To be honest... I don't even know if the doctors ever told us what kind of dementia my dad has... but he's 92 and got diagnosed a year ago. He failed the test they give. He's probably started about 10 years ago with symptoms, but didn't really start getting out of control until the past year (and that's when we had to get him to the geriatric testing center) He is now in a nursing home.
Anyway... back in March 2018 he was able to walk with a cane. Now he is in a wheelchair and cannot walk at all. He keeps pointing to his throat and says that his throat is closing up and he can't swallow his food. He chokes a lot now when he is eating and his food is mostly mashed up. And he is having a hard time feeding himself so now we usually feed him.
Is this the disease progressing? In just 4 months?
Each individual case is different.
Your dad's ability to walk has probably been declining for some time. How long has be been using a cane, for example? It isn't a case of being able to walk with no problems at all on Monday, and needing a wheelchair on Tuesday. It may seem shocking when it finally reaches the wheelchair point, but it didn't happen overnight.
The swallowing difficulty has probably also been more gradual than you noticed.
The symptoms that are very noticable depend on what region of the brain is under attack. In some forms of dementia, the progression from one area to another in the brain follows a predictable pattern. In others it seems somewhat more "random," In some cases the progression seems extremely rapid and in others the decline is seems much more gradual.
Here is a short video showing how ALZ progresses. https://www.youtube.com/watch?v=Eq_Er-tqPsA
Other forms of dementia progress in different patterns, but they all progress (get worse). For example, in LBD the defect in the brain is not plaques and tangles but instead "bodies" of a mutant protein. In ALZ the part of the brain where hallucinations occur is impaired fairly late in the disease. In LBD that region is impaired early, and hallucinations might be the first noticeable symptom.
I think the general answer to your question is "Yes, this is the disease progressing."
If your dad is having a hard time swallowing "thin" liquids (water, broth, anything that's easily pourable) and he's coughing afterwards, you may need a thickener.
There's a product called Thick-It that you can add to any liquid and it will thicken it to whatever consistency he'd need. It's available without a prescription. I got Mom's on Amazon. There is no flavor to the granules.
But, by all means, have him evaluated because aspiration pneumonia (a pneumonia caused by inhaling/choking on liquids or food and it gets into the lungs) is a further assault to an already weakened body.
Read up on the stages of Alzheimer's either here or Alz.org. His changes seem consistent for end stages of the disease. I'm sorry. My mom is there too. It's so hard to watch. ((hugs))
A dilation (widening) is usually performed with a tube down the throat to open it back up but has to be done under sedation.
I certainly am not insinuating that your father is/was a drinker but this condition is very common in alcoholics. My dad was an alcoholic and he had many dilations in his later years.
Has he had his evaluation yet?