Table 2.
Epidemiological studies of air pollutants and cognitive impairment.
| Year | Measured exposure | Study population | Participants | Age at testing | Outcomes | Citation |
|---|---|---|---|---|---|---|
| In utero exposure | ||||||
| 2006 | PAH levels in third trimester and cord blood. | Mother-child pairs Black or Dominican-American mothers in New York City. | 183 | 1, 2, and 3 years. | No effect at 1 and 2 years of age. Reduced BSID-II scores at 3 years with high PAH. | Perera et al., 2006 [58] |
| 2009 | PAH levels in third trimester and cord blood. | Mother-child pairs Black or Dominican-American mothers in New York City. | 249 | 5 years. | ∼4 point reduction in full-scale and verbal IQ with high PAH exposure. | Perera et al., 2009 [59] |
| 2010 | PAH levels over 48 h during. second or third trimester of pregnancy. | Mother-child pairs in Krakow, Poland. | 214 | 5 years. | ∼4 point reduction in non-verbal IQ associated with PAH exposure. | Edwards et al., 2010 [60] |
| 2014 | NO2, NOx, PM2.5, and PM10 levels. | Metaanalysis of studies with European children from Germany, France, Italy, Greece, and Spain | 9482 | 1–6 years. | Higher NO2 exposure associated with reduced psychomotor development. No pollutant associated with reduced cognitive development. | Guxens et al., 2014 [62] |
| 2014 | NO2, SO2, O3, non-methane hydrocarbons, THC, and CO exposure during pregnancy. | Taiwanese mother–child pairs multiple villages in Taiwan. | 533 | 6 and 18 months. | Non-methane hydrocarbons exposure during 2nd and 3rd trimester associated with reduction in gross motor skills. No other exposure showed significant effect. | Lin et al., 2014 [65] |
| 2015 | PM2.5, NO2, benzene, and distance of residence to major roadway. | Spanish mother–child pairs in the Guipuzcoa region. | 438 | 2 years. | Reduced BSID motor score with increasing PM2.5, decreased mental score with NO2, no changes with benzene or distance to roadway. | Lertxundi et al., 2015 [63] |
| 2015 | PM2.5, black carbon, and distance of residence to major roadway during third trimester, from birth to age 6, and the year before assessment. | Mother-child pairs in eastern Massachusettes area. | 1109 | Mean age 8 years. | Prenatal lower distance to major roadway associated with decreased non-verbal IQ and visual motor ability. Other exposures showed no significant changes. | Harris et al., 2015 [66] |
| 2016 | NO2, PM2.5, PMcoarse, and PM10 levels at birth, as well as distance of residence to major roadway. | Italian mother–child pairs. | 719 | 7 years. | Increasing NO2 levels and decreasing distance to roadway associated with decreased verbal IQ and verbal comprehension IQ by WISC-III. | Porta et al., 2016 [64] |
| Early life exposure | ||||||
| 2008 | General air pollution by residence in high pollution versus low pollution areas. | Children in Mexico City, Mexico, and Polotitlán, Mexico. | 73 | Mean age 9.5 years. | Residence in Mexico City associated with reduced performance age in verbal IQ, full scale IQ, and multiple sub-tests by WISC-R assessment. | Calderón-Garcideuñas et al., 2008a [45] |
| 2008 | Black carbon levels at residence from birth to testing. | Mother-child pairs in the Boston, Massachusetts area. | 202 | 8–11 years. | Higher BC exposure associated with decreased matrices and composite performance in the Kaufman Brief Intelligence Test. | Suglia et al., 2008 [70] |
| 2009 | General air pollution by residence for at least 3 years in high pollution versus low pollution areas. | Second and third grade students either in central or northern districts of Quanzhou, Fujian Province, China. | 861 | 8–10 years. | Residence in the higher pollution central area associated with impaired performance risk for Visual Simple Reaction Time, Continuous Performance, Digit Symbol, Pursuit Aiming, and Sign Register by Neurobehavioral Evaluation System and Jinyi Psychomotor Test Battery tests. | Wang et al., 2009 [72] |
| 2010 | NO2 exposure over 1 year. | Spanish male children age 4 | 210 | 5 years. | Decreases in general performance, motor function, and perceptual performance in MSCA tests comparing lowest NO2 exposure group to highest. | Freire et al., 2010 [67] |
| 2011 | General air pollution by residence in high pollution versus low pollution areas. | Children in Mexico City, Mexico, and Polotitlán, Mexico. | 30 | Mean age 7 years. | Decreased vocabulary and memory performance by WISC-R assessment. | Calderón-Garcideuñas et al., 2011 [71] |
