Reviewedby: LaurenEvelynChaby, UniversityofMichigan,UnitedStates SimoneMacri, IstitutoSuperiorediSanità(ISS),Italy
*Correspondence: IsabelleMueller isabelle.mueller001@umb.edu
Received: 13March2019
Accepted: 26June2019
Published: 09July2019
Citation: MuellerIandTronickE(2019)Early LifeExposuretoViolence: DevelopmentalConsequenceson BrainandBehavior. Front.Behav.Neurosci.13:156. doi:10.3389/fnbeh.2019.00156
doi:10.3389/fnbeh.2019.00156
EarlyLifeExposuretoViolence: DevelopmentalConsequenceson BrainandBehavior
IsabelleMueller 1*and EdTronick 1,2
1DevelopmentalandBrainSciencesProgram,DepartmentofPsychology,UniversityofMassachusettsBoston,Boston,MA, UnitedStates, 2DepartmentofNewbornMedicine,HarvardMedicalSchool,Boston,MA,UnitedStates
Exposuretointimatepartnerviolence(IPV)canhavelong-lastingeffectsonachild’s socio-emotionalandneurologicaldevelopment.Researchhasfocusedontheeffectsof IPVonwomenorolderchildren,whilethedevelopmentalconsequencesofexposure todomesticviolenceduringearlychildhoodarelesswelldocumented.However,one wouldexpectsignificantdevelopmentaleffectssincetheinfant’sbrainandstress-related systemsareespeciallysusceptibletoenvironmentalstimuli.Thegoalofthismini-review istoexaminehowfindingsoninfantexposuretoIPVcanberelatedtoriskandresilience ofdevelopmentininfancy.Wedescribetheknowneffectsofwitnessingviolenceduring theperinatalperiodonsocio-emotionaldevelopmentandthepossiblepathwaysby whichIPVaffectsbrainandstress-regulatingsystems.ExposuretoIPVduringinfancy disruptstheinfant’semotionalandcognitivedevelopment,thedevelopmentofthe Hypothalamus-Pituitary-Adrenal(HPA)axisandbrainstructuresrelatedtowitnessing itself(auditoryandvisualcortex).Thefindingsareembeddedinthecontextofthe resourcedepletionhypothesis.Acentralproblemisthedearthofresearchonexposure toIPVduringinfancy,itseffectoncaregiving,andinfantdevelopment.Nonetheless,the availableevidencemakesitclearthatpoliciesforpreventionofIPVarecriticallyneeded.
Keywords:intimatepartnerviolence,domesticviolence,infancy,development,braindevelopment
INTRODUCTION
Thelong-termconsequencesofexposuretoadversityininfancyhavebeenwelldocumented, especiallyitseffectsonachild’sdevelopmentandincreasedvulnerabilityforlatermentalhealth problems(Kessleretal., 2010; Carretal., 2013; Reubenetal., 2016).Whileadversitiessuchas chronicneglectorabusehavebeenextensivelydescribedintheliterature,thenegativeconsequences ofexposuretointimatepartnerviolence(IPV)arelesswelldocumented.Primaryreasonsfor thedearthoffindingsarethatcasesofIPVoftengounreportedoutoffearofconsequencesor getpalliatedbytheindividualsinvolved.IPVasdefinedbytheCentersforDiseaseControland Preventionisoneintimatepartnerexercisingcoercivecontrolovertheother,includingphysical andsexualviolence,aswellasthreatsofphysicalorsexualviolence,andemotionalabusein thecontextofphysicalandsexualviolence(Saltzmanetal., 1999; Breidingetal., 2015).Asthe officialdefinitionsuggests,mostresearchhasfocusedontheeffectsofIPVonwomen,also,child exposuretoIPVisoftentreateddifferentfromchildmaltreatment.Yet,anestimated10%–20% ofchildrenlivingintheUSareannuallyexposedtoIPV(Carlson, 2000).ACanadianincidence
studyindicatedthatupto34%ofsubstantiatedinvestigations intochildabuseandneglectwerecharacterizedaschildexposure toIPV(Trocmé, 2010).Researchisexceptionallyscarceonthe effectsofexposuretoIPVduringtheperinatalphaseandinfancy, eventhoughtheassumedharmissignificantenoughforthe WHOtorecommendstandardizedscreeningforIPVduring pregnancyandtocallforincreasedresearchonpreventionfor IPV’sadverseeffects(WorldHealthOrganization, 2011).
