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Environmental exposure to manganese in air: Tremor, motor and cognitive symptom profiles
Citation:
Kornblith, E., S. Casey, D. Lobdell, M. Colledge, AND R. Bowler. Environmental exposure to manganese in air: Tremor, motor and cognitive symptom profiles. NEUROTOXICOLOGY. Elsevier B.V., Amsterdam, Netherlands, 64:152-158, (2018). https://doi.org/10.1016/j.neuro.2017.09.012
Impact/Purpose:
This study addresses research questions under Sustainable and Healthy Communities (2.62 Community Public Health and Wellbeing). The present study reports findings of a study investigating whether subtypes of tremor and no tremor symptoms exist in manganese (Mn) neurotoxicity as they do in Parkinson’s disease in adult residents environmentally exposed to manganese (Mn) living in two Ohio towns. The study was conducted through the Regional Applied Research Effort which is a joint effort between Region 5 and ORD Scientists.
Description:
Background: Excessive exposure to manganese (Mn) may cause parkinsonian-like motor and tremor symptoms and adverse cognitive effects, including problems with executive functioning (EF), resembling those found in later-stage Parkinson’s disease (PD). Studies seeking to differentiate PD patients into subgroups with associated cognitive and functional outcomes using motor and tremor symptoms identified tremor-dominant (TD) and non-tremor dominant (NTD) subtypes. It is unclear whether differing patterns of pathophysiology and symptoms exist in Mn neurotoxicity, as they do in PD. Methods: Residents of East Liverpool (n=83) and Marietta, OH (n=99) exposed to chronic (>10 years) environmental Mn through industrial pollution were administered neuropsychological measures and a physician-rated scale of movement-disorder symptoms. Two-step cluster analysis was used to group residents based on tremor symptoms, bradykinesia/rigidity symptoms, gait disturbance, and executive function. Cluster membership was validated using modeled air-Mn exposure and a computerized tremor measure. Results: Elevated tremor and motor symptoms and executive dysfunction were observed, and TD and NTD symptom clusters were identified. Two additional clusters were also identified: Executive Dysfunction and Normal Functioning. The NTD residents, with elevated levels of gait disturbance and other movement disorder symptoms, did not evidence EF impairment, as predicted. Instead, residents with EF impairment formed their own cluster, and were relatively free of movement disorder symptoms. Conclusions: Results resemble reports in the PD literature with TD and NTD clusters identified, but executive dysfunction did not cluster with NTD symptoms. PD and Mn exposure likely have differing pathophysiology and developmental courses, and therefore different symptom patterns, even when similar symptoms are present.
URLs/Downloads:
DOI: Environmental exposure to manganese in air: Tremor, motor and cognitive symptom profiles