Her doctor may have an opinion about the state of her health and cognitive condition, however, I would consult with an attorney who regularly handles Competency matters in court. They will know what the court requires in order to find that someone is not competent and needs a Guardian to handle the finances, health matters or both.
I'd make notes about all the things that you have observed to discuss with the attorney. They know what evidence you will need. Some jurisdictions look at the person's ability to manage their household, handle their finances, use proper judgment in business affairs, resist exploitation, make proper healthcare decisions, handle their hygiene, etc. It's not always about memory. Judgment may also be a big factor.
Your question is about the difference in Alzheimers and dementia. People who have the disease of Alzheimers, eventually, will progress to the point of having dementia. As do those with other diseases that effect the brain. Here's a link about it from this site.
I'd make notes about all the things that you have observed to discuss with the attorney. They know what evidence you will need. Some jurisdictions look at the person's ability to manage their household, handle their finances, use proper judgment in business affairs, resist exploitation, make proper healthcare decisions, handle their hygiene, etc. It's not always about memory. Judgment may also be a big factor.
Your question is about the difference in Alzheimers and dementia. People who have the disease of Alzheimers, eventually, will progress to the point of having dementia. As do those with other diseases that effect the brain. Here's a link about it from this site.
https://www.agingcare.com/alzheimers-dementia
I'll also PM you a link about it on the Alzheimers website.