• PDtrials - Parkinson's Disease Clinical Trials
• /Clinical Research 101

A

AUTONOMIC NERVOUS SYSTEM: Controls automatic functions, such as heartbeat, digestion, salivation, and blood pressure.

B

BASELINE: Beginning measurements against which a participant’s progress can be quantified at the end of a study.

BRADYKINESIA: Slowness of movement.

C  

CARBIDOPA: Drug given in combination with levodopa to ensure that more of the latter reaches the brain and changes into dopamine, rather than being broken down in the bloodstream. This allows for lower doses of levodopa to be used, reducing the risk of nausea, vomiting, and other side effects.

CLINICAL: Dealing with or based on observation and treatment of people, as opposed to basic science carried out in the laboratory or in animals.

CLINICAL INVESTIGATOR: A medical researcher responsible for carrying out a clinical trial according to its protocol.

CLINICAL TRIAL (CLINICAL STUDY): A scientific study involving human participants to determine the safety and efficacy of new therapies or new ways of using known treatments.

CLINICAL RESEARCH: Patient-oriented research conducted with human participants (or on material of human origin such as tissues and specimens) for which an investigator directly interacts with human participants. This area of research includes: mechanisms of human disease, therapeutic interventions, clinical trials, or development of new technologies.

COENZYME Q10 (CoQ10): An enzyme that improves the function of the "powerhouses" (mitochondria) that produce energy in cells and "mops up" potentially harmful chemicals generated during normal metabolism. People with Parkinson’s have low levels of this potent antioxidant in mitochondria and exhibit impaired mitochondrial function. Levels can be increased by taking CoQ10 supplements, although clinical trial results are not clear that this is beneficial.

COGNITIVE: Related to mental activities having to do with perception, memory, judgment, and reasoning.

COMPARISON TREATMENT: Treatment used as a relative measure in controlled trials to “test” a treatment or “prove” its effectiveness in the absence of some absolute or relative measure of success. The effect of a treatment is measured against a comparison treatment administered over the same time period and under similar conditions.

CONTROL GROUP (COMPARISON GROUP): Clinical trial participants who are given either a standard treatment or a placebo instead of the investigational drug or treatment being tested.

D

DE NOVO: Literally Latin meaning “from the beginning”, generally refers to Parkinson’s patients who have not yet begun medication for their disease.

DEEP BRAIN STIMULATION (DBS): Procedure in which a small, surgically implanted, battery-operated medical device delivers electrical stimulation, and "turns-off" brain regions that produce Parkinson’s symptoms.

DEGENERATIVE: Gradual deterioration of organs and cells along with loss of function.

DEMENTIA: A decline in higher-level brain functions, such as memory, reasoning and personality.

DOPAMINE: A "chemical messenger" that regulates movement by assisting in the effective communication (transmission) of electrochemical signals in the brain from one nerve cell (neuron) to another. As dopamine producing cells degenerate with advancing PD, they no longer produce enough to regulate neurons elsewhere in the brain, resulting in a loss of control of movements, leading to symptoms such as slowed movements, tremor, and rigidity.

DOPAMINE AGONIST: A chemical or drug that mimics the role of dopamine in the brain.

DOUBLE-BLIND: Clinical study design in which neither investigators nor participants know who is receiving the investigational drug and who is receiving a placebo.

DYSKINESIA: Twisting, turning or other abnormal involuntary movement usually involving the arms, legs, trunk, and head. It is most commonly associated with long-term use of levodopa.

DYSPHAGIA: Difficulty in swallowing.

E

EFFICACY: The extent to which a specific intervention, procedure, or regimen produces a beneficial result under ideal conditions.

ELIGIBILITY CRITERIA: Guidelines for determining who can qualify to participate in a specific clinical trial. Requiring that all participants share certain characteristics (e.g. age, gender, medical history) ensures that trial results will be due to what is under study and not other factors, helping researchers achieve accurate and meaningful results.

ESSENTIAL TREMOR: A common movement disorder that causes tremor, most often affecting the head, chin, outstretched hands or voice. The cause is unknown, although it does run in some families.

EXPERIMENTAL DRUG: See INVESTIGATIONAL DRUG.

EVIDENCE-BASED MEDICINE: Medical approach that integrates clinical expertise, patient expectations, and “best evidence” from relevant research into decision making about individual patient care. This approach is designed to make medicine more reliable and improve patient health outcomes.

EXPERIMENTAL GROUP: Study participant group which receives the drug, device, treatment, or intervention under investigation, rather than the standard treatment for the illness or a placebo.

F

FREEZE ATTACKS: The sudden loss of ability to move.