Researchshowsthatexposuretoadversityoverthefirst 5yearsoflifecanhavelastingeffectsonbraindevelopment (Perry, 2002; Foxetal., 2010; BickandNelson, 2016). Throughoutthissensitiveperiod,interactionswiththeprimary caregiversareavitallearningenvironmentandaprimary developmentalcontext.Bothpositiveandnegativeexperiences alikeaffectthesocio-emotionalandcognitivedevelopment ofthechildandmaturationofassociatedbrainstructures (Schore, 2001).Twocriticalaspectsoftheinteractionwiththe primarycaregiversareessentialforbraindevelopment:(1)a secureongoingrelationshiporattachmentbetweencaregiver andchild;and(2)asensitiveco-regulationwiththecaregiver inthepresenceofastressortohelpthechildtodevelop andincreaseitscapacityforindependentemotionregulation. Asecureongoingrelationshiptoacaretaker(s)isfundamentalfor successfuldevelopment.Critically,asecurerelationshipbuffers theinfant’shormonalstressresponseandtherefore,protects thedevelopingbrainfromharmfuleffectsofstresshormones (GunnarandDonzella, 2001; Tronick, 2017).Incontrast,alack ofself-experiencedsecurityforthechildleadstoanincreased riskforbehavioralproblems(Dozieretal., 2001; Belskyand Fearon, 2002)anddecreasedenvironmentalexplorationwhich compromisesthedevelopmentofcognitiveskillsassociated withschoolreadiness(Mossetal., 1993).Ongoingcaregiver relationshipsthatdonotprovideasenseofsafetyfailtobufferthe hormonalstressresponsesexposingtheinfants’braintoadverse stresseffects(ZeanahandGleason, 2010).
Emotionregulationreferstothechild’sabilitytomodulate andadjusttoherlevelsofarousal(Coleetal., 2004).The frontallobe,centralforthedevelopmentofemotionregulation, undergoesaperiodofrapidgrowthandsynapticexcessaround 6–18monthsofage,makingthisacriticalperiodfortheinfant tolearnhowtorespondtoemotions(Dawson, 1994; Nelson andBosquet, 2004).Untilself-regulationofemotioniswell developedthecaregiversareasourceofexternalregulationfor thechild,hencethecaregiversplayavitalroleinthedevelopment ofemotionregulatorybehaviors.Sensitiverespondingtothe child’sregulatoryneedsbyacaregiverhelpsthechildtoregulate stressandtobettercontrolstresshormones.This,inturn, helpsthechildtolearnhowtoregulateherselfmoreeffectively. Emotionregulationskillsarenecessaryforthechildforlearning andfocusattention,essentialskillstoexcelinschool(Perry, 2001; Cooketal., 2017).Bycontrast,insensitivecaretaking compromisesthechild’sregulationofarousalandstress.Simply put,adistressedorhighlyarousedchilddoesnotfeelsafeandis unabletoengagewithpeopleorobjectsintheworld(Wittling andSchweiger, 1993; Schore, 2001; Cooketal., 2017).Thus,less optimalregulationbyacaretaker(s)canbecometoxicforthe child.Insum,theseearlyexperiencesofsensitiveregulationor
insensitivemaltreatmentanddysregulationarecriticalforthe child’sdevelopmentbeitgoodorill(SroufeandRutter, 1984; Tronick, 2017).
