Slow-SPEED: protocol for three randomised trials of remotely delivered exercise to prevent Parkinsons disease

The Slow-SPEED protocol outlines the design of the world's first non-pharmacological randomized controlled trials investigating the feasibility and efficacy of a remotely delivered, gamified exercise intervention for preventing Parkinson's disease across three distinct prodromal subgroups in the Netherlands, the United Kingdom, and the United States.

The Gist

The Big Idea: Catching Parkinson's Before It Starts

Imagine Parkinson's disease (PD) not as a sudden storm, but as a slow-growing weed in a garden. By the time you see the ugly leaves (the shaking, stiffness, and slowness of movement), the roots have already gone deep, and the damage is hard to undo.

Scientists have realized that if we want to stop the weed, we need to pull it out when it's just a tiny sprout. This early stage is called the "prodromal phase." It can last for years or even decades before the actual disease shows up.

The Slow-SPEED project is a massive, international experiment to see if we can stop that weed from growing by using exercise.

The Three Gardens (The Three Trials)

Instead of testing everyone, the researchers are looking at three specific groups of people who are very likely to develop Parkinson's in the future. Think of them as three different "gardens" being tested in three different countries:

1. The Netherlands (Slow-SPEED-NL): They are studying people who have a specific sleep disorder called REM Sleep Behavior Disorder. These are people who physically act out their dreams (like punching or kicking in their sleep). It's like a smoke alarm that's already going off, signaling a fire is coming.
2. The United Kingdom (Slow-SPEED-UK): They are studying people who have lost their sense of smell (hyposmia). Losing your nose's ability to smell is often one of the very first warning signs of Parkinson's, long before any shaking starts.
3. The United States (Slow-SPEED-US): They are studying people who carry specific genetic "keys" (mutations in the LRRK2 or GBA1 genes) that make them much more likely to get Parkinson's. These people are like houses with a known weak foundation.

The Solution: The "Gamified" Remote Coach

The researchers want to know: Can we get these people to exercise more, and will that stop Parkinson's?

But here's the catch: Asking people to go to a gym every day for 3 to 5 years is impossible. Most people would quit. So, they invented a digital solution.

• The App: Participants get a special smartphone app called "Slow-SPEED." It's like a video game for your health.
• The Virtual Coach: Instead of a human trainer yelling at you, you have a friendly, programmed robot coach on your phone. It sends you videos, tips, and encouragement.
• The Goal: You wear a smartwatch (like a Fitbit). The app sets you a weekly "step goal" and a "heart rate goal."
  • The Intervention Group: They are challenged to increase their activity by up to 100% (double what they usually do).
  • The Control Group: They are asked to increase activity by only 10% (just a tiny nudge). This is the "active control" group, so they aren't left doing nothing, but they aren't the ones getting the "super dose" of exercise.

Why "Remote"?

Imagine trying to train a whole country to run a marathon by making them all drive to a single stadium every week. It's too expensive and too hard.

The Slow-SPEED trials are fully remote. You do everything from your living room. You get your instructions on your phone, you track your steps on your watch, and you send the data back to the scientists automatically. This is like a digital gym that fits in your pocket, making it possible to test thousands of people without them ever needing to visit a lab.

What Are They Measuring?

The scientists are looking for two main things:

1. Can we keep people moving? (Feasibility): Can this app actually get people to walk more for 3 years without them getting bored or quitting?
2. Does it stop the disease? (Efficacy): Do the people who exercise more stay healthy longer? Do they show fewer signs of Parkinson's developing?

They are checking this by looking at:

• Step counts: Are they walking more?
• Digital Biomarkers: Using the phone to check for tiny changes in how they walk, shake, or write (like a digital fingerprint of the disease).
• Blood and Scans: In some countries, they will also take blood samples or MRI brain scans to see if exercise is changing the biology of the brain.

The "Slow" in Slow-SPEED

Why is it called "Slow"? Because Parkinson's is a slow disease. To see if exercise works, you can't just watch for a month. You have to watch for 18 to 36 months (1.5 to 3 years). It's a marathon, not a sprint.

Why This Matters

If this works, it changes everything.

• No Pills Needed: It proves you might not need a new expensive drug to stop Parkinson's; you might just need a better way to get people moving.
• Scalable: If an app works in the Netherlands, UK, and US, it can be downloaded by anyone, anywhere, even in places without fancy hospitals.
• Prevention: It shifts the focus from "curing" the disease once it's bad, to preventing it before it starts.

The Bottom Line

The Slow-SPEED trials are a giant, high-tech experiment to see if a smartphone game that encourages walking and running can act as a shield, protecting vulnerable people from developing Parkinson's disease. It's about turning the tide on a disease that has been too fast for us to stop, by slowing it down with the power of movement.

Technical Summary

Based on the provided preprint, here is a detailed technical summary of the Slow-SPEED protocol paper.

1. Problem Statement

• The Clinical Gap: Parkinson's Disease (PD) affects nearly 12 million people globally, yet no disease-modifying treatment exists. Current diagnoses occur at advanced stages of neurodegeneration when damage is likely irreversible, leading to disappointing results in trials targeting clinically manifest disease.
• The Opportunity: Intervening during the prodromal phase (pre-motor stage) offers a window to delay or prevent the onset of clinically manifest PD.
• The Challenge:
  • Duration: Prodromal PD can last 20+ years, requiring long-term trials (18–36 months) to detect meaningful changes.
  • Scalability: Traditional trials rely on frequent in-person contact, which is not scalable for population-wide prevention.
  • Adherence: Maintaining high compliance with lifestyle interventions (exercise) over long periods is difficult without robust support mechanisms.
  • Intervention: There is a need for non-pharmacological interventions with pleiotropic effects (affecting multiple pathophysiological pathways) rather than monomorphic drug mechanisms.

