Evaluating Mineral Biomarkers as Mediators and Moderators of Behavioural Improvements in a Randomized Controlled Trial of Multinutrients for Children with ADHD.

Essential minerals are cofactors for synthesis of neurotransmitters supporting cognition and mood. An 8-week fully-blind RCT of multinutrients for ADHD demonstrated three times as many children (age 6-12) had significantly improved behavior ("treatment responders") on multinutrients (54%) compared to placebo (18%). The aim of this secondary study was to evaluate changes in fasted plasma and urinary mineral concentrations following the intervention, and their role as mediators and moderators of treatment response. Fourteen essential or trace minerals were measured in plasma and/or urine at baseline and week 8 from 86 participants (49 multinutrient, 37 placebo). Two-sample t-tests/Mann-Whitney U-tests compared 8-week change between treatment and placebo groups, which were also evaluated as potential mediators. Baseline levels were evaluated as potential moderators, using logistic regression models with clinical treatment response as the outcome. After 8 weeks, plasma boron, chromium (in females only), lithium, molybdenum, selenium, and vanadium, and urinary iodine, lithium, and selenium increased more with multinutrients than placebo, while plasma phosphorus decreased. These changes did not mediate treatment response. However, baseline urinary lithium trended toward moderation: participants with lower baseline urinary lithium were more likely to respond to multinutrients (p=0.058). Additionally, participants with higher baseline iron were more likely to be treatment responders regardless of treatment group (p=0.036.) These results show that multinutrient treatment response among children with ADHD is independent of their baseline plasma mineral levels, while baseline urinary lithium levels show potential as a non-invasive biomarker of treatment response requiring further study.