| 2012 | NO2 and PM10 exposure at school and homel. | Children in the area around Schipol-Amsterdam airport, Schipol, Netherlands. | 485 | 9–11 years. | NO2 levels at school, but not at home, linked to small memory span reduction in digit memory span test. | van Kempen et al., 2012 [68] |
| 2013 | Black carbon levels at residence from birth to testing. | Mother-child pairs in the Boston, Massachusetts area. | 174 | 7–14 years. | Male, but not female, children in higher 3 quartiles of BC exposure showed increased hit reaction time and commission errors in Connor's Continuous Performance Test. | Chiu et al., 2013 [69] |
| 2015 | PAH levels in cord blood and 48 h PAH monitoring at home at 3 years of age. | Children in Krakow, Poland. | 170 | 7 years of age. | Depressed verbal IQ index (WISC-R – vIQ score). RR = 3.0 with ln-unit increase in cord blood PAH, RR = 1.6 with postnatal exposure. | Jedrychowski et al., 2015 [61] |
| 2015 | Benzene biomarker trans,trans-muconic acid in urine, distance weighted traffic density, and time spent in traffic before testing. | 9th grade highschool students in Flanders, Belgium. | 606 | Mean age 15 years. | One SD increase in approximated traffic exposure associated with 0.26 SD decrease in sustained attention by Neurobehavioral Evaluation System. No other metrics significant. | Kicinski et al., 2015 [73] |
| 2016 | Lifelong residence in Mexico City Metro Area. | Children in Mexico City, Mexico with either APOE ɛ3/ɛ3 or APOE ɛ3/ɛ4 genotypes. | 105 | Mean age 12 years. | APOE ɛ3/ɛ4 females showed decreased performance IQ and full scale IQ by WISC-R assessment compared to APOE ɛ3/ɛ3. Male children showed no statistician difference. | Calderón-Garcideuñas et al., 2016 [74] |
| Adult to elderly exposure | ||||||
| 2006 | General air pollution by residence in high or low pollution areas for at least 10 years. | Elderly from either Mexico City, Mexico, or Actopan, Mexico. | 189 | 60 years or greater. | Increased cognitive impairment in high pollution area patients age 80 + by MMSE, as well as increased lipoperoxides. | Sánchez-Rodríguez et al., 2006 [75] |
| 2008 | Air pollution index at residence compared to region gross domestic product. | Elderly from 22 different provinces in China. | 7358 | 65 years or greater. | Higher air pollution index associated with lower performance in activities of daily living and cognition as measure by MMSE. Effect was exacerbated by residence in higher GDP areas. | Sun and Gu 2008 [76] |
| 2009 | Lifetime PM10 and ozone exposure estimated from annual exposure metrics. | Adults living in the United States | 1764 | Mean age 37 years. | No statistically significant effect seen in simplem reaction time, symbol-digit substitution, or serial-digit learning tests with PM or ozone exposure. | Chen and Schwartz 2009 [87] |
| 2009 | PM10 levels by 5 year average, and distance of residence to major roadway. | Elderly women living in the Ruhr district and surrounding areas in Germany. | 399 | Mean age 74 years. | Participants age 74 + showed impaired performance in CERAD-plus, Stroop, and sniffing tests associated with increasing traffic exposure. | Ranft et al., 2009 [88] |
| 2010 | Air pollution index at residence. | Elderly from 22 different provinces in China. | 15,973 | 65 years or greater. | Residence in higher air pollution index areas associated with increased cognitive deficit by MMSE, decreased performance in activities of daily living, and increased cumulative deficits index. | Zeng et al., 2010 [78] |
| 2011 | Black carbon levels at residence. | United States male veterans in the Boston, Massachusettes area. | 680 | Mean age 71 years. | Each doubling of BC increases risk for MMSE score ≤ 25 OR 1.3. | Power et al., 2011 [79] |
| 2012 | Distance of residence to nearest major roadway and black carbon levels. | Seniors from Boston, Massachusettes area. | 765 | Mean age 78 years. | Distance of residence to major roadway inversely correlated with immediate and delayed recall on Hopkins Verbal Learning Test, trailmaking test performance, and letter and category fluency. Black carbon exposure associated with impaired immediate recall, but no other metrics. | Wellenius et al., 2012 [77] |
| 2012 | PM2.5 and PMcoarse at residence for the preceeding month, year, 2 years, 5 years, and since 1988. | Women residing in the United States | 19,307 | 70-81 (mean 74) years. | Cognitive decline determined by telephone interview for cognitive status per 2 year assessment period increased with highest quintile of exposure for both PM fractions. PM10 exposures long than the preceeding month associated with impaired cognition, PM2.5 only with exposure since 1988. | Weuve et al., 2012 [83] |
