Table 4.
Metals and Parkinson's disease.
| Metal | Study | Levels of metal | Findings | Ref. |
|---|---|---|---|---|
| Essential | ||||
| Manganese (Mn) | Review of available clinical, neuroimaging, and neuropathological studies in humans and nonhuman primates exposed to Mn | ---- | Mn-induced Parkinsonism does not involve degeneration of midbrain dopamine neurons and that L DOPA is not an effective therapy | [189] |
| Group 1 (G1): miners, welders, and bordering residents (they showed signs of Parkinsonism) Group 2 (G2): miners, welders, and bordering residents (had a routine clinical examination) Group 3 (G3): PD Group 4 (G4): cases of healthy and unexposed |
The blood screening of manganese shows a high level upper than 15 μg/L in the two first groups (G1 and G2) | High levels of manganese The authors underline the gravity of manganese-induced Parkinsonism |
[190] | |
| Iron (Fe) | Thirty-three PD patients and 26 age- and sex-matched healthy volunteers were included in this study | PD in SNc = 163.47 ± 49.16 ppb HV SNc = 85.18 ± 30.57 ppb p value < 0.01 |
PD is closely related to iron deposition in the SNc | [194] |
| Copper (Cu) | The brain tissue samples were from patients with idiopathic PD and incidental Lewy body disease (ILBD) and age-matched control subjects | Control subjects (SN) = 70 PD patients (SN) = 38 ILBD patients (SN) = 35 μg/g dry weight |
Decreased cellular Cu levels and disrupted Cu pathways in vulnerable brain regions in PD. Regional changes in SOD1 specific activity that reflect the pattern of neurodegeneration in PD |
[196] |
| 50 PD patients diagnosed according to the UK PD Brain Bank criteria | Serum Cu Controls subjects = 1200 μg/L PD subjects = 700 μg/L |
Low serum Cu concentration is related to PD development and predominantly affects the nonmotor symptoms of PD | [197] | |
| Zinc (Zn) | Meta-analysis to evaluate whether circulating Zn levels in the serum, plasma, and cerebrospinal fluid (CSF) are altered in PD | Zn levels were significantly lower in PD patients vs. controls (SMD = −0.59; 95% CI [−1.06, −0.12]; p = 0.014) | This study suggests that reduced Zn levels in the serum and plasma are associated with an increased risk for PD | [199] |
| 60 patients who were registered in the 13th Regional Health Board (DIRES) and diagnosed with PD as determined by a certified specialty neurologist | PD patients with psychotic complications = 624.1 ± 56.9 μg/g The patient group who did not report any psychotic complications = 513.9 ± 47.9 μg/g Control group (459.3 ± 32.1 μg/g) |
Showed that patients with depression and patients with one or more of the psychotic complications of hallucination, illusion, paranoid ideation, altered dream phenomenon, and confusion exhibited significantly higher Zn concentrations in hair | [200] | |
| 238 PD patients and 302 controls | Controls subjects = 1293 ± 385 μg/L PD subjects = 923 ± 338 μg/L |
Zn level in PD patients was significantly decreased regardless of age status, suggesting that reduced plasma Zn concentration might be a potential signal for PD early warning | [201] | |
| Cobalt (Co) | Two sites were selected: 1. Luqiao district, Taizhou 2. Huangyan District, Taizhou, as the reference area, 20 km north of Luqia | Blood concentrations Reference group = 0.35 ng/mL Exposed group = 0.5 ng/mL |
Co in subjects' blood was associated with the alterations of the biomarkers of BBB and OS | [204] |
| A 46-year-old man developed rapidly progressing Parkinson's disease symptoms after metal-on-metal total hip arthroplasty. | Serum Co: metal-on-metal total hip arthroplasty = 116 μg/L Co | After revision, the patient's serum Co level fell below 1 μg/L, and the PD symptoms improved | [203] | |
| Lead (Pb) | Bone Pb concentrations were measured using 109 Cd excited K-shell X-ray fluorescence from 330 PD patients (216 men, 114 women) and 308 controls (172 men, 136 women) | OR for PD in the highest quartile was 3.21 [95% confidence interval (CI), 1.17–8.83] | Cumulative Pb exposure among typical PD patients seen in our movement disorders clinics strengthens the evidence that cumulative exposure to lead increases the risk of PD | [205] |
| Aluminum (Al) | Examined melanin-containing neurons of the substantia nigra in patients with PD and controls | PD 1 neuromelanin = 147.0 ± 7.0 Cytoplasm = 11.0 ± 2.4 Neutrophil = 9.8 ± 1.8 Control neuromelanin = 14.1 ± 1.4 Cytoplasm = 80.0 ± 1.0 Neutrophil = 4.5 ± 0.7 |
The accumulation of Al, which is known to promote oxidant stress, may account for the selective degeneration of neuromelanin-containing neurons in PD | [206] |
| 42 healthy controls and 45 drug naive PD patients | Control is 0.190 μg/dL and 0.32 μg/dL for PD | The serum Al level was significantly increased in PD patients | [208] | |
| Cadmium (Cd) | A 64-year-old man suffered from acute exposure to cadmium | Cd concentration (blood 1.49 mg/dL, normal 0.11–0.66 mg/dL; urine 47.9 mg/L, normal 0.13–8.93 mg/L) | Three months after exposure, the patient developed Parkinsonian features. The case suggests that cadmium intoxication may damage the basal ganglia, resulting in Parkinsonism. | [212] |
| Brain samples from people with neurodegenerative diseases | Cd was found in the locus coeruleus of all ten individuals examined | In individuals with AD or PD, a marked loss of locus coeruleus neurons was seen, with numerous collections of macrophage-bound and free neuromelanin pigment. | [211] |
SN: substantia nigra; BBB: blood-brain barrier; OS: oxidative stress; PD: Parkinson's disease.