UPLC-QTOF-MS Links Urine Profiles to ADHD

Exposure to a common type of pesticide called organophosphates (OPs) has been linked to higher levels of cell-damaging stress in the body, as well as an increased risk of ADHD. However, scientists still do not fully understand what is happening on a metabolic level in ADHD, or exactly how pesticide exposure might contribute to it. To fill this gap, researchers characterized urinary metabolomic profiles associated with ADHD and examined their associations with OPs exposure and oxidative stress, with these urine samples analyzed using nuclear magnetic resonance (NMR) spectroscopy and ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry analysis (UPLC-QTOF-MS). A paper based on this work was published in the journal Metabiologics.¹

What's Already Known about ADHD and Pesticide Exposure, and what Gap Does This Study Fill?

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common behavioral and developmental conditions in children, affecting roughly 6% to 14% of children around the world.^2,3 ADHD is a condition shaped by many different factors working together, such as genetics, brain chemistry, psychological influences, and exposure to things in the environment are all thought to play a role in why it develops.^4,5 However, scientists still do not know exactly how environmental exposures might actually lead to ADHD on a biological level.¹

The authors of the paper state that most studies looking at body chemistry in relation to ADHD have only focused on markers tied to the disorder itself, without also considering markers of environmental exposures, like pesticide byproducts. On the flip side, studies focused on pesticide exposure have looked at links to brain development or cell-damaging stress but have not examined how these exposures might affect body chemistry specifically in children with ADHD.¹ One recent study⁶ following a group of children in Spain from birth found that pesticide levels in urine during early pregnancy were linked to changes in how the body processes vitamin B6, while exposure later in pregnancy was linked to disruptions in amino acids, brain-signaling chemicals, and the body's detox processes. “However,” write the authors of the paper,¹ “evidence remains scarce regarding whether early childhood exposure is associated with urinary metabolic alterations in ADHD children. Therefore, it is still unknown if OPs exposure and oxidative stress are associated with distinct urinary metabolomic profiles that could help in the explanation of ADHD-related biological disturbances.

Do Urine Chemical Patterns Differ Between Children with and without ADHD, and Could Pesticide Exposure or Oxidative Stress Explain These Metabolic Differences?

In this study, researchers looked at urine samples from 67 children with ADHD and 98 children without the condition. They measured two specific substances: one that reflects exposure to a type of pesticide, and another that reflects the level of cell-damaging stress happening in the body. Based on how much of each substance was found, the children were sorted into "high" and "low" groups.¹

The researchers found that the overall pattern of chemical byproducts in urine looked notably different between children with ADHD and those without. Several specific compounds also varied depending on whether a child had high or low pesticide exposure or cell stress markers. Notably, substances related to the body's main energy-production process were found at higher levels in children with ADHD, and these levels rose alongside both pesticide exposure and cell stress markers. Further analysis pointed to disruptions in how the body produces energy and processes amino acids (the building blocks of protein).¹

Using statistical modeling, the researchers were able to identify a set of 11 specific compounds that, together, could reasonably distinguish between children with and without ADHD, and this pattern held up well when tested on a separate, independent group of children.¹

“This metabolomic analysis,” write the authors of the paper,¹ “suggests that OPs exposure and oxidative stress may be associated with metabolic changes in ADHD, particularly in energy metabolism and amino acid pathways. The identified biomarker panel may help distinguish children with ADHD from controls. Larger studies with multiple exposure assessments are warranted.”

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References

1. Tseng, H. Y.; Lo, C. J.; Subramani, B. et al. Targeted and Untargeted Urinary Metabolomic Analyses of Organophosphate Pesticides Exposure and Attention-Deficit/Hyperactivity Disorder in Children. Metabolomics 2026, 22 (4), 135. DOI: 10.1007/s11306-026-02495-5
2. Ayano, G.; Demelash, S.; Gizachew, Y. et al. The Global Prevalence of Attention Deficit Hyperactivity Disorder in Children and Adolescents: An Umbrella Review of Meta-Analyses. J Affect Disord. 2023, 339, 860-866. DOI: 10.1016/j.jad.2023.07.071
3. Faraone, S. V.; Banaschewski, T.; Coghill D, et al. The World Federation of ADHD International Consensus Statement: 208 Evidence-based conclusions about the disorder. Neurosci Biobehav Rev. 2021, 128, 789-818. DOI: 10.1016/j.neubiorev.2021.01.022
4. Faraone, S. V.; Perlis, R. H.; Doyle, A. E. et al. Molecular Genetics of Attention-Deficit/Hyperactivity Disorder. Biol Psychiatry 2005, 57 (11), 1313-23. DOI: 10.1016/j.biopsych.2004.11.024
5. Poddar, A.; Gaddam, S.; Sonnaila, S. et al. Unraveling Attention-Deficit/Hyperactivity Disorder Etiology: Current Challenges and Future Directions in Treatment. NeuroSci. 2025, 6 (2), 41. DOI: 10.3390/neurosci6020041
6. López-Flores, I.; González-Alzaga, B.; Romero-Molina, D. et al. Gestational Exposure to Organophosphate Pesticides and Maternal Urine Metabolomic Profile in the GENEIDA Birth Cohort. Environ Toxicol Pharmacol. 2025, 118, 104793. DOI: 10.1016/j.etap.2025.104793