Effect of Long-term Outdoor Air Pollution and Noise on Cognitive And

International Journal of Hygiene and Environmental Health 218 (2015) 111

Contents lists available at ScienceDirect

International Journal of Hygiene andEnvironmental Health

jo u r n al homepage: www.elsev ier .com/ locate / i jheh

Review

Effect o oispsycho

Lilian Tzi SchMohamm yra,a IUF-Leibniz Rb Department o yc Medical Faculd Swiss Tropicae University of

a r t i c l e i n f o

Article history:Received 2 June 2014Received in revised form 20 August 2014Accepted 26 August 2014

Keywords:Cognitive funcDepressionDementiaAir pollutionNoiseParticulate ma

a b s t r a c t

It has been hypothesized that air pollution and ambient noise might impact neurocognitive function. Earlystudies mostly investigated the associations of air pollution and ambient noise exposure with cognitivedevelopment in children. More recently, several studies investigating associations with neurocognitive

Introductio

While thtion and di2010; Rckthe effect oeven thougprominent challenges air pollutionet al. (2002of brain tissrespectively

CorresponE-mail add

http://dx.doi.o1438-4639/ tion

tter

function, mood disorders, and neurodegenerative disease in adult populations were published, yieldinginconsistent results. The purpose of this review is to summarize the current evidence on air pollution andnoise effects on mental health in adults. We included studies in adult populations (18 years old) pub-lished in English language in peer-reviewed journals. Fifteen articles related to long-term effects of airpollution and eight articles on long-term effects of ambient noise were extracted. Both exposures wereseparately shown to be associated with one or several measures of global cognitive function, verbal andnonverbal learning and memory, activities of daily living, depressive symptoms, elevated anxiety, andnuisance. No study considered both exposures simultaneously and few studies investigated progressionof neurocognitive decline or psychological factors. The existing evidence generally supports associationsof environmental factors with mental health, but does not sufce for an overall conclusion about theindependent effect of air pollution and noise. There is a need for studies investigating simultaneously airpollution and noise exposures in association mental health, for longitudinal studies to corroborate nd-ings from cross-sectional analyses, and for parallel toxicological and epidemiological studies to elucidatemechanisms and pathways of action.

2014 Elsevier GmbH. All rights reserved.

n

e associations of air pollution on cardiovascular func-sease have been shown in many studies (Brook et al.,ler et al., 2011), comparatively little is known aboutf long-term air pollution on neurocognitive function,h sustained neurocognitive function at older age is aelement of healthy ageing and will be one of the mainin our ageing societies. The rst link between ambient

and neurotoxicity was made by Caldern-Garciduenas). This work was based on a histological comparisonue from dogs, living in high- and low-pollution areas,. Dogs from highly polluted areas had more damages to

ding author. Tel.: +49 1522 9412016.ress: [email protected] (L. Tzivian).

the bloodbrain barrier, degeneration of cortical neurons, apoptoticglial white cells, non-neuritic plaques and neurobrillary tanglescompared to dogs from low-polluted areas. Since then, several epi-demiological and toxicological studies have investigated chroniceffects of air pollution and ambient noise on neurocognitive func-tion in children and adults.

Most of the epidemiological studies investigated whether theeffect of air pollution was related to the development of cogni-tion during childhood and possible changes of it in adolescence(Edwards et al., 2010; Freire et al., 2010; Perera et al., 2008;Siddique et al., 2011). Investigations on the effect of air pollutionon neurocognitive function in adults are still rare. In a recentreview, Guxens and Sunyer (2012) summarized studies on neuro-psychological effects of air pollution, including 12 children studies,and four studies of adult populations of which one concentratedon short-term air pollution effects. In the most current review(Block et al., 2012), six studies were related to neurocognitive

rg/10.1016/j.ijheh.2014.08.0022014 Elsevier GmbH. All rights reserved.f long-term outdoor air pollution and nlogical functions in adults

viana,, Angela Winklerb, Martha Dlugajb, Tamaraad Vossoughia, Kateryna Fuksa, Gudrun Weinma

esearch Institute for Environmental Medicine, Dsseldorf, Germanyf Neurology, University Hospital of Essen, University of Duisburg-Essen, Essen, Germanty, Heinrich Heine University of Dsseldorf, Dsseldorf, Germanyl and Public Health Institute, Basel, SwitzerlandBasel, Basel, Switzerlande on cognitive and

ikowskia,d,e, Barbara Hoffmanna,c

2 L. Tzivian et al. / International Journal of Hygiene and Environmental Health 218 (2015) 111

and psychological functions of adults. These reviews hypothesizeda potential role of air pollution on white matter lesions andcerebrovascular pathology in adults that can lead to cognitivechanges in adults. A role of PM in cognitive decits and behaviorimpairmen2012; Guxe

The assoless investinoise and n(Elmenhorseffect on irSalame andof the studibe related tand lead toVermeer an

Knowledneurocognihow particuhypothesizevates pro-incausing an iInammatolation and Hirano et aties in the a

The secovous systemPathologicastages of Al(UFP) wererons after e2008). Whiexposure adescribing paffecting ne

Recentlyrocognitiveand Calderoparticipantsations withnoise levelmay have cgistic effectdate whicheffects on nreview the and ambienneurocognidisease in a

Methods of

We perfambient airnitive functadults usinScholar. Losure duringdays or hoFor this seadisease, anfunction, coimpairmendisease, pe

noise exposure, particulate matter, particul*, ultrane particles,ne PM, trafc, alone and in combination. The exact searchhistory is available on request. An additional search was per-formed based on the references of the retrieved articles meeting

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g-terting f theckerre, tlongtternt in children and elderly was also proposed (Block et al.,ns and Sunyer, 2012).ciation of noise with neurocognitive function is evengated. Most studies on association between ambienteurocognitive functions measured short-term effectst et al., 2010; Schapkin et al., 2006) or investigated therelevant speech in adults (Clark and Srqvist, 2012;

Baddeley, 1982; Smith and Broadbent, 1992). In mostes, occupational and environmental noise was found too annoyance that can disturb normal human activities

somatic and psychosomatic health effects (Passchier-d Passchier, 2000).ge about biological pathways linking air pollution totive impairment is still scarce. Two possible pathways oflate matter PM can affect neurocognitive function wered (Genc et al., 2012). Respiratory intake of PM acti-ammatory cytokines in human macrophages, therebynammatory response and subsequent oxidative stress.ry compounds can spill over into the systemic circu-penetrate the bloodbrain barrier (Genc et al., 2012;l., 2003). This leads to different histological abnormali-nimal brain (Nemmar et al., 2001).nd pathway is related to direct entry of PM into the ner-

through the olfactory bulb following nasal inhalation.l changes in the olfactory bulb were observed in earlyzheimers disease (AD) (Doty, 2008). Ultrane particles

observed in human olfactory bulb periglomerular neu-xposure to air pollution (Caldern-Garciduenas et al.,le these pathways pertaining to long-term air pollutionre a major research subject, there is a lack of studiesossible pathways of long-term ambient noise exposureurocognitive functions., further epidemiological studies on long-term neu-

effects of air pollution and noise were published (Blockn-Garciduenas, 2009). These studies investigated adult, used multiple cognitive tests and explored associ-

various air pollutants and a wide range of ambients. As air pollution and ambient noise in many casesommon sources, such as trafc, they may have syner-s on neurocognitive function. There are no reviews to

integrate the studies on both air pollution and noiseeurocognitive function. The purpose of this article is toup-to-date articles investigating effects of air pollutiont noise on different aspects of mental health, namelytive function, mood disorders and neurodegenerativedult populations.