2. Methodology

The paper outlines the design of three parallel, double-blind, randomized controlled trials (RCTs) conducted across three countries: Netherlands (NL), United Kingdom (UK), and United States (US).

Study Design & Populations

The trials target three complementary prodromal subgroups, each carrying a high risk of developing PD:

1. Slow-SPEED-NL (n=110): Individuals with isolated/idiopathic REM sleep behavior disorder (iRBD), confirmed via video-polysomnography.
2. Slow-SPEED-UK (n=110): Individuals with olfactory dysfunction (hyposmia), defined as scoring below the 15th percentile on the UPSIT smell test.
3. Slow-SPEED-US (n=600): Genetic carriers of LRRK2 G2019S or GBA1 N370S variants (identified via 23andMe).

Intervention

• Type: A remotely delivered, gamified physical activity intervention via a dedicated smartphone app ("Slow-SPEED app").
• Mechanism:
  • Virtual Coach: Provides automated feedback, tips, and health education (no human interaction).
  • Gamification: Visualizes progress toward personalized weekly targets.
  • Targets: Participants in the intervention arm are encouraged to increase baseline step counts and Moderate-to-Vigorous Physical Activity (MVPA) by up to 100%. The active control group is encouraged to increase by up to 10%.
  • Monitoring: Participants wear a Fitbit Charge 6 wrist tracker to monitor step counts and heart rate (for MVPA calculation: ≥64% of age-predicted max HR).
• Duration: 18 months (UK), 24 months (NL), and 36 months (US).

Outcomes

• Primary Endpoint: Change in daily step count from baseline (4 weeks prior) to the final 12 weeks of follow-up.
• Co-Primary Endpoint (US only): Change in an integrated prodromal load score (summarizing digital motor and non-motor measures).
• Secondary Endpoints:
  • Feasibility of increasing MVPA.
  • Digital biomarkers (active/passive) of motor function (gait, tremor, bradykinesia) via the Roche PD Research app.
  • Biological biomarkers: Blood (metabolism, inflammation, proteins), optional skin biopsies (UK), and brain MRI (NL only).
  • Non-motor symptoms (sleep, cognition, autonomic function).

Statistical Analysis

• Principle: Intention-to-treat (ITT).
• Model: Mixed-effects models (constrained longitudinal data analysis) comparing intervention vs. active control, adjusting for baseline step counts, time, age, sex, and trial-specific strata.
• Data Handling: Continuous monitoring allows for high-frequency data points (every 4 weeks), utilizing unstructured covariance to account for within-person correlations.

3. Key Contributions

• First Non-Pharmacological Prevention Trials: These are the first RCTs globally specifically designed to test a non-drug intervention for PD prevention in prodromal populations.
• Fully Remote Trial Architecture: Demonstrates a scalable blueprint for decentralized trials using e-consent, remote monitoring, and digital coaching, eliminating the need for frequent clinic visits.
• Harmonized Multi-Cohort Design: By using shared devices, endpoints, and protocols across three distinct prodromal populations (iRBD, Hyposmia, Genetics), the study enables pre-specified individual-participant-data meta-analyses.
• Gamified Behavioral Change: Introduces a novel, automated virtual coaching system to sustain long-term adherence to lifestyle changes without human resource intensity.
• Comprehensive Biomarker Integration: Combines continuous digital phenotyping (wearables, smartphone apps) with traditional biomarkers (MRI, blood, skin) to create a multi-modal view of disease progression.

4. Results

• Status: As of the preprint date (March 2026), this is a protocol paper; no efficacy results are reported yet.
• Recruitment Status:
  • NL: First participant randomized June 7, 2024; expected completion end of 2026.
  • US: First participant randomized November 24, 2025.
  • UK: Protocol under ethical review (IRAS ID 362207) as of late 2025.
• Preliminary Feasibility: The paper argues feasibility based on prior success of the same app in the STEPWISE trial (clinically manifest PD) and strong partnerships with sleep centers and 23andMe (40,000+ genetic carriers).

5. Significance

• Paradigm Shift: Moves PD research from "treating symptoms" to "preventing onset." If successful, this could delay or prevent PD in high-risk individuals.
• Scalability: The remote, app-based model is potentially applicable to low-resource settings and other chronic disease prevention trials, overcoming the logistical bottlenecks of traditional in-person trials.
• Mechanistic Insight: Exercise is hypothesized to have a pleiotropic mode of action (neuroplasticity, inflammation reduction, metabolic health) that may be more effective than single-target pharmacological agents.
• Future Platform: The Slow-SPEED program is designed to evolve into a platform for testing multiple interventions (dietary, pharmacological) and expanding to other at-risk populations, establishing a reusable infrastructure for decentralized prevention science.

Limitations Noted:

• Potential underrepresentation of minority ethnic groups and lower socioeconomic status due to reliance on digital access and existing research cohorts.
• Lack of CSF biomarkers or dopaminergic imaging due to cost/logistics.
• Risk of adherence decline over long durations (mitigated by gamification and incentives).
• Use of age-predicted heart rate for MVPA may not account for individual medication effects or autonomic dysfunction.