My Mom’s Alzheimer’s is getting worse, and I wonder if planning nice days and outings is worth it anymore?

My Husband LOVED going for a ride. He loved going to Sam's Club or Costco (free samples ya know)
I liked taking him because I would use the store as his walking for the day. They had large carts that he would use for stability prior to his use with a walker. And after he started using a walker the carts are tall enough that they were actually more comfortable at times than a regular walker (Until I found a larger tall one)
BUT I stopped when it was no longer SAFE for him or me to get him into the car.
I would base the outings on safety.
If it is not safe to get her into the car or out of the car then stop.
Don't worry about a destination and "going" to a place. Make the outing a ride through a park, or a county road.
One thing I learned from my Husband is .... Live in the moment....
don't think about if she remembers the ride, the park, the dinner or who was there or what was served. Does that really matter? What matters is...Did she enjoy herself during that moment?

Your mom lives only in the moment. Yesterdays never were and tomorrows don't exist. Taking walks, going to the dog park or eating out somewhere have no lasting effect on her. Continue to do what you're doing especially if it makes YOU feel better. Don't worry about if the experience went good or bad, enjoy the moment with her.

Just keep it simple. Don't go overboard trying to plan something great that she will forget soon after. My mom forgets the same day and then will have that "bored to tears" look as soon as we get back. Keep it easy....a trip to a park, dollar store, a restaurant like panera, etc. After seeing my mom for several years forget about everything nice done for her and focusing on what she doesn't have, I don't think the "adventures" had a lasting impact at all. That being said....don't choose to stay at home, try to live your life as much as you can and go to the places you like for you...taking your mother to join in, but not because you are trying to please her. I love driving around and looking at crystal stores....she just comes along and it gets her out of the house and helps us both.

I'm guessing that the "nice events" you're planning are more for your sake than they are for your moms. and that's ok, I certainly get that you want to have theses special memories with your mom, even though chances are great that she doesn't remember them all at this point. But the fact that your profile says that mom is living in assisted living and not memory care, leaves me to believe that she may be remembering more than you realize.
As long as you both are having a good time on these outings, I see no need to stop them. There will come a day soon enough when you will have no choice but to stop them, so enjoy them while you can. Wishing you many more fun outings with your mom.

I cared for my mom until her death. We did outings until she could no longer sit up. The options changed over time. Movie and lunch, pedicures, a walk at the zoo or botanical gardens (pre and post wheelchair. Later on we still did walks at the park, or we would go to the river, set up her nice lounge chair and just enjoy fresh air and sunshine. We did this even when she could no longer talk. I do think it was good for her. It was also very good for us. It helped lift our spirits which in turn made us better caregivers. Just consider your mom's needs and choose accordingly.

Squid62, as other have said, these "fun" outings will have no long-term impact for your Mom, but they're worth doing as long as you can both enjoy them in the moment. However, at some point they'll likely start to have a long-term impact on your own well-being and your patience with your Mom, i.e. when they become more torture than fun. If they're at that point, then I suggest either modifying the outings or your expectations of them, or just quit doing them.

My and my wife's experience with my Dad was that for several years, outings and even long-distance overnight trips required careful "what-if" planning and preparations, reduced expectations, lots of on-the-road flexibility, and a sense of humor. In spite of all the predictable mishaps, my Dad seemed to enjoy these frequent outings and road trips, although he didn't remember any parts of them, neither good nor bad, for more than an hour or two, certainly not for a full day. Then, at some point they became too hard on him, me and my wife, so we stopped doing them.

Kudos to you for taking your Mom on outings and best wishes for both of you as your routines have to change along with progression of the disease..

I'm pretty sure making someone happy for a short time will add to them enjoying their lives, whether or not they remember it later.

There are some good answers here. I'd add that if the person with dementia or memory loss appears to enjoy the outing and behaves well, then it's a win, unless or until taking them becomes too difficult for you to manage. (Difficulties that arise might include risk of your loved one wandering off and getting lost, or physical issues of trying to get them in and out of the car, or bathroom issues due to incontinence, which is never fun to deal with away from home.) If the person more often becomes anxious or agitated during outings, or seems more difficult to calm down or get to sleep after outings, then that's a sign they've been too stimulated and the outings aren't positive for their wellbeing anymore. Another hint is to space out outings/events, don't overdo with several days in a row, as the person (and you) will overtire. And as others have said, keep things simple!

I believe if they seem to be enjoying it even for a few minutes, it's worth it for all concerned. It's making good memories for you with your loved one, even if they may forget, they enjoyed it at the moment and you'll have the memories once they are gone.

You are living in the moment so yes, for that moment it is worth it. Wheather she remembers in 5 min. is not important. They are still happy in the moment.