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Abstract: The olfactory function can be affected by occupational and environmental exposure to various neurotoxicants that can be transported through the olfactory pathway. Olfactory impairment is a highly recurrent non-motor dysfunction in Parkinson''s disease and is considered an early predictive sign of neurodegeneration. Changes in olfactory perception may be caused by a dopaminergic dysregulation, possibly related to changes at the level of dopamine receptors. Manganese is an essential element that can become neurotoxic in various conditions inducing an overload in the organism. Being actively transported through the olfactory tract, manganese can cause impairment of olfactory function and motor coordination in different age groups like children and elderly. Odor and motor changes are interrelated and may be caused by a Mn-induced dopaminergic dysregulation affecting both functions. Given these findings, further research is imperative on the possible role of manganese exposure as a pathogenetic factor for Parkinsonism. [Copyright &y& Elsevier]

Background Manganese (Mn) is an essential element required for growth and development, but higher body burdens have been associated with neurobehavioral decrements in children. Objectives We examined whether prenatal or postnatal Mn measured in deciduous teeth was associated with scores on a test of visuospatial learning and memory. Methods Deciduous teeth were collected from 142 participants (ages 10–14 years) residing near varied ferro‑manganese industry in Italy. Mn concentrations were measured in prenatal and postnatal tooth regions by laser ablation inductively coupled plasma mass spectrometry (ICP-MS). The Virtual Radial Arm Maze (VRAM), an animal-human analogue task, was used to assess visuospatial learning and memory. We used generalized additive, linear and zero-inflated Poisson mixed regression models to estimate associations between prenatal or postnatal Mn concentrations and repeated measures of all four VRAM outcomes: time, distance, working and reference memory errors. Effect measure modification by sex was examined in stratified models. Results U-shaped associations between prenatal Mn and VRAM outcomes were observed among girls only (p GAMM = 0.001 to 0.02 in stratified models). Compared to the mid-tertile of prenatal Mn, girls in the highest tertile took 7.7 s [95% CI: − 6.1, 21.5] longer to complete the task, traveled 2.3 maze units [0.1, 4.4] farther, and committed more working and reference memory errors (β for count ratio = 1.33 [1.01, 1.83]; 1.10 [0.98, 1.24], respectively). This association was not observed among boys. In contrast, for postnatal Mn, no significant associations were found, and patterns were similar for boys and girls. Conclusions The prenatal period may be a critical window for the impact of environmental Mn on visuospatial ability and executive function, especially for females. [ABSTRACT FROM AUTHOR]