Has anyone put a safety gate to prevent a dementia adult from going down stairs?

If you think this is going to be long term a door can be installed and removed later. The other suggestion would be to move the bed downstairs so that he does not have to do them at all. Much safer and he will be used to the bed in a new location when it becomes more and more difficult for him to go up stairs or when he is no longer able to do stairs at all. Sooner or later all care and transferring will have to be done, bed to chair and stairs will become impossible. Save the money on the door and get a downstairs bathroom more accessible if you don't have an accessible bathroom now.

We had a gate installed at the top of the stairs. It was anchored to the wall but was a difficult to open gate. It served its purpose and if had been for the long term would have had something sturdier installed. I was not confident that the gate would have held up to a fall for trying to force it open. Damage to the wall from mounting can be fixed and was the least of my concerns.

I wouldn't count on a gate to deter an adult. My late husband broke his fibia when he leapt over the guard rail of his hospital bed. He fractured his fibia, and Four months later he died of the fall that resulted from this incident. Try to find a sturdier solution,

A lady I cleaned for had a half door installed across the basement stairway, she said her husband would stand there shaking and pulling it to try and get downstairs, so I would be apprehensive putting up anything that isn't very sturdy. I have read that sometimes a black mat placed in front of a doorway will keep them from crossing it because they perceive it to be a hole in the ground, I don't know anyone who has tried it though. There are probably some good ideas using technology... perhaps some type of motion sensor alarm when he approaches off limit areas?

Look for a Gatekeepers dealer near you, they make matching wood/paint/stain heavy duty gates that are high enough and strong enough to withstand an adult's weight.

Grandma1954 -- You've offered a perfect and comprehensive solution with an eye to future adjustments that will be needed.

Just curious is 1954 the year you were born? My older son was born in 1955.

Depends on your mother's mental state. Would she try to climb over it? My mother did.
I considered putting up a gate at the head of the stairs so I could bring Mom for an overnight visit. Sis had a single story home with a dog gate with a door, to keep the dog out of the living room. Mom tried to climb over the gate, several times, she once even made it over, even though sis told her not to. She couldn't remember long enough to learn to open the gate first.
Knowing Mom could not follow instructions I never brought her home overnight the last few years. I knew she got up several times and I couldn't stay up all night to watch her. (Actually she didn't care at that point as for years before that she only paced when I brought her for a visit)

I want to caution anyone who may be putting a gate or installing a door at the top of a stairway. NEVER have the door swing into the stairway, I've heard of too many instances where an improperly latched door has lead to tragic falls. The same goes for gates, if there is even the remotest possibility they will climb over or push it off the supports (and anything not screwed into studs can probably be rattled loose) then it is better to do without.

debdaughter -- No the nursing home didn't blame me for my husband's fall, and I told the medical examiner that I didn't blame the nursing home staff. The medical examiner didn't ask if thought anyone was at fault, but I just wanted him to know my opinion.

Llamalover47..I got one of the "Command hooks" and hung a $1.00 mirror from Dollar Tree on the wall in the shower. The problem with the bench seats in a typical shower is once the person looses upper body strength the start to slump forward or to one side. This can cause the "patient" to slip forward and fall off the bench. Some shower chairs can be tilted back a bit like a wheel chair back or a gait belt can be used to hold a person upright so they do not slump forward.
I am lucky I do have a roll in shower with no lip or edge so it makes it very easy.
And by "wet room" I just mean that there is nothing that will be damaged by water should it get wet. The vanity is up a bit off the floor so I don't have to worry if the floor gets very wet, the tiles are all non slip. This way the water dripping off the wheelchair does not present a problem for me or the CNA that help a few times a week.