G

GAIT: Way of walking, which is diminished in people with Parkinson’s who tend to shuffle their feet, take too short steps, and not swing one or both arms.

GENE: Units of heredity that are made of DNA and contained in every cell. They produce proteins that control biological development and function.

GENE THERAPY: An experimental treatment for diseases caused by defective genes. Healthy genes are inserted into cells that contain defective genes, in hope that the cell will adopt the healthy gene.

GENETIC: Referring to a condition that is caused by a person's genes (heredity).

GLIAL CELL-LINE DERIVED NEUROTROPHIC FACTOR (GDNF): Shown in preclinical models to promote the survival, re-growth, and enhanced function of dopamine neurons in the brain, when the brain is infused with GDNF, accompanied by improvement in motor symptoms. With the establishment of reliable and safe delivery approaches, trophic factors are thought to represent one of the most promising approaches to develop neuroprotective and neurorestorative therapies in the short term.

GLOBUS PALLIDUS STIMULATION: Small electrical shocks generated by a pacemaker-like device implanted under the skin of the chest and attached to an electrode with its tip in the globus pallidus region of the brain. It is effective for the long-term treatment of disabling tremor and involuntary movements (dyskinesia), but does not improve walking or balance.

H

HALLUCINATION: A sensory experience of something that does not exist outside the mind, caused by various physical and mental disorders, or by reaction to certain toxic substances.

HYPOPHONIC: Relating to hypophonia, or the reduction in the volume and clarity of one's voice.

I

IDIOPATHIC: Of, relating to, or designating a disease having no known cause

INVESTIGATIONAL DRUG: Drug that is being tested in clinical trials prior to receiving FDA approval for use on the open market or as a treatment for a particular condition.

IRB: See INSTITUTIONAL REVIEW BOARD.

INCLUSION/EXCLUSION CRITERIA: Standards used to identify appropriate participants for a specific clinical trial and ensure the safety of those who enroll. These criteria include factors such as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions.

INFORMED CONSENT: The process of providing information to potential study participants to help them decide whether or not to enroll in a specific clinical trial.

INFORMED CONSENT DOCUMENT: Describes potential risks and benefits to study participants, and details about the study itself, such as its purpose, duration, required procedures, and key contacts. Although participants must sign the document in order to enroll in a clinical trial, informed consent is not a contract, and the participant may withdraw from the trial at any time.

INSTITUTIONAL REVIEW BOARD (IRB): A committee of physicians, statisticians, researchers, community advocates, and others chosen by an institution to initially approve and periodically review research projects involving human participants. Federal law requires this to ensure protection of participants’ safety, rights and welfare.

INTERVENTIONAL TRIAL: Structured to determine whether an investigational drug, other intervention, (e.g. gene transfer, vaccine, medical device, magnetic or electrical stimulation, or surgical procedure), or new way of using known therapies is safe and effective under controlled environments.

INVESTIGATIONAL NEW DRUG (IND) APPLICATION: The vehicle through which a sponsor advances a new drug from preclinical development, including animal studies, to clinical trials, involving human participants.

L

LEVODOPA: A compound that is converted into dopamine (the brain chemical which is deficient in people with Parkinson's) in the brain.

M

MAGNETIC RESONANCE IMAGING (MRI): A non-invasive technique that uses magnetism to create detailed pictures of the inside of the human body.

MASKED FACE: Loss of facial expression and reduced blink rate and eye movement make a person appear to be staring off in the distance, which can be misinterpreted as lack of interest or depression.

MOVEMENT DISORDERS SPECIALIST: A neurologist with advanced training to diagnose and treat movement disorders, such as Parkinson's disease.

MOTOR SYMPTOMS: The physical symptoms of PD, such as balance, rigidity, tremor, freeze attacks, controllable movements (dyskinesia), slowness of movement (bradykinesia), walking/gait, postural difficulties*, writing difficulty, swallowing difficulty* (dysphagia), muscle pain*, masked face*, speech problems* and general loss of motor skills.

N

NATURAL HISTORY STUDIES: Observational studies to improve understanding of neurological conditions. Participants continue receiving medical care from their primary care physician, who will order routine laboratory tests and diagnostic tests (X-rays, CT-scans, and nuclear imaging) as necessary. No investigational treatments are administered under this protocol.

NEUROIMAGING: Non-invasive techniques (e.g. computed tomography, magnetic resonance imaging, and positron-emission tomography) for measuring brain structure and function that may reveal important insights into aspects of PD not directly related to biomarkers and treatment trials.

NEUROLOGIST: A physician skilled in the diagnosis and treatment of diseases of the nervous system.

