Amyloid beta (Aβ or Abeta): A peptide of 36–43 amino acids that appears to be the main constituent of amyloid plaques in the brains of Alzheimer's disease patients.

ApoE: Apolipoprotein E is a cholesterol transport protein and has been found in the amyloid plaques in Alzheimer's disease. It comes in several types or "alleles" -2, 3, and 4. Each person has two alleles (one from each parent) which you can have in any combination of the three types. Apolipoprotein E-4 has been shown to increase the risk of Alzheimer’s disease but does not cause Alzheimer’s disease, whereas apolipoprotein E-2 decreases the risk of Alzheimer’s disease. Apolipoprotein E-3, the allele that occurs most commonly, neither increases nor decreases the risk of Alzheimer’s disease. (Finding out one’s apolipoprotein E type is NOT a genetic test for Alzheimer’s disease. Although more people with E-4 eventually get the disease than those with E-3 or 2, some people with E-4 never get Alzheimer’s.)

Assent: Demonstrating an agreement to participate in research by actively and willingly taking part in the research. People with memory loss or Alzheimer's disease may be legally unable to consent to research participation, but they must assent to participation. This means that although they are unable to legally consent, they will not be forced to participate.

Biomarker: A substance or characteristic that is used as an indicator of a biological state. Some examples of biomarkers are elevated PSA levels, which may indicate prostate cancer, and elevated blood pressure readings, which may indicate high blood pressure. Find out more about biomarkers here.

Cerebrospinal Fluid (CSF): A clear, colorless liquid that delivers nutrients to the brain. It also provides a cushion to the brain and spinal cord, which together are part of the central nervous system. CSF interacts very closely with the brain, and can provide a window into changes that may be occurring there.

Clinical trial: A research study that is designed to answer specific questions about the safety and effectiveness of new therapies or new ways of using known treatments.

Consensus diagnosis: A process in which ADRC psychiatrists, neurologists, neuropsychologists, expert memory testers, clinical nurses, and research social workers discuss the findings from a research appointment and assign a research participant a diagnosis.

Control: A healthy person with no memory complaints. Researchers are interested in studying control participants because they provide an example of normal brain aging to compare to the aging process that occurs in people with dementia.

De-identified data: Data that are labeled with a study code and contain no personal or identifying information which could link a particular research participant to a specific group of data.

Dementia: Any type of memory or cognitive impairment that progresses over time, interferes with daily functioning and abilities, and cannot be reversed using known treatments.

Double-blind, placebo-controlled clinical trial: A clinical trial design in which neither the research participants nor the study staff know which participants are receiving the experimental medication and which participants are receiving a placebo (an inactive substance that looks identical to the experimental medication but has no pharmacological effect) or another therapy. Double-blind trials are thought to produce objective results because the expectations of researchers and participants about the experimental drugs' effectiveness do not affect the outcome of the trials.

Durable Power of Attorney: A document that names a person to handle all of another person's affairs if that person becomes incapacitated. For people with Alzheimer's disease, especially those who participate in research, it is important that a family member or friend has obtained a notarized Durable Power of Attorney form regarding medical decision making.

Eligibility Requirements or Exclusion Criteria: See inclusion/exclusion criteria. 

Familial Alzheimer's disease: An uncommon form of Alzheimer's disease that usually strikes earlier in life (defined as before the age of 65, usually between 50 and 65 years of age, but can be as early as 15) and is inherited in an autosomal dominant fashion, identified by genetics and other characteristics such as the age of onset.

Inclusion/exclusion criteria: The medical or social standards determining whether a person may or may not be allowed to enter a clinical trial. These criteria are based on such factors as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions. It is important to note that inclusion and exclusion criteria are not used to reject people personally, but rather to identify appropriate participants and keep them safe.

Informed consent: The process of educating and legally protecting people who participate in research before deciding whether or not to participate. At the ADRC this process begins with a research nurse explaining the basics of our research over the phone. Before arriving for a visit at the ADRC, participants receive documents known as consent forms; these forms thoroughly describe the procedures, tests, data collection, and privacy protection of the study. When participants arrive for their first appointment, we will begin by reviewing these forms and fully answering any questions about study participation.

