Dementors question

[GKJPO]

No: HPFGUIDX 56657

Something about the dementors has been really bothering me.  In LV's 
graveyard speech, he talked about breaking people out of Azkaban 
along with bringing in the dementors themselves.  What good would the 
Lestranges be to LV after spending all this time in Azkaban?  Hence, 
my questions.

Do you all think the Death Eaters were allowed to keep their sanity 
and their wits?  This doesn't seem the case from the account of 
Crouch Jr. there.  On the other hand, is it possible for dementors to 
take the life force they have sucked in and pass it on to someone 
else or restore it to the original person?  Or do you think that's a 
little too much B Horror Movie-esque (Night of the Living Dead)?

I just can't decide what I think.  I don't have a good feeling about 
it though.
Kristen