NEUROLOGY: The scientific study of the nervous system, especially in respect to its structure, functions, and abnormalities.

NEUROPROTECTION: Relating to mechanisms within the nervous system that can slow or stop the progression of PD by protecting neurons from cellular damage caused by the disease.

NEURORESTORATIVE: The process of reversing the effects of the degeneration of brain and nerve tissue stimulate the regeneration of lost brain and nerve tissue and/or protect cells that may otherwise die prematurely.

NEUROTRANSMITTER: A chemical that carries signals between nerves, sometimes called a chemical messenger. Dopamine is a neurotransmitter.

NEW DRUG APPLICATION (NDA): Process through which sponsors formally propose that the FDA approve a new pharmaceutical for sale and marketing. The NDA must include data gathered during pre-clinical animal studies and human clinical trials.

NON-MOTOR SYMPTOMS: Contribute to severe disability and impaired quality of life in advanced Parkinson's disease. Symptoms include anxiety, depression, cognitive mood swings, dementia, constipation, pain, genitourinary problems, sudden drop in blood pressure upon standing (orthostatic hypotension), excessive sweating, and sleep disturbances, sense of smell, vision, memory, weight loss, psychosis, hallucinations, and loss of energy.

O

OBSERVATIONAL TRIAL: Focused on understanding more about a disease, which is critical to developing new treatments, therapies, or preventions. These trials involve no intervention, but may include genetic studies of families with a history of Parkinson's, measurement of brain or motor activity, or studies of environmental factors associated with a disease.

OCCUPATIONAL THERAPY: A treatment that helps people achieve independence in all areas of their lives and addresses psychological, social, and environmental factors that may hinder functioning.

OPEN-LABEL: A trial design that allows the researcher and the study participant to know what treatment the participant is receiving. This is the opposite of double-blind study.

P

PET: See POSITRON EMISSION TOMOGRAPHY

PARKINSON'S DISEASE: A chronic, slowly progressive disease of the nervous system characterized by the combination of tremor, rigidity, bradykinesia and stooped posture, among other symptoms.

PARKINSON’S-PLUS SYNDROMES: Syndromes that tend to have more rapid disease progression, more pronounced disability, and shorter survival time than typical medication-responsive PD. Parkinson's plus syndromes include: dementia with lewy bodies (DLB), progressive supranuclear palsy (PSP), multiple system atrophy (MSA), coriticobasal degeneration (CBD), and PD with amyotrophic lateral sclerosis (ALS).

PARKINSONIAN SYNDROMES: A group of diseases characterized by symptoms (e.g. tremor, rigidity or stiffness, slow movements and difficulty maintaining balance) common in Parkinson's disease.

PHARMACOLOGIC: Related to the science of drugs including their origin, composition, therapeutic use, and toxicology.

PHASE I TRIALS: Phase of drug testing in which treatment is tested in people for the first time. A small group of people (20-80) is monitored to evaluate the drug or treatment's safety and effectiveness as well as how the drug is metabolized in humans and to determine the effects of different doses.

PHASE II TRIALS: Phase of drug testing in which the drug or treatment is given to a larger group of people (100-300) to provide preliminary measures of efficacy and to further evaluate its safety in humans.

PHASE III TRIALS: Phase of drug testing in which the study drug or treatment is given to large groups of people (1,000-3,000) to determine the drugs effectiveness, side-effects, tolerability.

PHASE IV TRIALS: Post-approval phase of drug testing to examine the effects of drugs once they are available and used by the public. This phase provides additional information including the drug's risks, benefits, and how best to use it.

PLACEBO: An inactive substance or procedure (often a pill, liquid, or powder) that has no biological effect. In clinical trials, experimental treatments are often compared with placebos to assess the treatment's effectiveness. In some studies, the participants will be assigned to a control group and will receive a placebo instead of an active drug or treatment.

PLACEBO CONTROLLED STUDY: A method of investigation in which one group of participants is given an inactive substance or procedure (the placebo), while another group is given the investigational drug. The results obtained are compared to see if the investigational treatment is more effective in treating the condition.

PLACEBO EFFECT: A physical or emotional change, occurring after a substance is taken or administered, or a procedure performed, that is not the result of any biological property of the substance. The change may be beneficial, reflecting the expectations of the participant and, often, the expectations of the person giving the substance.

PRE-CLINICAL: Testing of investigational drugs or treatments in the laboratory or in animals before trials in humans are carried out.

PRIMARY CARE PROVIDER (PCP): A main health care provider (doctor, physician assistant, or nurse practitioner) in non-emergency situations.

PRINCIPAL INVESTIGATOR: Person responsible for management of a clinical trial, ensuring it is conducted in compliance with the study protocol.

