2021: Association of DBH Gene Polymorphism, Iodide, Fluoride, and their Interaction with Children's Intelligence

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2021: Association of DBH Gene Polymorphism, Iodide, Fluoride, and their Interaction with Children's Intelligence

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Guo Baihui, Yu Jingwen, Cui Yushan, Gao Tongning, Zhao Liang, Wei Wenbin, Liu Hongliang - "Association of dopamine beta-hydroxylase gene polymorphism, iodide, fluoride, and their interaction with children's intelligence" Journal of Environmental Hygiene 11(2): 134-140 (2021)
http://hjwsxzz.bosihw.cn/browsing/brows ... ?id=245328


Objective: To investigate the influence of dopamine beta-hydroxylase (DBH) gene polymorphism, iodine, fluoride, and their interaction on children's intelligence.

Methods: Three schools were selected according to the history of water iodine concentration in Tianjin, and then cluster sampling was performed to select 299 children. Combined Raven's Test was used to measure the children's intelligence level; urine samples were collected and then arsenic-cerium catalytic spectrophotometry and the fluoride-ion selective electrode method were used to measure urinary iodine and fluoride levels, respectively; polymerase chain reaction -restriction fragment length polymorphism was used to determine DBH genotype.

Results: The children aged (10-12) years in the high iodine area 2 had a significantly lower intelligence level than those in the high iodine area 1 and the suitable iodine area (108.24±13.69 vs 114.48±11.91/113.10±12.54, F =3.45 , P <0.05). The multivariate logistic regression analysis showed that urinary fluoride was a risk factor for intelligence impairment ( OR =2.32, 95% CI: 1.09-4.95, P <0.05). The DBH gene, urinary fluoride, and urinary iodine had no interaction with intelligence, and the DBH gene had no mediating effect on intelligence impairment induced by iodine and fluoride.

Conclusion: The intelligence level of children aged (10-12) years tends to decrease in the areas where the concentration of water iodine is over 300 μg/L in Tianjin. The DBH gene, urinary fluoride, and urinary iodine have no interaction with intelligence, and the DBH gene has no mediating effect on intelligence, which requires further research.

From the text: "Under the control of gender and age, the mediation effect of DBH gene on urinary iodine, urinary fluoride and children’s intelligence level was tested. The results showed that Z mediation was -0.006 and 0.543, respectively, suggesting that urinary iodine and urinary fluoride have an effect on children’s intelligence. Among the effects, the DBH gene does not have a mediating effect."



As documented in many other studies before, the data shows urinary fluoride levels correlating positively with urinary iodine levels. (Is it really "excessive iodine" intake or is it fluoride that is causing these higher urinary iodine levels?)

It is unfortunate that, once again, thyroid hormones were not investigated. Neither were serum fluoride levels. There is no information on fluoride water concentrations.

DBH and the Thyroid

In the 1980s, many experiments were conducted investigating the influence of thyroid status on DBH.

In 1980, Stolc et al. reported that serum DBH activity was inversely related to thyroid status in both humans and rats. In newborn rats, DBH activity was found to be four times higher than in adults (Gripois & Valens, 1983). In depressed patients, TSH levels were found to be positively correlated to DBH levels, while no significant correlation was found in normal subjects (Kjellman et al., 1986), pointing to the possible involvement of the D3 deiodinase. In neonatal rats, hypothyroidism (reduced thyroid hormone) completely suppressed DBH (Gripois et al., 1983; 1986).

Japanese researchers investigating plasma DBH activity in hyperthyroidism found DBH activity correlated to T3 (Tanaka et al., 1979;1980). Tanaka et al. had employed propranolol in their investigations, an anti-thyroid substance that, like fluoride, increases rT3 and decreases T3 (Wirsinga, 1991). rT3 levels are used as biomarkers in fluoride poisoning (Lin et al., 1992; Shashi & Singla, 2013).


Gripois D, Valens M - "Evolution of plasma dopamine-beta-hydroxylase in hypo- and hyperthyroid young rats" Biol Neonate 43(5-6):229-33 (1983)

Gripois D, Valens M, Diarra A, Roffi J - "Influence of neonatal hypothyroidism on the response of the adrenal medulla of young rats to a physiological stimulation" Pathol Biol (Paris) 33(10):993-7 (1985)

Gripois D, Valens M. - "Adrenal dopamine beta-hydroxylase induction in the young rat: influence of thyroid hormones" Mol Cell Endocrinol 45(1):77-80 (1986)

Lin Jin, Lin Fafu, Zhao Hongxin, Jiang Jiyong, Xu Xunfeng - "A study on the relationship between serum rT3 and environmental iodine or fluoride levels" Endemic Disease Bulletin (3):68-70 (1992)
http://www.nmglib.com:8901/article/deta ... ?id=720441

Kjellman BF, Beck-Friis J, Ljunggren JG, Ross SB, Undén F, Wetterberg L - "Serum dopamine-beta-hydroxylase activity in patients with major depressive disorders" Acta Psychiatr Scand 73(3):266-70 (1986)

Shashi A, Singla S - "Syndrome of Low Triiodothyroinine in Chronic Fluorosis" International Journal of Basic and Applied Medical Sciences 3(1):152-160 (2013)
https://pdfs.semanticscholar.org/e78b/0 ... 1594834242

Stolk JM, Hurst JH, Nisula BC - "The inverse relationship between serum dopamine-beta-hydroxylase activity and thyroid function" J Clin Endocrinol Metab 51(2):259-64 (1980)
https://academic.oup.com/jcem/article-a ... 59/2677934

Tanaka T, Nakagawa T, Tamai H, Suematsu H, Kuma K, Matsuzuka F, Hidaka H, Miyaji K - "Plasma dopamine-beta-hydroxylase activity and thyroid suppressibility in Graves' disease" Metabolism 28(8):828-30 (1979)

Tanaka T, Yamaguchi T, Kuma K, Hidaka H. - "Effect of beta-adrenergic blockade on plasma dopamine-beta-hydroxylase activity and triiodothyronine in hyperthyroidism" Endocrinol Jpn 27(4):447-50 (1980)
https://www.jstage.jst.go.jp/article/en ... 7/_article

Wiersinga WM - "Propranolol and thyroid hormone metabolism" Thyroid 1(3):273-7 (1991)
https://www.liebertpub.com/doi/10.1089/ ... i%3Arid%3A
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