My first reaction is “how odd!” Why would anyone want more junk mail?  Do you think your mother knows that stealing mail is a federal crime? Although this topic is a bit out of the ordinary, it happens more than you think.

The answer to my questions is, of course not.  Your mother is either quite nosy or is a bit confused.

Let’s start with the nosy mom. If your mother just takes mail for the thrill of it, she probably shoplifts too, and it is not a new problem.  If you are certain that she is of sound mind; it is time to have a talk with her about the risks of what she is doing.  She is not going to like you very much for pointing it out to her. She may feel that her age protects her to a certain extent, but all she needs is one very angry person to press charges for her life to become very unpleasant.  It is important that someone lets her know that she is committing a crime and needs to stop. 

If the mail theft is a new problem, your mother is likely a bit confused.  A bit of altered reality is not uncommon in the early stages of dementia.  Reasoning with an individual who cannot respond to reason is an exercise in futility.  This individual needs supervision to live safely, and whether that is in the future or at present depends on the severity of the situation.

The first thing to do is give the mail back to the people she stole it from, and second is to schedule an appointment with her doctor for an evaluation.  Be honest with the physician as to why you are coming in.  Hoping that the doctor will just know is preposterous.  You will need to disclose your concerns openly and honestly, and hopefully your mother will let you come along and participate. 

It is not going to be easy to confront this situation.  Be it a lifelong bad habit or a new phenomenon of an altered mind it is going to be challenging to correct.  It is important to protect your mother and keep her safe. 

I wish you the best.