Any suggestions for dealing with someone with Alzheimer’s who has begun acting like a child?

Dementia and/or dementia-like behavior can be extremely difficult & frustrating to deal with, that's for CERTAIN! It's important for you to realize that DH is now limited in what he's capable of doing & is not intentionally trying to act like a child. He may not get much worse than this, nobody can say.

I suggest you read this 33 page booklet (which is a free download) which has THE best information ever about managing dementia and what to expect with an elder who's been diagnosed with it.

Understanding the Dementia Experience, by Jennifer Ghent-Fuller 
https://www.smashwords.com/books/view/210580

Jennifer is a nurse who worked for many years as an educator and counsellor for people with dementia and their families, as well as others in caring roles. She addresses the emotional and grief issues in the contexts in which they arise for families living with dementia.

The full copy of her book is available here:
https://www.amazon.com/Thoughtful-Dementia-Care-Understanding-Experience/dp/B09WN439CC/ref=sr_1_2?crid=2E7WWE9X5UFXR&keywords=jennifer+ghent+fuller+books&qid=1657468364&sprefix=jennifer+ghent%2Caps%2C631&sr=8-2

She also has published a workbook entitled, “It Isn’t Common Sense: Interacting with People Who Have Memory Loss Due to Dementia.”

https://www.amazon.com/Isnt-Common-Sense-Interacting-Dementia/dp/1481995995/ref=sr_1_4?crid=2E7WWE9X5UFXR&keywords=jennifer+ghent+fuller+books&qid=1657468655&sprefix=jennifer+ghent%2Caps%2C631&sr=8-4

Here is a list of useful tips from her e-book I found to be excellent:

The “Dont's”
· Do not reason and argue
· Do not demand that they reason or problem-solve
· Do not demand that they remember
· Do not demand that they get their facts straight
· Do not correct their ideas or scold them
· Do not reorient them
· Do not think that they are being uncooperative on purpose
· Do not think that they really do remember, but are pretending not to
· Do not use a “bossy” dictatorial attitude in care
· Do not act with impatience

The Do's
· Enter into their frame of reality, or their 'world'
· Be aware of their mood or state of mind
· Use few words and simple phrases
· OR use no words, just friendly gestures and simple motions
· Do everything slowly
· Approach from the front
· Wait for a slow response
· Constantly reassure them that everything is 'OK'
· Keep people with dementia comfortable 'in the moment' - every moment
· Maximize use of remaining abilities
· Limit TV or radio programs which they may feel are frighteningly real
· Maintain privacy
· Provide a safe physical environment

Language Needs
· Use short words
· Use clear and simple sentences
· Speak slowly and calmly
· Questions should ask for a “yes” or “no” answer
· Talk about one thing at a time
· Talk about concrete things; not abstract ideas
· Use common phrases
· Always say what you are doing
· If they repeat their question, repeat your answer as you did the first time · Give them a longer time to process information
· Wait patiently for a response
· Be accepting of inappropriate answers and nonsense words
· Speak softly, soothingly and gently

Care Needs
· Recognize that receiving personal care feels intrusive
· Reassure with your tone and manner
· Do one thing at a time
· Talk through the care “play-by- play”
· Be aware of your body language and use it to communicate relaxation and reassurance
· Be sincere
· Use a soft, soothing touch
· Be aware of the individual’s unique triggers
· Be aware that a person with dementia may not accurately judge whether a situation is threatening to them
· They may respond to fear, pain or anxiety by defending themselves with what we call “aggression”
· If they become distressed, stop immediately and allow them time to calm down – don’t try to restart the activity right away
You need to change your behaviour to adapt to the dementia because the person with the disease cannot.

Wishing you the best of luck with a difficult situation.

You deal with it just like you do with any of the other symptoms of dementia, and that is one day at a time and often one minute at a time.
As with all the stages, they typically don't last long before another step down is taken, so I would say to try and be grateful that he's at least not violent, angry, aggressive or wandering(yet.)
And make sure that you're taking good care of yourself and getting out and about doing fun things that you enjoy without your husband. And if possible, find a local caregivers support group that you can unload with and find people that understand exactly what you're going through, and will be there to support you on this journey that will only continue to get worse.
Best wishes.

Play with him. Interact with him in his reality. Keep him safe and healthy and love him.

Nothing you can do to stop it. Unfortunately, it is part of his disease. If you cannot tolerate and ignore it, you should start facility shopping. It will get worse, much worse.

Get him some really great toys for Christmas.

Embrace that child, play with them, give them love and joy. Focus on his needs. You will frustrate yourself trying to change it or letting it get to you. From their perspective, you are different as well. It amazes me my Mom's resilience to have dealt with so many new faces, as I was often "a good friend".

You will need support in this. It is hard to see a loved one, much less your spouse, go through this. Sounds like you will soon need physical caregiving help as well. God bless you!

Its part of the Dementia. I believe as the brain dies they revert back to childhood. Long term memory goes too.

Coloring and arts and crafts were very popular in my mom's MC.

What popped into my mind was to get him some legos and let him build something. Maybe a puzzle that you could work with him.

Go to TEEPA SNOW's website. She is one of the country's leading experts on dementia and has many on-line webinars, free YouTubes, etc. It is a wealth of information on how another / a loved one / can communicate with a person inflicted with dementia. I feel the short answer is: you observe and be with the person where they are. It isn't a matter of changing a person as their brain has / is changing. All you can do is 'hold their hand' and / or somehow let them know they are loved. Voice / tone / touch all matter. And, it is now often the only way to 'get in there' - to connect. Gena / Touch Matters