The association between mercury levels and autism spectrum disorders: A systematic review and meta-analysis
Journal of Trace Elements in Medicine and Biology
Volume 44, December 2017, Pages 289-297
https://doi.org/10.1016/j.jtemb.2017.09.002 Received 23 May 2017, Revised 30 August 2017, Accepted 1 September 2017, Available online 4 September 2017.
The association between mercury levels and autism spectrum disorders: A systematic review and meta-analysis
Author
Tina Jafari a b, NoushinRostampour c, Aziz A.Fallah d, AfshinHesami a
a Clinical Biochemistry Research Center, Shahrekord University of Medical Sciences, Sharhekord, Iran
b Department of Biochemistry and Nutrition, Faculty of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran
c Department of Pediatrics, Shahrekord University of Medical Sciences, Shahrekord, Iran
d Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord 34141, Iran
Abstract
Background & aims
The relationship between mercury and autism spectrum disorders (ASD) has always been a topic of controversy among researchers. This study aimed to assess the relationship between ASD and mercury levels in hair, urine, blood, red blood cells (RBC), and brain through a meta-analysis.
Methods
A systematic search was performed in several databases including PubMed, ISI Web of Science, Cochrane register of controlled trials, Google Scholar, Scopus, and MagIran until June 2017. Case-control studies evaluating concentration of total mercury in different tissues of ASD patients and comparing them to the healthy subjects (control group) were identified. Necessary data were extracted and random effects model was used to calculate overall effect and its 95% corresponding confidence interval (CI) from the effect sizes.
Results
A total of 44 studies were identified that met the necessary criteria for meta-analysis. The mercury level in whole blood (Hedges = 0.43, 95% CI: 0.12, 0.74, P = 0.007), RBC (Hedges = 1.61, 95% CI: 0.83, 2.38, P < 0.001), and brain (0.61 ng/g, 95% CI, 0.02, 1.19, P = 0.043) was significantly higher in ASD patients than healthy subjects, whereas mercury level in hair (−0.14 mg/g, 95% CI: −0.28, −0.01, P = 0.039) was significantly lower in ASD patients than healthy subjects. The mercury level in urine was not significantly different between ASD patients and healthy subjects (0.51 mg/g creatinine, 95% CI: −0.14, 1.16, P = 0.121).
Conclusions
Results of the current meta-analysis revealed that mercury is an important causal factor in the etiology of ASD. It seems that the detoxification and excretory mechanisms are impaired in ASD patients which lead to accumulation of mercury in the body. Future additional studies on mercury levels in different tissues of ASD patients should be undertaken.
