Brains Sweep Themselves Clean of Toxins During Sleep
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Transcript of Brains Sweep Themselves Clean of Toxins During Sleep
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1/10/2015 BrainsSweepThemselvesCleanOfToxinsDuringSleep:ShotsHealthNews:NPR
http://www.npr.org/templates/transcript/transcript.php?storyId=236211811 1/3
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Copyright2013NPR.Forpersonal,noncommercialuseonly.SeeTermsofUse.Forotheruses,priorpermissionrequired.
ROBERTSIEGEL,HOST:
Thequestionofwhypeopleandanimalsneedsleephasbotheredscientistsfordecades.Andnow,researchersthinkthatthey'vefoundatleastpartoftheanswer.NPR'sJonHamiltonreportsonastudythatshowsthatduringsleep,thebrainflushesouttoxins,includingasubstancelinkedtoAlzheimer'sdisease.
JONHAMIILTON,BYLINE:Fromanevolutionarypointofview,sleepseemslikeabadidea.Afterall,whenyou'resnoozing,it'seasyforanothercreaturetoremoveyoufromthegenepool.That'sespeciallytrueifyou'reasmallrodent,saystheUniversityofRochester'sMaikenNedergaard.
DR.MAIKENNEDERGAARD:Foraanimallikeamouseorrat,it'sverydangeroustosleepbecauseit'smuchmorevulnerableforcatsthatwouldcomeandeatit.
JONHAMILTON,BYLINE:Sosleepmusthavesomereallyimportantsurvivalfunction.Tofindoutwhatthatmightbe,Nedergaardledateamthatstudiedthebrainsofsleepingmice.Andthescientistsnoticedthatduringsleep,somethingoddwashappeningtothesystemthatcirculatescerebrospinalfluidthroughthebrainandnervoussystem.
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1/10/2015 BrainsSweepThemselvesCleanOfToxinsDuringSleep:ShotsHealthNews:NPR
http://www.npr.org/templates/transcript/transcript.php?storyId=236211811 2/3
NEDERGAARD:Itwaspumpingfluidintothebrainandremovingfluidfromthebraininaveryrapidpace.
HAMILTON:Nedergaardsaystheteamrealizedthiswaspossibleinpartbecausewhenmicewenttosleep,theirbraincellsactuallyshrank,soitwaseasierforfluidtocirculate.Whenananimalwokeup,shesays,thebraincellsenlargedagainandtheflowbetweencellsslowedtoatrickle.
NEDERGAARD:It'salmostlikeopeningandclosingafaucet.It'sthatdramatic.
HAMILTON:Nedergaardandherteamhadpreviouslyshownthatthefluidwascarryingawaywasteproductsthatbuildupinthespacesbetweencells.
NEDERGAARD:It'slikeadishwasher.It'sfloatingbyallthecells,whicharethedishes,andwashingthem.
HAMILTON:That'simportantbecausewhat'sgettingwashedawayduringsleeparewasteproteinsthataretoxictobraincells.Nedergaardsaysthisprocesscouldexplainwhywedon'tthinkclearlyafterasleeplessnightandwhyaprolongedlackofsleepcanactuallykillananimaloraperson.Butwhydoesn'tthebraindothissortofhousekeepingallthetime?Nedergaardthinksit'sbecausecleaningtakesalotofenergy.
NEDERGAARD:It'sprobablynotpossibleforthebraintobothcleanitselfandatthesametimebeingawareofthesurroundingsandtalkandmoveandsoon.
HAMILTON:Andthatwouldexplainwhyanimalshaveevolvedtoneedsleep.Nedergaardsaysthecleaningprocesshasbeenobservedinratsandbaboonsbutnotyetinhumans.Evenso,itcouldofferanewwayofunderstandinghumanbraindiseases,includingAlzheimer's.That'sbecauseoneofthewasteproductsremovedfromthebrainduringsleepisbetaamyloid,thesubstancethatformsstickyplaquesassociatedwithAlzheimer's.Nedergaardsaysthat'sprobablynotacoincidence.
NEDERGAARD:Isn'titinterestingthatAlzheimerandallotherdiseasesassociated
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1/10/2015 BrainsSweepThemselvesCleanOfToxinsDuringSleep:ShotsHealthNews:NPR
http://www.npr.org/templates/transcript/transcript.php?storyId=236211811 3/3
withdementia,theyarelinkedtosleepdisorders.Sothepatientwouldsleeplessandlessandtheywouldnothavedeepsleep.
HAMILTON:ResearcherswhostudyAlzheimer'ssayNedergaard'sresearchcouldhelpexplainanumberofrecentfindingsrelatedtosleep.RandallBatemanofWashingtonUniversityinSt.LouiswaspartofateamthatstudiedhowsleepaffectslevelsofthatAlzheimer'sprotein,betaamyloid.
DR.RANDALLBATEMAN:Betaamyloidconcentrationscontinuetoincreasewhileapersonisawake.Andthenafterpeoplegotosleep,thatconcentrationofbetaamyloiddecreases.Thisreportprovidesabeautifulmechanismbywhichthismaybehappening.
HAMILTON:BatemansaysthereportalsooffersatantalizinghintofanewapproachtoAlzheimer'sprevention.
BATEMAN:ItdoesraisethepossibilitythatonemightbeabletoactuallycontrolsleepinawaytoimprovetheclearanceofbetaamyloidandhelppreventamyloidosisthatwethinkcanleadtoAlzheimer'sdisease.
HAMILTON:ThenewresearchappearsinthejournalScience.JonHamilton,NPRNews.
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