| 2014 | PM2.5 at residence averaged for 2004. | United States adults. | 13,996 | 50 years or greater. | Residence in areas with higher PM levels linked with reduced cognition by the telephone interview for cognitive status. | Ailshire and Crimmins 2014 [82] |
| 2014 | NO2, PM2.5, and Ozone levels at residence. | Elderly from the Los Angeles Basin area. | 1496 | Mean age 60.5 years. | High PM2.5 exposure associated with reduced verbal learning by California Verbal Learning Test. No other exposure showed significance. | Gatto et al., 2014 [80] |
| 2014 | PM2.5 and PM10 from traffic and all sources at residence. | London, England civil servants. | 2867 | Mean age 66 years. | 5 year decline in memory score with 20 word free recall test when examining only participants who remained in London between study points with all source exposures. | Tonne et al., 2014 [85] |
| 2015 | PM2.5 levels at residence. | United States adults. | 780 | 55 years or greater. | Reduced cognitive function as measured by errors on abbreviated Short Portable Mental Status Questionnaire associated with increasing PM exposure. | Aishire and Clarke 2015 [81] |
| 2015 | NOx, NO2, PM2.5, PM10, and traffic load within 100 m of residence. | Elderly women living in the Ruhr district and surrounding areas in Germany. | 789 | Mean age 73 years. | All exposures linked to decreased figure drawing scores in CERAD testing, however traffic exposure was only significant in those with at least one APOE ɛ4 allele. No other CERAD subtest showed significant change with any exposure. | Schikowski et al., 2015 [89] |
| 2016 | PM2.5 levels at residence. Neighborhood stressors were measured as a second variable. | United States adults. | 779 | 55 years or greater. | PM2.5 levels or high neighborhood stress alone were not correlated with increased errors on abbreviated SPMSQ, but exposure to both results in increased risk of errors. | Ailshire et al., 2017 [86] |
| 2017 | PM2.5 by satellite data and geocoding. | Adults in China, Ghana, India, Mexico, South Africa, and Russia. | 45,625 | Mean age 58 years. | Increased overall disability score by World Health Organization Disability Assessment Schedule | Lin et al., 2017 [84] |
| AD and dementia outcomes | ||||||
| 2015 | O3 and PM2.5 levels. | Elderly in Taiwan. | 95,690 | 65 years and older. | Strong association of both O3 (HR 3.11 per 10.91 ppb) and PM2.5 (HR 2.38 per 4.43 μg/m3) increases with AD incidence over follow up. | Jung et al., 2015 [11] |
| 2015 | 12 year PM10 and 14 year O3 exposure at residence. | Taiwanese retirees. | AD 249, VaD 125, Control 497. | 60 years or greater. | AD and VaD risk increased with higher exposure to either pollutant (OR highest vs. lowest exposure tertile AD 4.17 for PM, 2 for O3; VaD 3.61 PM and 2.09 O3). | Wu et al., 2015 [94] |
| 2016 | City of residence average PM2.5 from 1999 to 2010. | Medicare enrollees in the United States east coast. | 9,817,806 | 65 years or greater | Increased risk of PD (HR 1.08), AD (HR1.15), and dementia (HR 1.08) per 1 μg/m3 increase in airborne | Kioumourtzoglou et al., 2016 [93] |
| 2016 | Annual mean NOx concentrations at residence. | Residents in the area of Umeå, Sweden. | 1806 | 55–85 years | Increased risk of AD and VaD in highest exposure quartile vs. lowest (HR 1.38 AD, 1.47 VaD) | Oudin et al., 2016 [12] |
| 2016 | NOx, NO2, PM2.5, PMcoarse, and PM2.5 absorbance levels at residence. | Adults from the Ruhr area of Germany. | 2050 | 50–80 years. | PM2.5 levels associated with overall and amnestic MCI incidence (HR 1.16 and 1.22 per IQR), while PM 10 (1.07) and NO2 (1.13) were only associated with amnestic MCI risk. | Tzivian et al., 2016 [92] |
| 2017 | PM2.5 at residence. | Elderly women of European ancestry in the United States. | 3647 | 65–79 years | Exposure above 12 μg/m3 associated with increased cognitive delcine (HR 1.81) and dementia (HR 1.92) APOE allele status modulated risk. | Cacciottolo et al., 2017 [10] |
| 2017 | Distance of residence to nearest major roadway. | Residents of Ontario, Canada of at least 5 years. | 2,165,268 | 55 years or greater. | Living 200 m or closer to the nearest major roadway increased risk of dementia incidence, up to HR 1.07 when living within 50 m. Incidence of PD not affected. | Chen et al., 2017a [90] |
| 2017 | PM2.5, NO2, and O3 levels at residence. | Residents of Ontario, Canada of at least 5 years. | 2,066,639 | 55 years or greater. | Increase dementia incidence risk with PM2.5 (HR 1.04 per IQR increase) and NO2 (HR 1.1 per IQR increase), but not O3 exposure. | Chen et al., 2017b [91] |