Volume 28, Issue 4 (Iran South Med J 2026)
Iran South Med J 2026, 28(4): 758-774 |
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Yousefipour Z, Hamidi A, Ravanipour M, Omrani A, Ravanipour M. Association between Heavy Metal Exposure Assessed by Environmental Monitoring and ADHD: A Systematic Review. Iran South Med J 2026; 28 (4) :758-774
URL: http://ismj.bpums.ac.ir/article-1-2395-en.html
URL: http://ismj.bpums.ac.ir/article-1-2395-en.html
1- Department of Medicine, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
2- Department of Medical Library & Information Sciences, School of Paramedicine, Bushehr University of Medical Sciences, Bushehr, Iran
3- Department of Nursing, School of Nursing and Midwifery, Bushehr University of Medical Sciences, Bushehr, Iran
The Persian Gulf Tropical Medicine Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran
4- Department of Pediatrics, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
5- Department of Environmental Health Engineering, School of Health and Nutrition, Bushehr University of Medical Sciences, Bushehr, Iran ,ravan.mas@gmail.com
2- Department of Medical Library & Information Sciences, School of Paramedicine, Bushehr University of Medical Sciences, Bushehr, Iran
3- Department of Nursing, School of Nursing and Midwifery, Bushehr University of Medical Sciences, Bushehr, Iran
The Persian Gulf Tropical Medicine Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran
4- Department of Pediatrics, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
5- Department of Environmental Health Engineering, School of Health and Nutrition, Bushehr University of Medical Sciences, Bushehr, Iran ,
Abstract: (49 Views)
Background: Given the prevalence and numerous problems of people with attention deficit hyperactivity disorder and the multifactorial nature of this disorder, heavy metals have recently been a focus for researchers as an environmental risk factor. However, the available evidence regarding exposures assessed through environmental monitoring and their association with ADHD is scattered and heterogeneous. Therefore, the present study aimed to investigate the association of exposure to heavy metals assessed through environmental monitoring with attention deficit hyperactivity disorder.
Materials and Methods: The present systematic review was performed in accordance with the PRISMA guidelines. A search was conducted in the Scopus, Web of Science, and PubMed databases, selected for their comprehensive coverage, extensive indexing, and high scientific credibility. All English-language articles published up to September 20, 2024 were searched without time limits. Relevant keywords were used based on MeSH terms, and all stages of screening– of the title, abstract, and full text of the articles– were performed based on the inclusion and exclusion criteria by two independent researchers. Observational studies that assessed exposure to heavy metals through environmental sampling (water, food, and other environmental sources) were included in the study. Finally, the required data were extracted from the final retrieved articles and the methodological quality of the included studies was assessed using a specifically designed checklist. The data analysis method was descriptive and meta-analysis was not possible due to heterogeneity in the findings of the studies.
Results: Out of 19,416 search results, after removing 6,694 duplicates and performing screening, five articles were finally selected for the final analysis. Most of the studies were observational and conducted in the last five years, mainly in European countries. The most common sources of pollutants studied included drinking water (three studies) and food (two studies). The most common metals studied were manganese and methylmercury, and the outcomes evaluated included ADHD diagnosis, related behavioral symptoms, and subtypes of this disorder. Overall, about half of the studies (2 studies) reported a positive and significant association between heavy metal exposure and ADHD, while two studies reported no significant association and one study reported a different association based on ADHD subtype.
Conclusion: This systematic review showed that the available evidence, although limited and heterogeneous, supports a potential association of exposure to some heavy metals– particularly manganese and methylmercury– assessed through environmental monitoring of drinking water and dietary intake with the occurrence or some subtypes of ADHD. However, the small number of studies, the focus on limited exposure sources, and failure to examine concurrent exposures limit the possibility of drawing definitive conclusions. These findings emphasize the importance of strengthening environmental monitoring systems and conducting more comprehensive studies to more accurately assess the risk of ADHD in children.
Materials and Methods: The present systematic review was performed in accordance with the PRISMA guidelines. A search was conducted in the Scopus, Web of Science, and PubMed databases, selected for their comprehensive coverage, extensive indexing, and high scientific credibility. All English-language articles published up to September 20, 2024 were searched without time limits. Relevant keywords were used based on MeSH terms, and all stages of screening– of the title, abstract, and full text of the articles– were performed based on the inclusion and exclusion criteria by two independent researchers. Observational studies that assessed exposure to heavy metals through environmental sampling (water, food, and other environmental sources) were included in the study. Finally, the required data were extracted from the final retrieved articles and the methodological quality of the included studies was assessed using a specifically designed checklist. The data analysis method was descriptive and meta-analysis was not possible due to heterogeneity in the findings of the studies.
Results: Out of 19,416 search results, after removing 6,694 duplicates and performing screening, five articles were finally selected for the final analysis. Most of the studies were observational and conducted in the last five years, mainly in European countries. The most common sources of pollutants studied included drinking water (three studies) and food (two studies). The most common metals studied were manganese and methylmercury, and the outcomes evaluated included ADHD diagnosis, related behavioral symptoms, and subtypes of this disorder. Overall, about half of the studies (2 studies) reported a positive and significant association between heavy metal exposure and ADHD, while two studies reported no significant association and one study reported a different association based on ADHD subtype.
Conclusion: This systematic review showed that the available evidence, although limited and heterogeneous, supports a potential association of exposure to some heavy metals– particularly manganese and methylmercury– assessed through environmental monitoring of drinking water and dietary intake with the occurrence or some subtypes of ADHD. However, the small number of studies, the focus on limited exposure sources, and failure to examine concurrent exposures limit the possibility of drawing definitive conclusions. These findings emphasize the importance of strengthening environmental monitoring systems and conducting more comprehensive studies to more accurately assess the risk of ADHD in children.
Keywords: Attention Deficit Hyperactivity Disorder, environmental monitoring, heavy metals, Systematic Review, environmental exposure
Type of Study: Review Systematic and Meta Analysis |
Subject:
Environmental Health
Received: 2025/09/19 | Accepted: 2026/02/17 | Published: 2026/02/24
Received: 2025/09/19 | Accepted: 2026/02/17 | Published: 2026/02/24
References
1. Amnie AG. Current Evidence and Diverse Perspectives on Attention-Deficit/Hyperactivity Disorder: A Systematic Review. J Psychol Res 2022; 4(2): 4384. [DOI]
2. Posner J, Polanczyk G, Sonuga-Barke E. Attention-deficit hyperactivity disorder. Lancet 2020; 395 (10222): 450-462. [DOI]
3. Mazarei Z, Hamidi A, Ravanipour M, et al. Endocrine Disruptors and Attention Deficit Hyperactivity Disorder: A Systematic Review of Environmental Monitoring Exposure Studies. Iran South Med J 2025; 28(3): 724-743. [Article]
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