Toxic heavy metal concentrations in multiple sclerosis patients: a systematic review and meta-analysis

Abstract

The present meta-analysis was performed to assess the association between MS patients and control subjects in terms of their circulating levels of arsenic (As), lead (Pb), mercury (Hg), and cadmium (Cd). We searched Medline/PubMed, Scopus, Web of Science, and Embase up until June 2020 to identify all studies that examined the concentrations of heavy metals in MS patients. Statistical tests used to assess inter-study heterogeneity were Cochrane's Q test and the I 2 statistic. Given the observed significant heterogeneity, the random-effects model was employed to pool the weighted mean differences (WMDs) and the corresponding 95 % confidence intervals (CIs). Out of a total of 1181 articles, 16 studies with 1650 participants (772 patients with MS and 878 controls) were included in this review meta-analysis. Pooled results using random-effects model showed that the levels of Pb (WMD= 0.73 µg/L, 95 % CI= 0.33 to 1.12, P< 0.001), As (WMD= 2.48 μg/L, 95 % CI= 1.44 to 3.53, P <0.001; I 2 = 98.9 %, P <0.001), and Cd (WMD= 0.17 μg/L, 95 % CI= 0.09 to 0.26, P <0.001) were significantly higher in MS patients than those of the controls. However, there were no significant differences in the levels of Hg (WMD= -0.14 µg/L, 95 % CI= -0.77 to 0.49, P= 0.658) among both groups. Sensitivity analysis indicated that after excluding one-by-one study, the overall pooled WMD of Pb was changed. This meta-analysis showed that patients with MS had significantly higher levels of circulatory As and Cd compared to the controls. Yet, there was no statistically significant difference between circulating levels of Hg and Pb among MS patients and controls. See also Figure 1 (Fig. 1) .

Searching for the Relationship between the Concentration of Heavy Metals in the Blood and the Clinical Course of Multiple Sclerosis: A Cross-Sectional Study in Poland

“…Apart from studies confirming a higher incidence of MS in areas where soils contain high concentrations of lead [ 7 , 34 , 35 , 36 ], there are also studies showing no such relationships [ 37 , 38 ]. The only meta-analysis conducted to date in the field of toxic heavy metal concentrations in MS patients did not show any significant differences in blood lead levels between MS patients and healthy controls [ 39 ]. Therefore, the hypothesis about higher exposure to heavy metals among MS patients living in large cities in Poland has not been confirmed.…”

Neuron Protection by EDTA May Explain the Successful Outcomes of Toxic Metal Chelation Therapy in Neurodegenerative Diseases

“…Regarding MS, the role of TMs and of particulates and gaseous pollutants present in the air as putative triggers of both the development and relapse of MS has been shown [ 10 ]. Moreover, patients with MS have significantly higher levels of circulating As and Cd compared to controls [ 11 ].…”

Helicobacter pylori infection and risk of multiple sclerosis: An updated meta‐analysis

“…6 Although the pathogenesis of MS remains to be fully understood, 7 this disease is associated mainly with complex interactions between genetic and environmental factors. 8,9 Linked to the "hygiene hypothesis," it has been speculated that infection with particular microorganisms, particularly those occurring in childhood, may have a protective effect against allergic and autoimmune diseases. 10 In this regard, several studies have examined the possible involvement of infectious agents, such as Epstein-Barr virus and Toxocara spp., in promoting MS development, 8,[11][12][13] and others have suggested that parasites (e.g., Toxoplasma gondii, Necator americanus, and Trichuris suis) might prevent MS. [14][15][16] There is also been considerable debate as to whether Helicobacter pylori (H. pylori) is involved in development of MS or not.…”

“…Despite the various treatment strategies presently used, such as interferon (a drug in the disease‐modifying therapies class) prescription for inhibiting disease progression, faster diminishing of attacks, and reducing the bothersome symptoms of MS, 5 current therapeutic options for the treatment of MS remain inadequate 6 . Although the pathogenesis of MS remains to be fully understood, 7 this disease is associated mainly with complex interactions between genetic and environmental factors 8,9 . Linked to the “hygiene hypothesis,” it has been speculated that infection with particular microorganisms, particularly those occurring in childhood, may have a protective effect against allergic and autoimmune diseases 10 .…”