the search

ormed a literature search of articles relating long-term pollution and ambient noise with mental health (cog-ions, neurocognitive diseases and mood disorders) ing the two major search engines PubMed and Googleng-term exposure was dened as the average expo-

at least one year. Short-term exposures during theurs before outcome assessment were not included.rch, the following keywords were used: Alzheimersxiety, central nervous system, cognition, cognitivegnitive decline, depression, dementia, mild cognitive

t, mood disorders, neurocognitive effect, Parkinsonsripheral nervous system, vertigo, air pollution, noise,

the incstudiesexposuulationin Engfrom effects

Result

Thearticletions oof ambordersstudy (Six of 2013; Wellentherefo(2012)nitive aircraf

Study d

NinanalysanalyscasecWellenwith reIn thewere p187 wIn the was pevalue)conduwomeformed(Powe

Of noise ies pea case(Tableprospe(Yoshi2007),gated.

Exposu

Lonestimatime oup (Dotherefoin the use pan criteria. Inclusion criteria for the articles were: (1)ted to the effect of air pollution and ambient noiseon mental health; (2) studies related to adult pop-18 years old); (3) epidemiologic studies publishedlanguage in peer-reviewed journals. We excludedreview ecologic studies and studies on short-term

ature search was nished in November 2013. In total, 22e retrieved, of which 14 investigated long-term associa-ollution, and seven investigated long-term associationsnoise exposure on neurocognitive functions, mood dis-neurodegenerative disease in adults. Additionally, oneson et al., 2007) considered both, air pollution and noise.2 reviewed studies (Bocquier et al., 2013; Gatto et al.,ssen et al., 2013; Loop et al., 2013; Power et al., 2013;t al., 2012) were published within the last 2 years andere not included in the reviews of Guxens and Sunyer

Block et al. (2012); four of them analyzed neurocog-ts of air pollution, and twothe effects of trafc andse.

and exposures******

dies related to air pollution conducted cross-sectionalf those six studies were carried out as cross-sectional

ongoing cohort studies; two studies conductedl analysis (Table 1). In three studies (Lim et al., 2012;t al., 2012; Weuve et al., 2012), follow-up examinationsed assessments of cognitive function were performed.y of Lim et al. (2012), three follow-up examinationsmed, each 3 years apart, but from 560 participants onlyxamined all the three times during the study period.

by Wellenius et al. (2012), the follow-up examinationed approximately 16.8 months after baseline (median

he study by Weuve et al. (2012), a reexamination wasafter 4.3 years. Two studies were performed only innft et al., 2009; Weuve et al., 2012) and two were per-the same study population which included only menl., 2011, 2013).t studies investigating the association of long-termeurocognitive function or mood disorders, four stud-ed cross-sectional analyses, two studies conductedtrol analysis; and two studies were cohort studiesOne of them (Bocquier et al., 2013) had a retro-

design. One study was performed only in womend Osada, 1997). In one casecontrol study (Persson et al.,matic versus non-asthmatic participants were investi-

sessment

m air pollution exposure is mostly approximated byaverage exposure at the address of residence at the

outcome assessment or during the years of follow-y et al., 1993). The exposure contrasts investigated are,he spatial patterns of air pollution concentration which

run tend to be relatively stable due to similar land-s and long-term meteorology (Cesaroni et al., 2012;

L. Tzivian et al. / International Journal of Hygiene and Environmental Health 218 (2015) 111 3

Table 1Main characteristics of epidemiological studies exploring the association of long-term air pollution on cognitive and psychological functions in adults, by alphabetical orderof authors.

Authors, year ofpublication, country

Type of analysis Study population N(age)

Exposure Principal outcomes/tests Investigated cognitive andpsychological functions

Caldern-Garciduenaset al., 2004, Mexico

Cross-sectional N = 19 (51.2 4.9) PM, O3 Alzheimer like pathology; COX2and mRNA levels

Histological examinations

Caldern-Garciduenaset al., 2009, Mexico

Cross-sectional N = 87 (21.0 2.6) PM2.510, PM2.5 University of Pennsylvania smellidentication test (UPSIT)

Olfactory function

Chen and Schwartz,2009, USA

Cross-sectional N = 1764(37.4 10.9)

PM10, O3 Simple reaction time test (SRTT),Symbol-digit substitution test(SDST), Serial-digit learning test(SDLT)

Attention and informationprocessing speed, verbalmemory

Finkelstein and Jerrett,2007, Canada

Casecontrol N = 52,986 (notavailable)

NO2, Ambient Mn l-DOPA prescription; physiciansdiagnosis of Parkinson disease (PD)

Gatto et al., 2013, USA Cross-sectional N = 1496(60.5 8.1)

O3, NO2, PM2.5 Boston Naming Test, Symbol digitmodalities test, Trail Making Test(TMT) A/B, Letter-numbersequencing, Animal naming,California verbal learning test,Paragraph recall, Faces, Blockdesign, Judgment of lineorientation

Attention, informationprocessing speed,confrontation naming,executive functions, verbalmemory, nonverbalmemory, visuoconstruction

Lim et al., 2012,Republic of Korea

Longitudinalfollow-up 3 years

N = 357 (71.0 5.0) PM10, CO, SO2, NO2,O3

Korean version of the Geriatricdepression scale-short form(SGDK-K)

Depressive symptoms

Loop et al., 2013, USA Cross-sectional N = 20,150(64.0 9.2)

PM2.5 Incidence of cognitivedeclineSix-Item Screener

Persson et al., 2007,Sweden

Casecontrol N = 22,693(43.0 13.0)

NOx, Woodburning; industrialsmells

Psychic trait anxiety score Anxiety

Power et al., 2011,USA

Cross-sectional N = 680 (71.0 7.0) BC Mini-Mental State Examination(MMSE), Pattern comparison task,Digit span backward test,Long-term verbal immediate recall(IR) and delayed recall (DR),Constructional praxis

Attention, workingmemory, long-term verbalmemory(immediate/delayed recall,consolidation andrecognition),visuoconstruction, globalcognition

Power et al., 2013, USA Cross-sectional N = 629 (70.0 7.1) BC MMSE, Pattern comparison task,Digit span backward test,Long-term verbal IR and DR,Constructional praxis

Attention, workingmemory, long-term verbalmemory,visuoconstruction, globalcognition

