← All sources
Effects of nicotinamide riboside on NAD+ levels, cognition, and symptom recovery in long-COVID: a randomized controlled trial
Single-centre Boston RCT (n=58 long COVID): high-dose NR (2000 mg/day) raised blood NAD+ within weeks, but intention-to-treat comparisons showed no significant between-group benefits on composite cognition, fatigue, sleep quality, anxiety, or depression versus placebo despite high early dropout in the continuous-NR arm.
Design
- 24-week, double-blind; 58 participants with long COVID
- Randomization 2:1: continuous NR 20 wk vs 10 wk placebo → 10 wk NR
- Primary: cognitive battery (ECog, RBANS, TMT-B); secondary: FSS, BDI, BAI, PSQI
Biochemistry vs clinical nulls
- NAD+: 2.6–3.1× rises after 5–10 wk on NR in continuous arm; minimal change on initial placebo in crossover arm then rise after switch
- Cognition / fatigue / sleep / mood: no significant between-group differences (p ≈ 0.20–0.84 range across endpoints in abstract)
- Dropouts: 32–51% by 10–20 wk in continuous NR arm vs ~14% on placebo windows—interpret power and tolerability
Post-hoc caveat
Authors report within-NR-phase exploratory improvements in some executive, fatigue, sleep, and depression measures when pooling NR exposure windows—hypothesis-generating only.
Publication
Wu CY, et al. EClinicalMedicine. 2025 Nov 12;89:103633. PMID 41357333.
Outcomes
- NAD+ Level% (Percent Change)
- No significant between-group differences for ECog, RBANS, TMT-B, FSS, PSQI, BAI, or BDI in primary ITT-style comparisons (p = 0.47–0.84).