ExposuretoIPVcaninfluenceboththeinfantandthe caretaker,interferingwiththedyadicco-regulationofemotions. IPVcandisruptthecaregiver’sabilityforoptimalcaregiving astheymayhavedifficultyregulatingtheirownemotions inthecontextofviolenceorareaffectedbyIPV-related psychopathologysuchasdepressionandanxiety(Letourneau etal., 2011; Pelsetal., 2015).SeveralstudiesfindthatIPVleads topoormother-infantattachment.Womenwhoexperienced IPVduringpregnancyorinthefirstpostpartumyearhad weakerattachmentstotheirinfants,perceivedtheirinfantsas moredifficult,andhadmoredoubtsabouttheirparenting qualitiescomparedtowomennotexposedtoIPV(Zeitlinetal., 1999; Huth-Bocksetal., 2004; QuinlivanandEvans, 2005). ThiscorroboratesresearchindicatingthatexposuretoIPVis ariskfactorforthedevelopmentandmaintenanceofsecure attachmentsbetweenmotherandchild(Simsetal., 1996; Zeanah etal., 1999).
EXPOSURETOIPVDURINGTHE PERINATALPERIOD
Increasingevidenceindicatesthatself-reportedIPVduring pregnancyandtheperinatalperiodisassociatedwithpoor healthoutcomesforthefetus,newborn,andinfantupto1year postpartum(Cokkinidesetal., 1999; BoyandSalihu, 2004; Coker etal., 2004; Rosenetal., 2007; Sarkar, 2008).Exposuretoviolence increasessignificantriskfactorsduringtheperinatalperiod, suchasafour-timesashighriskforantepartumhemorrhage,a conditionthatcanbefatalfortheunborn(Janssenetal., 2003; HanandStewart, 2014).Wellestablishedaswellareincreased riskforlowbirthweight(Lipskyetal., 2003; Silvermanetal., 2006; Rosenetal., 2007),intrauterinegrowthrestriction(Janssen etal., 2003),pretermdelivery(Lipskyetal., 2003; Sarkar, 2008), andoverallincreasedfetalmorbidity(forreviewsee Boyand Salihu, 2004; Donovanetal., 2016).
Furthermore,maternalhigh-stresslevelsduringpregnancy, forexample,duetoexposuretoIPVcanaffectthefetus anditsneurohormonalchemistry.Thewombisashared environmentwiththemotherandexperiencesthataffecthercan, inturn,affectthedevelopingfetus.Forexample,theplacenta producesanenzyme(11beta-hydroxysteroiddehydrogenase type2)thatbreaksdowncortisoltoaninactiveform,protecting thedevelopingfetalbrainfromitsharmfuleffects.During pregnancyexposuretohigh-stresscontextsincreasematernal cortisolalongwithadownregulationoftheenzymecanresult inmorecortisolreachingthefetus.Thisexposurecanlead tochangesinbehavioraldevelopment(O’Donnelletal., 2009; DavisandSandman, 2010; Conradtetal., 2013; Ramborger etal., 2018),alargerinfantcortisolresponse,aslowerrate ofrecoveryafterexperiencingastressor(Davisetal., 2011), aswellasmaketheinfantmoresusceptibletostresslater inlife(DavisandSandman, 2010).Conradtfoundthathigh stressduringpregnancyleadstoepigeneticchangesinboththe motherandtheinfantandreducedattentionalcapacitiesin
infantsat4monthsofage(Conradtetal., 2013).Whileonlytwo studieshavelookedatthestressexposureofwomenexposed toIPVduringpregnancy,bothfoundasignificantincreasein self-reportedstresslevels(Chambliss, 2008)andhigherlevelsof thestresshormonecortisol(HanandStewart, 2014)relatedto IPVduringpregnancy.