Ranft et al., 2009,Germany

Cross-sectional N = 399 (74.1 2.6) PM10 Neuropsychological CERAD-Plusbattery: MMSE, TMT, Stroopcolor-word test, long-term verbalIR and DR, Constructional praxis,DR of gures

Attention, informationprocessing speed,confrontation naming,executive functions, verbalmemory, nonverbalmemory,visuoconstruction, globalcognition, depression,olfactory function

Sun and Gu, 2008,China

Cross-sectional N = 7358(83.6 11.4)

API** MMSE; Activity of daily living(ADL); Self-reported health

Global cognition,satisfaction with health,ability to perform everydayactivities

Wellenius et al., 2012,USA

Cohort follow-up(median), 16.8years

N = 765 (78.1 5.4) Proximity tonearest road, BC

MMSE; Hopkins verbal learningtest-revised (HVLT-R); TMT;Clock-in-the-box test (CIB);Category and letter uency tests

Global cognition,long-term verbal memory,attention and informationprocessing speed,executive functions,cognitive exibility,divided attention

Weuve et al., 2012, USA Cohort follow-up4.3 years

N = 10,409(74.0 2.2)

PM10; PM2.5,Coarse PM

Telephone interview for cognitivestatus (TICS); 10-Words DR; EastBoston memory test (EBMT);Category uency; Digit spanbackward test, modied MMSE

Global cognition, long termverbal memory, executivefunctions

Zeng et al., 2010, China Cohort follow-up 7years

N = 15,873 (86.3) API** ADL; MMSE; cumulative decitsindex (DI); telephone interview forcognitive status, Self-reportedhealth

Global cognition, ability toperform everydayactivities, satisfaction withhealth

*Additionally other environmental factors were measured.**Air pollution index that includes SO2, NO2, PM10, CO, O3.


Table 2Main characteristics of epidemiological studies exploring the association of ambient noise on cognitive and psychological functions in adults.

Authors, year of publication,country

Type of analysis Study population N Exposures Principal outcomes/tests Investigated functions

Bocquier et 6h#

Brand et al., oise

Brink, 2011, fc;; aircr

Chiovenda e vel fo

Franssen et LAEQ, 2, 22-23

Hardoy et al noise

Persson et a soundrs; traentila

Yoshida and

*Restricted to # LAEQequiva## LDENday, e

Wang et al.tory of parinto accounstudies (Caviduals fromin low-pollZeng et al.,low, mediuair pollutioDatabase.

Eleven sdifferent tecmeasured cand Schwar2009), threitoring statPersson et use regressof residentiet al., 2012;studies useroad or prosure to trafWellenius e

Particulalate matter most frequethem was pet al., 2007from industthe studiespollution indioxide (SOand O3 was

biens (Past cof th

(Fraoise. al., 2013, France Retro-prospectivelongitudinal follow-up1 year

N = 190,617(41.5 12.5)

LAEQ, 22-

2009, Switzerland Qualitative-quantitativecasecontrol

N = 63 (56.4 16.0) Trafc n

Switzerland Longitudinal follow-up5 years

N > 8000 (45.2) Road trarailwaynoise

t al., 2007, Italy Cross-sectional N = 81 (42.2 7.7) Noise le8 h/day

al., 2013, Netherlands Cross-sectional N = 11,812 (>18.0) LDEN##;h#; LAEQ

., 2005, Italy Cross-sectional N = 355 (1875) Aircraft

l., 2007, Sweden Casecontrol N = 22,693(43.0 13.0)

LDEN##, neighbonoise; v

Osada, 1997, Japan Cross-sectional N = 366 (20.0-60.0) LDEN##

psychological outcomes.lent sounds levels calculated over the corresponding time period.vening, night equivalent sound level over 24 h.

, 2013). In most studies, the individual residential his-ticipants before the outcome assessment is not takent. Four studies exploited contrasts between cities: twoldern-Garciduenas et al., 2004, 2009) compared indi-

highly polluted cities with those from communitiesution areas. The two other studies (Sun and Gu, 2008;

Amsourcethe moSeven studiescraft n 2010) compared participants living in the cities withm and high gross domestic products, using citywiden indices obtained from the Chinese Natural Resources

tudies exploited within-city exposure contrasts usinghniques, alone or in combination. Four studies assignedoncentrations from the nearest monitoring site (Chentz, 2009; Lim et al., 2012; Loop et al., 2013; Ranft et al.,e studies interpolated residential exposure from mon-ions using GIS-based techniques (Gatto et al., 2013;al., 2007; Weuve et al., 2012), ve studies used land-ion models to estimate small-scale spatial contrastsal exposure (Finkelstein and Jerrett, 2007; Wellenius

Power et al., 2011, 2013; Ranft et al., 2009) and threed trafc indicators such as proximity to the nearestximity to high trafc as markers of long-term expo-c-related air pollution (Finkelstein and Jerrett, 2007;t al., 2012, Ranft et al., 2009).te matter less than 2.5 m in diameter (PM2.5), particu-less than 10 m in diameter (PM10) and ozone (O3) werently investigated in the reviewed studieseach one ofresented in four different studies. One study (Persson) investigated exhaust fumes, wood burning and smellrial production without specifying the PM fractions. In

of Sun and Gu (2008) and Zeng et al. (2010), an airdex (API) assessing combined concentrations of sulfur2), nitrogen dioxide (NO2), PM10, carbon monoxide (CO)

used.

from neighTrafc noismental noiet al., 2007,et al., 2009databases (surrogate mexposure mequivalent during the ies, noise l(Bocquier estudy (Chioofcers wercraft noise e2013; Hardaddressed tegories of 5mathemati

Outcome as

In mostogical testsdomains, sufunctions, wterm noisemostly useMean number ofanxiolytic-hypnotic purchases

Migraine; headache; depressivedisorders; anxiety disorders*

Emotional status

aftSelf-reported health* Satisfaction with

health

r Digit span forward WAIS-R;attentive matrices; Digit spanbackward; arithmetic reasoning;Raven PM38; Stroop color-wordtest; State-trait anxietyinventory; prole of moodstates*

Attention andinformationprocessing, executivefunctions, workingmemory, inhibition,verbal memory,emotional status

3-7

h#

Self-reported healthquestionnaire (VOEG)*

Satisfaction withhealth

Generalized anxiety disorder(GAD); anxiety disorder nototherwise specied (NOS); majordepressive disorder; depressivedisorder NOS; eating disorder

Emotional status

fromfction

Psychic Trait Anxiety score * Emotional status

General nuisance, interferencewith daily activities,psychological symptoms*

Satisfaction withhealth

t chronic noise is the sound generated by environmentalsschier-Vermeer and Passchier, 2000). Road trafc wasommonly investigated environmental source of noise.e eight studies investigated road trafc noise and twonssen et al., 2013; Hardoy et al., 2005) investigated air-In one study (Franssen et al., 2013), the additional noise

borhood and from ventilation systems was assessed.e assessment was performed using dedicated environ-se prediction models (Bocquier et al., 2013; Persson