Informed consent is also meant to ensure participant safety and to prevent unethical research on vulnerable populations. Our researchers take seriously the declining memory and cognitive ability of people with memory loss. We evaluate each participant's ability to understand the research process, and if participants are unable to provide informed consent because of problems with memory or confusion, authorized legal representatives may be able to give permission in their place. In instances where authorized legal representatives provide informed consent for participants, we will only enroll and perform procedures with participants if they assent to the research; that is, they must be active and willing participants.

Institutional review board (IRB): A committee of physicians, statisticians, researchers, community advocates, and others that ensures that a clinical trial is ethical and that the rights of study participants are protected. All clinical trials in the United States must be approved by an IRB before they begin conducting research; they are also regulated by periodic IRB reviews.

Legally authorized representative: A person who is legally able to make decisions on behalf of someone else. This capacity is commonly given in a Durable Power of Attorney form.

Lewy bodies: In terms of their appearance, Lewy bodies are too small to see with the naked eye, but through the lens of a microscope, they typically appear as round bodies surrounded by a lighter halo. Lewy bodies are a buildup of a protein called alpha-synuclein, though the reason that these protein aggregations form in some brain cells and not others is still unclear and a matter of ongoing research.

Lumbar puncture: A research medical procedure where a small amount of spinal fluid is taken from a person's lower back. Find out more information about lumbar punctures here.

Mini Mental State Examination (MMSE): A brief 30-point cognitive test that is used to screen for cognitive  impairment. It is commonly used as a screen for dementia. It is also used to estimate the severity of impairment at a given point in time and to follow the course of changes in memory and other thinking functions in an individual over time.

parkinsonism: A set of several clinically recognizable neurologic features, characterized by tremor, decreased bodily movement, rigidity, and postural instability.

Placebo: An inactive substance that looks identical to an active experimental medication but has no pharmacological effect. Comparing the results from participants taking experimental medications and participants taking placebos may indicate whether changes in the experimental medication group are a result of the treatment.

Phase-I trials: Initial studies that aim to determine the metabolism and pharmacological actions of medications in humans, to identify the side effects associated with increasing doses, and to gain early evidence of effectiveness. These trials may include patients and/or healthy control participants.

Phase-II trials: Controlled clinical studies that aim to evaluate the effectiveness of medications for a particular symptom or set of symptoms in patients with the condition that is being studied and to determine the common short-term side effects and risks of the medications. These trials may include patients and/or healthy control participants.

Phase-III trials: Expanded controlled and uncontrolled trials that are conducted after preliminary evidence suggesting effectiveness of the drug has been obtained and that aim to gather additional information to evaluate the overall benefit-risk relationship of the medications and provide an adequate basis for prescribing the medications. These trials may include patients and/or healthy control participants.

Randomly assigned (randomization): A method based on chance by which study participants are assigned to research groups, for example, to groups that receive experimental medications and groups that receive a placebo (an inactive substance that looks identical to an active experimental medication but has no pharmacological effect). By equally distributing people with particular characteristics among all the trial groups, randomization controls for differences that researchers are not interested in studying.

Research registry: A large collection of people who are interested in participating in research studies. A registry maintains updated medical records on participants and informs participants when they may be eligible for particular research studies. You can find out more about ADRC registry participation here.

Research study companion: Anyone who knows the research participant well and is able to answer potentially sensitive questions about the participant's daily functioning and behavior. For most people, this is a spouse or a child, but the study companion can also be a close friend or a neighbor.

Repository: A facility where a collection of biological samples (like blood or CSF) is stored.

Study sponsor: An organization that provides funding for a study and monitors the funded studies to ensure compliance with the research protocol. Study sponsors are commonly government agencies, not-for-profit science organizations, and pharmaceutical companies.

Tau proteins: Proteins that stabilize the structures of the cell. They are abundant in neurons in the central nervous system and are less common elsewhere. When tau proteins are defective, and no longer stabilize microtubules properly, they may result in dementias, such as Alzheimer's disease.

Voluntary: Participating out one's own free will, without compulsion or obligation, and having the power to end participation whenever someone chooses. All of our research at the ADRC is voluntary.

† Definitions are adapted from www.clinicaltrials.gov.