

Clinical trial: An organized research program conducted with patients to evaluate a new medical treatment, drug, or device.

Co-existing illness: A medical condition that exists simultaneously with another, such as arthritis and dementia.

Cognitive abilities: Mental abilities, such as judgment, memory, learning, comprehension, and reasoning.

Cognitive symptoms: In Alzheimer's disease, the symptoms that relate to loss of thought processes, such as learning, comprehension, memory, reasoning, and judgment.

Combativeness: Episodes of aggression.

Competence: A person's ability to make informed choices.

Computed (axial) tomography (CAT or CT) scan: A technique in which multiple X-rays of the body are taken from different angles in a very short period of time. These images are collected by a computer to give a series of images that look like "slices" of the body. In diagnosing dementia, CT scans can reveal tumors and small strokes in the brain.

Conservator: In some states, the guardian who manages an individual's assets.

Continuum of care: Care services available to assist individuals throughout the course of a disease.

Controls: A group of people or animals in a research trial that does not receive a treatment or other intervention, or that is not affected by the disease being studied. This group is used as a standard to compare any changes in a group that receives treatment or has the disease. In Alzheimer's research, patients often are compared with controls of the same age (age-matched) to rule out the effects of age on study results.

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