题目内容：
A．Folkwisdomholdsthatwinteristhemostcommontimeforsuicides,withdepressivesymptomsstrengthenedbycold,darkweather.Anotherviewsuggeststhatsuicidesincreasearoundtheholidays,whenstrugglingpeoplefeelleftoutoftheculturalcheer.Infact,studiesdatingbacktothelate1800sfindthatsuicidespeakinthespringandarelowestinwinter.One1995studypublishedinthejournalSocialScience&Medicineexaminedmonthlysuicideratesin28countriesandfoundthatin25intheNorthernHemisphere(半球),suicidesweremostcommoninMayanddeclinedinFebruary.SimilarfindingsoccurintheSouthernHemisphere--inSouthAfrica,forexample,suicidespeakinthesouthernspring,inSeptemberandOctober,accordingtoa1997studyinthejournalPsychiatryResearch.
B．Therewere38,364suicidesintheUnitedStatesin2010,accordingtothemostrecentdatafromtheCentersforDiseaseControlandPrevention(CDC．.Thosenumbersputsuicideasthe10thleadingcauseofdeathforallages,andthethirdleadingcauseofdeathforpeople15to24yearsold.Womenaremorelikelythanmentosaytheyhavesuicidalthoughts,but79percentofcompletedsuicidesintheUnitedStatesaredonebymen.Thisisperhapsbecausementendtochoosemorelethal(致命的)meansforsuicide:About56percentofmalesuicidedeathsarecausedbyguns.Incontrast,themostcommonwayforwomentocompleteasuicideisbypoisoning.
C．Predictingwhowillattemptorcompleteasuicideisamajorbarriertoprevention.Understandingwhyspringtimeisamorecommontimeforsuicidemighthelpexplainmotivations,buteventhisquestionisnoteasy.Whenthespringpeakinsuicideswasfirstdiscoveredinthelate1800s,thefieldofpsychologycastaroundforexplanations.Onetheoryheldtheheatofspringandsummerledtoexcessenergy,whichexpresseditselfinviolence.Anothertheorysuggestedtheintensityofsociallifeinthespringandsummerwastoblame.
D．Someresearchersstillbelievethatweathermaydrivetheincreaseinsuicidesinspring.It'spossiblethatpeoplewhoaredepressedcan'tgathertheenergytomakeandgothroughwithasuicideplaninthewinter,saidDr.AdamKaplin,aprofessoratJohnsHopkinsinBaltimore."Maybespringcomesandtheirmoodsarestilldown,andtheygetactivatedenoughtokillthemselves,"Kaplinsaid.
E．Thesocialexplanationsuggestspeoplewhoarevulnerabletosuicidalbehaviorfacemorechallengeswhentheweatherwarmsandsocialinteractionincreases.Alternatively,peoplewhoarestrugglingmayfeelleftoutoftheincreaseinsocialengagements--essentially,theyfeelthattheisolationofwinterhaswithdrawnforeveryoneexceptforthem.Supportingthesesocialtheories,the1995surveyofsuicideacrosstheglobefoundthattheseasonalityofsuicidewasgreaterinagriculturaleconomiesthanindustrialones.
Agriculturalcountriesaremoreseasonal,whileindoorworktendstosmoothouttheeffectsofweatherandsunlightonsociallife.Industrialcountriesshowothersmallpeaks,theresearchersnoted,particularlyinthefall.Thesepeaksmaybelinkedtothestartoftheacademicschoolyear.
F．Socialpressuresaren'ttheonlypotentialexplanationfortheincreaseinsuicideinspring.Someresearcherssuspectthatphysicalprocessesaretoblame.Depression,suicidalthoughtsandbehaviorshavelongbeenlinkedtoinflammation(炎症),achronicbodilyresponsethatoccursduringtimesofstress.Inflammationismarkedbyanoveractiveimmunesystemanddilated(膨胀的)bloodvessels,andithasbeenlinkedtochronicconditionsrangingfromasthma(哮喘)toheartdisease.
G．Theinflammationlinktodepressioniswell-establishedinstudiesineverythingfrommicetohumans,Kaplinsaid.Miceinjectedwithinflammation-triggeringcompoundsstopsocializingandworkingforsweets.Humansgiveninflammation-linkedsubstancearelikelytobecomingdepressedasasideeffect--infact,Kaplinsaid,25percentofpatientsgiventhetreatmentdevelopclinicaldepressionwithinweeks.In2012,MichiganStateUniversityresearchersfoundthatincreasedlevelsofquinolinicacid(喹啉酸),acompoundgeneratedbyinflammation,wererelatedtothelevelofsuicidalthoughtsapersonhad.Theresearchwasonlyinsuicidalpatients,notpeoplewhoweredepressedbutnotsuicidal;butthefindingssuggestedthatbodilyinflammationmightaffectthemind.
H．Someresearchersseealinkbetweenthisinflammationandspringtime.In2013,Danishresearchersfoundanassociationbetweensuicidesandtheamountoftreepollen(花粉)intheair.Theresearchersanalyzed13,700suicidesinapopulationof2.86millionDanesandfoundthatsuicidesincreasedastheamountofpollenintheairincreased.
I．Otherthantheinflammationlink,suicideattemptsalsohavebeenlinkedtoairpollutionlevels,accordingtoa2010studyofemergencyroomvisitsforsuicideattemptsinVancouver,Canada.Thosefindingsappearedin2010inthejournalEnvironmentalHealthInsights.Thefindingsoflinksbetweensuicideandirritants(刺激物)intheenvironmentare"provocative",Kaplinsaid,thoughtheassociationisnotyetproven.
J．"It'sjustlettingpeopleknowsuicidemightnotbefromweakness.Itmightnotbeacharacterflaw,"Kaplinsaid."Thismightbearesultofsomethingofbiologicalsignificanceresultsinanillnesssettingoffclinicaldepressionthatrequirestreatment."
IntheUS,suicidehasbecomethe3rdmajorreasonofdeathforpeopleaged15to24.
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