EXPOSURETOIPVDURINGINFANCYAND EARLYCHILDHOOD
IPVhasahighincidence(70%–80%)tooccurduringthefirst yearpostpartumwhenatleastoneincidentofIPVduring pregnancywasreported(Martinetal., 2001; Charlesand Perreira, 2007).
SymptomsofTraumaand Psychopathology
Intheabsenceoflanguage,traumaisdifficulttodiagnose inyounginfants.Nonetheless,symptomsreportedininfants exposedtoIPVareconsistentwiththedefinitionoftraumain the ZerotoThree(Organization)andDC:0-3RRevisionTask Force (2005),whichprovidesdiagnosticclassificationcriteria formentalhealthdisordersininfancyandearlychildhood. DescriptionsofinfantsexposedtoIPVincludeeatingproblems, sleepdisturbances,andmooddisturbances(Layzeretal., 1986). Clinicalstudiesfindpoorsleepinghabits,poorergeneralhealth, higherirritability,andincreasedscreamingandcrying(Alessi andHearn, 2007).Astudylookingatmultipleformsoftraumata ininfants,includingIPV,foundthattraumaduetowitnessinga threattoacaregiverwasrelatedtothemostseveresymptoms andincreasedhyperarousalandfear(ScheeringaandZeanah, 1995; ZeanahandGleason, 2010, 2015).Moreover,thenumber oftraumasymptomsshowsanassociationwiththenumberof IPVepisodeswitnessed(Bogatetal., 2006),indicatingthatan accumulationoftraumasymptomswiththeaccumulationofIPV incidentswitnessedbytheinfant.Nexttosymptomsofincreased arousal,fear,andaggression,interferencewithdevelopmentwas themostfrequentlyreportedsymptomoftraumaininfantswho witnessedsevereformsofIPV.Forexample,thetemporaryloss ofanalreadyacquireddevelopmentalskill,suchastoilettraining orevenlanguage.Anexceptionalstudythatobserved1-year-old infantsinanexperimentallysimulatedsituationofadultconflict foundthatchildrenwhopreviouslywereexposedtoIPVathome asinfantsshowedincreasedbehavioraldistresscomparedto childrenwhohadnopreviousexposure.Thefindingisindicative ofanincreasedsensitivitytostressasaresultofIPVinthe firstyearoflife(DeJongheetal., 2005).Nexttoamuch-needed increaseinclinicalassessmentandlongitudinalmonitoringof IPV,experimentalstudiesofsimulatedIPVcombinedwith neurologicandneurohormonalmeasuresoninfantsandchildren wouldgreatlyadvanceourunderstandinghowIPVinfluencesthe developmentofregulatoryskillsandsensitivitytostress.
‘‘Violencebecomestraumaticwhenthevictimdoesnothave theabilitytoconsentordissent,which,inturn,islinked withtheuniversalexperienceofhelplessnessandhopelessness engenderedbyvictimization’’(Sluzki, 1993,p179).Exposure toviolence,suchasIPV,hasbeenrecognizedasastressor
withamagnitudetoproducelong-termconsequences,including PTSDsymptomsinchildren.PreschoolchildrenexposedtoIPV showmorebehaviorproblems(Hughes, 1988)andsignificantly lowerself-esteemthandoolder,school-agedchildrenexposed toIPV(Elbow, 1982).Experiencingabusiveviolenceinthe homeinterfereswiththechild’sdevelopingsenseofsecurityand beliefinasafe,justworldandexceedsthechild’scapacityfor self-regulation.EvidenceshowsthatexposuretoIPVincreases thechild’sattentiontowardsthreateningstimuli,abehavioral patternthatisknowntoincreasetherisktodevelopinternalizing problems,includingsocialandgeneralanxiety,socialwithdrawal anddepression(KielandBuss, 2011; Luebbeetal., 2011; Miller, 2015).Externalizingandbehavioralproblemsinchildren exposedtoIPVarealsoreportedtobeelevatedcomparedto unexposed(Graham-BermannandPerkins, 2010).Thus,theage offirstexposuretoviolencealongwiththecumulativeamount ofviolencewitnessedbothhaveasignificanteffectandincrease theriskforthedevelopmentofexternalizingbehavior(GrahamBermannandPerkins, 2010).Thereisasignificantoverlapin psychosocialproblemsofchildrenwhoeitherwitnessedIPVor werephysicallyabusedthemselves.Ameta-analysisreportedthat bothgroupsshowedsignificantlymoreadversepsychological outcomescomparedtochildrenwhowereneitherexposedto IPVnorphysicallyabusedthemselvesathome(Kitzmannetal., 2003).Insum,itappearsthatanyviolence,includingexposure toIPVathomecanhavedetrimentaleffectsonchildren’s mentalhealth.
