concerned about my dad.

My dad has spells where he shows signs of dementia this is a very early stage & it comes and goes, 2 years ago he didn't know who the president was and it was in the middle of November and he had shorts on because he thought it was June.  I live in a different state then him so I drive 4 hours away taking him to dr appointments and making sure his meds are not interacting with eachother, he seemed great.  But I just got off the phone with him tonight and he was saying off the wall things again and it just makes me concerned that he is getting worse!  My sister lives 20 mins away from and she doesn't check on him!!!   It drives me nuts.  So is there anything I can do to get him a place here?  He is on his own but he is a Vet and he gets help from the VA Hospital.  His girlfriend is a drunk and goes along with his nonsense