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Alzheimer's Disease Health Center

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Glossary of Alzheimer's Disease Terms


Pacing: Aimless wandering or walking back and forth, often triggered by things like pain, hunger, or boredom, or by some distraction in the environment, such as noise, smell, or temperature.

Paranoia: Suspicion and fear of someone else that is not based on fact.

Parkinson's disease: A progressive, nervous system disease with an unknown cause in which nerve cells in a specific area of the brain begin to die off. People with Parkinson's disease lack the neurotransmitter dopamine and have symptoms such as tremors, speech impairments, movement difficulties, and often dementia later in the course of the disease.

Peripheral nervous system (PNS): One of the two major divisions of the nervous system. Nerves in the PNS connect the central nervous system with sensory organs, other organs, muscles, blood vessels, and glands.

Personal care: See activities of daily living.

PET scan: See positron emission tomography scan.

Pharmacology: The study of drugs, including their composition, production, uses, and effects in the body.

Pick's disease: A type of dementia in which damage to nerve cells causes dramatic alterations in personality and social behavior but typically does not affect memory until later in the disease.

Pillaging: Taking things that belong to someone else. A person with dementia may think something belongs to him or her, even when it clearly does not.

Placebo: An inactive material that looks the same as an active drug; for example, a sugar pill. (See double-blind, placebo-controlled study.)

Plaques and tangles: See amyloid plaque and neurofibrillary tangle.

Positron emission tomography (PET) scan: An imaging scan that measures the brain function.

Possible Alzheimer's disease: A suspicion of Alzheimer's disease based on the patient's medical history and the results of neurological, psychiatric, and clinical exams, neuropsychological tests, and laboratory studies.

Premature aging: Physical changes related to aging that occur ahead of what would be expected for a person's chronological age.

Presenilins: Proteins that may be linked to early onset Alzheimer's disease.

Principal: The individual signing the power of attorney to authorize another person to legally make decisions for him or her.

Prions: Protein segments that may cause infection and may lead to some forms of dementia.

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