CognitiveDevelopment
WitnessingIPVdoesnotonlyaffectsocio-emotional development,severalstudieshavefoundanimpactona child’sIQandcognitivefunctions,suchasmemory(Jouriles etal., 2008; Graham-Bermannetal., 2010).Astudyon 1,116twinsfoundthatchildhoodexposuretoIPVwasrelated toadecreasedIQcomparedtounexposedchildren,andthe severityandnumberofviolentepisodesexposedtoathomewere associatedwithagreaterdecreaseinIQ.Anotherstudyfound thatchildrenwhowitnessedIPVonaveragehadan8-point lowerIQthanunexposedchildren,evenwhencontrollingfor possibleconfoundingvariablessuggestinganinterplaybetween trauma-relateddistressandcognitiveskillsinchildrenwho witnessedIPVathome(Delaney-Blacketal., 2002; Koenenetal., 2003).Aswithemotionaldevelopment,alongitudinalstudy foundthatseverecompromisingcognitiveeffectsarecumulative andthatrepeatedandincreasedexposuretoIPVwaspredictive ofschoolengagement(SchnurrandLohman, 2013).
IMPACTOFIPVONBRAINDEVELOPMENT
Adversechildhoodexperiences,includingexposuretoIPV,have measurableeffectsonmultipleareasofthebrain.Eventhough thereisnostudylookingdirectlyattheeffectofexposureto IPVonthebrainduringinfancy,wecanlookatretrospective studiesofdifferentbrainstructuresmaturingduringinfancy andearlychildhood.Exposuretoadverseexperiences,including IPV,affectsthedevelopmentoftheHypothalamus-Pituitary-
Adrenal(HPA)axisandbrainstructuresrelatedtowitnessing itself(auditoryandvisualcortex).
TheHPAAxis
Adversityhasbeenreportedtoaffectthedevelopmentofthe HPAAxis.TheHPAaxisisacriticalstressresponsesystem, enablingappropriaterespondingtostressorsandthereturn ofthebodytohomeostasis.Whilethisstressresponseis essentialandhelpfultoadapttoeverydaystressorsappropriately, achronicactivationduetochronicexposuretostresscan predisposetopsychological,immuneandmetabolicalterations, andassociateddetrimentaleffectsduetoexposuretoexcess glucocorticoids.Ininfancyandchildhood,theHPAaxisand cortisolreactivityarestillmaturing(GunnarandDonzella, 2001), makingthesystemvulnerabletoadverseexperiences(Tarullo andGunnar, 2006).Moreimportant,changesduetohigh-stress exposureduringthiscriticaltimeofmaturationmaynotonlybe long-lastingbutalsobehardertotreatasanormalfunctioning mayneverhavebeenestablished.