Yoshida and Osada, 1997), direct measurements (Brand), mandatory noise mapping available through ofcialBrink, 2011; Chiovenda et al., 2007), or by the use ofarkers such as occupation. Most commonly, the noiseetrics dayeveningnight noise level, dened as the

sound level over 24 hLDEN (Leq(24 h)), or the noise levelnight period (226 h)LNIGHT were used. In three stud-evels were stratied for analysis to groups of 5 dB(A)t al., 2013; Brink, 2011; Yoshida and Osada, 1997). In onevenda et al., 2007), high road trafc noise exposed policee compared to low noise exposed ofce employees. Air-xposure for two cross-sectional studies (Franssen et al.,oy et al., 2005) was assessed by proximity of residentialo the nearest airport, and additionally stratied into cat-

dB(A), derived from the National Aerospace Laboratorycal noise model (Franssen et al., 2013).

sessment

of the studies related to air pollution, neuropsychol- investigating the impairment of different cognitivech as working memory, verbal memory or executiveere used. Studies investigating the association of long-

exposure with the central nervous system functionsd different assessment methods than studies on air


pollution. Only two cognitive tests (Digit span test and Stroopcolor-word test) were used both in air pollution and noise stud-ies, making direct comparisons between air pollution and noiseeffects difcult. Few studies investigated mood disorders, clinicaldiagnosis o

Most stusensitivity tMini-Menta2011, 20132012; Weu30-item selassessed wItem ScreenIn this test,orientation

Among tion and infrequently. 2013; Ranftof targets hcorrectly peof attentionpattern comstitution tetest (Chen athe symbolattention anused to cheeffects is thtest assesse

Anotherbal memorywords) thatpant (GattoWellenius etrial, the nuof verbal mlist, the parwords (delarecognitionshown to thously learnefor verbal iand needs tusing a storined using study of Cheassessed wiof eight num

Some stufor nonverb2009) and frecall test ccommon rof the facessented, andrecognized ticipants.

The exaoutcome innitive exibTrail Makinet al., 2012)in order witnumber of exibility a

assessed using a semantic category test in which a high numberof items generated for the same category (for instance, animals)indicated a 2012; Weu

phoe nure ofd w

et aand tcase,rgansesset, thelor nk insred. ithm

cognral st2013

or eral ss nsis optionn-Gmatimonino anal sfactocatio

ility -item

cogew snal ance

press009

logicic Deinclutivity

usinvssony-relontrxiet

Hard Mea2013State

ivity heck010, or o

at letrast, addplaied.

(Brn onf disease, medication intake or pathological ndings.dies used comprehensive, but unspecic tests with lowo assess global cognitive function. In seven studies, thel State Examination (MMSE) was used (Power et al.,; Ranft et al., 2009; Sun and Gu, 2008; Wellenius et al.,ve et al., 2012; Zeng et al., 2010), which consists of af-administered questionnaire, and which can also beith a telephone interview. One study applied the Six-er to assess global cognitive function (Loop et al., 2013).

three items have to be recalled, and additionally the to year, month and day of the week was checked.more specic test of neurocognitive domains, atten-formation processing speed was investigated mostSeveral studies used the Trail Making Test A (Gatto et al.,

et al., 2009; Wellenius et al., 2012), in which a numberave to be connected in the correct order. The number ofrformed connections during certain time was a marker

and psychomotor speed. Other studies applied a test onparison (Power et al., 2011, 2013), a symbol-digit sub-

st (Chen and Schwartz, 2009), a simple reaction timend Schwartz, 2009) and a complex attention test like

digit modalities test (Gatto et al., 2013) to check thed memory of participants. An additional test that wasck participants attentive capacity in studies of noisee attentive matrices test (Chiovenda et al., 2007); thisd information processing as well.

frequently tested domain of cognitive function is ver-. It was in most cases assessed using word lists (1016

were presented once or several times to the partici- et al., 2013; Power et al., 2011, 2013; Ranft et al., 2009;t al., 2012; Weuve et al., 2012). After every learningmber of immediately recalled words serves as measureemory. After a delay and/or an additional interferenceticipants were asked to recall the previously learnedyed recall). Furthermore, most researchers included a

trial at the end of the test in which a list of words wase participants, and asked which ones were on the previ-d list. One study (Gatto et al., 2013) examined memory

nformation that exceeds the immediate memory spanhe contribution of meaning to retention and recall byy recall test. In this study comprehension was exam-recall questions and multiple-choice questions. In then and Schwartz (2009), short-term verbal memory wasth a serial-digit learning test by reproducing a sequencebers.dies additionally examined the memory performanceal material like previously drafted gures (Ranft et al.,aces (Gatto et al., 2013). Faces immediate and delayedonsisted of 16 colored pictures of faces together withst and family name were presented. Later recognition

was checked using 12 faces from 16 that were pre- additional 12 distracted faces. The amount of correctlyfaces was a marker of visual episodic memory of par-

mination of executive function was another main many studies, assessed with various specic tests. Cog-ility and divided attention were measured using theg Test B (Gatto et al., 2013; Ranft et al., 2009; Wellenius. In this test, a number of targets need to be connectedh numerous letter targets on alternating sequence. Thecorrectly performed connections measured cognitivend divided attention of participants. Verbal uency was

using atest, thmeasuassesseWeuve2013) latter ning, owas asthis tesin a coblue inmeasuwas ar

Thein seve2011, design

Sevto assediagnoprescriCalderinamples. A42-amadditiothe olIdentipossibized 40in mild

A fadditiodisturbsis. Deet al., 2demioGeriatrwhich and ac(2007)(Gustaanxiet

In cined an2007; 1997).et al., Mood only.

Actwere cet al., 2factorshavingin constudiescal comexaminstudiesliving ibetter performance (Gatto et al., 2013; Wellenius et al.,ve et al., 2012). Similarly, verbal uency was checkednematic category test (Wellenius et al., 2012). In thismber of words beginning with a given letter served as

phonematic uency. Moreover, working memory wasith the digit span backwards (Power et al., 2011, 2013;l., 2012), a letternumber sequencing task (Gatto et al.,he Clock-in-the-Box test (Wellenius et al., 2012). In the

not only examining working memory, but also plan-ization and visuoconstruction were tested. Inhibitiond with the Stroop color-word test (Ranft et al., 2009). In

name of a color (e.g., blue, green or red) is printedot denoted by the name (e.g., the word red printed intead of red ink), and a reaction time to name a color isAn additional outcome used in studies of noise effectsetic reasoning (Chiovenda et al., 2007).itive domain of visual construction was also assessedudies (Gatto et al., 2013; Ranft et al., 2009; Power et al.,) using the Judgment of Line Orientation task, blockgure drawing (constructional praxis).studies used clinical diagnoses or pathological ndingservous system effects of air pollution. A physiciansf Parkinsons disease (PD) and related medication

was investigated in Finkelstein and Jerrett (2007).arciduenas et al. (2004) investigated postmortem brainon and Alzheimer like pathology in autopsy brain sam-g others, cyclooxygenase-2 (COX2) expression and thecid form of -amyloid (A42) were examined. In antudy performed by Caldern-Garciduenas et al. (2009),ry functions using University of Pennsylvania Smelln Test (UPSIT) test were investigated as a marker of

