Advance Directive: Any written statement that expresses a person's wishes in advance.

Alzheimer Disease: First described as a disease of the brain causing memory loss and serious mental deterioration by Alois Alzheimer, a German physician. It is the most common form of dementia, which describes the condition that results in progressive loss of mental functions.

Clinical Drug Trial: A study testing the safety, and efficacy of new drug already on the market on a certain group of people

Cognitive impairment: Short-term memory loss and difficulty finding words.

Cohort study: A study conducted by pinpointing a group of people and following and undergoing the study protocol, measuring different things along the way, but making no alterations to a person's lifestyle or daily habits.

Competency/capacity: A sufficiency of means for the necessities and conveniences of life; the quality or state of being competent; having requisite or adequate ability or qualities; having the capacity to function or develop in a particular way.

Dementia: Common clinical syndrome characterized by decline in cognitive function from previously attained intellectual level that is sustained for months or years.

Encephalopathy: Any dysfunction of the brain.

Feasibility: The determination of whether something is worthwhile or not

Gerontology: The multi-disciplinary study of aging which encompasses the biological, psychological, sociological, health, and economic aspects of aging.

Incompetence: The state or act of being incompetent and the inability to function properly.

Incontinence: Loss of control of the bladder or bowel.

"Let Me Decide" Advance Health Care Directive: Document which lets others know one's wishes about medical treatment.

Longitudinal: Dealing with the growth or change of an individual or group over a period of years.

Pick's Disease: A form of pre-senile dementia which involves progressive irreversible loss of memory, deterioration of intellectual functions, disordered emotions, apathy, speech disturbances, and disorientation.