Duringinfancyandearlychildhood,theproductionofthe stress-hormonecortisolappearstobebufferedandinsensitiveto anumberofstressors.Inboth,humansandrodents,maternal caregivinghasbeenidentifiedasaprimaryfactorintheinfants HPAhyporesponsivity(Lupienetal., 2009).Thisbuffering effectthroughthecaregiverlikelyprotectstheinfantbrainfrom theharmfuleffectsofhighlevelsofcortisolandistherefore evenmorecriticalinhigh-stressenvironmentssuchasonesin whichthereischronicexposuretoIPV.Inhumans,sensitive caregivingandco-regulationhavebeenshowntocontributeto lowerlevelsofcortisol,whilelowerqualityofcareorinsecure attachment,asoftenreportedforchildrenwithexposureto IPV,areoftenassociatedwithelevatedlevelsofthestresshormone(SpanglerandGrossmann, 1993; Nachmiasetal., 1996; Dettlingetal., 2000; Ahnertetal., 2004; Mülleretal., 2015).Onestudyreportedthatsalivarycortisollevelsin1-yearoldinfantsarenegativelycorrelatedwithelectroencephalogram (EEG)potentials,indicatingthatbrainactivityisdirectlyaffected byelevatedlevelsofcortisol(GunnarandNelson, 1994).Chronic highlevelsofcortisolleadtocelldeath,especiallyinthosebrain structureswithahighdensityofglucocorticoidreceptors(Virgin etal., 1991).Forexample,celldeathhasbeenfoundinhumans takinghigh-dosecortisolmedication(e.g.,forasthma).Adults andchildrenshoweddecreasedverbalmemory,andadeclinein explicitmemory,bothcognitivefunctionsthatarerelatedtothe hippocampus(Benderetal., 1991; Newcomeretal., 1994),and theobservedeffectsweredose-dependent.Thatamedicalformof cortisolcanhavesuchasevereimpactoncognitiveperformance stronglysuggeststhatstress-linkedcortisolconcentrationsdueto chronicexposuretoIPVoranyhigh-stressenvironmentcanhave harmfulconsequencesforthedevelopingbrainoftheinfant.
AuditoryandVisualCortex
Witnessingevenjustverbalabusebetweencaregiversaspartof IPV,withoutphysicalviolence,canhaveobservableimpactson thedevelopingbrain.Magneticresonanceimaging(MRI)scans showdifferencesingraymatterdensityinthearcuatefasciculus intheleftsuperiortemporalgyrus,anareainvolvedinlanguage
processing,withareductioninyoungadultswhoreported witnessingparentalverbalabusestartingattheageof3–13years. Inasimilarsample,diffusiontensorimaging(DTI)scansfound asignificantreductionofwhitemattervolumeintemporal gyrusassociatedwithexposuretoverbalabuse.Critically,these reductionsshowedasignificantcorrelationtoverbalIQand languagecomprehension(Choietal., 2009; Tomodaetal., 2011).
Thevisualcortexprocessesemotionalstimulationand information.Strikingly,repeatedvisualexposuretoIPVwas relatedtoreducedvolumeinthevisualcortexanddiminished connectionsbetweenvisualcortexandlimbicsystem.Most important,theobservedreductionsinbrainvolumeandintraneuronalconnectionsweredirectlyassociatedtothechronicity ofexposurebeforetheageof12(Choietal., 2012; Tomodaetal., 2012).ThesefindingsindicatethatearlyexposuretoIPV,suchas witnessingverbalabusebetweencaregiverscouldhaveaffected theintegrityofspecificbrainstructures.
SUMMARYANDFUTUREDIRECTIONS
Thegoalofthismini-reviewwastoexaminetheevidence oftheimpactofexposuretoIPVduringtheperinatalphase throughearlychildhood.ThedefinitionofIPVisadultfocused andissubsumedbyother(poorlydefined)terms(e.g.,neglect, maltreatment).Incontrasttoneglect,witnessingIPVoccurs whenacaregiverispresentandisdistinctfromviolent maltreatment,aswhenachildisexposedtoIPVthewitnessed violenceisnotdirectedagainstthechild.Thesekindsof maltreatmentarelikelytoaffectthechilddifferentlyinphysical termsandpsychologicalterms.Forexample,howthechild cognitivelyprocesseseachofthoseexperiencesmayradically differ.Moreover,IPVandotherformsofmistreatmentalmost alwaysco-occur,makingitproblematictoidentifysingular effectsspecifictoIPV.Theseproblemsmakeitdifficultto evaluatemanyofthestudiesfortheeffectsofIPVseparate fromotherformsofmistreatment.Ofcourse,intherealworld, exposuretoIPVisinactualityanassemblageofdevelopmentally disruptiveactionswhichwillmostoftenhavemultiplephysical andpsychologicaleffectsonthechild.
