Neurological and neuropsychological features in Parkinsonian patients exposed to neurotoxic metals

Background: Environmental exposure to heavy metals and especially manganese (Mn) took place in Valcamonica, Italy, where a high prevalence of Parkinsonism was observed (age and sex standardized 407/100,000; 95% CI: 393.87-420.12), and the Standardized Morbidity Ratios was associated with environmental Mn levels. Methods: A cross sectional study compared Parkinsonian patients residents in Valcamonica with patients from Brescia, Italy. Age- and sexmatched healthy individuals were recruited as controls. The protocol included information on clinical, occupational, residential history and life habits, neuro-psychological testing, and assessment of genetic polymorphism. Results: The target group included 65 patients and 52 controls from Valcamonica, 28 patients and 14 controls from Brescia. Age at onset of the disease was lower in women from both areas. After adjusting for age and age at onset, patients from Valcamonica showed more severe motor impairment at the UPDRS scale, higher damage of cognitive and motor functions at MMSE, Token and Trial Making tests. Genetic variables showed a different allelic distribution of DRD4 gene between cases and controls, outside Valcamonica, where a less frequent familiarity for parkinsonism was reported. Conclusions: Parkinsonian patients with previous exposure to metals showed a more severe neuropsychological phenotype, without detectable contribution from genetic factors.