This is a copy of my response to an email I received from someone who sought advice on dealing with his new neighbor who is an adult with Aspergers syndrome because this new neighbor is showing up at his door and talking about the same stuff way too often...
"I totally understand what you are starting to experience. I have an adult autistic friend who says the SAME things to me over and over again, and every time I see him. Another one calls me about ten times a day, ahh!
This is very common behavior with Asperger's syndrome. For, these folks have a hard time socially. They have difficulty with social graces because they have a hard time catching on and understanding what the rest of us consider to be socially appropriate. They are often very literal in their understanding and often don't understand, perceive and empathize with others feelings and points of view. They can be or seem self-absorbed and be emotionally immature at times or often, and dependent also, especially when someone is kind to them. My opinion is that this new neighbor that keeps showing up at your door wants to be friends, friendly or neighborly with you. And, he doesn't realize he's becoming a pest. I've found that the best way to handle such an abundance of friendliness is polite honesty. For example, I told my phone friend I can only talk to him about once a week. So, I pick up the phone only about once a week. I also politely remind him that I have six kids, a messy house, etc to take care of. He takes it very well. As for my friend that repeats, I half tune him out, and say an occasional "Yeah", "Okay" and "Uh huh". And, when he kept flaking out when we made appointments at the barber for him, I finally said that if he doesn't show up next time, then he's not getting a haircut ever again--so he showed up next time. I haven't had an autistic friend show up at my door at all times of the day and night before, but we have had a neighbor boy show up about that often. We told him not to come over on Sundays, and we set a few rules that he needs to follow or he goes home.
Basically, your neighbor is socially and emotionally innocent, like a child. Just be patient, kind, honest and straight forward. He may very well not understand, get confused and get mixed messages if you don't tell him in plain terms when are good times to visit, including specific hours and days, how often, etc. But also keep it short. I think that a good idea to do the next time he shows up at your door, ask him what he wants, does he want to come in and visit, is he lonely, bored, want to be your friend, etc. Asking him what is up and what he wants every time he comes would be good. And, if he shows up more often than you tell him he can, at the wrong times, or when you don't feel like visiting, the first few times, tell him that he's coming over too often, at the wrong time, that you're busy or it's not a good time. He will probably comply with your request. However, if he still doesn't get it, I advise you to close the curtains and don't answer the door. Like the rest of us, autistic folks have different personalities and it's possible he may get hurt, offended, angry, etc. But if so, don't worry, he'll get over it. And, you'll know he'll be over it when he starts showing up again, heh heh... My repeating friend sometimes doesn't call me for months because he got upset at something usually trivial I said or done, then calls again when he's gotten over it--and wants my help again. I know of another autistic adult who gets so easily offended at stuff--usually minor again-- that he doesn't call his family for years at a time.
...Thank you for seeking help about this situation. I'm glad you wrote me, you obviously have a lot of care and concern about others, and asking for advice in dealing with your neighbor shows this. And, I also applaud you for taking steps to be polite to your neighbor while at the same time, protecting yourself so that you don't get emotionally drained...