PROGRESSIVE SUPRANUCLEAR PALSY (PSP): A rare brain disorder diagnosed by the identification of early gait instability and difficulty moving the eyes. PSP is often misdiagnosed because some of its symptoms are very much like those of PD. Although PSP gets progressively worse and there is no effective treatment for it, the disease itself is not directly life-threatening.

PROTOCOL: A plan that is the basis for the conduct of a clinical trial ensuring the health of participants, and the solutions to specific research questions. A protocol describes what types of people may participate in the trial, the schedule of tests, procedures, medications and dosages, and the length of the study.

PSYCHOSIS: A loss of contact with reality often accompanied by hallucinations. Psychosis can be caused by some PD medications and is more common in patients with advanced Parkinson's.

R

RANDOMIZATION: A method based on chance by which study participants are assigned to a treatment group (arm). Randomization minimizes the differences among groups by equally distributing people with particular characteristics among all the trial arms. The researchers do not know which treatment is better.

RANDOMIZED TRIAL: Study in which participants re randomly assigned between experimental treatment and control arms; the “gold standard” in clinical trials, to minimize differences between the groups being compared and safeguard against bias. Occasionally placebos are used.

RESTING TREMOR: A tremor of a limb that increases when the limb is at rest.

RIGIDITY: A symptom in which muscles feel stiff and display resistance to movement even when another person tries to move the affected part of the body.

S

SCREENING: Period of selection of clinical trial participants based on ELIGIBILITY CRITERIA.

SELEGILINE: Inhibitor that increases the amount of dopamine in the brain to help control the symptoms of Parkinson's in people who are taking levodopa and carbidopa in combination (Sinemet). Selegiline may help people with Parkinson's to decrease the dose of levodopa/carbidopa needed to control symptoms, stopping the effects of levodopa/carbidopa from wearing off between doses, and increasing the length of time that levodopa/carbidopa will continue to control symptoms.

SPECT: See SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY.

SPONSOR: Organizations, medical institutions, foundations, pharmaceutical companies, or federal agencies (e.g. National Institutes of Health, Department of Defense, and Department of Veteran's Affairs) that fund clinical trials.

SIDE EFFECTS: Any undesired actions or effects of a drug or treatment. Negative or adverse effects may include such symptoms as headache, nausea and upset stomach. In some cases, side-effects may cause more severe medical problems.

SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (or SPECT): A nuclear medicine test that produces three-dimensional images of the brain, showing blood flow and function in different brain regions.

STANDARD TREATMENT: A treatment currently in wide use and considered to be effective in the treatment of a specific disease or condition.

STEM CELLS: Immature cells that go on to develop specialized functions. Scientists work primarily with two types of stem cells. Adult stem cells are immature cells found in specialized tissues, such as the brain or muscles. They might be able to develop into any type of cell found in the tissue from which they originated. Embryonic stem cells are immature cells found in embryos with the potential to develop into a wide variety of specialized cell types.

SUBSTANTIA NIGRA (SN): A small region in the brain stem, just above the spinal cord. Cells within the SN produce and release a chemical called dopamine, a neurotransmitter that controls movement and balance and is essential to the proper functioning of the central nervous system (CNS).

SUBTHALAMIC NUCLEUS STIMULATION (STN): A neurosurgical procedure for the alleviation of motor symptoms of Parkinson’s and the debilitating medication-induced dyskinesias. High frequency stimulation of the STN is achieved by implanting electrodes precisely in the STN, and later, activating and programming the neurostimulator, and adjusting medications to maximize the therapeutic effects and minimize the stimulation-induced side effects.

T

TAI CHI: Rhythmic patterns of gentle, flowing movements coordinated with breathing. Described as "meditation in motion," Tai chi promotes serenity, connecting the mind and body, stress reduction, and improvements to overall health. Tai chi is generally safe for people of all ages and levels of fitness.

THERAPY: Another word for “treatment”.

TRANSCRANIAL MAGNETIC STIMULATION (TMS): Brief electrical currents are passed through an insulated wire coil placed on the subject's scalp and the coil, creating magnetic pulses that pass into the brain.

TREMOR: Shaking or rhythmic movement, especially in the hands but in other parts of the body. Often occurs when at rest, such as in the RESTING TREMOR.

U

ULTRASOUND: An imaging technique that creates images of areas inside the body using sound waves.

W

WEARING-OFF: The process, over time, of medication lasting for fewer and fewer hours, causing the re-emergence of motor symptoms, non-motor symptoms, and autonomic nervous system dysfunction (e.g. sweating and hypersalivation) before the next dose.