of AD. This test includes self-administrated standard-s, of which 10 items strongly predict conversion to AD

nitive impairment (MCI) patients.tudies also investigated mood disorders, either asoutcomes or to statistically control for psychologicals in the air pollution-neurocognitive function analy-ion was assessed in two studies (Lim et al., 2012; Ranft). It was identied by application of the Center of Epi-al Studies Depression Scale (Ranft et al., 2009) or of thepression Scale-Short Form (SGDS-K) (Lim et al., 2012),des questions about general life attitude, satisfaction. Anxiety was investigated in the study of Persson et al.g the Swedish Universities Scales of Personality score

et al., 2000) that summarizes positive answers to sevenated statements.ast to air pollution studies, most noise studies exam-y and depression (Bocquier et al., 2013; Chiovenda et al.,oy et al., 2005; Persson et al., 2007; Yoshida and Osada,n number of anxiolytic-hypnotic purchases (Bocquier), the State-Trait Anxiety Inventory and the Prole of

(Chiovenda et al., 2007) were assessed in noise studies

of daily living and instrumental activities of daily livinged in two air pollution studies (Sun and Gu, 2008; Zeng). These self-reported activities included personal-careutdoor possibilities. For these instruments, participantsast one activity limitation were dened as disabled,

to persons without any disabilities. In these Chineseitionally self-reported health, as a number of physi-nts (e.g. back pain) and symptoms (e.g. tiredness), wasSelf-reported health was also investigated in two noiseink, 2011; Franssen et al., 2013), and activity of dailye study (Yoshida and Osada, 1997).


Reported associations

The reviewed studies reported their results in a very heteroge-neous way (Table 3). Even if the same instruments were used, theresults wercomparisonanalysis of

Association In 10 stu

formance wperformancperformancLongitudinaa positive cindex (API)supported bpopulation (Zeng et al.,outcome asassociated 18 determin

Similar rmatter withGeographic20,150 aduof PM2.5 onand mixed (were suppoStudy Cogntion of highdecline wa4.3 years. Ghighest ver

Inconsiseffect of pawas associaanalysis of tversus LateUS Americalevels weretion processand socio-eNational HeUSA residen

Associatshowed incof Gatto et cognitive fucic cognitiincreasing utive functiassociated wwas associaanother croterm exposattention aeven after health covation assessmsuch incons

Associatnitive functto the nearestudies shoPower et a

(NAS) cohort participants, an adverse association between BC con-centration and global cognitive function assessed by MMSE testwas found. This adverse effect of BC on cognitive function wasfound predominantly in overweight and obese individuals (p of

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ociattudie013;e generally not presented in a way that allows direct between studies. This prohibits a systematic meta-results.

with air pollutiondies, the effect of ambient air pollution on cognitive per-as investigated. In the earliest studies, global cognitivee tests were used. In the rst study on global cognitivee conducted in 7358 Chinese adults from the Chinesel Health Longevity Survey (CLHLS) (Sun and Gu, 2008),ross-sectional association of the citywide air pollution

with reduced MMSE was found. These results werey a consecutive longitudinal analysis in a larger sub-

of 15,873 participants from the same CLHLS population 2010), using similar methods both for exposure and forsessment. A one unit increase in API in this study waswith a 0.9% increase in odds for MMSE score less thaned as cognitive impairment.esults were obtained for the association of particulate

cognitive functions in the cross-sectional Reasons for and Racial Differences in Stroke (REGARDS) study oflts in USA (Loop et al., 2013), where a signicant effect

incidence of cognitive decline was observed for urbanurbanrural) areas, but not for rural areas. These resultsrted by the longitudinal analysis of the Nurses Healthitive Cohort (Weuve et al., 2012), in which an associa-er levels of PM2.5-10 and of PM2.5, with global cognitives found in 10,409 women over a follow-up period oflobal cognitive decline was signicantly bigger in thesus lowest quintile of exposure.tent results were found in studies investigating therticulate matter on specic cognitive domains. PM2.5ted with lower verbal learning in the cross-sectionalhe Women Isoavone Soy Health Trial (WISH) and Early

Intervention trial With Estradiol (ELITE) study of 1499n adults (Gatto et al., 2013). In contrast, increased PM10

not associated with reduced attention and informa-ing speed and verbal memory after adjustment for raceconomic status (SES) in the cross-sectional study of thealth and Nutrition Examination Survey study of 1764ts (Chen and Schwartz, 2009).ions of gaseous pollutants with cognitive function alsoonsistent results. Although in the cross-sectional studyal. (2013), O3 and NO2 were not associated with globalnction, they were associated with the functions of spe-ve domains. In this study at high O3 levels (49 ppb),ozone concentration was associated with lower exec-on, while at the intermediate level (3449 ppb) it wasith higher logical memory. Exposure to ambient NO2

ted with lower logical memory (Gatto et al., 2013). Inss-sectional study (Chen and Schwartz, 2009), long-ure to high levels of O3 was associated with a lowernd information processing speed and verbal memory,adjustment for age, sex, gender, SES, life-style andriates. Differences in tests applied for cognitive func-ent in these two studies can be a possible reason for

istent results.ions of other trafc-related exposures with global cog-ion were investigated in four studies, using proximityst road and concentration of BC as exposures. All thesewed similar results. In two cross-sectional studies ofl. (2011, 2013) performed on Normative Aging Study

interacHowevtensionseen. Iet al., 2MMSEnitive MMSEticipanyears. in cogwas pethe InAging in womWellen

Thediseaseies of Alzheiair polsion afound concencentra

Assdepresin fourcompanicanNOx costudy, cultieseatingclotheassociawere sing thein activet al., 2ciationcities wthose tigatedof Korwere foPM10 aThe asof hypwere fdisease

AssociaOnl

tive fuworkefound the Strlevel.

Assthree set al., 2 = 0.1) and in ever smokers (p for interaction = 0.07).o evidence for effect modication by diabetes, hyper-oking or body-mass index (BMI) on the MMSE score was

