Adverse event

An unfavorable change in health that can occur during a clinical trial or study or within a certain time period after . These can range from mild ( e . g ., nausea ) to serious or life-threatening ( e . g ., stroke ). This change may or may not be related to the intervention being studied . See also : intervention

Alpha-synuclein

A protein normally found in brain cells and the main component of clumps , called Lewy bodies , in the brains of people with Parkinson ’ s . Researchers believe that the alpha-synuclein in Lewy bodies is associated with death or damage to brain cells . A mutation in the gene SNCA that directs the production of the alpha-synuclein protein is the basis for a rare , inherited form of Parkinson ’ s disease . See also : SNCA

Arm

A specific group of study participants within a clinical trial . For example , in an interventional trial , one “ arm ” may receive the investigational treatment and another “ arm ” receives placebo . See also : interventional trial

Baseline data

Demographic information ( e . g ., age and gender ) and other information such as symptoms , medications or measurements on specific tests that is collected from participants at the beginning of a clinical trial or study .

Biomarker

A measurable , biological characteristic that can be used to determine the risk , presence or progression of a disease . For example , high blood pressure is a biomarker of potential heart disease . No biomarker of Parkinson ’ s has yet been validated , but researchers are working toward such a measure .

Blinding

A clinical trial strategy where the researchers and participants do not know which participants are taking placebo ( inactive substance ) and which are receiving the intervention . In single blinding , only one group ( either researchers or participants ) knows which participants are taking placebo or intervention . In double blinding , neither group knows . See also : intervention ; placebo

Breakthrough therapy designation

A U . S . FDA process that speeds the development and review of new therapies that may treat a serious condition if early clinical trial data indicate that the drug may be more efficacious than available therapies . See also : efficacy ; U . S . Food and Drug Administration

44 Navigating Clinical Trials : A Guide for Parkinson ’ s Patients and Families