Table 3.
Reference | Study Design | Population | Exposure | Outcome | Main Findings |
---|---|---|---|---|---|
Alzheimer’s Disease | |||||
Emard, 1994 [63] | Retrospective ecological | 129 definite or probable AD cases born in the Saguenay-Lac-Saint-Jean territory of Quebec | Difference between birthplace residential and municipal average levels of Mn in soil | AD clinical diagnosis | Number of cases with higher average Pb concentration near residence at birth in comparison to municipal average (n = 35) differs from number of cases with lower average Pb concentrations near residence at birth in comparison to municipal average (n = 12) p < 0.05 |
Tong, 2014 [186] | Case-control | Patients and age-matched controls from Beijing Geriatric Hospital 10 with CDR = 0 (mean age 75.0, SD: 5.2) 10 with CDR = 0.5 (mean age 7.2, SD: 4.1) 4 with CDR = 1 (mean age = 75.2, SD: 2.7) 16 with CDR > 2 (mean age 75.9, SD: 7.7) |
Blood Mn | MMSE, CDR | Inverse correlation between MMSE score and Mn level, positive correlation between CDR and Mn level in unadjusted analysis, though selection criteria not defined. |
Du, 2017 [206] | Meta-analysis | 17 studies of Mn exposure and AD and/or MCI | Serum Mn | AD diagnosis, MCI | AD patients had lower Mn levels than controls (SMD −0.39, 95% CI −0.71, −0.08), and AD + MCI individuals also had lower Mn levels than controls (SMD −0.37, 95% CI −0.6, −0.13). |
Cognitive function | |||||
Mergler, 1999 [200] | Cross-sectional | 273 randomly sampled residents (mean age 43.4 (SD 13.9) for women, 45.1 (SD 14.4) for men) living near former Mn alloy plant in SW Quebec | Blood Mn (μg/L) | Scores on neuropsychological battery including: learning and recall, visuo-perceptive speed, verbal naming, cognitive flexibility. | Higher MnB (≥7.5 μg/L) associated with poorer learning and recall aggregate score, within which MAS acquisition, delayed recall, visual recognition, and visual reproduction scores were significantly different |
Santos-Burgoa, 2001 [201] | Cross-sectional | 73 randomly sampled residents (mean age 43.35, SD: 18.36) of two towns in Hidalgo, Mexico near primary ore refineries | Blood Mn (μg/L) | Scores on neuropsychological battery including: MMSE, digit span, verbal fluency, trail making, neurological exam | OR of low (≥17) MMSE adjusted for schooling was 4.92 (90% CI 1.39–17.38) for blood Mn above the median versus below. |
Bowler, 2007 [202] | Cross-sectional | 43 confined-space welders (mean age 43.8, SD: 10) on SF-Oakland Bay Bridge who had worked with inadequate PPE, all males | Blood Mn (μg/L), plasma Mn, urine Mn, Cumulative Exposure Index (CEI) based on Mn-air duration and type of welding | Comprehensive neuropsych exam including WAIS-III, WMS | Inverse dose-response relationship between CEI and/or blood Mn and IQ, executive function, sustained concentration and sequencing, verbal learning, working memory, and immediate memory. |
Solis-Vivanco, 2009 [204] | Cross-sectional | Proportional sample (n = 288) of residents (mean age 44.7) from 8 communities in Hidalgo, Mexico near Mn deposits and refineries | Blood Mn (μg/L), air Mn concentration from nearest monitor (μg/m3) | Cognitive battery including MMSE, digit span, world list test, word association test | OR of 1.75 (95% CI 1.01 – 3.06) for poor performance on digit span in those with air Mn of >0.1 μg/m3 vs <0.1 μg/m3. Blood Mn not significantly associated with any neuropsychological tests. |
Menezes-Filho, 2011 [203] | Cross-sectional | 77 mothers of school-aged children living near ferro-manganese alloy plan in Brazil | Hair Mn (μg/g), blood Mn (μg/L) | Raven Progressive Matrix | Maternal hair Mn associated with worse performance on Raven Progressive Matrix (one log-unit of Mn associated with −2.69 points, 95% CI: −5.42 – 0.05) |
de Sousa Viana, 2014 [199] | Cross-sectional | Residents living > 5 years in one of two communities (Cotegipe: n = 42, mean age 32.9, SD: 6.35, Santa Luzia: n = 47, mean age 34.2, SD: 10.8) near ferromanganese refinery in Brazil. | Scalp hair, axillary hair, fingernail, saliva Mn (all μg/g) | Neuropsychological battery including: WAIS-III, test of executive function, attention, and memory | In adjusted linear regression, inverse association between log hair Mn and IQ (−4.76, 95% CI: −9.17, −0.36) and log fingernail Mn and visual working memory (−3.33, 95% CI: −6.15, −0.52). |
Bowler, 2015 [205] | Cross-sectional | 86 residents (mean age 56, SD: 10.8) living > 10 years in one of two towns in Ohio with high airborne Mn | Estimated long-term air Mn (μg/m3) exposure | Neuropsychological battery including WAIS-III, tests of cognitive flexibility and executive functioning, memory, verbal skills | In linear regression, air Mn concentrations associated with working (−0.19) and visuospatial memory scores (−0.16), and verbal reasoning score (−0.19), though these were not significant at α = 0.05. |
Mn, manganese; SD, standard deviation; CDR, Clinical Dementia Rating Scale (0.5 = MCI, 1 = Mild Dementia, ≥2 = Dementia); MMSE, Mini-Mental State Examination; CI, confidence interval; SMD, standardized mean difference; OR, odds ratio; WAIS-III, Wechsler Adult Intelligence Scale; WMS, Wechsler Memory Scale; RAVLT, Rey Auditory Verbal Learning Test; MCI, mild cognitive impairment.