lein ▁path ologies . ▁ ▁Pres entation ▁ ▁The ▁syn uc lein op ath ies ▁have ▁shared ▁features ▁of ▁par kin son ism , ▁imp a ired ▁cogn ition , ▁sleep ▁dis orders , ▁and ▁visual ▁hall uc in ations . ▁ ▁Syn uc lein op ath ies ▁can ▁sometimes ▁overlap ▁with ▁t au op ath ies , ▁possibly ▁because ▁of ▁interaction ▁between ▁the ▁syn uc lein ▁and ▁t au ▁prote ins . ▁ ▁RE M ▁sleep ▁behavior ▁dis order ▁( R BD ) ▁is ▁a ▁par as om nia ▁in ▁which ▁individuals ▁with ▁R BD ▁lose ▁the ▁par al ysis ▁of ▁mus cles ▁( at onia ) ▁that ▁is ▁normal ▁during ▁rapid ▁eye ▁movement ▁( RE M ) ▁sleep , ▁and ▁act ▁out ▁their ▁dream s ▁or ▁have ▁other ▁ab normal ▁movements ▁or ▁vocal izations . ▁▁ ▁Ab normal ▁sleep ▁behav iors ▁may ▁appear ▁dec ades ▁before ▁any ▁other ▁sympt oms , ▁often ▁as ▁an ▁early ▁sign ▁of ▁a ▁syn uc lein op ath y . ▁ ▁On ▁aut ops y , ▁ 9 4 ▁to ▁ 9 8 % ▁of ▁individuals ▁with ▁pol ys om n ography - conf ir med ▁R BD ▁are ▁found ▁to ▁have ▁a ▁syn uc lein op ath y — most ▁commonly ▁D L B ▁or ▁P D . ▁ ▁Other ▁sympt oms ▁of ▁the ▁specific ▁syn uc lein op ath y ▁usually ▁manifest ▁within ▁ 1 5 ▁years ▁of ▁the ▁diagn osis ▁of ▁R BD , ▁but ▁may ▁emer ge ▁up ▁to ▁ 5 0