MOBILIZE Boston Study of 765 participants (Wellenius, an increase in BC level was also associated with loweres and worse performance of additional specic cog-. Proximity to major road was associated with a lower

affected only a part of the other cognitive tests in par-ith at least college education and those younger than 77c exposure was associated with reduced performance

tests as well in the study of Ranft et al. (2009) thatmed on 399 Germany women, a part of the Study ofce of air pollution on Lung function, Inammation andA) cohort. In this study, the association was not presentlder than 74 years, which corresponds to the study oft al. (2012).ciation of air pollution with two neurodegenerativeD and PDwas investigated in three studies. Two stud-ern-Garciduenas et al. (2004, 2009) indicated more-related changes in individuals with higher exposure ton (reduced olfactory functions, increased COX2 expres-ccumulation of A42). Finkelstein and Jerrett (2007)sociation with prevalence of PD only for an increasedon of ambient manganese (Mn), but not for NO2 con-.ions of air pollution with mood disordersanxiety and, and with activities of daily livingwere investigatedies. In the casecontrol study of Persson et al. (2007)22,693 asthmatic and non-asthmatic participants, a sig-ociation of exhaust fumes from trafc approximated bytrations with anxiety was found. In a cross-sectionalnd Gu (2008) found that API was associated with dif-

oping with personal care activities (bathing, dressing, instrumental activities (cooking, shopping, washingis study also showed poor self-reported health to bewith an increase in air pollution index. These resultsrted by the longitudinal study of Zeng et al. (2010), link-with poor self-reported health and increased difcultiesf daily living at 4.3 years over a follow-up period (Zeng. However, in the study of Sun and Gu (2008), the asso-PI with activity of daily living were found only for the

high gross domestic product (GDP), and not found for low GDP. An association with depression was inves-he longitudinal study in 357 inhabitants of Republicim et al., 2012). Increased levels of PM10, O3 and NO2

to increase the emotional symptoms of depression, andionally increased the somatic and affective symptoms.tion with O3 was stronger in participants with a historydemia than among those without, and little differences

between participants with and without cardiovascularD) or myocardial infarction (Lim et al., 2012).

with noise study investigated the association of noise with cogni-ns in 81 police ofcers from high trafc areas and ofceiovenda et al., 2007). A signicant effect of noise wasithmetic reasoning, difculties in logical reasoning andolor-word test adjusting for gender, age and education

ions of noise with health status were investigated ins, reporting inconsistent results (Brink, 2011; Franssen

Yoshida and Osada, 1997). In the earliest cross-sectional


Table 3Results of studies on long-term air pollution and noise effect on cognitive and psychological functions in adults, by outcome.

Authors, year of publication Covariates Obtained results*

Effect of air pollutionNeurocognitive assessmentCognitive functionsSun and Gu, 2008 P, L, E 1 unit air pollution index (API): For high gross domestic product (GDP): MMSE score = 2.67,

p < 0.001. For medium GDP: MMSE score = 1.84, p < 0.001Chen and Schwartz, 2009 P, L, H Increased PM10: SDLT =0.48, 95% CI 0.270.68; SDST = 0.10, 95% CI 0.050.15. After adjustment

for race and SESnon-signicant effect. Increased O3: SDST = 0.11, 95% CI 0.010.22; SDLT = 0.52, 95% CI 0.031.01

Ranft et al., 2009 P, L, H, E Trafc exposure: CERAD-plus battery b = 3.8, p < 0.1; Stroop test b = 5.1, p < 0.01; Snifng testb = 1.3, p < 0.05 (age 74). No independent effect of PM10

Zeng et al., 2010 P, L 1 unit API: cognitive impairment OR = 1.009, p < 0.05Power et al., 2011 P, L, H BC (doubling concentration, g/m3): MMSE OR = 1.3, 95% CI 1.11.6Wellenius et al., 2012 100 m from major road: MMSE < 26 for at least college education OR = 1.54, 95% CI 1.102.17; for

77 years OR = 1.34, 95% CI 1.011.76. Not associated with HVLT-R recognition, TMT Part A ad CIB.Interquartile increase in BC (0.11 g/m3): MMSE < 26, OR = 1.15, p = 0.06; worse performance ofHVLT = R immediate recall, p = 0.046

Weuve et al., 2012 P, L PM2.510: worse global cognitive score (p for trend 0.01); worse for highest vs. lowest level(p = 0.003). Highest vs. lowest quintile of PM2.5: changes in global cognitive score for women(p = 0.03). Global cognitive score (SD/2 years) per 10 g/m3 increment: PM2.510 0.020 (95% CI0.32 to 0.008); PM2.5: 0.018 (95% CI 0.035 to 0.002)

Gatto et al., 2013 P, L None association with global cognition. Per 10 g/m3 PM2.5: lower verbal learning ( = 0.32,p = 0.05). NO2 > 20 ppb: lower logical memory ( = 0.62, p = 0.095). O3 > 49 ppb: lower executivefunction ( = 0.66, p = 0.059). O3 range 3449 ppb: higher logical memorywomen ( = 0.46, 95%CI 0.090.83), adults 60 y. o. ( = 0.51, 95% CI 0.110.91)

Loop et al., 2013 P, L, H, E Per 10 g/m3 PM2.5: for urban areaincident cognitive impairment OR = 1.40 (95% CI 1.061.85);for mixed areasincident cognitive impairment (OR = 0.32, 95% CI 0.110.98). No associations forrural area and total population

Power et al., 2013 P, L, H BC (doubling concentration, g/m3): for lacked an HFE C282Y low MMSE (OR = 1.37, 95% CI1.081.73); for at least one HFE H63D variant (OR = 1.74, 95% CI 1.06, 2.87). HFE C282 modies theassociation between BC and global cognitive function

Neurodegenerative diseasesAlzheimers diseaseCaldern-Garciduenas et al., 2004 Frontal cortex tissue: Elevation of COX2 mRNA in high-exposure group (p = 0.009); elevation of

COX2 immunoreactivity (p = 0.01). Hippocampus tissue: Elevation in COX2 mRNA in high-exposuregroup (p = 0.045); no differences in COX2 immunoreactivity between high and low-exposuregroups (p = 0.37)

Caldern-Garciduenas et al., 2009 Mean UPSIT scores lower for high-exposure group (p = 0.03). No differences in UPSIT scores indifferent APOE statuses (p = 0.52)

Parkinson disease (PD)Finkelstein and Jerrett, 2007 P 10 g/m3 increases in Mn: PD or Dopa prescription for men OR = 1.041, 95% CI 0.9971.09; for

female: OR = 1.035, 95% CI 0.971.10. With type of clinic as confounder OR = 1.044 (95% CI1.001.09)

Activity of daily living and mood disordersAnxietyPersson et al., 2007 P, H Exhaust form trafc: anxiety OR = 1.66, p = 0.001Activity of daily livingSun and Gu, 2008 P, K, E 1 unit API: For high GDP: difculties in ADL ( = 1.41, p < 0.01); instrumental ADL ( = 0.98,

p < 0.001), self-related health (OR = 2.20, p < 0.001). For medium GDP instrumental ADL = 0.6,p < 0.001, self-related health, (OR = 1.87, p < 0.001), no associations with ADL

Zeng et al., 2010 P, L 1 unit API: increased ADL disability (25%, p < 0.001); increased health decits (8%, p < 0.05)DepressionLim et al., 2012 P, L, H Interquartile increase of PM10: Increase in composite score of emotional symptoms: 38.2%, p < 0.01,

NO2 118.2%, p < 0.05. Increase in somatic symptoms score 38.9%, p < 0.05. Increase in affectivesymptoms score 11.5%, p < 0.01. O3: Increase in composite score of emotional symptoms 132.5%,p < 0.05

Effect of noiseNeurocognitive assessmentCognitive functionsChiovenda et al., 2007 P Differences between police ofcers from high trafc areas and ofce workers: Raven PM38

