Involving a medical practioner is not necessarily a good idea. I write from experience of the last few years and currently.
My Dad has the beginnings of dementia and floats in and out at random times and also has paranoia. We noticed this two (2) years ago and discussed it with the local doctor and got a geriatrician involved. Both could not see that his problem(s) were in fact a 'problem'. My Dad is a very good cameleon when it suits him.
In that period, due to his paranoia, he changed his power of attorney giving all the power to the medical profession. These are the same people who are hamstrung by legal requirements that in many regards failed my Dad. We and others, saw person after person abuse him financially, yet could not legally help him. $1,000's have been lost.
He has given away some very valuable items and tools, and it is heartbreaking especially the personal items.