What tests determine dementia or Alzheimer’s?

Start your education process!! You have much to learn and it is all out there for you. Most states have a Council on Aging program. Call them, they have everything you need to know, assistance to offer, (in-home safety is essential!) You're at the point of needing facts, so stop relying on impressions that possibly are wrong. Testing is generally (or was, for us) by a neuropsychologist who did a comprehensive evaluation. It is not invasive and took about four hours. An MRI may also be done to actually see (the best way we have) any present deterioration of the brain. A diagnosis is made with these results. Each case is unique; what is true for my partner may well not be true for your loved one. One size does not fit all when it comes to dementia! I know you will find reliable answers suiting the needs of your family. Set up a Primary Care appointment, get Elder Care involved for local information and assistance, and it was a good idea to come here and ask. We are on this road and have experiences to share. The best of everything to you and your family!

Medicare covered a comprehensive neurological exam, mri, neuropsy testing and consultation with a psychiatric nurse practioner to assess mental health. That's how we got my mom's diagnosis.

I'm curious, if he has medicare, why do you say he has no insurance? Medicare IS insurance.

primary will start the process, call ahead of time to explain your concerns so the dr. can start the referral process to neurologists, etc.

My 85 year old mother never used her Medicare. We finally used it when she had to be diagnosed for dementia. Unless your father has never enrolled in Medicare, which doesn't seem likely since you are required to do so at age 65, he has it, although he may not have ever used it.

Medicare A is required at 65 and covers hospitals, etc. Medicare B is available at 65 but must be enrolled in and a monthly coverage fee is deducted from your Social Security check. It covers doctor's visit (not prescriptions - that is Medicare D or get a supplement elsewhere). Call local Social Security office and see what they have on file for him. Do read all the many Medicare informational booklets that they send you.

We found with my mother that it didn't make a difference whether she got an official "Alzheimer's" diagnosis. Her doctor evaluated her without any expensive tests and said she had severe dementia. We proceeded from there.
I agree with GenKazdin to start the education process. My mother has died, but my father now also has dementia. This website has been extremely valuable, not only for legal suggestions, but also helpful hints on know how to understand and survive dealing with our confused loved ones. : )
My sister and I were able to get a Personal Services Contract that protected some of my dad's assets. Medicaid Done Right was extremely helpful in getting him on Medicaid. We found a wonderful assisted living facility. My dad is very happy and my sister and I have gone from being nursemaids and house cleaners back to being his daughters. Our time together now is precious.
Hang in there.

Thank you for sharing your experience with me, that is reassuring. I was referring to lack of private insurance. I did not know Medicare covered all the testing. I’ve been under the impression Medicare doesn’t cover much, so I’m grateful for that info. Is a primary doc sufficient to start the process or is a specialist necessary?

CaringForDoc, five years ago my now 96-year-old dad was diagnosed as having mid-stage dementia "consistent with Alzheimer's" by a geriatric specialist MD using the Montreal Cognitive Assessment (MOCA) test. He was reevaluated three years later, again using the MOCA test, by another MD and was found to be in late-stage dementia. His MOCA tests took about an hour each, as I recall. My understanding is that the MOCA test is similar to, but more comprehensive than, the Mini-Mental State Examination (MMSE), which I believe is more commonly used. Your dad's Medicare insurance will pay either 80% of the cost, or perhaps 100% if it's part of an annual wellness exam.

There are various causes of dementia, with Alzheimer's being the far most prevalent. The MOCA and MMSE are good, quick, non-invasive tests for diagnosing dementia and, as I understand it, help doctors who specialize in dementia determine the root cause, but are not precise in that regard. I think either of those tests is a good place to start and if dementia is indicated, then there should be a discussion about whether more invasive testing is warranted.

Just to say, the name tests are often not sensitive to certain dementias.

My mom, with vascular dementia 
was still scoring 15/15 on minimentals until way late in her progression. But she couldn't REASON! 
There were adequate memory skills but no executive functioning, sequencing or reasoning skills. This is a reason to get a full neuropsych workup. It tells the whole story.

Why doesn't he have Medicare?