My mom comes to visit me 5 months out of a year. I have realized she is stealing from me. How do I deal with this?

Questions questions, I'm afraid...

Where does your mother live the other seven months of the year?
What is her state of health, physical and mental?
WHAT "stuff", and where did she lift it from? It makes a huge difference. Your wallet, from the kitchen counter, could be a simple mistake. Your classic punk rock collection, from inside your sound system, then you have to wonder if her brain is working right.

Also... if you didn't want to make a big deal of it, why didn't you just retrieve the items and return them yourself, without comment? How did your mother respond when you talked to her about this? - did she seem to understand, was she sorry, what?

I was a therapist in nursing homes for decades. There were many residents that were in various stages of dementia that were collectors. They wandered around, rifling through other rooms, end tables, and would pick up things and hoard them in their room. I always thought it was because of a restlessness vague free floating anxiety similar to how you feel when you have misplaced something. One woman had thousands of straws in her drawer, one picked up shiny things.
My Dad “steals” those gift cards in stores and hoards them at home. They are not worth anything unless they are activated,but I am not sure he knows that.
Often, the rules that apply to the general population-do not take things without permission-are rules that don’t apply to the elderly with brain damage, memory problems, executive problem solving problems.
One other thing, even if she knows the items are not hers, she may think she should have them for some reason we will never know. I would never call it stealing-more like collecting-you will never know how an 80+ year old brain functions.

As CountryMouse said - why didn't you just put the stuff back?

Also, a lot depends on "what" she is lifting. If it is inconsequential, let it go. But if it is valuable, you may need to "check her luggage" before she leaves.

I have heard of this - she really can't help herself and with Dementia, she will most likely forget you checked her bag upon leaving.

Compare it to checking your child's backpack for "forbidden" goods.

Ciaobella, is this new behavior? Or has she always done things like this? If she wasn't the type of person to take things before, it sounds as if she may be confused. Does she seem otherwise OK?

83 years old is within the age range for dementia. Has she been checked?

If this is new behavior, please tell her doctor. So many of us on here know, as that plaque spreads through the brain, we see new behaviors from our loved ones. If that’s what is causing her to steal, then she probably has no control over it. Perhaps check her bags now every time she leaves.

I agree with countrymouse more information is needed.

We had a family member that began stealing as what we later realized was the early stages of Alzheimer's. A fine Christian lady who could not explain why she was taking things she didn't even need from stores and homes, most often didn't seem to remember taking them. She was living alone and still functioning well when this began.

Can you provide more info?
New behavior
Kind of items stolen
Her reaction to being caught

My mom takes money from my wallet, pills from my medicine cabinet and easily hidden valuables, intentional and knowingly - yep, she's a thief. I never leave anything I care about where she has access. So you can see why more info would be helpful.

I agree that there is too little information, but the suggestions above are all good. My experience with, memory loss and other issues of aging is that it's not "theft" in the way the word is used normally. Sometimes the believe it is theirs; they have something similar and believe it is theirs, they think it will be "needed" on their trip or especially at Assisted Living . They don't remember taking or hiding something and are usually horrified when it is revealed that they took something. My friend will take the dog leash, my iphone, a fork, a loaf of bread or a whole shelf of books and stash them somewhere in her room. This is fairly challenging, but it is not theft - rather a fairly common action typical of Dementia.