(t = 3.24, p = 0.002); arithmetic reasoning (t = 2.30, p = 0.024), Stroop color-word test (t = 2.02,p = 0.047)

Activity of daily living and mood disordersActivity of daily livingYoshida and Osada, 1997 P Noise 70 dB(A): appetite loss (OR = 5.2***)AnxietyHardoy et al., 2005 General anxiety disorder OR = 2.0 (95% CI 1.04.2); Anxiety disorder NOS OR = 2.9 (95% CI 1.04.1)Persson et al., 2007 P Associated with anxiety: trafc noise 55 dB(A), OR = 1.32, p = 0.009; sound from neighbors

OR = 1.47, p = 0.001; trafc vibration OR = 1.37, p = 0.042; sound (other) OR = 1.72, p = 0.003. Soundfrom ventilation not associated with anxiety

General nuisanceYoshida and Osada, 1997 P Noise 70 dB(A): OR = 5.2***Brand et al., 2009 Difference between groups with different noxious environment (X2 = 34.0, p < 0.001)**DepressionYoshida and Osada, 1997 P Noise 70 dB(A): OR = 2.9***

Hardoy et al., 2005 P Major depressive disorder and depressive disorder NOSnot related to aircraft noise


Table 3 (Continued)

Authors, year of publication Covariates Obtained results*

Bocquier et al., 2013 P, H Censors blockneighborhood environment: low deprivation, intermediate deprivation, highdeprivation. Regardless deprivation: RR = 1.33 (95% CI 1.021.24) for LAEQ, 22-6 h# 55 dB(A). For

ow deate anations

Health statuYoshida and e OR =Brink, 2011 d modFranssen et ted to

61, (95I 1.26% CI 1

Ppersonal fa hnicitchildren, coun ng, exBMI. Hhealth , diabehypertension, olluti*Results relate**Results are r***Condence# LAEQequiva## LDENday, e

study perfowomen, an status, adjuhouse was only effect inhibiting adinal studyyears of follels was fouroad noise Lstatus and sFrassen et astatus and within a radwas observand LDEN health. Highand tirednedegree of uOsada (199

Three stsion (Yoshid2005). Yoshciated withbeing a criti190,617 Fredepressive of low sociointermediasignicant. disordersotherwise sin the crossthe effect ovicinity of Ecities or rur

While Hsion, anxietnoise (Hardand no accinhibits a cbetween aigated in a cno signica

er rod soted ted

tionsdies on n. Onlf boiffertion

noistion

ssion

his rend snt asoods th, andunctre oisenLAEQ, 22-6 h# 55 dB(A) in l70 dB(A), with the noise level of 70 dB(A)cal threshold. Bocquier et al. (2013) found in a cohort ofnch that the effect of trafc noise on purchase of anti-

howevtion anassociaassocia

AssociaStu

noise scarceation owith dassocialution,interac

Dis cu

In t2013 adifferetion, mexpand(2012)nitive fexposufar to ddrugs was only positive in participants living in areaseconomic deprivation, while for participants living in

te and high deprivation areas such an effect was non-In contrast to these studies, two forms of depressivemajor depressive disorder and depressive disorder notpeciedwere not found to be related to aircraft noise-sectional study of Hardoy et al. (2005). In this study,f aircraft noise was investigated in people living in thelmas airport in contrast to a sample of people living inal or mining villages of Italy.ardoy did not nd associations of noise with depres-y disorders were found to be associated with aircraftoy et al., 2005). No multiple models were constructedurate noise levels were specied in this study, whichomparison with other mentioned studies. Associationrcraft noise and anxiety disorders were also investi-asecontrol study of Persson et al. (2007) that foundnt effect of aircraft noise on the trait anxiety (p = 0.101),

and outcomexpand the

All preseand noise wleast for onations diffein the cognet al., 2013)in air pollutcomes wasassociationdepressionair pollutiolittle, mostexposures s

Differenmental heaTill now, tprivation level RR = 1.16 (95% CI 1.011.32) (reference LAEQ, 22-6 h#

d high deprivation and for other noise levels (4550 andnon-signicant effect

3.0***. No associations with listlessnessel

noise exposure during the night. Noise 60 dB(A): poor% CI 1.012.56). LDEN##: headache (OR = 1.16, 95% CI 1.011.34),1.70), listlessness (OR = 1.17, 95% CI 1.011.36), not fully rested in.031.41). Remaining seven complainsnon-signicant

y, childhood SES, education level, marital status, number of survivingercise, leisure activities, dark sh consumption, computer experience,tes, incident stroke, presence of depressive symptoms, dyslipidemia,on, temperature, season.

ad trafc noise, sounds from neighbors, trafc vibra-und from other sources were shown to be signicantlywith anxiety. Sound from ventilation systems was notwith anxiety.

with air pollution and noiseinvestigating the concurrent effects of air pollution andeurocognitive outcomes in the same population arey one of the reviewed studies investigated the associ-th air pollution and trafc noise (Persson et al., 2007)ent aspects of mental health in the same study. Thes were calculated for each one of the exposures (air pol-e) separately. However, possible synergistic relations ors between these two exposures were not investigated.

view, we analyzed 22 studies published until Novemberummarized the effect of environmental exposures onpects of mental health, namely neurocognitive func-

disorders and neurodegenerative disease. This reviewe works of Guxens and Sunyer (2012) and Block et al.

supports a possible role of air pollutants on neurocog-ion in the adult population and a role of long-term noisen mood disorders. However, no evidence is available sotangle the effects of these two closely related exposures

es. In this review, we add newly published studies and

investigated outcomes.nted studies, assessing the association of air pollutionith neurocognitive functions, found an association at

e of the investigated pollutants. However, these associ-red in effect size (Gatto et al., 2013; Loop et al., 2013) anditive domain that showed positive associations (Gatto

and are therefore not easily comparable. Additionally,ion studies, an association with AD- and PD-related out-

observed for highly exposed participants. A positive of air pollution and noise was also found for anxiety,

and impaired activities of daily living. Associations ofn and noise with mental health outcomes overlappedly due to a lack of common outcomes to both types oftudied.t associations of air pollution and noise with aspects oflth can also be a result of different biological pathways.he biological pathways of an effect of long-term air


pollution or noise exposure on the brain are not completelyclaried. Two different biological pathways were proposed forlong-term effects of air pollution. First, the direct respiratory intakeof air pollutants can provoke a local inammatory effect that leadsto productithe systemand damagshown in tolevels of dieexpression brain micromay affect Ranft et al.that were increase in the hippoca

Possibletion have nHowever, etion and nopollution dewell as noistion memoris known asing and mem2005). Thuswhich showneurotransmndings bylarly, associfunctions wmale mice eto sub-chrolike symptothe biologicical functioshown thatin human (the release thalamus ththat is respo

Some coand they hi

Concurrent

Only onand noise ainformationpollution anhigh correlaent noise arin time andnoise, and able. It is theexposure in

