My MIL has been living with us that last 2 years. For someone with dementia is it a common thing that they mess with just one persons' things? She will fill my shampoo/body wash with water, she does things to my tooth brush, she will take my laundry out of the washer and throw on the cement floor or take and hide just my stuff. She does not do this with my husbands or kids belongings. Is this part of the dementia?
We have never had a great relationship and I feel this is not her dementia, but she is using it as an excuse.
I'd be tempted to go in to her belongs and do the same! I wouldn't wash her clothes anymore, and definitely put a keyed lock on your bathroom door. That would stop the tampering, watering down your soap and playing with your toothbrush.
2 years is long enough! Your husband needs to get a spine and have her placed. This is very unfair to you to have to deal with MIL's spiteful manipulation! She could poison your toothbrush and possibly get you very sick. Meanwhile, I would get a new bathroom lockset (requiring a KEY) and get hubby to install it.
That will prevent most of her behaviors. MIL will be temporarily conquered, but will find another way to tamper with your things until she is out of your home.
I would definitely keep her from accessing any of your things. Find a way to secure your personal items, like the toothbrush - who knows what she's doing with that?!
Yes, dementia makes people do crazy things. Everyone is different and the behaviors they take on are always so unexpected. But, I don't think it's typical for a dementia patient to pick on just one person and do horrible things with just your stuff. I truly think she is just confused about her relationship with her son and sees you as a threat to that, and the dementia is causing her to act out badly with no impulse control.
Keep your things out of her reach, just as you would a curious, mischievous toddler. You will have to watch her as you would watch a toddler. She could do something even more harmful to you or herself.
Good luck with that.
You are going to need to keep your eyes on her. Its like having a toddler. I have a split level so my Mom was in the bottom level where she had her own bath. I put a baby gate across the door so she would not wander. There was a back door to get her easily out of the house and a little patio where she could sit.
You may want to consider placing her if she has the money. Don't know how you can raise kids and keep an eye on her 24/7. I was babysitting my 20 month old grandson when I had to take Mom in. My daughter had to put him in Daycare.
It's a function of her broken brain, paranoia, insecurity, memory impairment, etc. Avoid confronting her about it. With her broken brain now you are the only one who can change or adjust. Obviously stop leaving out anything she might have easy access to. Read some of the comments on this thread to know how common an issue it is:
https://www.agingcare.com/discussions/grossed-out-and-need-to-vent-just-caught-mom-using-my-toothbrush-to-comb-her-hair-138180.htm