Plain language summary: what symptoms should be measured in clinical studies for early-stage Parkinson's?

Clinical studies test whether a new treatment is safe and if the treatment works in people who have a particular condition. Most current questionnaires used in clinical studies investigating Parkinson's measure symptoms in people who have been diagnosed for many years. This means that these existing questionnaires may not be useful for people living with early-stage Parkinson's, where the symptoms experienced can be quite different to later stages, or may not show if a new treatment is helpful for them. The most common symptoms in Parkinson's are involuntary shaking of parts of the body (“tremor”), slow movement (“bradykinesia”) and stiff, inflexible muscles (“rigidity”), which worsen with time. Symptoms specific to early-stage Parkinson's are not fully understood and research is ongoing in this area. New measures are therefore needed to assess the symptoms affecting people living with early-stage Parkinson's, especially the symptoms that they find most troublesome. This study investigated which symptoms are of most importance to people in the earlier stages of their condition and which would be appropriate to measure in future clinical studies. The research team that led the study was made up of people living with Parkinson's, as well as technical experts and representatives from Parkinson's patient organizations (Parkinson's UK and the Parkinson's Foundation). The participants in the study were people living with early-stage Parkinson's and their care partners. Slowness of movement (called “bradykinesia”) was noted as a key symptom. “Functional slowness” was especially noted. This symptom caused people to feel slower during many daily tasks, such as brushing teeth, walking and cooking. The loss of ability to move easily and freely, termed “mobility”, was also a key symptom. It was noticeable in walking abnormalities and difficulties performing “fine motor skills”. These are tasks that require precision, dexterity and coordination. Other impactful symptoms were: tremor, rigidity/stiffness, feelings of exhaustion (fatigue), depression, sleeping problems and pain. The personal views gathered in this study show the wide-ranging effects of early-stage Parkinson's. The study also identifies functional slowness and loss of mobility as key symptoms that would be appropriate to measure in future early-stage Parkinson's clinical studies to test if treatments are working or not.