title: MRI pallidal signal in children exposed to manganese in drinking water.
abstract: BACKGROUND
  Manganese (Mn) can have neurotoxic effects upon overexposure. We previously reported poorer cognitive and motor development in children exposed to Mn through drinking water, suggesting possible neurotoxic effects from Mn in water. Hyperintensity in the globus pallidus (GP) on T1-weighted magnetic resonance imaging (MRI) indicates excessive brain Mn accumulation. Previous studies have reported GP hyperintensity related to Mn exposure in occupationally exposed individuals. However, no study has used MRI in children exposed to Mn in drinking water and who show no sign of overt intoxication.
  
  
  OBJECTIVE
  To examine MRI signal intensity in the GP in children exposed to contrasted levels of Mn in drinking water.
  
  
  METHODS
  We enrolled 13 children exposed to low Mn concentration in water and 10 children (ages 9-15 years) with high concentration (median of 1 and 145μg/L, respectively). We calculated three MRI T1 indexes: (i) standard pallidal index (PI) using frontal white matter as reference; (ii) PI using pericranial muscles as reference; and (iii) T1 relaxation time. Each MRI index was compared between exposure groups, and with respect to the estimated Mn intake from water consumption.
  
  
  RESULTS
  The standard PI did not differ between Mn-exposure groups. However, children in the group with high water-Mn concentration had significantly lower pericranial muscles PI than those with lower exposure and, accordingly, higher T1 relaxation time. Mn intake from water consumption was not correlated with the standard PI, but was significantly related to the pericranial muscles PI and T1 relaxation time. Motor performance was significantly lower in the high-exposure group.
  
  
  CONCLUSIONS
  We observed lower signal intensity in the GP of children with higher exposure to Mn from drinking water. This result stands in contrast to previous MRI reports showing GP hyperintensity with greater Mn exposure. Differences in exposure pathways are discussed as a potential explanation for this discrepancy.
authors.affiliation: Department of Psychology, Université du Québec à Montréal, Québec, Canada; Sainte-Justine University Hospital Research Center, Montréal, Québec, Canada.
authors.forename: Laurie-Anne
authors.initials: LA
authors.lastname: Dion
authors.affiliation: Sainte-Justine University Hospital Research Center, Montréal, Québec, Canada; Centre for Interdisciplinary Studies in Biology, Health, Society and Environment (CINBIOSE), Université du Québec à Montréal, Québec, Canada; Department of Environmental and Occupational Health, Université de Montréal, Montréal, Québec, Canada. Electronic address: maryse.bouchard@umontreal.ca.
authors.forename: Maryse F
authors.initials: MF
authors.lastname: Bouchard
authors.affiliation: Department of Chemistry, Université de Montréal, Québec, Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Sauvé
authors.affiliation: Department of Civil, Geological and Mining Engineering, École Polytechnique de Montréal, Québec, Canada.
authors.forename: Benoit
authors.initials: B
authors.lastname: Barbeau
authors.affiliation: BarcelonaBeta Research Center, Pasqual Maragall Foundation, Barcelona, Spain; Department of Radiology, CHUM Notre-Dame Hospital, Montréal, Québec, Canada.
authors.forename: Alan
authors.initials: A
authors.lastname: Tucholka
authors.affiliation: Sainte-Justine University Hospital Research Center, Montréal, Québec, Canada.
authors.forename: Philipe
authors.initials: P
authors.lastname: Major
authors.affiliation: Department of Radiology, CHUM Notre-Dame Hospital, Montréal, Québec, Canada; MR Clinical Science, Philips Healthcare, Markham, Ontario, Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Gilbert
authors.affiliation: Centre for Interdisciplinary Studies in Biology, Health, Society and Environment (CINBIOSE), Université du Québec à Montréal, Québec, Canada.
authors.forename: Donna
authors.initials: D
authors.lastname: Mergler
authors.affiliation: Department of Psychology, Université du Québec à Montréal, Québec, Canada; Sainte-Justine University Hospital Research Center, Montréal, Québec, Canada; Centre for Interdisciplinary Studies in Biology, Health, Society and Environment (CINBIOSE), Université du Québec à Montréal, Québec, Canada.
authors.forename: Dave
authors.initials: D
authors.lastname: Saint-Amour
mesh_terms: D000293:Adolescent; D002648:Child; D060766:Drinking Water / Q000008:administration & dosage; D005260:Female; D005917:Globus Pallidus / Q000000981:diagnostic imaging* / Q000187:drug effects*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008345:Manganese / Q000008:administration & dosage* / Q000378:metabolism; D011596:Psychomotor Disorders / Q000139:chemically induced* / Q000000981:diagnostic imaging*; D013054:Spectrophotometry, Atomic
chemical_list: D060766:Drinking Water; D008345:Manganese
keywords: Children; Globus pallidus; MRI; Manganese; Neurotoxicity; Water