The goal of this randomised controlled trial is to evaluate whether a specific dietary intervention can reduce core symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) in adults aged 18 to 50 years. The study also aims to understand how changes in diet may influence quality of life, neurocognitive function, and gut-brain signaling through the microbiota.
The main questions it aims to answer are:
1. Does a high-fiber, fermented food-based diet reduce ADHD core symptoms over a 12-week period, as measured by the Conners' Adult ADHD Rating Scale (CAARS)?
2. Does the diet improve neurocognitive function, mood, food reward, individual goals, and other quality-of-life outcomes?
3. How does the diet affect gut microbial composition, inflammation, and stress-related biomarkers?
4. Is the diet well-accepted and feasible to follow?
Researchers will compare a combination intervention diet (high in fiber and fermented foods) to a control diet based on general healthy eating guidelines to assess differences in symptom improvement and biological outcomes.
Participants will:
1. Complete six study visits over a 24-week period (screening, baseline, weeks 4, 8, 12, and optional follow-up at week 24).
2. Be randomly assigned to one of two dietary groups after baseline assessments.
3. Provide stool, saliva, urine, and blood samples at multiple timepoints.
4. Undergo cognitive testing and EEG recording to assess brain function.
5. Wear a wristband to track sleep and activity patterns.
6. Use a nutrition app to log dietary intake and receive weekly dietary support.
7. Complete validated questionnaires on ADHD symptoms, mood, eating behavior, gastrointestinal health, sleep, and lifestyle factors. Feasibility and acceptability of following the diet will also be self-reported.
This study includes both adults diagnosed with ADHD and matched controls without a psychiatric condition to better understand the mechanisms and potential differential responses to dietary intervention.