Diversity of

Studies rlution use dthe effect oflution used studies, invtive functiodifferent te

necessary to conduct studies on air pollution and noise using thesame clinical and subclinical outcomes to be able to adequatelycompare and tease apart the effect of either exposure.

ual s

en innoiseimpopairm009;lutiobgroutivelyge mg therly p

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cogf Chwas alent tf Wes pe

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pot2013on of pro-inammatory cytokines which can pass intoic circulation and can disrupt the bloodbrain barriere brain cells (Genc et al., 2012). This pathway wasxicological studies. For instance, rats exposed to highsel exhaust showed elevated levels of interleukin IL-1and elevated levels of tumor-necrosis factor TNF inglia (Levesque et al., 2011). Secondly, air pollution

olfactory functions (Caldern-Garciduenas et al., 2004;, 2009), similar to that found in animal models. Dogshighly exposed to air pollution showed a signicantDNA damage in olfactory bulbs, the frontal cortex andmpus (Caldern-Garciduenas et al., 2002).

associations between noise and neurocognitive func-ot been investigated in epidemiological studies so far.xperimental studies showed similar effects of air pollu-ise on animals. For example, 10 months exposure to aircreased spatial learning in mice (Fonken et al., 2011), ase exposure for 15 days produces working and recogni-y decits in rats (Haider et al., 2012). The hippocampus

the key region critically involved in both, spatial learn-ory formation (Broadbent et al., 2004; Kahlmann et al.,

, the toxicological ndings from experiments in rodents, that noise exposure causes changes in hippocampalitter signaling in rats (Cui et al., 2012), support the

Fonken et al. (2011) and Haider et al. (2012). Simi-ations of both air pollution and noise with psychologicalere also demonstrated in animal studies. For example,xposed to long-term PM2.5 exposure and rats exposednic noise exposure were found to display depressive-ms (Fonken et al., 2011; Naqvi et al., 2012). However,al pathways of possible effects of noise on psycholog-n are not well established yet. Briey, animal studies

noise provokes mild acute stress similar to that occurArnsten and Goldman-Rakic, 1998). This stress evokesof high levels of noradrenaline and dopamine in hypo-at in turn impairs the regulation of prefrontal cortexnsible for cognitive abilities (Arnsten, 2009).

mmon problems were identied in the reviewed studiesnder a full comparison of results of these studies.

environmental exposures

e of the reviewed studies analyzed both air pollutionssociation (Persson et al., 2007). However, even though

on both exposures was available, no analysis with aird noise simultaneously was conducted, possibly due totion of these two exposures. Air pollution and ambi-e both related to trafc and often occur simultaneously

space. The effect of air pollution may be modied by synergism between the two exposures seems possi-refore necessary to include both air pollution and noiseto account when investigating the effect of either.

outcomes

elated to cognitive and psychological effect of air pol-ifferent panels of tests than studies, which investigated

noise. Most of the studies exploring the effect of air pol-a large battery of objective cognitive tests, while in noiseestigators mostly used self-reported outcomes. Cogni-n was less investigated in noise studies, and completelysts were performed for its assessment. It is therefore

Individ

Whtrafc is also ing imet al., 2air polthe surespecolder adilutinof elde

Longitu

Onlits assostrengair polnitive to norm2009; Wrelatedstudy oozone equivastudy ochangesimilaryears aing theof cogn

Additio

Motook pconfouisfactioan impcovariastudies

SimcurrenChen aet al., triglycan atteyses asone cliand no

Role of

Fivewomehave bMeyerenvirotigatedet al. (usceptibility

vestigating the effect of trafc proximity (indicator for as well as for trafc-related air pollution) or noise, itrtant to take into account a rising prevalence of hear-ent with age. In two out of 22 reviewed studies (Ranft

Wellenius et al., 2012), an association of trafc-relatedn with decreased cognitive function was found only inp of younger participants (74 years and 77 years,), but not in the older group. A decline in hearing inay lead to a lower sensitivity to trafc noise, thereby

effect of noise in study populations with a large fractionarticipants.

l data on cognitive decline

studies on progression of cognitive impairment andion with air pollution and ambient noise also limit thethe existing evidence. In adults, long-term exposure ton and ambient noise may have a negative effect on cog-ion that will result in cognitive impairment additionalognitive aging. Only two studies (Chen and Schwartz,e et al., 2012) performed a comparison of air pollution-

nitive decline with normal aging-related decline. In theen and Schwartz (2009), an increase in 10 ppb of annualssociated with the decline in cognitive functions that iso 3.5 till 5.3 years normal-aging decline. Similarly, in theuve et al. (2012), differences in rates of global cognitiver 10 g/m3 of PM2.510 and PM2.5 exposures were foundhe difference in rates between women who were 12

in age. There is an urgent need for studies investigat-ciation of environmental exposures with progression

decline in older age.

ovariates

dies investigating air pollution or noise associationsnal characteristics and life-style factors as potentials into account. However, depressive symptoms, sat-ith health and activities of daily living might playnt role in cognitive performance. The effect of theseis poorly investigated both in air pollution and noise

, the role of comorbidities is poorly investigated in they of evidence. Five of reviewed studies (Brink, 2011;

chwartz, 2009; Loop et al., 2013; Lim et al., 2012; Ranft) included factors related to CVD (BMI, hypertension,

level) as intermediates in sensitivity analyses, showingion of effect in some studies. These are important anal-

suggest that general or cardiovascular health may be pathway through which a possible effect of air pollutionan be mediated.

er in studies of neurocognitive functions

he 22 reviewed studies were performed only in men or differences in different domains of cognitive function

described in several studies (Darley and Smith, 1995;y, 1989; Torres et al., 2006). However, few studies oftal exposures and cognitive function specically inves-

ential effect modication by sex. For example, Gatto) showed that logical memory was more affected by


long-term air pollution exposure in women than in men. In mousemodels, sex differences in behavioral patterns and neuron differ-entiation due to exposure to nano-sized particulate matter werefound (Davis et al., 2013). The role of sex in modifying effect esti-mates is largbiological mand stratic

A lack of inf

Althougair pollutioaddress is nyears of livfor participthe whole pestimates fo

Conclusion

Investigtal health rexposures rshown to benitive funcin several sof reviewedambient airtive functiolong-term eies investigin associatiroborate ntoxicologicaand pathwa

Acknowled

Lilian Tzdoctoral feJerusalem, IFoundation

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ations on the association of air pollution and noise men-eceived increased attention during recent years. Botheviewed in this article (air pollution and noise) were

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Effect of long-term outdoor air pollution and noise on cognitive and psychological functions in adultsIntroductionMethods of the searchResultsStudy design and exposures******Exposure assessmentOutcome assessmentReported associationsAssociation with air pollutionAssociation with noiseAssociations with air pollution and noise

DiscussionConcurrent environmental exposuresDiversity of outcomesIndividual susceptibilityLongitudinal data on cognitive declineAdditional covariatesRole of gender in studies of neurocognitive functionsA lack of information on the length of residential exposure

ConclusionsAcknowledgementsReferences

Effect of Long-term Outdoor Air Pollution and Noise on Cognitive And

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