Exposure to high levels of manganese has been associated with progressive parkinsonism. Following complaints by residents in a South African town where a large manganese smelter operates, we designed a study to investigate neurological health effects (motor and cognitive) in adults. The objective of this analysis reported was to evaluate the correlation between parkinsonism and self-reported symptoms and health status, and fine-motor control.Methods
Parkinsonism was assessed by a movement disorders specialist, using the Unified Parkinson Disease (PD) Rating Scale motor score (UPDRS3). The 39–item PD Questionnaire (PDQ-39) was used to assess participants’ Parkinson disease-specific quality of life. PD symptoms were self-reported, using a standard screening questionnaire. The grooved peg board timed test was used to measure fine motor speed and visuo-motor coordination. We used locally weighted scatterplot smoothing (LOWESS) to graphically evaluate the associations of UPDRS3 score with age, grooved peg board times for both dominant and non-dominant hands, PDQ-39 score, and PD symptom questionnaire score. We also used LOWESS to evaluate the relationship between PDQ-39 score and symptom questionnaire score. We assessed correlations using Spearman coefficients.Results
The LOWESS plots and Spearman coefficients indicated positive associations (p<0.001), suggesting that individuals with higher UPDRS3 scores were older (ρ=0.24), took longer to complete the grooved pegboard test (dominant ρ=0.31, non-dominant ρ=0.28), had higher PDQ-39 scores (ρ=0.28), and had more PD symptoms (ρ=0.35). Furthermore, PDQ-39 score was highly correlated (ρ=0.70) with screening questionnaire score.Discussion
The strong correlations between parkinsonism and the administered tests showed that the tests used in this study are robust for identifying individuals with neurological health effects, are useful in large scale epidemiological studies, and may augment data obtained from a clinical specialist’s examination.