My dad is planning to run away from home. What can I do to stop him?

This is why I educate caregivers or anyone with the potential to be caring for or who may be concerned for persons with cognitive impairment on the importance of creating a "care team!" Of course, a geriatric care manager like myself is helpful for families and caregivers who prefer eldercare expertise in creating such a team. The care team consists of a wide variety of professional healthcare individuals who will develop a care plan based on needs or concerns presented initially. The care plan will follow the care journey as the care team continues a cyclical assessment, plan, and evaluation on a regular basis for the life of the case.
At the onset, as a care manager, the very first medical professional would be either the aging loved one's own PCP or preferably a board-certified geriatric-psychiatrist who can assist me with helping the caregiver get conservatorship if they do not already have POA.
If the caregiver already has a healthcare proxy or POA, then it is a matter of having the physician deem the loved one to be decisional or not; in other words, is the aging loved one with known memory impairment or cognitive decline able to make appropriate or good health care decisions.
It is best for a caregiver to first have written evidence of an aging loved one's mental capacity before making any decision.
And it is a good idea to share the accountability of making tough elder care decisions with the eldercare professionals who do so on a daily basis and are knowledgeable and wil help on a continuum.
I also lead a caregiver support group where I coach caregivers on these very issues and STRONGLY would recommend that caregivers caring for those with dementia of any kind or at any stage be involved in a local caregivers support group. Go to https://alz.org and find a local caregiver support nearby. During the pandemic, our groups are meeting by Zoom, or most are!

Place a tracker on his shoes. They make some that go on the shoelaces. My mother never noticed them. Twice,I got a call from someone who found her lost across the street from her assisted living.

Imho, eliminate all methods he would use to run away from home, e.g. no auto, no credit cards, no debit card, no cash, etc.

People are saying just put him in Memory care. The Memory care facility here is $5,000/$8,000 a month. We don't all have that and make too much for any help.

We can only control so much. My sister, a nurse who works w/ the elderly, tells me all the time “Sometimes something worse has to happen in order for change to take place.

This is an answer from way out in left field. “Wandering” used to be a substantial reason for death, and might still be – it is not likely to figure as ‘cause’ on a death certificate. An older person would wander off, but die of exposure or from an accident (or exposure following an accident).

This site has regular discussions about the ethics of keeping people alive when their quality of life has gone. The supervision, the medical treatments etc keep them alive when they are ready for the end. If your father really wants to do something dangerous, and risk the consequences, is it your responsibility to stop him? Is it in the best interests of both of you? Is an alternative to notify the proper authorities and then just wait to see what happens? Just a thought….

Does he still drive? Maybe hide the keys. Put alarms on doors so you know if he goes outside. Dementia patients often can’t be reasoned with. However, changing subjects is very helpful because it puts the previous thoughts out of their minds. Redirection works well if he’s in the act of leaving. Direct him to a dessert or tv show. Camaras are helpful too, especially the ones that can be viewed from a phone. This way other family members can keep an eye on him too. It’s a challenge taking care of people with dementia but by giving them reasonable simple choices, it deverts the anger often associated with it. You must remember that your dad isn’t the same as he once was, some times it’s the illness talking. Don’t take it to heart. By giving choices he will feel like he’s still in control. Hope this helps you

More info is needed. What do you call "mild" dementia. You don't say whether he lives with you or not but wifi cameras are a huge help. You can program them to alert you when there is motion at the entrance door or garage. There are inexpensive, easy to set up & very good cameras on Amazon. You can put a tracker on his car, which would really be key in locating him. If he uses a cell, you can set it to find his location.
Lastly, have a heart to heart with him and tell him how much he means to you and how worried you would be if he left. Is there anyone in your family that would be willing to make this journey with him? It may be invaluable time spent together that you won't regret.
Best of luck to you.

I have been told over and over to sabotage their transportation. Hide keys, pull a spark plug wire, etc. Take the Uber app off his phone, accidentally cancelling phone service, etc. Good luvk