OnehypothesisonhowIPVaffectsdevelopmentcanbe derivedfromadevelopmentalframework:witnessingIPV depletesresourcesthatnormallywouldbe—shouldbe—utilized forgrowthanddevelopment(Hobfoll, 1989; Tronick, 2017). Itiswellestablishedthatsecureandsensitivecaregivingis fundamentalforthefavorabledevelopmentofbrainstructures associatedwithregulatorycapacities.Suchcaretakingis, essentialforthechildtodevelopbehavioralself-regulation. TheoccurrenceofIPVdisruptsthisfavorablecaregiver-child interactionwhileitishappening,butcriticallynotonlywhileit isoccurring.Moreover,adultsonbothsideswhoareinvolved inIPVlikelyhavemuchmorepervasiveproblems,perhapsdue totheirownexposuretoIPV.Criticallyforthechild,their experienceofIPVaffectstheireverydaycaretaking(Letourneau etal., 2011; Pelsetal., 2015).Theeffectofthecaretaker’sstate afterIPVmeansthechildhasnotonlywitnessedIPVbutthatthe caretakerslikelylacktheresourcesforsensitiveandconsistent caregiving.Thus,theymaybeunabletohelpthechildregulateor
provideasenseofsafetywhenthechildneedsitmost,duringor afterwitnessinganepisodeofviolence.
Disruptionincaregivingisprevalent,andfamiliesdealing withIPVmostlikelyareaffectedbyco-occurringconditions suchasparentalmentalhealthproblemsassociatedwiththe abuse,suchasdepressionandanxietyorinconsistencyin caregivingduetoIPVrelatedcircumstances.Moreresearch andamorethoroughdistinctionbetweendifferentforms ofadversityareneededtounderstandhowexposureto IPVdistortsthefunctioninganddevelopmentofregulationassociatedbrainsystems. DeJongheetal. (2005) makean essentialsteptowardsamoreprofoundunderstandinghow sensitivitytostressasaresultofIPVdevelopsinthefirst yearoflifeastheirsistheonlyexperimentalstudyinhumans lookingatbehavioraleffectsofacuteexposuretoviolencein infantsthateitherhaveorhavenotbeenexposedtoIPV.An extensionofexperimentalresearchcouldassistingaininga deeperunderstandingofhowIPVdisruptscaregiving,successful
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co-regulationwiththecaregivertocopewithanacuteorchronic stressor,andthedevelopmentofself-regulationininfancy. ExaminingtheeffectsofIPVonphysiologicalandendocrine markersofstress,aswellasimagingmethodsdocumentingthe effectsofexposuretoviolenceoninfantsinexperimentalas wellasdescriptivestudieswillhelptoseparateprimaryand collateralcausesthatdisruptthechild’sfunctioningandhealthy development.AndwhilemuchneedstobelearnedaboutIPV, theavailableevidencemakesitclearthatpoliciesforprevention ofwitnessingIPVandexperiencingotherformsofmaltreatment arecriticallyneededfortheinsuringwell-beingofourinfantsand youngchildren.
AUTHORCONTRIBUTIONS
IMcontributedtothismanuscriptbyselectingandsummarizing relevantstudiesandwritingmultiplesections.IMandET contributedtothewritingandeditingofthereviewarticle.
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